Please explain this presentation in detail and deapth Prepare me for usmle questions Don't skip any topic I have test tmr Please explain everything in detail Add extra informatin that you fell like i should know as a medical student studying for usmle

Reading File

Running Command

cd /tmp/workspace/attachments/1a25d595-225c-4252-88ad-350928c21e31/ && python3 -c " import pdfplumber with pdfplumber.open('7 - Midbrain, Cerebellum, Dural Sinuses.pdf') as pdf: print(f'Total pages: {len(pdf.pages)}') for i, page in enumerate(pdf.pages): text = page.extract_text() print(f'--- PAGE {i+1} ---') print(text) print() " 2>&1 | head -500

Reading File

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Finding Sources

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I now have comprehensive content from the PDF and textbooks. Let me compile a detailed, USMLE-focused study guide:

🧠 Midbrain, Cerebellum & Dural Sinuses - Complete USMLE Study Guide

PART 1: THE MIDBRAIN (MESENCEPHALON)

Overview

The midbrain is the most rostral part of the brainstem, approximately 2 cm in length. It connects the forebrain (diencephalon) superiorly to the pons inferiorly. It is divided into three regions: tectum (posterior), tegmentum (middle), and crus cerebri/basis pedunculi (anterior), separated by the substantia nigra.

Anterior Surface - Key Structures

Structure	Details
Interpeduncular fossa	Deep midline depression on anterior surface
Posterior perforated substance	Floor of interpeduncular fossa; triangular grey matter; perforated by branches of the posterior cerebral artery
Crus cerebri (cerebral peduncles)	Paired columns flanking the interpeduncular fossa; contain corticospinal, corticobulbar, and corticopontine motor tracts
CN III (Oculomotor)	Emerges medially from the crus cerebri, exits through the interpeduncular fossa

Above the interpeduncular fossa (not midbrain itself but adjacent):

Mammillary bodies
Tuber cinereum
Optic chiasm

USMLE pearl: CN III is the nerve most vulnerable in uncal herniation. The uncus (medial temporal lobe) herniates over the tentorial notch, compressing CN III. The first sign is an ipsilateral blown (dilated, unreactive) pupil because the parasympathetic fibers of CN III travel on the outside of the nerve and are compressed first.

Posterior Surface (Tectum / Corpora Quadrigemina)

The tectum (Latin: "roof") = tectal plate = corpora quadrigemina = four bumps on the dorsal midbrain.

Colliculus	Modality	Associated Cranial Nerve	Function
Superior colliculi (2)	VISUAL	CN II (optic)	Reflex eye movements, tracking, pupillary light reflex coordination
Inferior colliculi (2)	AUDITORY	CN VIII (vestibulocochlear)	Auditory relay, sound localization

CN IV (Trochlear) - the only cranial nerve to exit from the posterior surface of the brainstem. It emerges inferior to the inferior colliculi, crosses the midline, and wraps around the lateral aspect of the midbrain.

USMLE pearl: CN IV is the only CN that:

Exits from the dorsal (posterior) surface

Has a complete decussation (crosses to the opposite side)

Is the longest intracranial CN

Innervates the superior oblique (SO4 - "SO Trochlear" or the "LR6SO4" mnemonic) Trochlear nerve palsy = head tilts AWAY from the affected side (contralateral head tilt compensates)

Cross-Section of the Midbrain

The midbrain is divided by the substantia nigra into:

Crus cerebri (anterior/basis) - descending motor tracts (corticospinal, corticopontine, corticobulbar)
Tegmentum (posterior to substantia nigra) - contains nuclei and ascending tracts

Important: Lateral Mesencephalic Sulcus separates the cerebral peduncle from the tegmental surface, extending from the medial geniculate body of the thalamus to the pontomesencephalic sulcus.

Rostral Midbrain (Level of Superior Colliculus)

CN III nucleus (oculomotor)
Edinger-Westphal nucleus
Red nucleus
Substantia nigra
Mesencephalic nucleus of CN V

Caudal Midbrain (Level of Inferior Colliculus)

CN IV nucleus (trochlear)
Substantia nigra
Mesencephalic nucleus of CN V

Nuclei of the Midbrain - Must Know!

Nucleus	Location	Function
Oculomotor nucleus (CN III)	Rostral midbrain tegmentum	Somatic motor: superior rectus, inferior rectus, medial rectus, inferior oblique, levator palpebrae superioris
Edinger-Westphal nucleus	Rostral midbrain, dorsal to CN III nucleus	Parasympathetic - ciliary muscle (accommodation), sphincter pupillae (pupil constriction)
Trochlear nucleus (CN IV)	Caudal midbrain tegmentum	Somatic motor: superior oblique muscle
Red nucleus	Midbrain tegmentum	Center for involuntary movements; origin of rubrospinal tract (facilitates flexor muscle tone)
Substantia nigra	Between crus and tegmentum	Dopamine production; involved in basal ganglia circuitry
Mesencephalic nucleus of CN V	Lateral midbrain	Proprioception from jaw muscles (masseter); unique - primary sensory neurons residing in the CNS

USMLE pearl - Sylvian (Cerebral) Aqueduct landmarks:

Projection from superior colliculi to aqueduct = points to CN IV nucleus (trochlear)

Projection from inferior colliculi to aqueduct = points to CN VI nucleus (abducens - in pons) The floor of the Sylvian aqueduct is the dorsal surface of the cerebral crus.

Substantia Nigra - Extra USMLE Info

The substantia nigra (Latin: "black substance") gets its color from neuromelanin (a byproduct of dopamine synthesis). It is divided into:

Pars compacta - dopaminergic neurons projecting to striatum (nigrostriatal pathway)
Pars reticulata - GABAergic output neurons

Parkinson disease = loss of dopaminergic neurons in pars compacta → depigmentation of substantia nigra. Classic triad: resting tremor, rigidity (cogwheel), bradykinesia.

Red Nucleus and Rubrospinal Tract

The red nucleus (nucleus ruber) in the tegmentum:

Receives input from: dentate nucleus of cerebellum (via dentatorubral fibers) and cerebral cortex
Gives rise to the rubrospinal tract which decussates in the midbrain (ventral tegmental decussation) and descends to spinal cord
Function: facilitates flexor muscle tone in upper limbs; inhibits extensor tone

PART 2: THE CEREBELLUM

Overview

"Little brain" - 10% of brain volume but ~50% of all brain neurons
Located in the posterior cranial fossa
Contains more neurons than any other brain region
Connected to brainstem by three cerebellar peduncles

Relations:

Superior: tentorium cerebelli, great cerebral vein (Vein of Galen), lingual gyrus
Anterior: brainstem, cerebral aqueduct, corpora quadrigemina, 4th ventricle
Posterior-lateral: occipital bone, sigmoid sinus, occipital sinus, confluence of sinuses

Gross Anatomy

Structure	Details
Hemispheres	Left and right lateral lobes
Vermis	Midline worm-like structure; 9 lobules (lingula, central lobule, culmen, declive, folium, tuber, pyramid, uvula, nodule)
Flocculonodular lobe	Flocculus + nodule; vestibulocerebellum
Arbor vitae	Tree-like appearance of white matter tracts when cut in sagittal section

Fissures

Fissure	Separates
Primary fissure	Anterior lobe from posterior lobe
Posterolateral fissure	Flocculonodular lobe from posterior lobe
Horizontal fissure	Superior surface from inferior surface

Functional Subdivisions - CRITICAL for USMLE

Division	Anatomic Location	Input	Function	Lesion =
Vestibulocerebellum	Flocculonodular lobe	Vestibular nuclei	Balance, equilibrium, eye movements, gaze stabilization (flocculus)	Truncal ataxia, nystagmus, inability to maintain balance
Spinocerebellum	Vermis + intermediate (paravermal) zone	Spinal cord (spinocerebellar tracts)	Ongoing motor execution; axial (vermis) and limb (intermediate) coordination	Vermis lesion = gait ataxia, truncal instability. Intermediate = ipsilateral limb ataxia
Pontocerebellum (Cerebrocerebellum)	Lateral hemispheres	Cerebral cortex via pontine nuclei	Motor planning and coordination of sequential movements; language	Intention tremor, dysmetria, dysdiadochokinesia

Memory trick: "VESTIBULOCEREBELLUM = BALANCE; SPINOCEREBELLUM = EXECUTION; PONTOCEREBELLUM = PLANNING"

Layers of the Cerebellar Cortex

From outside in (MOG = Molecular, Purkinje, Granular):

Layer	Cells	Neurotransmitter	Function
Molecular layer (outer)	Stellate cells, basket cells, parallel fibers (from granule cells), Purkinje dendrites	Both inhibitory	Stellate → Purkinje (GABA, inhibitory); Basket → Purkinje (GABA, inhibitory)
Purkinje cell layer (middle)	Purkinje cells	GABA (inhibitory)	SOLE OUTPUT of cerebellar cortex → deep cerebellar nuclei (inhibitory!)
Granular layer (inner)	Granule cells (excitatory), Golgi cells (inhibitory)	Glutamate (granule); GABA (Golgi)	Granule → Purkinje via parallel fibers (excitatory, Glutamate); Golgi → granule (GABA, inhibitory)

Summary of cortical circuits:

Excitatory inputs → Purkinje cells: Granule cells (via parallel fibers, glutamate) and Climbing fibers (from inferior olive, direct, powerful)
Inhibitory inputs → Purkinje cells: Stellate, basket cells (GABA)
Purkinje cells → Deep cerebellar nuclei: INHIBITORY (GABA)
Golgi cells → Granule cells: INHIBITORY (GABA - feedback inhibition)

High-yield USMLE: The output of Purkinje cells is ALWAYS inhibitory (GABA). All other cerebellar cortex cells except granule cells are also inhibitory. Granule cells are the ONLY excitatory cells in the cerebellar cortex.

Input Systems to Cerebellar Cortex

1. Mossy Fibers (majority of input)

Origin: spinocerebellar tracts, pontocerebellar, vestibulocerebellar
Synapse on granule cells
Granule cells → parallel fibers → Purkinje cell dendrites
Produce simple spikes in Purkinje cells

2. Climbing Fibers

Origin: inferior olivary nucleus (contralateral medulla)
Synapse DIRECTLY on Purkinje cell dendrites (very powerful)
Each climbing fiber contacts only ONE Purkinje cell, but wraps extensively around its dendrites
Each Purkinje cell receives input from ONE climbing fiber
Produce complex spikes (multiple excitatory bursts)
Role in cerebellar motor learning and error correction

Deep Cerebellar Nuclei - "Don't Eat Greasy Foods"

From lateral to medial: Dentate, Emboliform, Globose, Fastigial

Nucleus	Location	Connections	Function	Lesion
Dentate	Within lateral hemispheres	Efferents via superior cerebellar peduncle → thalamus (VL) → cortex; also → red nucleus	Fine dexterity, motor planning	Delays in initiating movements, impaired hand/finger coordination
Emboliform	Intermediate paravermal zone	Via superior cerebellar peduncle → red nucleus → rubrospinal tract (facilitates flexor tone)	Proprioception, limb control	Delayed check responses, action tremor
Globose	Between emboliform and fastigial	Together with emboliform = nucleus interpositus	Proprioception, stability; segmental reflexes	Truncal titubation, oscillation
Fastigial	Deep in vermis	Efferents via inferior cerebellar peduncle → vestibular nuclei, reticular formation	Stance, gait, extensor muscle tone	Abasia (inability to stand), gait ataxia

USMLE pearl: The fastigial nucleus is the only deep cerebellar nucleus whose efferents leave through the inferior cerebellar peduncle. All others (dentate, emboliform, globose) leave through the superior cerebellar peduncle.

Cerebellar Peduncles - The Most Tested Topic

Peduncle	Connects Cerebellum To	Primary Content	Direction
Superior cerebellar peduncle (brachium conjunctivum)	Midbrain	Mostly EFFERENT (output) from deep nuclei (dentate, emboliform, globose) to red nucleus and thalamus (VL nucleus) → cortex; also ventral spinocerebellar tract (afferent)	Output
Middle cerebellar peduncle (brachium pontis)	Pons	ONLY AFFERENT - from contralateral pontine nuclei (corticopontocerebellar fibers = mossy fibers)	Input only
Inferior cerebellar peduncle (restiform body)	Medulla	Mixed: afferent from spinal cord (dorsal spinocerebellar), inferior olive (olivocerebellar), vestibular nuclei; efferent to vestibular nuclei and reticular formation	Mostly input

USMLE mnemonic: "Superior = Send (output); Middle = Magnificent Mossy input only; Inferior = Into the medulla (mostly input)"

Superior cerebellar peduncle decussates in the MIDBRAIN - this is why ipsilateral cerebellar disease causes contralateral signs at thalamic/cortical levels, but clinical expression is ipsilateral (the limb ataxia is ipsilateral to the cerebellar lesion because the output ultimately crosses back).

Cerebellar Connections Summary

Afferents (input) to cerebellum:

From cerebral cortex: via corticopontine → pontine nuclei → middle cerebellar peduncle → mossy fibers (planning)
From spinal cord: spinocerebellar tracts → inferior/superior cerebellar peduncle → proprioception, touch
From inner ear/vestibular: via inferior cerebellar peduncle → flocculonodular lobe (equilibrium)
From inferior olivary nucleus: climbing fibers → inferior cerebellar peduncle → error correction/learning

Efferents (output) from cerebellum:

Purkinje cells → deep cerebellar nuclei (inhibitory, GABA)
Deep nuclei → red nucleus, thalamus (VL), vestibular complex, reticular formation
Main efferent pathway = superior cerebellar peduncle (dentate, emboliform, globose)
Fastigial efferents = inferior cerebellar peduncle

Vascular Supply of the Cerebellum

Artery	Origin	Supplies	Associated Syndrome
PICA (Posterior Inferior Cerebellar Artery)	Vertebral artery	Posterior-inferior cerebellum, lateral medulla, inferior cerebellar peduncle	Lateral medullary syndrome (Wallenberg syndrome)
AICA (Anterior Inferior Cerebellar Artery)	Basilar artery	Anterior-inferior cerebellum, middle cerebellar peduncle, lateral pons, inner ear	CN VII/VIII signs + cerebellar signs
SCA (Superior Cerebellar Artery)	Basilar artery	Superior cerebellum, superior cerebellar peduncle, pons	Superior cerebellar syndrome; may affect CN IV

USMLE high-yield - PICA stroke (Wallenberg syndrome): Ipsilateral facial sensory loss (CN V), ipsilateral Horner syndrome, ipsilateral palate/pharynx/vocal cord weakness (CN IX, X), contralateral body pain/temperature loss (spinothalamic tract), ataxia (cerebellar), nystagmus, dysphagia, dysarthria, hiccups.

Cerebellar Disorders - Signs and Symptoms

The classic mnemonic is DANISH (from some sources) - but for USMLE memorize:

Sign	Description	Notes
Dysdiadochokinesia	Inability to perform rapid alternating movements	Ask patient to rapidly pronate/supinate hands
Dysmetria	Inability to judge distance/aim accurately	Finger-nose test: overshooting (past-pointing)
Ataxia	Loss of coordination of movement; gait, balance, limb	Resembles intoxication
Nystagmus	Involuntary rhythmic eye oscillation	Often horizontal
Intention tremor	Tremor during voluntary movement, worsening near target	Differs from resting tremor of Parkinson disease
Scanning (staccato) speech	Slurred, irregular, explosive speech (dysarthria)
Hypotonia	Decreased muscle tone
Rebound phenomenon	Inability to stop movement when resistance is suddenly removed

Ipsilateral signs: Cerebellar lesions cause ipsilateral deficits (same side as the lesion).

Specific Cerebellar Syndromes for USMLE:

Joubert Syndrome:

Rare autosomal recessive genetic condition
Absence or underdevelopment of cerebellar vermis
Malformed brainstem
"Molar tooth sign" on MRI (hypoplastic vermis + elongated superior cerebellar peduncles)
Symptoms: hypotonia, ataxia, abnormal eye movements, breathing pattern abnormalities, intellectual disability

Dandy-Walker Syndrome:

Congenital malformation
Partial/complete absence of cerebellar vermis
Cystic dilation of 4th ventricle
Enlarged posterior fossa
Symptoms: slow motor development, convulsions, vomiting, raised intracranial pressure (hydrocephalus from enlarged 4th ventricle)
Associated with obstructive hydrocephalus

USMLE distinction: Joubert = vermis absent + brainstem malformed + molar tooth sign on MRI. Dandy-Walker = vermis absent + CYSTIC dilation of 4th ventricle + enlarged posterior fossa.

Friedreich Ataxia:

Autosomal recessive; GAA trinucleotide repeat expansion in frataxin gene (chromosome 9)
Degeneration of dorsal columns, spinocerebellar tracts, and corticospinal tracts
Symptoms: progressive ataxia, loss of proprioception, cardiomyopathy (most common cause of death), diabetes, kyphoscoliosis, pes cavus (high-arched feet), hammertoes
Onset: adolescence
Both cerebellar AND posterior column signs (absent DTRs but extensor plantar)

PART 3: DURAL SEPTA AND DURAL VENOUS SINUSES

Dural Septa (Reflections of Dura Mater)

These are folds of the dura mater that partition the cranial cavity:

Septum	Location / Function
Falx cerebri	Vertical midline fold; separates the left and right cerebral hemispheres; attaches to crista galli anteriorly, internal occipital protuberance posteriorly
Tentorium cerebelli	Horizontal shelf; separates cerebral hemispheres (supratentorial) from cerebellum (infratentorial); forms the "tent" over the posterior fossa; CN III/IV/VI and brainstem pass through the tentorial notch
Falx cerebelli	Vertical fold in posterior fossa; separates the two cerebellar hemispheres
Diaphragma sellae	Horizontal shelf over the sella turcica; forms the roof of the hypophyseal fossa; surrounds the pituitary stalk

USMLE clinical pearl - Tentorial herniation: The tentorium cerebelli is the most clinically important dural septum. In uncal herniation, the medial temporal lobe (uncus) herniates through the tentorial notch (incisura tentori), compressing CN III (ipsilateral blown pupil) and the contralateral cerebral peduncle (ipsilateral hemiplegia - Kernohan notch). Always check pupils in comatose patients!

Dural Venous Sinuses - Complete Guide

The dural venous sinuses are valveless venous channels formed between the periosteal and meningeal layers of the dura mater. They drain venous blood from the brain to the internal jugular vein.

Major Sinuses:

Sinus	Location	Drains Into	Notes
Superior sagittal sinus	Along the superior border of falx cerebri	Confluence of sinuses	Receives bridging veins from cerebral cortex; most common site of venous thrombosis
Inferior sagittal sinus	Along the inferior border of falx cerebri	Straight sinus
Straight sinus	Junction of falx cerebri and tentorium cerebelli	Confluence of sinuses	Receives: inferior sagittal sinus + great cerebral vein (Vein of Galen)
Confluence of sinuses (Torcular Herophili)	Internal occipital protuberance	Transverse sinuses bilaterally	Meeting point of superior sagittal, straight, and occipital sinuses
Transverse sinus	Along posterior edge of tentorium cerebelli	Sigmoid sinus	Bilateral
Sigmoid sinus	S-shaped; follows temporal bone	Internal jugular vein at jugular foramen	Bilateral; continuation of transverse sinus
Occipital sinus	Within root of falx cerebelli	Connects marginal sinus to confluence
Marginal sinus	Encircles foramen magnum	Vertebral venous plexus
Cavernous sinus	Either side of sella turcica/pituitary	Via inferior petrosal sinus → IJV; via superior petrosal sinus → sigmoid sinus	Most complex, most tested!
Superior petrosal sinus	Along superior border of petrous temporal bone	Cavernous sinus → sigmoid sinus
Inferior petrosal sinus	Along inferior border of petrous temporal bone	Cavernous sinus → IJV	Receives labyrinthine veins
Sphenoparietal sinus	Along lesser wing of sphenoid	Superior sagittal sinus → cavernous sinus
Basilar plexus	On clivus	Connects cavernous sinus to marginal sinus

The Cavernous Sinus - MOST TESTED USMLE TOPIC

The cavernous sinus is a paired venous sinus on either side of the sella turcica and pituitary gland.

Contents of the Cavernous Sinus (HIGH-YIELD):

Running THROUGH the sinus:

Internal carotid artery (with sympathetic plexus)
CN VI (Abducens) - runs freely through the sinus (most vulnerable to compression/thrombosis)

Running in the LATERAL WALL (from superior to inferior):

CN III (Oculomotor)
CN IV (Trochlear)
V1 (Ophthalmic branch of CN V)
V2 (Maxillary branch of CN V)

USMLE mnemonic for lateral wall contents: "O TOM CAT" - Oculomotor (III), Trochlear (IV), Ophthalmic V1, Maxillary V2, and free inside: Carotid Artery, Abducens (VI). Or just remember: 3, 4, V1, V2 in wall; 6 and ICA inside

Connections of the cavernous sinus:

Communicates with the angular vein (facial vein) via the superior ophthalmic vein - THIS IS WHY facial infections can spread intracranially!
Intercavernous sinuses connect left and right cavernous sinuses
Drains via inferior petrosal sinus → internal jugular vein
Drains via superior petrosal sinus → sigmoid sinus

Cavernous Sinus Thrombosis (CST):

Often from spread of facial/sinus infection (nose, paranasal sinuses, orbit)
Classic signs: proptosis, chemosis (conjunctival edema), periorbital edema, painful ophthalmoplegia
ALL eye movement cranial nerves are affected (III, IV, VI) → total ophthalmoplegia
CN V1/V2 involvement → facial pain
CN VI is often affected FIRST (it runs freely inside, not protected by the lateral wall)
Horner syndrome (sympathetic plexus around ICA is compressed)
Usually bilateral (infection crosses via intercavernous sinuses)

Vein of Galen

The great cerebral vein (Vein of Galen) is a large midline vein that:

Drains deep structures of the brain (internal cerebral veins, basal veins of Rosenthal)
Courses posteriorly beneath the splenium of the corpus callosum
Drains into the straight sinus (at the junction of falx cerebri and tentorium)
Located just superior to the cerebellum

Vein of Galen malformation is a congenital arteriovenous malformation important in pediatrics - presents in neonates with high-output heart failure, hydrocephalus, and a cranial bruit.

PART 4: EXTRA USMLE HIGH-YIELD TOPICS

Parinaud Syndrome (Dorsal Midbrain Syndrome)

Compression/lesion of the superior colliculi (e.g., pineal gland tumor, hydrocephalus):

Paralysis of upward gaze (most classic sign)
Convergence-retraction nystagmus on attempted upward gaze
Light-near dissociation (pupils react to accommodation but not light)
Eyelid retraction (Collier sign)
"Sunset sign" in neonates with hydrocephalus

Weber Syndrome (Midbrain - Ventral)

Lesion of the crus cerebri + CN III fascicles (commonly due to posterior cerebral artery or superior cerebellar artery territory stroke):

Ipsilateral CN III palsy (eye "down and out," ptosis, dilated pupil)
Contralateral hemiplegia (corticospinal tract involvement)

Benedikt Syndrome (Midbrain - Tegmentum)

Lesion of the tegmentum including red nucleus + CN III:

Ipsilateral CN III palsy
Contralateral involuntary movements (tremor, choreiform movements) due to red nucleus damage

Claude Syndrome

Combination of Weber + Benedikt features
CN III palsy + contralateral ataxia (red nucleus/superior cerebellar peduncle involvement)

CN III vs CN VI Palsy Comparison

Feature	CN III Palsy	CN VI Palsy
Eye position	Down and out	Medially deviated
Pupil	Dilated (if compressive) or normal (if ischemic - diabetic)	Normal
Ptosis	Present	Absent
Common cause	Posterior communicating artery aneurysm (compression), uncal herniation	Increased ICP (long intracranial course), cavernous sinus

Cerebellar Ataxia vs. Sensory Ataxia

Feature	Cerebellar Ataxia	Sensory (Posterior Column) Ataxia
Romberg test	Negative (falls with eyes OPEN too)	Positive (falls only with eyes CLOSED)
Gait	Wide-based, staggering	Stamping, high-stepping
Nystagmus	Often present	Absent
Cause	Cerebellar lesion	Dorsal column / peripheral nerve lesion (B12 deficiency, tabes dorsalis)

USMLE Quick Review Table - Cerebellar Nuclei

Nucleus	Peduncle	Input	Clinical Lesion
Dentate	Superior (out)	Lateral hemisphere Purkinje cells	Impaired fine dexterity, initiation delay
Emboliform + Globose (Interpositus)	Superior (out)	Intermediate zone Purkinje cells	Action tremor, heel-shin ataxia
Fastigial	Inferior (out)	Vermal Purkinje cells	Truncal ataxia, abasia

Summary: Key Relationships to Memorize

Inferior olive → climbing fibers → cerebellar cortex (Purkinje cells) - learning
Pontine nuclei ← cerebral cortex → middle cerebellar peduncle → mossy fibers
Superior cerebellar peduncle decussates in the midbrain (below inferior colliculus) - key in crossed syndromes
Purkinje cells ONLY output of cortex, always GABA/inhibitory
Facial vein → superior ophthalmic vein → cavernous sinus (infection spread route)
CN VI most vulnerable in cavernous sinus (runs freely inside)
Tentorium separates supra- from infratentorial compartments; tentorial notch = CN III vulnerable
Vein of Galen → straight sinus → confluence of sinuses

Good luck on your test tomorrow! The highest-yield topics are: cavernous sinus contents and thrombosis, cerebellar peduncle contents (especially that middle peduncle = afferent only), Purkinje cell = GABA/inhibitory, the deep cerebellar nuclei mnemonic, midbrain cross-section syndromes (Weber, Benedikt, Parinaud), and the tentorial herniation/CN III blown pupil scenario.

Create a printable USMLE study sheet with midbrain cross-section diagrams and clinical syndromes

Reading File

Running Command

mkdir -p /tmp/workspace/usmle-neuro && ls /tmp/workspace/usmle-neuro/

Writing File

~/usmle-neuro/build_sheet.py

#!/usr/bin/env python3
"""
USMLE Study Sheet: Midbrain, Cerebellum & Dural Sinuses
Printable A4 PDF with cross-section diagrams and clinical syndromes
"""
import math
from reportlab.lib.pagesizes import A4, letter
from reportlab.lib import colors
from reportlab.lib.units import cm, mm, inch
from reportlab.platypus import (
    SimpleDocTemplate, Paragraph, Spacer, Table, TableStyle,
    HRFlowable, PageBreak, KeepTogether
)
from reportlab.lib.styles import getSampleStyleSheet, ParagraphStyle
from reportlab.lib.enums import TA_CENTER, TA_LEFT, TA_RIGHT
from reportlab.platypus import Flowable
from reportlab.graphics.shapes import Drawing, Circle, Rect, Line, Polygon, String, Ellipse, Path
from reportlab.graphics import renderPDF
from reportlab.graphics.shapes import Group
import reportlab.graphics.shapes as shapes

# ── Colour palette ──────────────────────────────────────────────────────────
C_BG        = colors.HexColor('#F8F9FA')
C_DARK      = colors.HexColor('#1A1A2E')
C_ACCENT    = colors.HexColor('#16213E')
C_BLUE      = colors.HexColor('#0F3460')
C_RED       = colors.HexColor('#E94560')
C_GOLD      = colors.HexColor('#F5A623')
C_GREEN     = colors.HexColor('#27AE60')
C_PURPLE    = colors.HexColor('#8E44AD')
C_TEAL      = colors.HexColor('#1ABC9C')
C_ORANGE    = colors.HexColor('#E67E22')
C_LIGHTBLUE = colors.HexColor('#AED6F1')
C_LIGHTRED  = colors.HexColor('#FADBD8')
C_LIGHTYELLOW = colors.HexColor('#FEF9E7')
C_LIGHTGREEN  = colors.HexColor('#D5F5E3')
C_LIGHTPURPLE = colors.HexColor('#E8DAEF')
C_LIGHTGREY = colors.HexColor('#ECF0F1')
C_HEADER_BG = colors.HexColor('#1A1A2E')
C_SUBHEADER = colors.HexColor('#16213E')
C_WHITE     = colors.white
C_PINK      = colors.HexColor('#FDEDEC')

PAGE_W, PAGE_H = A4

# ── Styles ───────────────────────────────────────────────────────────────────
styles = getSampleStyleSheet()

def make_style(name, parent='Normal', **kw):
    s = ParagraphStyle(name, parent=styles[parent], **kw)
    return s

H1 = make_style('H1', fontSize=18, leading=22, textColor=C_WHITE,
                spaceAfter=4, fontName='Helvetica-Bold', alignment=TA_CENTER)
H2 = make_style('H2', fontSize=13, leading=16, textColor=C_WHITE,
                spaceAfter=3, fontName='Helvetica-Bold', alignment=TA_LEFT)
H3 = make_style('H3', fontSize=10, leading=13, textColor=C_BLUE,
                spaceAfter=2, fontName='Helvetica-Bold')
BODY = make_style('BODY', fontSize=8, leading=10.5, textColor=C_DARK,
                  spaceAfter=2, fontName='Helvetica')
BODY_SM = make_style('BODY_SM', fontSize=7.2, leading=9.5, textColor=C_DARK,
                     fontName='Helvetica')
BOLD_SM = make_style('BOLD_SM', fontSize=7.5, leading=9.5, textColor=C_DARK,
                     fontName='Helvetica-Bold')
PEARL = make_style('PEARL', fontSize=7.5, leading=10, textColor=C_DARK,
                   fontName='Helvetica', leftIndent=6,
                   borderPad=4, backColor=C_LIGHTYELLOW)
TABLE_HDR = make_style('TABLE_HDR', fontSize=7.5, leading=9.5,
                       textColor=C_WHITE, fontName='Helvetica-Bold',
                       alignment=TA_CENTER)
TABLE_CELL = make_style('TABLE_CELL', fontSize=7, leading=9,
                        textColor=C_DARK, fontName='Helvetica')
TABLE_CELL_C = make_style('TABLE_CELL_C', fontSize=7, leading=9,
                          textColor=C_DARK, fontName='Helvetica',
                          alignment=TA_CENTER)
MNEMONIC = make_style('MNEMONIC', fontSize=8, leading=10.5, textColor=C_PURPLE,
                      fontName='Helvetica-Bold', alignment=TA_CENTER)
CAPTION = make_style('CAPTION', fontSize=7, leading=9, textColor=colors.grey,
                     fontName='Helvetica-Oblique', alignment=TA_CENTER)


# ── Coloured banner helper ────────────────────────────────────────────────────
class ColorBanner(Flowable):
    def __init__(self, text, width, height=18, bg=C_HEADER_BG, style=H2):
        super().__init__()
        self.text = text
        self.bw = width
        self.bh = height
        self.bg = bg
        self.style = style

    def wrap(self, aw, ah):
        return self.bw, self.bh

    def draw(self):
        c = self.canv
        c.setFillColor(self.bg)
        c.roundRect(0, 0, self.bw, self.bh, 4, fill=1, stroke=0)
        c.setFillColor(C_WHITE)
        c.setFont(self.style.fontName, self.style.fontSize)
        c.drawCentredString(self.bw / 2, (self.bh - self.style.fontSize) / 2 + 1, self.text)


class SectionBanner(Flowable):
    """Full-width coloured section header"""
    def __init__(self, text, width, height=22, bg=C_BLUE):
        super().__init__()
        self.text = text
        self.bw = width
        self.bh = height
        self.bg = bg

    def wrap(self, aw, ah):
        return self.bw, self.bh

    def draw(self):
        c = self.canv
        c.setFillColor(self.bg)
        c.rect(0, 0, self.bw, self.bh, fill=1, stroke=0)
        c.setFillColor(C_WHITE)
        c.setFont('Helvetica-Bold', 11)
        c.drawString(8, (self.bh - 11) / 2 + 1, self.text)


# ── Midbrain cross-section diagram ───────────────────────────────────────────
class MidbrainDiagram(Flowable):
    """Schematic cross-section of the midbrain at level of superior colliculus"""
    def __init__(self, w=220, h=190, title="Rostral Midbrain (Superior Colliculus Level)"):
        super().__init__()
        self.dw = w
        self.dh = h
        self.title = title

    def wrap(self, aw, ah):
        return self.dw, self.dh

    def draw(self):
        c = self.canv
        cx, cy = self.dw / 2, self.dh / 2 - 10

        # Background
        c.setFillColor(colors.HexColor('#F0F4F8'))
        c.roundRect(0, 0, self.dw, self.dh - 14, 8, fill=1, stroke=0)

        # Title
        c.setFillColor(C_BLUE)
        c.rect(0, self.dh - 14, self.dw, 14, fill=1, stroke=0)
        c.setFillColor(C_WHITE)
        c.setFont('Helvetica-Bold', 7)
        c.drawCentredString(self.dw / 2, self.dh - 10, self.title)

        # Outer midbrain outline (oval)
        c.setStrokeColor(C_DARK)
        c.setLineWidth(1.5)
        c.setFillColor(colors.HexColor('#FDFEFE'))
        c.ellipse(cx - 72, cy - 62, cx + 72, cy + 62, fill=1, stroke=1)

        # Cerebral aqueduct (Sylvian aqueduct) - small oval at top
        c.setFillColor(colors.HexColor('#AED6F1'))
        c.setStrokeColor(C_BLUE)
        c.setLineWidth(1)
        c.ellipse(cx - 7, cy + 28, cx + 7, cy + 44, fill=1, stroke=1)
        c.setFillColor(C_BLUE)
        c.setFont('Helvetica', 5.5)
        c.drawCentredString(cx, cy + 34, 'Aq.')

        # Tectum (posterior - top region)
        c.setFillColor(colors.HexColor('#D5F5E3'))
        c.setStrokeColor(C_GREEN)
        c.setLineWidth(0.8)
        # draw a region above the aqueduct
        p = c.beginPath()
        p.moveTo(cx - 30, cy + 28)
        p.curveTo(cx - 50, cy + 52, cx + 50, cy + 52, cx + 30, cy + 28)
        p.curveTo(cx + 10, cy + 30, cx - 10, cy + 30, cx - 30, cy + 28)
        p.close()
        c.drawPath(p, fill=1, stroke=1)
        c.setFillColor(C_GREEN)
        c.setFont('Helvetica-Bold', 6)
        c.drawCentredString(cx, cy + 46, 'TECTUM')
        c.setFont('Helvetica', 5.5)
        c.drawCentredString(cx, cy + 40, '(Sup. Colliculus)')

        # Periaqueductal grey
        c.setFillColor(colors.HexColor('#FDEBD0'))
        c.setStrokeColor(C_ORANGE)
        c.ellipse(cx - 18, cy + 14, cx + 18, cy + 50, fill=1, stroke=1)
        c.setFillColor(C_ORANGE)
        c.setFont('Helvetica', 5.5)
        c.drawCentredString(cx, cy + 19, 'PAG')

        # Oculomotor nucleus (CN III)
        c.setFillColor(colors.HexColor('#FADBD8'))
        c.setStrokeColor(C_RED)
        c.setLineWidth(1)
        c.ellipse(cx - 9, cy + 5, cx + 9, cy + 18, fill=1, stroke=1)
        c.setFillColor(C_RED)
        c.setFont('Helvetica-Bold', 5.5)
        c.drawCentredString(cx, cy + 10, 'CN III nuc')

        # Edinger-Westphal
        c.setFillColor(colors.HexColor('#E8DAEF'))
        c.setStrokeColor(C_PURPLE)
        c.ellipse(cx - 7, cy + 18, cx + 7, cy + 28, fill=1, stroke=1)
        c.setFillColor(C_PURPLE)
        c.setFont('Helvetica', 5)
        c.drawCentredString(cx, cy + 22, 'E-W')

        # Red nucleus (left and right)
        for side, lx in [(-1, cx - 26), (1, cx + 26)]:
            c.setFillColor(colors.HexColor('#FADBD8'))
            c.setStrokeColor(C_RED)
            c.circle(lx, cy + 8, 12, fill=1, stroke=1)
            c.setFillColor(C_RED)
            c.setFont('Helvetica-Bold', 5.5)
            c.drawCentredString(lx, cy + 6, 'Red')
            c.drawCentredString(lx, cy + 11, 'Nuc')

        # Substantia nigra (curved band)
        c.setFillColor(colors.HexColor('#2C3E50'))
        c.setStrokeColor(colors.black)
        c.setLineWidth(0.5)
        for side, sx in [(-1, -1), (1, 1)]:
            bx = cx + side * 20
            p = c.beginPath()
            p.moveTo(bx - side * 12, cy - 8)
            p.curveTo(bx - side * 16, cy - 22, bx + side * 16, cy - 22, bx + side * 12, cy - 8)
            p.curveTo(bx + side * 8, cy - 4, bx - side * 8, cy - 4, bx - side * 12, cy - 8)
            p.close()
            c.drawPath(p, fill=1, stroke=1)
        c.setFillColor(C_WHITE)
        c.setFont('Helvetica-Bold', 5.5)
        c.drawCentredString(cx - 20, cy - 14, 'SN')
        c.drawCentredString(cx + 20, cy - 14, 'SN')

        # Crus cerebri (anterior, bilateral large ovals)
        for side, bx in [(-1, cx - 36), (1, cx + 36)]:
            c.setFillColor(colors.HexColor('#D6EAF8'))
            c.setStrokeColor(C_BLUE)
            c.setLineWidth(1)
            c.ellipse(bx - 22, cy - 54, bx + 22, cy - 22, fill=1, stroke=1)
            c.setFillColor(C_BLUE)
            c.setFont('Helvetica-Bold', 5.5)
            c.drawCentredString(bx, cy - 42, 'Crus')
            c.drawCentredString(bx, cy - 36, 'Cerebri')
            c.setFont('Helvetica', 4.8)
            c.drawCentredString(bx, cy - 30, '(motor tracts)')

        # Medial lemniscus
        for side, lx in [(-1, cx - 20), (1, cx + 20)]:
            c.setFillColor(colors.HexColor('#A9DFBF'))
            c.setStrokeColor(C_GREEN)
            c.rect(lx - 8, cy - 8, 16, 10, fill=1, stroke=1)
            c.setFillColor(C_GREEN)
            c.setFont('Helvetica', 4.5)
            c.drawCentredString(lx, cy - 1, 'Med')
            c.drawCentredString(lx, cy - 5.5, 'Lemn')

        # CN III nerve exits
        for side, ex, ey, angle in [(-1, cx - 72, cy - 20, 30), (1, cx + 72, cy - 20, -30)]:
            c.setStrokeColor(C_RED)
            c.setLineWidth(1.5)
            c.line(cx + side * 18, cy + 4, ex, ey)
            c.setFillColor(C_RED)
            c.setFont('Helvetica-Bold', 6.5)
            tx = ex - 12 if side == -1 else ex + 1
            c.drawString(tx, ey - 5, 'CN III')

        # Labels on outside right
        label_x = self.dw - 2
        c.setFillColor(C_DARK)
        c.setFont('Helvetica', 5.5)
        labels = [
            (cy + 50, 'Tectum (Superior Colliculus)'),
            (cy + 22, 'E-W nucleus (parasymp)'),
            (cy + 8,  'CN III nucleus (somatic motor)'),
            (cy - 14, 'Substantia Nigra (DA)'),
            (cy - 38, 'Crus Cerebri (motor)'),
        ]
        for ly, txt in labels:
            c.line(label_x - 32, ly, label_x - 2, ly)
            c.drawRightString(label_x, ly - 2, txt)


# ── Caudal Midbrain cross-section diagram ────────────────────────────────────
class CaudalMidbrainDiagram(Flowable):
    """Schematic cross-section at level of inferior colliculus"""
    def __init__(self, w=220, h=190, title="Caudal Midbrain (Inferior Colliculus Level)"):
        super().__init__()
        self.dw = w
        self.dh = h
        self.title = title

    def wrap(self, aw, ah):
        return self.dw, self.dh

    def draw(self):
        c = self.canv
        cx, cy = self.dw / 2, self.dh / 2 - 10

        c.setFillColor(colors.HexColor('#F0F4F8'))
        c.roundRect(0, 0, self.dw, self.dh - 14, 8, fill=1, stroke=0)

        c.setFillColor(C_RED)
        c.rect(0, self.dh - 14, self.dw, 14, fill=1, stroke=0)
        c.setFillColor(C_WHITE)
        c.setFont('Helvetica-Bold', 7)
        c.drawCentredString(self.dw / 2, self.dh - 10, self.title)

        # Outer outline
        c.setStrokeColor(C_DARK)
        c.setLineWidth(1.5)
        c.setFillColor(colors.HexColor('#FDFEFE'))
        c.ellipse(cx - 72, cy - 62, cx + 72, cy + 62, fill=1, stroke=1)

        # Aqueduct
        c.setFillColor(colors.HexColor('#AED6F1'))
        c.setStrokeColor(C_BLUE)
        c.setLineWidth(1)
        c.ellipse(cx - 7, cy + 28, cx + 7, cy + 44, fill=1, stroke=1)
        c.setFillColor(C_BLUE)
        c.setFont('Helvetica', 5.5)
        c.drawCentredString(cx, cy + 34, 'Aq.')

        # Inferior colliculus tectum
        c.setFillColor(colors.HexColor('#FDEBD0'))
        c.setStrokeColor(C_ORANGE)
        p = c.beginPath()
        p.moveTo(cx - 30, cy + 28)
        p.curveTo(cx - 50, cy + 52, cx + 50, cy + 52, cx + 30, cy + 28)
        p.curveTo(cx + 10, cy + 30, cx - 10, cy + 30, cx - 30, cy + 28)
        p.close()
        c.drawPath(p, fill=1, stroke=1)
        c.setFillColor(C_ORANGE)
        c.setFont('Helvetica-Bold', 6)
        c.drawCentredString(cx, cy + 46, 'TECTUM')
        c.setFont('Helvetica', 5.5)
        c.drawCentredString(cx, cy + 40, '(Inf. Colliculus)')

        # PAG
        c.setFillColor(colors.HexColor('#FDEBD0'))
        c.setStrokeColor(C_ORANGE)
        c.ellipse(cx - 18, cy + 14, cx + 18, cy + 50, fill=1, stroke=1)

        # CN IV nucleus
        c.setFillColor(colors.HexColor('#E8DAEF'))
        c.setStrokeColor(C_PURPLE)
        c.ellipse(cx - 9, cy + 5, cx + 9, cy + 18, fill=1, stroke=1)
        c.setFillColor(C_PURPLE)
        c.setFont('Helvetica-Bold', 5.5)
        c.drawCentredString(cx, cy + 10, 'CN IV nuc')

        # Mesencephalic nucleus V (bilateral small dots)
        for sx in [cx - 22, cx + 22]:
            c.setFillColor(colors.HexColor('#D5F5E3'))
            c.setStrokeColor(C_TEAL)
            c.circle(sx, cy + 22, 7, fill=1, stroke=1)
            c.setFillColor(C_TEAL)
            c.setFont('Helvetica', 4.8)
            c.drawCentredString(sx, cy + 20, 'Mes V')

        # Substantia nigra
        c.setFillColor(colors.HexColor('#2C3E50'))
        c.setStrokeColor(colors.black)
        c.setLineWidth(0.5)
        for side in [-1, 1]:
            bx = cx + side * 20
            p = c.beginPath()
            p.moveTo(bx - side * 12, cy - 8)
            p.curveTo(bx - side * 16, cy - 22, bx + side * 16, cy - 22, bx + side * 12, cy - 8)
            p.curveTo(bx + side * 8, cy - 4, bx - side * 8, cy - 4, bx - side * 12, cy - 8)
            p.close()
            c.drawPath(p, fill=1, stroke=1)
        c.setFillColor(C_WHITE)
        c.setFont('Helvetica-Bold', 5.5)
        c.drawCentredString(cx - 20, cy - 14, 'SN')
        c.drawCentredString(cx + 20, cy - 14, 'SN')

        # Crus cerebri
        for side, bx in [(-1, cx - 36), (1, cx + 36)]:
            c.setFillColor(colors.HexColor('#D6EAF8'))
            c.setStrokeColor(C_BLUE)
            c.setLineWidth(1)
            c.ellipse(bx - 22, cy - 54, bx + 22, cy - 22, fill=1, stroke=1)
            c.setFillColor(C_BLUE)
            c.setFont('Helvetica-Bold', 5.5)
            c.drawCentredString(bx, cy - 42, 'Crus')
            c.drawCentredString(bx, cy - 36, 'Cerebri')

        # CN IV exits POSTERIORLY - arrow from CN IV nucleus
        c.setStrokeColor(C_PURPLE)
        c.setLineWidth(1.5)
        c.line(cx, cy + 18, cx, cy + 62)
        # Then curves around - simplified arrow going up and around
        c.setFillColor(C_PURPLE)
        c.setFont('Helvetica-Bold', 6)
        c.drawCentredString(cx + 30, cy + 60, 'CN IV exits')
        c.drawCentredString(cx + 30, cy + 54, 'DORSALLY')
        c.setFont('Helvetica', 5)
        c.drawCentredString(cx + 30, cy + 48, '(only CN dorsal exit)')


# ── Cavernous sinus diagram ───────────────────────────────────────────────────
class CavernousSinusDiagram(Flowable):
    def __init__(self, w=230, h=170):
        super().__init__()
        self.dw = w
        self.dh = h

    def wrap(self, aw, ah):
        return self.dw, self.dh

    def draw(self):
        c = self.canv

        # Background
        c.setFillColor(colors.HexColor('#F8F9FA'))
        c.roundRect(0, 0, self.dw, self.dh, 6, fill=1, stroke=0)

        # Title
        c.setFillColor(colors.HexColor('#8E44AD'))
        c.rect(0, self.dh - 14, self.dw, 14, fill=1, stroke=0)
        c.setFillColor(C_WHITE)
        c.setFont('Helvetica-Bold', 7)
        c.drawCentredString(self.dw / 2, self.dh - 10, 'CAVERNOUS SINUS - Coronal Cross-Section')

        cy = self.dh / 2 - 8

        # Sella turcica / pituitary in middle
        c.setFillColor(colors.HexColor('#FAD7A0'))
        c.setStrokeColor(C_ORANGE)
        c.setLineWidth(1)
        c.roundRect(self.dw / 2 - 22, cy - 20, 44, 34, 4, fill=1, stroke=1)
        c.setFillColor(C_DARK)
        c.setFont('Helvetica-Bold', 6.5)
        c.drawCentredString(self.dw / 2, cy + 8, 'PITUITARY')
        c.drawCentredString(self.dw / 2, cy + 1, '(Sella Turcica)')
        c.setFont('Helvetica', 5.5)
        c.drawCentredString(self.dw / 2, cy - 7, 'Diaphragma')
        c.drawCentredString(self.dw / 2, cy - 12, 'Sellae (dura roof)')

        # Left cavernous sinus
        lx = 52
        c.setFillColor(colors.HexColor('#AED6F1'))
        c.setStrokeColor(C_BLUE)
        c.setLineWidth(1.5)
        c.roundRect(lx - 38, cy - 38, 76, 72, 8, fill=1, stroke=1)
        c.setFillColor(C_BLUE)
        c.setFont('Helvetica-Bold', 6.5)
        c.drawCentredString(lx, cy + 26, 'LEFT')
        c.drawCentredString(lx, cy + 20, 'CAVERNOUS')
        c.drawCentredString(lx, cy + 14, 'SINUS')

        # Right cavernous sinus
        rx = self.dw - 52
        c.setFillColor(colors.HexColor('#AED6F1'))
        c.setStrokeColor(C_BLUE)
        c.roundRect(rx - 38, cy - 38, 76, 72, 8, fill=1, stroke=1)
        c.setFillColor(C_BLUE)
        c.setFont('Helvetica-Bold', 6.5)
        c.drawCentredString(rx, cy + 26, 'RIGHT')
        c.drawCentredString(rx, cy + 20, 'CAVERNOUS')
        c.drawCentredString(rx, cy + 14, 'SINUS')

        # ICA inside each sinus
        for sx in [lx, rx]:
            c.setFillColor(colors.HexColor('#E74C3C'))
            c.setStrokeColor(colors.darkred)
            c.circle(sx, cy - 5, 9, fill=1, stroke=1)
            c.setFillColor(C_WHITE)
            c.setFont('Helvetica-Bold', 5.5)
            c.drawCentredString(sx, cy - 7, 'ICA')

        # CN VI inside each sinus (close to ICA)
        for sx in [lx + 14, rx - 14]:
            c.setFillColor(colors.HexColor('#F9E79F'))
            c.setStrokeColor(colors.goldenrod)
            c.circle(sx, cy - 5, 7, fill=1, stroke=1)
            c.setFillColor(C_DARK)
            c.setFont('Helvetica-Bold', 5.5)
            c.drawCentredString(sx, cy - 7, 'VI')

        # Lateral wall contents - left side (listed outside)
        lw_labels = ['III (CN3)', 'IV (CN4)', 'V1 (ophthal)', 'V2 (maxill)']
        c.setFillColor(C_DARK)
        c.setFont('Helvetica', 5.5)
        for i, lbl in enumerate(lw_labels):
            y = cy + 12 - i * 11
            c.setFillColor(colors.HexColor('#D5F5E3'))
            c.setStrokeColor(C_GREEN)
            c.rect(4, y - 4, 38, 9, fill=1, stroke=1)
            c.setFillColor(C_DARK)
            c.setFont('Helvetica', 5.5)
            c.drawString(6, y - 1, lbl)

        # Same on right
        for i, lbl in enumerate(lw_labels):
            y = cy + 12 - i * 11
            c.setFillColor(colors.HexColor('#D5F5E3'))
            c.setStrokeColor(C_GREEN)
            c.rect(self.dw - 42, y - 4, 38, 9, fill=1, stroke=1)
            c.setFillColor(C_DARK)
            c.setFont('Helvetica', 5.5)
            c.drawString(self.dw - 40, y - 1, lbl)

        # Lateral wall label
        c.setFillColor(C_GREEN)
        c.setFont('Helvetica-Bold', 5.5)
        c.drawCentredString(23, cy - 38 + 4, 'LATERAL')
        c.drawCentredString(23, cy - 38 - 2, 'WALL')
        c.drawCentredString(self.dw - 23, cy - 38 + 4, 'LATERAL')
        c.drawCentredString(self.dw - 23, cy - 38 - 2, 'WALL')

        # Intercavernous sinus
        c.setStrokeColor(C_BLUE)
        c.setLineWidth(1.5)
        c.line(lx + 38, cy, rx - 38, cy)
        c.setFillColor(C_BLUE)
        c.setFont('Helvetica', 5.5)
        c.drawCentredString(self.dw / 2, cy + 4, 'Intercavernous sinus')


# ── Cerebellar peduncle diagram ───────────────────────────────────────────────
class CerebellarPeduncles(Flowable):
    def __init__(self, w=230, h=130):
        super().__init__()
        self.dw = w
        self.dh = h

    def wrap(self, aw, ah):
        return self.dw, self.dh

    def draw(self):
        c = self.canv
        c.setFillColor(colors.HexColor('#F8F9FA'))
        c.roundRect(0, 0, self.dw, self.dh, 6, fill=1, stroke=0)

        # Title
        c.setFillColor(C_TEAL)
        c.rect(0, self.dh - 14, self.dw, 14, fill=1, stroke=0)
        c.setFillColor(C_WHITE)
        c.setFont('Helvetica-Bold', 7)
        c.drawCentredString(self.dw / 2, self.dh - 10, 'CEREBELLAR PEDUNCLES')

        cy = self.dh / 2 - 6
        cx = self.dw / 2

        # Cerebellum (big right oval)
        c.setFillColor(colors.HexColor('#D5F5E3'))
        c.setStrokeColor(C_GREEN)
        c.setLineWidth(1.5)
        c.ellipse(cx + 20, cy - 42, cx + 110, cy + 42, fill=1, stroke=1)
        c.setFillColor(C_GREEN)
        c.setFont('Helvetica-Bold', 8)
        c.drawCentredString(cx + 65, cy + 5, 'CEREBELLUM')

        # Brainstem (left rect)
        c.setFillColor(colors.HexColor('#D6EAF8'))
        c.setStrokeColor(C_BLUE)
        c.setLineWidth(1.5)
        c.roundRect(8, cy - 38, 55, 76, 6, fill=1, stroke=1)
        c.setFillColor(C_BLUE)
        c.setFont('Helvetica-Bold', 7)
        c.drawCentredString(35, cy + 28, 'MIDBRAIN')
        c.drawCentredString(35, cy + 8, 'PONS')
        c.drawCentredString(35, cy - 16, 'MEDULLA')

        # Superior cerebellar peduncle (top)
        c.setFillColor(colors.HexColor('#FDEDEC'))
        c.setStrokeColor(C_RED)
        c.setLineWidth(2)
        c.roundRect(cx - 14, cy + 16, cx - 14 + 50, 18, 4, fill=1, stroke=1)
        c.setFillColor(C_RED)
        c.setFont('Helvetica-Bold', 6)
        c.drawCentredString(cx + 11, cy + 22, 'SUPERIOR ped.')
        c.setFont('Helvetica', 5)
        c.drawCentredString(cx + 11, cy + 17, 'OUTPUT (efferent) → midbrain/thalamus')

        # Middle cerebellar peduncle (middle)
        c.setFillColor(colors.HexColor('#EBF5FB'))
        c.setStrokeColor(C_BLUE)
        c.setLineWidth(2)
        c.roundRect(cx - 14, cy - 5, cx - 14 + 50, 18, 4, fill=1, stroke=1)
        c.setFillColor(C_BLUE)
        c.setFont('Helvetica-Bold', 6)
        c.drawCentredString(cx + 11, cy + 3, 'MIDDLE ped. (ONLY AFFERENT)')
        c.setFont('Helvetica', 5)
        c.drawCentredString(cx + 11, cy - 2, 'Input from contralat. pontine nuclei')

        # Inferior cerebellar peduncle (bottom)
        c.setFillColor(colors.HexColor('#E8F8F5'))
        c.setStrokeColor(C_TEAL)
        c.setLineWidth(2)
        c.roundRect(cx - 14, cy - 26, cx - 14 + 50, 18, 4, fill=1, stroke=1)
        c.setFillColor(C_TEAL)
        c.setFont('Helvetica-Bold', 6)
        c.drawCentredString(cx + 11, cy - 18, 'INFERIOR ped. (mixed)')
        c.setFont('Helvetica', 5)
        c.drawCentredString(cx + 11, cy - 23, 'Input: spinal cord, olive, vestib.')

        # Arrows
        c.setStrokeColor(C_RED)
        c.setLineWidth(1.5)
        c.line(63, cy + 25, cx - 14, cy + 25)  # sup - bidirectional but mostly out

        c.setStrokeColor(C_BLUE)
        c.line(63, cy + 4, cx - 14, cy + 4)    # middle in only

        c.setStrokeColor(C_TEAL)
        c.line(63, cy - 17, cx - 14, cy - 17)  # inferior


# ──────────────────────────────────────────────────────────────────────────────
#  BUILD THE PDF
# ──────────────────────────────────────────────────────────────────────────────
def build_pdf(path):
    doc = SimpleDocTemplate(
        path,
        pagesize=A4,
        leftMargin=1.2 * cm, rightMargin=1.2 * cm,
        topMargin=1.2 * cm, bottomMargin=1.2 * cm,
        title="USMLE Neuro Study Sheet - Midbrain, Cerebellum, Dural Sinuses",
        author="Orris AI"
    )

    W = PAGE_W - 2.4 * cm   # usable width
    story = []

    # ── MASTER HEADER ─────────────────────────────────────────────────────────
    header_table = Table(
        [[Paragraph('🧠 USMLE NEURO HIGH-YIELD', H1),
          Paragraph('Midbrain · Cerebellum · Dural Sinuses', H2)]],
        colWidths=[W * 0.5, W * 0.5]
    )
    header_table.setStyle(TableStyle([
        ('BACKGROUND', (0, 0), (-1, -1), C_HEADER_BG),
        ('ROWBACKGROUNDS', (0, 0), (-1, -1), [C_HEADER_BG]),
        ('VALIGN', (0, 0), (-1, -1), 'MIDDLE'),
        ('TOPPADDING', (0, 0), (-1, -1), 8),
        ('BOTTOMPADDING', (0, 0), (-1, -1), 8),
        ('LEFTPADDING', (0, 0), (-1, -1), 10),
        ('RIGHTPADDING', (0, 0), (-1, -1), 10),
        ('ROUNDEDCORNERS', (0, 0), (-1, -1), [6, 6, 0, 0]),
    ]))
    story.append(header_table)
    story.append(Spacer(1, 4))

    # ── SECTION 1: MIDBRAIN DIAGRAMS ──────────────────────────────────────────
    story.append(SectionBanner('SECTION 1 - MIDBRAIN ANATOMY & CROSS-SECTIONS', W, bg=C_BLUE))
    story.append(Spacer(1, 4))

    diag_table = Table(
        [[MidbrainDiagram(w=int(W * 0.48), h=190),
          CaudalMidbrainDiagram(w=int(W * 0.48), h=190)]],
        colWidths=[W * 0.5, W * 0.5]
    )
    diag_table.setStyle(TableStyle([
        ('VALIGN', (0, 0), (-1, -1), 'TOP'),
        ('LEFTPADDING', (0, 0), (-1, -1), 2),
        ('RIGHTPADDING', (0, 0), (-1, -1), 2),
    ]))
    story.append(diag_table)
    story.append(Spacer(1, 4))

    # Key structures table
    story.append(ColorBanner('KEY MIDBRAIN NUCLEI', W, height=14, bg=C_ACCENT))
    story.append(Spacer(1, 3))

    nuc_data = [
        [Paragraph('<b>Nucleus</b>', TABLE_HDR),
         Paragraph('<b>Location</b>', TABLE_HDR),
         Paragraph('<b>CN / Function</b>', TABLE_HDR),
         Paragraph('<b>USMLE Pearl</b>', TABLE_HDR)],
        [Paragraph('CN III (Oculomotor)', TABLE_CELL),
         Paragraph('Rostral midbrain tegmentum', TABLE_CELL),
         Paragraph('SR, IR, MR, IO, LPS muscles', TABLE_CELL),
         Paragraph('"Down & out" + ptosis + dilated pupil = CN III palsy', TABLE_CELL)],
        [Paragraph('Edinger-Westphal', TABLE_CELL),
         Paragraph('Dorsal to CN III nucleus', TABLE_CELL),
         Paragraph('Parasymp → ciliary m., sphincter pupillae', TABLE_CELL),
         Paragraph('Pupillary constriction + accommodation; compressed FIRST in uncal herniation', TABLE_CELL)],
        [Paragraph('CN IV (Trochlear)', TABLE_CELL),
         Paragraph('Caudal midbrain tegmentum', TABLE_CELL),
         Paragraph('Superior oblique muscle', TABLE_CELL),
         Paragraph('Only CN exiting DORSALLY; complete decussation; longest intracranial CN; SO4 / LR6', TABLE_CELL)],
        [Paragraph('Red Nucleus', TABLE_CELL),
         Paragraph('Midbrain tegmentum', TABLE_CELL),
         Paragraph('Involuntary movement center → rubrospinal tract (flexor tone)', TABLE_CELL),
         Paragraph('Receives dentate output → relays to thalamus; lesion = contralateral tremor (Benedikt)', TABLE_CELL)],
        [Paragraph('Substantia Nigra', TABLE_CELL),
         Paragraph('Between crus & tegmentum', TABLE_CELL),
         Paragraph('Dopamine (nigrostriatal pathway)', TABLE_CELL),
         Paragraph("Lost in Parkinson's → depigmentation; resting tremor, rigidity, bradykinesia", TABLE_CELL)],
        [Paragraph('Mesencephalic V', TABLE_CELL),
         Paragraph('Lateral midbrain', TABLE_CELL),
         Paragraph('Proprioception from jaw muscles', TABLE_CELL),
         Paragraph('ONLY primary sensory neurons in the CNS (not in ganglion)', TABLE_CELL)],
    ]

    nuc_tbl = Table(nuc_data, colWidths=[W * 0.18, W * 0.17, W * 0.28, W * 0.37])
    nuc_tbl.setStyle(TableStyle([
        ('BACKGROUND', (0, 0), (-1, 0), C_BLUE),
        ('ROWBACKGROUNDS', (0, 1), (-1, -1), [C_WHITE, C_LIGHTGREY]),
        ('GRID', (0, 0), (-1, -1), 0.4, colors.lightgrey),
        ('VALIGN', (0, 0), (-1, -1), 'MIDDLE'),
        ('TOPPADDING', (0, 0), (-1, -1), 3),
        ('BOTTOMPADDING', (0, 0), (-1, -1), 3),
        ('LEFTPADDING', (0, 0), (-1, -1), 4),
        ('RIGHTPADDING', (0, 0), (-1, -1), 4),
    ]))
    story.append(nuc_tbl)
    story.append(Spacer(1, 5))

    # ── SECTION 2: CLINICAL SYNDROMES ─────────────────────────────────────────
    story.append(SectionBanner('SECTION 2 - MIDBRAIN CLINICAL SYNDROMES (HIGH-YIELD)', W, bg=C_RED))
    story.append(Spacer(1, 4))

    syn_data = [
        [Paragraph('<b>Syndrome</b>', TABLE_HDR),
         Paragraph('<b>Lesion Site</b>', TABLE_HDR),
         Paragraph('<b>Signs & Symptoms</b>', TABLE_HDR),
         Paragraph('<b>Common Cause</b>', TABLE_HDR)],
        [Paragraph('WEBER', TABLE_CELL),
         Paragraph('Crus cerebri + CN III fascicles', TABLE_CELL),
         Paragraph('Ipsilateral CN III palsy (↓↓ eye, ptosis, mydriasis) + Contralateral hemiplegia', TABLE_CELL),
         Paragraph('PCA / SCA infarct', TABLE_CELL)],
        [Paragraph('BENEDIKT', TABLE_CELL),
         Paragraph('Tegmentum: Red nucleus + CN III fascicles', TABLE_CELL),
         Paragraph('Ipsilateral CN III palsy + Contralateral tremor/choreiform movements (red nucleus)', TABLE_CELL),
         Paragraph('Paramedian midbrain infarct', TABLE_CELL)],
        [Paragraph('CLAUDE', TABLE_CELL),
         Paragraph('Red nuc + SCP + CN III', TABLE_CELL),
         Paragraph('CN III palsy + contralateral ataxia (SCP involvement)', TABLE_CELL),
         Paragraph('Rare midbrain infarct', TABLE_CELL)],
        [Paragraph('PARINAUD\n(Dorsal Midbrain)', TABLE_CELL),
         Paragraph('Superior colliculi / pretectum', TABLE_CELL),
         Paragraph('↑ Gaze palsy, convergence-retraction nystagmus, light-near dissociation, Collier sign (lid retract), "sunset sign" in babies', TABLE_CELL),
         Paragraph('Pineal tumor, hydrocephalus, MS', TABLE_CELL)],
        [Paragraph('UNCAL HERNIATION', TABLE_CELL),
         Paragraph('CN III compressed at tentorial notch', TABLE_CELL),
         Paragraph('Ipsilateral dilated pupil (FIRST sign) → then CN III palsy, contralateral hemiplegia (Kernohan notch = ipsi hemiplegia)', TABLE_CELL),
         Paragraph('Epidural/subdural hematoma, large infarct, tumor', TABLE_CELL)],
    ]

    syn_tbl = Table(syn_data, colWidths=[W * 0.15, W * 0.20, W * 0.40, W * 0.25])
    syn_tbl.setStyle(TableStyle([
        ('BACKGROUND', (0, 0), (-1, 0), C_RED),
        ('ROWBACKGROUNDS', (0, 1), (-1, -1), [C_LIGHTRED, C_WHITE, C_LIGHTRED, C_WHITE, C_LIGHTRED]),
        ('GRID', (0, 0), (-1, -1), 0.4, colors.lightgrey),
        ('VALIGN', (0, 0), (-1, -1), 'MIDDLE'),
        ('TOPPADDING', (0, 0), (-1, -1), 3),
        ('BOTTOMPADDING', (0, 0), (-1, -1), 3),
        ('LEFTPADDING', (0, 0), (-1, -1), 4),
        ('RIGHTPADDING', (0, 0), (-1, -1), 4),
        ('FONTNAME', (0, 1), (0, -1), 'Helvetica-Bold'),
        ('FONTSIZE', (0, 1), (0, -1), 7.5),
        ('TEXTCOLOR', (0, 1), (0, -1), C_RED),
    ]))
    story.append(syn_tbl)
    story.append(Spacer(1, 5))

    # Mnemonic box
    mnem_data = [[
        Paragraph('🔑 <b>Weber</b> = W for "Walk away" (contralateral leg weak) + CN III | '
                  '<b>Benedikt</b> = B for "Bouncy" (tremor/involuntary movements) + CN III | '
                  '<b>Parinaud</b> = look UP at the Pineal gland (upward gaze palsy)', MNEMONIC),
    ]]
    mnem_tbl = Table(mnem_data, colWidths=[W])
    mnem_tbl.setStyle(TableStyle([
        ('BACKGROUND', (0, 0), (-1, -1), colors.HexColor('#F9F0FF')),
        ('BOX', (0, 0), (-1, -1), 1, C_PURPLE),
        ('TOPPADDING', (0, 0), (-1, -1), 5),
        ('BOTTOMPADDING', (0, 0), (-1, -1), 5),
        ('LEFTPADDING', (0, 0), (-1, -1), 8),
        ('RIGHTPADDING', (0, 0), (-1, -1), 8),
    ]))
    story.append(mnem_tbl)

    # ── PAGE BREAK ─────────────────────────────────────────────────────────────
    story.append(PageBreak())

    # ── SECTION 3: CEREBELLUM ─────────────────────────────────────────────────
    story.append(SectionBanner('SECTION 3 - CEREBELLUM: ANATOMY, CIRCUITS & DISORDERS', W, bg=C_GREEN))
    story.append(Spacer(1, 4))

    # Peduncles diagram + functional subdivisions table side by side
    ped_func_table = Table(
        [[CerebellarPeduncles(w=int(W * 0.46), h=130),
          Spacer(6, 1),
          # Functional subdivisions as mini-table inside
          Table([
              [Paragraph('<b>Functional Subdivisions</b>', TABLE_HDR)],
              [Table([
                  [Paragraph('<b>Division</b>', BOLD_SM), Paragraph('<b>Location</b>', BOLD_SM), Paragraph('<b>Input</b>', BOLD_SM), Paragraph('<b>Function</b>', BOLD_SM), Paragraph('<b>Lesion</b>', BOLD_SM)],
                  [Paragraph('Vestibulocerebellum', TABLE_CELL), Paragraph('Flocculonodular lobe', TABLE_CELL), Paragraph('Vestibular nuclei', TABLE_CELL), Paragraph('Balance, eye mvmt, gaze stab.', TABLE_CELL), Paragraph('Truncal ataxia, nystagmus', TABLE_CELL)],
                  [Paragraph('Spinocerebellum', TABLE_CELL), Paragraph('Vermis + Intermediate', TABLE_CELL), Paragraph('Spinal cord', TABLE_CELL), Paragraph('Motor execution (ongoing)', TABLE_CELL), Paragraph('Gait ataxia / limb ataxia', TABLE_CELL)],
                  [Paragraph('Pontocerebellum', TABLE_CELL), Paragraph('Lateral hemispheres', TABLE_CELL), Paragraph('Cerebral cortex via pons', TABLE_CELL), Paragraph('Motor PLANNING, sequencing', TABLE_CELL), Paragraph('Intention tremor, dysmetria', TABLE_CELL)],
              ], colWidths=[W * 0.09, W * 0.10, W * 0.10, W * 0.10, W * 0.10])],
          ], colWidths=[W * 0.52], rowHeights=[14, None])
        ]],
        colWidths=[W * 0.46, 6, W * 0.52]
    )
    ped_func_table.setStyle(TableStyle([
        ('VALIGN', (0, 0), (-1, -1), 'TOP'),
        ('LEFTPADDING', (0, 0), (-1, -1), 2),
        ('RIGHTPADDING', (0, 0), (-1, -1), 2),
    ]))
    story.append(ped_func_table)
    story.append(Spacer(1, 5))

    # Cerebellar cortex layers
    story.append(ColorBanner('CEREBELLAR CORTEX LAYERS & CIRCUITS (ALWAYS TESTED)', W, height=14, bg=C_ACCENT))
    story.append(Spacer(1, 3))

    cortex_data = [
        [Paragraph('<b>Layer</b>', TABLE_HDR),
         Paragraph('<b>Cell Types</b>', TABLE_HDR),
         Paragraph('<b>Neurotransmitter</b>', TABLE_HDR),
         Paragraph('<b>What it does</b>', TABLE_HDR)],
        [Paragraph('Molecular (outer)', TABLE_CELL),
         Paragraph('Stellate cells, basket cells, parallel fibers (granule axons)', TABLE_CELL),
         Paragraph('GABA (stellate, basket → Purkinje) INHIBITORY', TABLE_CELL),
         Paragraph('Modulate Purkinje cell output; parallel fibers carry excitation along the axis', TABLE_CELL)],
        [Paragraph('Purkinje cell (middle)', TABLE_CELL),
         Paragraph('Purkinje cells ONLY', TABLE_CELL),
         Paragraph('GABA - ALWAYS INHIBITORY → deep nuclei', TABLE_CELL),
         Paragraph('SOLE OUTPUT of cerebellar cortex; inhibit deep cerebellar nuclei', TABLE_CELL)],
        [Paragraph('Granular (inner)', TABLE_CELL),
         Paragraph('Granule cells (excit.), Golgi cells (inhib.)', TABLE_CELL),
         Paragraph('Glutamate (granule); GABA (Golgi)', TABLE_CELL),
         Paragraph('Granule cells: ONLY excitatory neurons in cerebellar cortex; relay mossy fiber input', TABLE_CELL)],
    ]

    cortex_tbl = Table(cortex_data, colWidths=[W * 0.18, W * 0.27, W * 0.25, W * 0.30])
    cortex_tbl.setStyle(TableStyle([
        ('BACKGROUND', (0, 0), (-1, 0), C_GREEN),
        ('ROWBACKGROUNDS', (0, 1), (-1, -1), [C_LIGHTGREEN, C_WHITE, C_LIGHTGREEN]),
        ('GRID', (0, 0), (-1, -1), 0.4, colors.lightgrey),
        ('VALIGN', (0, 0), (-1, -1), 'MIDDLE'),
        ('TOPPADDING', (0, 0), (-1, -1), 3),
        ('BOTTOMPADDING', (0, 0), (-1, -1), 3),
        ('LEFTPADDING', (0, 0), (-1, -1), 4),
        ('RIGHTPADDING', (0, 0), (-1, -1), 4),
    ]))
    story.append(cortex_tbl)
    story.append(Spacer(1, 4))

    # Deep cerebellar nuclei + input fibers side by side
    left_col = [
        ColorBanner('DEEP CEREBELLAR NUCLEI (lat→med)', int(W * 0.48), height=14, bg=C_TEAL),
        Spacer(1, 3),
        Table([
            [Paragraph('<b>Nucleus</b>', TABLE_HDR),
             Paragraph('<b>Peduncle Out</b>', TABLE_HDR),
             Paragraph('<b>Projects To</b>', TABLE_HDR),
             Paragraph('<b>Lesion</b>', TABLE_HDR)],
            [Paragraph('Dentate', TABLE_CELL), Paragraph('Superior', TABLE_CELL),
             Paragraph('VL Thalamus → cortex; red nuc', TABLE_CELL), Paragraph('↓ fine dexterity, delayed initiation', TABLE_CELL)],
            [Paragraph('Emboliform', TABLE_CELL), Paragraph('Superior', TABLE_CELL),
             Paragraph('Red nucleus (rubrospinal)', TABLE_CELL), Paragraph('Action tremor, limb ataxia', TABLE_CELL)],
            [Paragraph('Globose', TABLE_CELL), Paragraph('Superior', TABLE_CELL),
             Paragraph('Red nucleus', TABLE_CELL), Paragraph('Truncal titubation', TABLE_CELL)],
            [Paragraph('Fastigial', TABLE_CELL), Paragraph('★INFERIOR★', TABLE_CELL),
             Paragraph('Vestibular nuclei, reticular', TABLE_CELL), Paragraph('Abasia, gait ataxia', TABLE_CELL)],
        ], colWidths=[int(W * 0.12), int(W * 0.10), int(W * 0.14), int(W * 0.12)])
    ]

    right_col = [
        ColorBanner('INPUT FIBERS', int(W * 0.46), height=14, bg=C_PURPLE),
        Spacer(1, 3),
        Table([
            [Paragraph('<b>Fiber</b>', TABLE_HDR),
             Paragraph('<b>Origin</b>', TABLE_HDR),
             Paragraph('<b>Synapse On</b>', TABLE_HDR),
             Paragraph('<b>Effect</b>', TABLE_HDR)],
            [Paragraph('Mossy fibers', TABLE_CELL), Paragraph('Spinocereb., pontocerebell., vestibulocerebell.', TABLE_CELL),
             Paragraph('Granule cells', TABLE_CELL), Paragraph('Simple spikes in Purkinje cells', TABLE_CELL)],
            [Paragraph('Climbing fibers', TABLE_CELL), Paragraph('Inferior olivary nucleus (contralateral)', TABLE_CELL),
             Paragraph('Purkinje cell dendrites DIRECTLY', TABLE_CELL), Paragraph('Complex spikes; motor learning/error correction; 1 climbing fiber per Purkinje cell', TABLE_CELL)],
        ], colWidths=[int(W * 0.10), int(W * 0.14), int(W * 0.11), int(W * 0.11)])
    ]

    # apply table styles
    for col_content in [left_col, right_col]:
        for item in col_content:
            if isinstance(item, Table):
                item.setStyle(TableStyle([
                    ('BACKGROUND', (0, 0), (-1, 0), C_TEAL if col_content is left_col else C_PURPLE),
                    ('ROWBACKGROUNDS', (0, 1), (-1, -1), [C_WHITE, C_LIGHTGREY]),
                    ('GRID', (0, 0), (-1, -1), 0.4, colors.lightgrey),
                    ('VALIGN', (0, 0), (-1, -1), 'MIDDLE'),
                    ('TOPPADDING', (0, 0), (-1, -1), 2),
                    ('BOTTOMPADDING', (0, 0), (-1, -1), 2),
                    ('LEFTPADDING', (0, 0), (-1, -1), 3),
                    ('RIGHTPADDING', (0, 0), (-1, -1), 3),
                ]))

    nuc_two_col = Table(
        [[item for item in left_col], [item for item in right_col]],
        colWidths=[W * 0.5, W * 0.5]
    )
    # Actually nest differently
    nuclei_tbl = Table(
        [[Table([[i] for i in left_col], colWidths=[W * 0.49]),
          Table([[i] for i in right_col], colWidths=[W * 0.47])]],
        colWidths=[W * 0.5, W * 0.5]
    )
    nuclei_tbl.setStyle(TableStyle([
        ('VALIGN', (0, 0), (-1, -1), 'TOP'),
        ('LEFTPADDING', (0, 0), (-1, -1), 2),
        ('RIGHTPADDING', (0, 0), (-1, -1), 2),
    ]))
    story.append(nuclei_tbl)
    story.append(Spacer(1, 4))

    # Cerebellar disorders
    story.append(ColorBanner('CEREBELLAR DISORDERS & SIGNS', W, height=14, bg=C_RED))
    story.append(Spacer(1, 3))

    signs_data = [
        ['Ataxia', 'Dysmetria (finger-nose)', 'Dysdiadochokinesia', 'Intention tremor',
         'Scanning speech', 'Hypotonia', 'Nystagmus', 'Rebound phenomenon'],
        ['Loss of coordination; wide-based gait; resembles intoxication; IPSILATERAL to lesion',
         'Overshoot/undershoot target; test with finger-nose-finger or heel-knee-shin',
         'Inability to perform rapid alternating movements (pronate/supinate rapidly)',
         'Tremor during voluntary movement, worst near target; ≠ resting tremor of Parkinson',
         'Slurred, irregular, explosive cadence',
         'Decreased resistance to passive stretch',
         'Horizontal; fast phase away from lesion',
         'Inability to stop movement when resistance removed; forearm example'],
    ]
    col_w = W / 8
    signs_tbl = Table(
        [[Paragraph(s, BOLD_SM) for s in signs_data[0]],
         [Paragraph(s, BODY_SM) for s in signs_data[1]]],
        colWidths=[col_w] * 8
    )
    signs_tbl.setStyle(TableStyle([
        ('BACKGROUND', (0, 0), (-1, 0), C_ORANGE),
        ('BACKGROUND', (0, 1), (-1, 1), colors.HexColor('#FEF9E7')),
        ('GRID', (0, 0), (-1, -1), 0.4, colors.lightgrey),
        ('FONTCOLOR', (0, 0), (-1, 0), C_WHITE),
        ('VALIGN', (0, 0), (-1, -1), 'MIDDLE'),
        ('TOPPADDING', (0, 0), (-1, -1), 3),
        ('BOTTOMPADDING', (0, 0), (-1, -1), 3),
        ('LEFTPADDING', (0, 0), (-1, -1), 3),
        ('RIGHTPADDING', (0, 0), (-1, -1), 3),
    ]))
    story.append(signs_tbl)
    story.append(Spacer(1, 4))

    # Joubert vs Dandy-Walker
    congen_data = [
        [Paragraph('<b>Syndrome</b>', TABLE_HDR),
         Paragraph('<b>Genetics</b>', TABLE_HDR),
         Paragraph('<b>Pathology</b>', TABLE_HDR),
         Paragraph('<b>Key Features</b>', TABLE_HDR),
         Paragraph('<b>Imaging Hallmark</b>', TABLE_HDR)],
        [Paragraph('Joubert', TABLE_CELL),
         Paragraph('AR; ciliopathy genes', TABLE_CELL),
         Paragraph('Absent/hypoplastic vermis + malformed brainstem', TABLE_CELL),
         Paragraph('Hypotonia, ataxia, abnormal eye mvmts, breathing irregularity', TABLE_CELL),
         Paragraph('"Molar Tooth Sign" on MRI (elongated SCPs)', TABLE_CELL)],
        [Paragraph('Dandy-Walker', TABLE_CELL),
         Paragraph('Multifactorial', TABLE_CELL),
         Paragraph('Absent/hypoplastic vermis + cystic dilation of 4th ventricle + enlarged posterior fossa', TABLE_CELL),
         Paragraph('Hydrocephalus, slow motor dev., convulsions, ↑ICP', TABLE_CELL),
         Paragraph('Large posterior fossa cyst on MRI/CT; absent vermis', TABLE_CELL)],
        [Paragraph('Friedreich Ataxia', TABLE_CELL),
         Paragraph('AR; GAA repeat in frataxin (chr 9)', TABLE_CELL),
         Paragraph('Degeneration: dorsal columns + spinocereb. tracts + corticospinal tracts', TABLE_CELL),
         Paragraph('Progressive ataxia, absent DTRs + extensor plantar, cardiomyopathy, diabetes, pes cavus', TABLE_CELL),
         Paragraph('Spinal cord atrophy; onset adolescence; cardiomyopathy = #1 cause of death', TABLE_CELL)],
    ]

    congen_tbl = Table(congen_data, colWidths=[W * 0.13, W * 0.12, W * 0.22, W * 0.27, W * 0.26])
    congen_tbl.setStyle(TableStyle([
        ('BACKGROUND', (0, 0), (-1, 0), colors.HexColor('#8E44AD')),
        ('ROWBACKGROUNDS', (0, 1), (-1, -1), [C_LIGHTPURPLE, C_WHITE, C_LIGHTPURPLE]),
        ('GRID', (0, 0), (-1, -1), 0.4, colors.lightgrey),
        ('VALIGN', (0, 0), (-1, -1), 'MIDDLE'),
        ('TOPPADDING', (0, 0), (-1, -1), 3),
        ('BOTTOMPADDING', (0, 0), (-1, -1), 3),
        ('LEFTPADDING', (0, 0), (-1, -1), 4),
        ('RIGHTPADDING', (0, 0), (-1, -1), 4),
    ]))
    story.append(congen_tbl)

    # ── PAGE BREAK ─────────────────────────────────────────────────────────────
    story.append(PageBreak())

    # ── SECTION 4: DURAL SINUSES ──────────────────────────────────────────────
    story.append(SectionBanner('SECTION 4 - DURAL SEPTA & DURAL VENOUS SINUSES', W, bg=C_PURPLE))
    story.append(Spacer(1, 4))

    # Dural septa table + cavernous sinus diagram side by side
    septa_rows = [
        [Paragraph('<b>Septum</b>', TABLE_HDR),
         Paragraph('<b>Location</b>', TABLE_HDR),
         Paragraph('<b>Separates</b>', TABLE_HDR),
         Paragraph('<b>Clinical Note</b>', TABLE_HDR)],
        [Paragraph('Falx cerebri', TABLE_CELL), Paragraph('Vertical midline; attached crista galli → int. occipital protuberance', TABLE_CELL),
         Paragraph('Left & right cerebral hemispheres', TABLE_CELL), Paragraph('Superior sagittal sinus along its superior border; inferior sagittal sinus along inferior border', TABLE_CELL)],
        [Paragraph('Tentorium cerebelli', TABLE_CELL), Paragraph('Horizontal shelf; anchored to petrous ridges', TABLE_CELL),
         Paragraph('Supratentorial (cerebrum) from infratentorial (cerebellum/brainstem)', TABLE_CELL),
         Paragraph('TENTORIAL NOTCH = gap where brainstem passes; site of uncal herniation & CN III compression', TABLE_CELL)],
        [Paragraph('Falx cerebelli', TABLE_CELL), Paragraph('Posterior fossa midline vertical fold', TABLE_CELL),
         Paragraph('Left & right cerebellar hemispheres', TABLE_CELL), Paragraph('Occipital sinus runs in its root', TABLE_CELL)],
        [Paragraph('Diaphragma sellae', TABLE_CELL), Paragraph('Horizontal over sella turcica', TABLE_CELL),
         Paragraph('Covers pituitary fossa; pituitary stalk passes through it', TABLE_CELL),
         Paragraph('Pituitary adenoma may bulge through this; restricts expansion of pituitary', TABLE_CELL)],
    ]

    septa_tbl = Table(septa_rows, colWidths=[W * 0.14, W * 0.24, W * 0.22, W * 0.38])
    septa_tbl.setStyle(TableStyle([
        ('BACKGROUND', (0, 0), (-1, 0), C_PURPLE),
        ('ROWBACKGROUNDS', (0, 1), (-1, -1), [C_LIGHTPURPLE, C_WHITE]),
        ('GRID', (0, 0), (-1, -1), 0.4, colors.lightgrey),
        ('VALIGN', (0, 0), (-1, -1), 'MIDDLE'),
        ('TOPPADDING', (0, 0), (-1, -1), 3),
        ('BOTTOMPADDING', (0, 0), (-1, -1), 3),
        ('LEFTPADDING', (0, 0), (-1, -1), 4),
        ('RIGHTPADDING', (0, 0), (-1, -1), 4),
    ]))
    story.append(septa_tbl)
    story.append(Spacer(1, 5))

    # Cavernous sinus diagram + sinuses table
    story.append(ColorBanner('CAVERNOUS SINUS (★★★ HIGHEST YIELD)', W, height=14, bg=C_PURPLE))
    story.append(Spacer(1, 3))

    cav_diag_tbl = Table(
        [[CavernousSinusDiagram(w=int(W * 0.45), h=170),
          Table([
              [Paragraph('<b>CONTENTS - MEMORIZE</b>', TABLE_HDR)],
              [Paragraph('<b>INSIDE the sinus:</b>', BOLD_SM)],
              [Paragraph('• Internal Carotid Artery (ICA) - with sympathetic plexus', TABLE_CELL)],
              [Paragraph('• CN VI (Abducens) - MOST VULNERABLE to compression', TABLE_CELL)],
              [Paragraph('<b>LATERAL WALL (superior to inferior):</b>', BOLD_SM)],
              [Paragraph('• CN III (Oculomotor)', TABLE_CELL)],
              [Paragraph('• CN IV (Trochlear)', TABLE_CELL)],
              [Paragraph('• V1 (Ophthalmic branch CN V)', TABLE_CELL)],
              [Paragraph('• V2 (Maxillary branch CN V)', TABLE_CELL)],
              [Paragraph('<b>Mnemonic: "O TOM CAT" or "3, 4, V1, V2 in wall; 6 + ICA inside"</b>', MNEMONIC)],
              [Paragraph('<b>CONNECTIONS:</b>', BOLD_SM)],
              [Paragraph('• Angular/facial vein → superior ophthalmic v. → cavernous sinus (infection spread!)', TABLE_CELL)],
              [Paragraph('• Intercavernous sinuses (L↔R communication)', TABLE_CELL)],
              [Paragraph('• → Inferior petrosal sinus → Internal jugular vein', TABLE_CELL)],
              [Paragraph('• → Superior petrosal sinus → Sigmoid sinus', TABLE_CELL)],
              [Paragraph('<b>CAVERNOUS SINUS THROMBOSIS:</b>', BOLD_SM)],
              [Paragraph('Proptosis + chemosis + painful ophthalmoplegia; CN VI palsy FIRST; bilateral (intercavernous); source = facial/sinus infection', TABLE_CELL)],
          ], colWidths=[W * 0.51])
        ]],
        colWidths=[W * 0.46, W * 0.54]
    )
    cav_diag_tbl.setStyle(TableStyle([
        ('VALIGN', (0, 0), (-1, -1), 'TOP'),
        ('LEFTPADDING', (0, 0), (-1, -1), 2),
        ('RIGHTPADDING', (0, 0), (-1, -1), 2),
    ]))
    story.append(cav_diag_tbl)
    story.append(Spacer(1, 5))

    # All dural sinuses table
    story.append(ColorBanner('ALL DURAL VENOUS SINUSES', W, height=14, bg=C_BLUE))
    story.append(Spacer(1, 3))

    sinuses_data = [
        [Paragraph('<b>Sinus</b>', TABLE_HDR),
         Paragraph('<b>Location</b>', TABLE_HDR),
         Paragraph('<b>Drains Into</b>', TABLE_HDR),
         Paragraph('<b>Clinical Significance</b>', TABLE_HDR)],
        [Paragraph('Superior Sagittal', TABLE_CELL), Paragraph('Superior border of falx cerebri', TABLE_CELL),
         Paragraph('Confluence of sinuses', TABLE_CELL), Paragraph('Receives bridging veins; most common site DVT → ↑ICP, seizures', TABLE_CELL)],
        [Paragraph('Inferior Sagittal', TABLE_CELL), Paragraph('Inferior border of falx cerebri', TABLE_CELL),
         Paragraph('Straight sinus', TABLE_CELL), Paragraph('Joins great cerebral vein at the straight sinus', TABLE_CELL)],
        [Paragraph('Straight Sinus', TABLE_CELL), Paragraph('Junction: falx cerebri + tentorium', TABLE_CELL),
         Paragraph('Confluence of sinuses', TABLE_CELL), Paragraph('Receives: inferior sagittal sinus + Vein of Galen', TABLE_CELL)],
        [Paragraph('Confluence (Torcular)', TABLE_CELL), Paragraph('Internal occipital protuberance', TABLE_CELL),
         Paragraph('Transverse sinuses', TABLE_CELL), Paragraph('Meeting point of sup. sagittal, straight, occipital sinuses', TABLE_CELL)],
        [Paragraph('Transverse', TABLE_CELL), Paragraph('Posterior edge of tentorium', TABLE_CELL),
         Paragraph('Sigmoid sinus', TABLE_CELL), Paragraph('Bilateral; thrombosis → ↑ICP, headache', TABLE_CELL)],
        [Paragraph('Sigmoid', TABLE_CELL), Paragraph('S-shaped; petrous temporal bone', TABLE_CELL),
         Paragraph('Internal jugular vein (jugular foramen)', TABLE_CELL), Paragraph('Near mastoid; mastoiditis can cause thrombosis (Gradenigo syndrome area)', TABLE_CELL)],
        [Paragraph('Cavernous', TABLE_CELL), Paragraph('Sides of sella turcica', TABLE_CELL),
         Paragraph('Via inf. petrosal sinus → IJV; via sup. petrosal → sigmoid', TABLE_CELL), Paragraph('See above - highest yield sinus', TABLE_CELL)],
        [Paragraph('Superior Petrosal', TABLE_CELL), Paragraph('Superior petrous bone', TABLE_CELL),
         Paragraph('Cavernous → sigmoid sinus', TABLE_CELL), Paragraph('Bridge between cavernous and sigmoid sinuses', TABLE_CELL)],
        [Paragraph('Inferior Petrosal', TABLE_CELL), Paragraph('Inferior petrous bone', TABLE_CELL),
         Paragraph('Cavernous → IJV', TABLE_CELL), Paragraph('Also receives labyrinthine veins from inner ear', TABLE_CELL)],
        [Paragraph('Occipital', TABLE_CELL), Paragraph('Root of falx cerebelli', TABLE_CELL),
         Paragraph('Confluence of sinuses', TABLE_CELL), Paragraph('Connects marginal sinus to confluence', TABLE_CELL)],
        [Paragraph('Marginal', TABLE_CELL), Paragraph('Around foramen magnum', TABLE_CELL),
         Paragraph('Vertebral venous plexus', TABLE_CELL), Paragraph('Connects dural sinuses to vertebral venous system', TABLE_CELL)],
    ]

    sinuses_tbl = Table(sinuses_data, colWidths=[W * 0.15, W * 0.22, W * 0.25, W * 0.38])
    sinuses_tbl.setStyle(TableStyle([
        ('BACKGROUND', (0, 0), (-1, 0), C_BLUE),
        ('ROWBACKGROUNDS', (0, 1), (-1, -1), [C_LIGHTBLUE, C_WHITE]),
        ('GRID', (0, 0), (-1, -1), 0.4, colors.lightgrey),
        ('VALIGN', (0, 0), (-1, -1), 'MIDDLE'),
        ('TOPPADDING', (0, 0), (-1, -1), 2),
        ('BOTTOMPADDING', (0, 0), (-1, -1), 2),
        ('LEFTPADDING', (0, 0), (-1, -1), 4),
        ('RIGHTPADDING', (0, 0), (-1, -1), 4),
    ]))
    story.append(sinuses_tbl)
    story.append(Spacer(1, 5))

    # ── FINAL QUICK-REVIEW FLASH BOX ──────────────────────────────────────────
    story.append(ColorBanner('RAPID-FIRE USMLE PEARLS', W, height=14, bg=C_GOLD))
    story.append(Spacer(1, 3))

    pearls = [
        '★ CN III palsy = "DOWN and OUT" eye + PTOSIS + DILATED pupil (parasympathetics on outside = compressed first)',
        '★ CN IV = only CN exiting DORSALLY; only CN with complete decussation; palsy = head tilt AWAY from lesion',
        '★ PURKINJE CELLS = sole output of cerebellar cortex; always INHIBITORY (GABA); receive mossy (simple spikes) & climbing (complex spikes) input',
        '★ FASTIGIAL nucleus = only deep nucleus whose efferents exit via INFERIOR cerebellar peduncle (all others = SUPERIOR)',
        '★ MIDDLE cerebellar peduncle = AFFERENT ONLY (pontine nuclei → cerebellum); largest peduncle',
        '★ SUPERIOR cerebellar peduncle = primarily OUTPUT (decussates in midbrain under inferior colliculus)',
        '★ CAVERNOUS SINUS lateral wall (superior→inferior): CN III, IV, V1, V2 | INSIDE: ICA + CN VI',
        '★ CN VI is MOST VULNERABLE in cavernous sinus (runs freely, not protected by lateral wall)',
        '★ Facial vein → superior ophthalmic vein → cavernous sinus: route of intracranial infection spread from face',
        '★ WEBER = ventral midbrain (crus) = CN III + contralateral hemiplegia | BENEDIKT = tegmentum = CN III + contralateral tremor',
        '★ PARINAUD = superior colliculi/pretectum: upward gaze palsy + light-near dissociation + convergence-retraction nystagmus (pineal gland tumor)',
        '★ DANDY-WALKER = absent vermis + cystic 4th ventricle + ↑ICP | JOUBERT = absent vermis + molar tooth sign on MRI',
        '★ Cerebellar ataxia = IPSILATERAL; Romberg NEGATIVE (falls with eyes OPEN too); vs sensory ataxia = Romberg POSITIVE',
        '★ PICA infarct = Wallenberg (lateral medullary) syndrome: ipsilateral face + contralateral body pain/temp loss + ataxia + Horner + dysphagia',
        '★ Vein of Galen → Straight sinus → Confluence → Transverse → Sigmoid → Internal Jugular Vein',
    ]

    pearl_rows = [[Paragraph(p, BODY_SM)] for p in pearls]
    pearl_tbl = Table(pearl_rows, colWidths=[W])
    pearl_tbl.setStyle(TableStyle([
        ('ROWBACKGROUNDS', (0, 0), (-1, -1), [C_LIGHTYELLOW, C_WHITE]),
        ('LEFTPADDING', (0, 0), (-1, -1), 6),
        ('RIGHTPADDING', (0, 0), (-1, -1), 6),
        ('TOPPADDING', (0, 0), (-1, -1), 2),
        ('BOTTOMPADDING', (0, 0), (-1, -1), 2),
        ('BOX', (0, 0), (-1, -1), 0.8, C_GOLD),
        ('LINEBELOW', (0, 0), (-1, -2), 0.2, colors.lightgrey),
    ]))
    story.append(pearl_tbl)
    story.append(Spacer(1, 6))

    # Footer note
    story.append(Paragraph(
        'USMLE Study Sheet — Midbrain, Cerebellum & Dural Sinuses | Generated by Orris AI | Good luck on your exam!',
        make_style('footer', fontSize=6.5, leading=9, textColor=colors.grey,
                   fontName='Helvetica-Oblique', alignment=TA_CENTER)
    ))

    doc.build(story)
    print(f"PDF written to: {path}")


if __name__ == '__main__':
    build_pdf('/tmp/workspace/usmle-neuro/USMLE_Neuro_StudySheet.pdf')

Running Command

cd /tmp/workspace/usmle-neuro && python3 build_sheet.py 2>&1

Running Command

ls -lh /tmp/workspace/usmle-neuro/USMLE_Neuro_StudySheet.pdf

Your 3-page printable USMLE study sheet is ready:

USMLE Neuro StudySheet

PDF Document · PDF

Here's what's packed into the 3 pages:

Page 1 - Midbrain

Two colour-coded cross-section diagrams side by side: Rostral midbrain (superior colliculus level) and Caudal midbrain (inferior colliculus level) - each showing the tectum, aqueduct, nuclei, substantia nigra, crus cerebri, red nucleus, and exiting cranial nerves
Complete nuclei table with every USMLE pearl (CN III, Edinger-Westphal, CN IV, Red nucleus, Substantia nigra, Mesencephalic V)
Clinical syndromes table: Weber, Benedikt, Claude, Parinaud, Uncal herniation - all with lesion site, signs, and causes

Page 2 - Cerebellum

Cerebellar peduncles diagram (Superior/Middle/Inferior) with direction of fiber flow
Functional subdivisions (Vestibulocerebellum / Spinocerebellum / Pontocerebellum)
Cortical layers table (Molecular/Purkinje/Granular) with neurotransmitters
Deep cerebellar nuclei: Don't Eat Greasy Foods (Dentate/Emboliform/Globose/Fastigial) with peduncle of exit
Mossy vs climbing fiber inputs
Signs of cerebellar disease + Congenital disorders (Joubert vs Dandy-Walker vs Friedreich's)

Page 3 - Dural Sinuses

Dural septa table (Falx cerebri / Tentorium / Falx cerebelli / Diaphragma sellae)
Cavernous sinus diagram with colour-coded lateral wall vs inside contents
Complete dural venous sinuses table (all 12 sinuses)
15 rapid-fire USMLE pearls in a boxed quick-review section at the bottom

Good luck tomorrow!

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