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Here is a complete, exam-ready breakdown of all 16 FMGE Anatomy Topics – January 2026:
🧠 FMGE Anatomy – Jan 2026: Complete Topic Notes
1. 🔬 Bowman Capsule (IBQ)
Structure: Double-walled epithelial cup surrounding the glomerulus; forms the renal corpuscle.
| Layer | Cell Type | Function |
|---|---|---|
| Parietal layer | Simple squamous epithelium | Structural boundary |
| Visceral layer | Podocytes (with foot processes = pedicels) | Filtration via slit diaphragm |
- Urinary/Bowman's space = space between visceral and parietal layers → collects filtrate
- Hydrostatic pressure in Bowman's capsule ≈ 18 mmHg → opposes filtration (↓ GFR)
- Filtration barrier = fenestrated endothelium + glomerular basement membrane (GBM) + slit diaphragm
IBQ Key: Bowman's capsule pressure opposes GFR; the visceral layer is made of podocytes, not squamous cells.
2. 🧠 Brain Image Marking – Corpus Callosum (IBQ)
Largest white matter commissure connecting the two cerebral hemispheres.
Parts (anterior → posterior):
| Part | Location | Function |
|---|---|---|
| Rostrum | Anteroinferior | Connects orbital frontal cortices |
| Genu | Anterior bend | Prefrontal connections (forceps minor) |
| Body (Trunk) | Middle | Motor & sensory areas |
| Splenium | Posterior | Visual cortex connections (forceps major) |
- Lies above the septum pellucidum and fornix
- Identified on midsagittal MRI as a C-shaped white matter structure
- Agenesis of corpus callosum → Bat-wing appearance of lateral ventricles (Probst bundles)
IBQ Key: On sagittal brain image → corpus callosum is the curved white band above the lateral ventricles. Splenium = most posterior.
3. ✋ Dorsal Interossei Muscles (IBQ)
Location: Between metacarpals in the hand (or metatarsals in the foot).
Hand Dorsal Interossei:
- Four muscles, each bipennate
- Origin: Adjacent sides of two metacarpals
- Insertion: Extensor hood + base of proximal phalanx
- Action: ABduct fingers from the middle finger axis (mnemonic: DAB – Dorsal ABduct)
- Nerve: Deep branch of ulnar nerve (C8, T1)
- Test: Spread fingers apart against resistance
Foot Dorsal Interossei:
- Abduct 2nd–4th toes relative to axis through 2nd toe
- 1st dorsal interosseus abducts the 2nd toe medially; 2nd–4th abduct 2nd–4th toes laterally
IBQ Key: DAB = Dorsal ABduct; PAD = Palmar ADduct. Nerve = deep ulnar nerve.
4. 🔙 Back Muscles Marking (IBQ)
Three layers of intrinsic back muscles:
| Layer | Muscle Group | Innervation |
|---|---|---|
| Superficial | Trapezius, Latissimus dorsi | Cranial nerve XI; thoracodorsal nerve |
| Intermediate | Serratus posterior superior/inferior | Intercostal nerves |
| Deep (Intrinsic) | Erector spinae (iliocostalis, longissimus, spinalis), Transversospinalis (semispinalis, multifidus, rotatores) | Dorsal rami of spinal nerves |
Erector spinae (iliocostalis + longissimus + spinalis) = prime extensors of the vertebral column
Multifidus = most important for segmental stabilization; tested in low back pain
IBQ Key: All intrinsic back muscles = dorsal rami innervation; Serratus posterior = extrinsic (ventral rami).
5. 🍽️ Esophageal Constrictions
Three physiological narrowings (clinically important for foreign body impaction & carcinoma sites):
| Constriction | Location | Level | Distance from Incisor |
|---|---|---|---|
| 1st (Upper) | Pharyngoesophageal junction – cricopharyngeus | C6 | ~15 cm |
| 2nd (Middle) | Aortic arch + Left main bronchus | T4–T5 | ~25 cm |
| 3rd (Lower) | Esophageal hiatus in diaphragm | T10 | ~40 cm |
- Narrowest = Upper (cricopharyngeus) constriction
- Foreign bodies most commonly lodge at upper constriction
- Carcinoma most common at middle third
IBQ Key: 15–25–40 cm from incisor teeth; narrowest = cricopharyngeus at C6.
6. 🗣️ Wernicke's Aphasia
Sensory/Receptive aphasia – caused by damage to Wernicke's area (posterior superior temporal gyrus, Brodmann area 22) in the dominant (left) hemisphere.
| Feature | Wernicke's Aphasia | Broca's Aphasia |
|---|---|---|
| Fluency | Fluent | Non-fluent |
| Comprehension | Impaired | Intact |
| Repetition | Impaired | Impaired |
| Paraphasias | Yes (phonemic + semantic) | Less common |
| Awareness | Patient unaware of errors | Frustrated |
| Location | Posterior temporal | Inferior frontal |
- Connected to Broca's area via the arcuate fasciculus → damage to this = conduction aphasia
IBQ Key: Fluent speech with poor comprehension → Wernicke's. Patient "jargon" but cannot understand language.
7. ❤️ Anterior Ventricular Artery (IBQ)
The anterior interventricular artery (AIVA) = Left Anterior Descending (LAD) artery:
-
Branch of: Left coronary artery (LCA)
-
Runs in: Anterior interventricular groove
-
Supplies:
- Anterior wall of left ventricle
- Anterior 2/3 of interventricular septum
- Apex of heart
- Right bundle branch + anterior fascicle of left bundle branch
-
"Widow maker" – occlusion → anterior MI (ST elevation in V1–V4)
-
Also gives off diagonal branches and septal perforators
IBQ Key: LAD = anterior interventricular artery; supplies anterior 2/3 of septum; occlusion → anterior STEMI.
8. 🩸 Cavernous Sinus Infection
Cavernous sinus = paired venous sinuses on either side of the sella turcica.
Contents (from medial to lateral along lateral wall):
Mnemonic: "O TOM CAT" or "Oh Three Can Abduct"
- Lateral wall: CN III (oculomotor), CN IV (trochlear), CN V1 (ophthalmic), CN V2 (maxillary)
- Within sinus: CN VI (abducens) + Internal Carotid Artery + sympathetic plexus
Cavernous Sinus Thrombosis (CST):
- Cause: Retrograde spread via valveless ophthalmic veins from:
- Dental infections (upper teeth), sinusitis, orbital/facial cellulitis
- Mortality: 30–40% (up to 100% if untreated)
- Features: Proptosis, chemosis, painful ophthalmoplegia, fever, meningism
- Specific: CN VI palsy earliest (abducens is most medial → first compressed)
Danger area of face = upper lip/nasal region → drains via facial vein → ophthalmic vein → cavernous sinus
IBQ Key: CN III, IV, V1, V2 in lateral wall; CN VI + ICA inside sinus; earliest CN affected = CN VI.
9. 📸 Chest X-ray Marking (IBQ)
Normal CXR landmarks:
| Structure | Right side | Left side |
|---|---|---|
| Hilum | Lower (R hilum) | Higher (L hilum normally 0.5–1.5 cm higher) |
| Cardiothoracic ratio | < 0.5 normal | |
| Right heart border | RA + SVC + IVC | |
| Left heart border | LA (top), LV (bottom) | |
| Trachea | Midline, slight deviation at carina (right) | |
| Aortic knuckle | — | Left, below arch |
| Costophrenic angles | Acute (sharp) = normal |
- PA vs AP: Heart appears larger in AP (portable CXR) due to magnification
- Left diaphragm is lower than right (liver elevates right)
IBQ Key: Right hilum is lower; left heart border = LV forming most; CT ratio < 0.5 = normal.
10. 👂 Tragal Pointer (IBQ)
- A landmark used in parotid surgery to identify the facial nerve (CN VII)
- The facial nerve exits the stylomastoid foramen and lies 1 cm deep and inferior to the tip of the tragal cartilage
- The pointer = tip of tragal cartilage
Other landmarks for facial nerve:
- Tragal pointer (1 cm deep and medial)
- Tympanomastoid suture line (nerve is just below)
- Posterior belly of digastric (nerve crosses its superficial surface)
IBQ Key: Tragal pointer → facial nerve is 1 cm deep and anteromedial to it; key landmark in parotidectomy.
11. △ Submental Triangle (IBQ)
Part of the anterior triangle of the neck.
| Boundary | Structure |
|---|---|
| Sides (lateral) | Anterior bellies of digastric muscles |
| Base (inferior) | Hyoid bone |
| Floor | Mylohyoid muscle |
| Apex | Chin (symphysis menti) |
Contents:
- Submental lymph nodes
- Small veins forming the anterior jugular vein
- (No major arteries or nerves)
Clinical: Submental lymph nodes drain the tip of tongue, lower lip, floor of mouth, chin → first station in oral cancer spread.
IBQ Key: Submental triangle = unpaired (midline); floor = mylohyoid; contents = submental lymph nodes.
12. 👅 Lingual Swelling (IBQ)
Development of the tongue:
| Swelling | Contribution | Origin |
|---|---|---|
| Two lateral lingual swellings | Anterior 2/3 of tongue (body) | 1st pharyngeal arch (mandibular) |
| Tuberculum impar (median tongue bud) | Small part of anterior 2/3 | 1st pharyngeal arch |
| Copula (Hypobranchial eminence) | Posterior 1/3 (root) | 2nd, 3rd, 4th arches |
| Epiglottic swelling | Epiglottis | 4th arch |
- Foramen cecum = junction between anterior 2/3 and posterior 1/3 → remnant of thyroglossal duct
- Thyroglossal cyst = remnant of thyroglossal duct; moves with tongue protrusion/swallowing
IBQ Key: Anterior 2/3 from 1st arch lateral lingual swellings; posterior 1/3 from copula (2nd–4th arch). Junction = sulcus terminalis.
13. 🔗 Ansa Cervicalis
A loop of nerves from the cervical plexus (C1–C3) that innervates the infrahyoid (strap) muscles.
Components:
| Root | Fibers | Path |
|---|---|---|
| Superior root | C1 fibers hitchhiking on CN XII | Descends from hypoglossal nerve |
| Inferior root | C2, C3 fibers | Descends lateral to IJV |
Muscles innervated (3 of 4 strap muscles):
- Sternohyoid, Sternothyroid, Omohyoid
- (Thyrohyoid is innervated by C1 via CN XII directly, not via ansa loop)
Clinical use: Ansa cervicalis–RLN anastomosis used to restore voice in advanced thyroid cancer with RLN sacrifice.
IBQ Key: C1–C3; superior root via CN XII; innervates sternohyoid, sternothyroid, omohyoid; thyrohyoid = C1 via CN XII (not ansa proper).
14. 🩸 Perforated Bleeding Ulcer
Posterior duodenal ulcer bleeds; anterior duodenal ulcer perforates.
| Type | Location | Complication | Vessel involved |
|---|---|---|---|
| Posterior DU | Posterior wall of 1st part of duodenum | Bleeding | Gastroduodenal artery (GDA) |
| Anterior DU | Anterior wall of 1st part | Perforation → air under diaphragm | — |
- GDA → lies behind 1st part of duodenum → eroded by posterior DU → massive hemorrhage
- Treatment: Underrunning (ligation) of GDA via anterior duodenotomy
- Posterior gastric ulcer perforates into lesser sac (not free peritoneal cavity)
Mnemonic: "PAP" – Posterior = bleed (Artery), Anterior = Perforate
IBQ Key: Posterior DU bleeds from GDA; anterior DU perforates. Surgery = underrun GDA.
15. 🦵 Great Saphenous Vein (IBQ)
Longest vein in the body.
Course:
- Begins at medial end of dorsal venous arch of foot
- Passes anterior to medial malleolus
- Runs up the medial aspect of leg and thigh
- Passes through saphenous opening (fossa ovalis) in fascia lata
- Drains into femoral vein at saphenofemoral junction (SFJ), ~3.5 cm below and lateral to pubic tubercle
Relations at the ankle: Accompanied by saphenous nerve (from femoral nerve) — closely adjacent
Relations at knee: Posteromedial (relation to saphenous nerve)
Tributaries at SFJ (6 tributaries):
- Superficial epigastric, superficial circumflex iliac, superficial external pudendal, deep external pudendal, posterior medial thigh vein, anterior medial thigh vein
Clinical: Used for coronary artery bypass graft (CABG), venous cutdown at ankle; varicose veins when valves fail.
IBQ Key: Anterior to medial malleolus; accompanied by saphenous nerve; drains into femoral vein via saphenous opening.
16. 🦷 Mandibular Foramen Contents
Two foramina in the mandible:
Mandibular Foramen (on medial ramus):
- Location: Medial surface of ramus of mandible; guarded anteriorly by lingula (bony spine)
- Contents:
- Inferior alveolar nerve (branch of V3)
- Inferior alveolar artery (branch of maxillary artery)
- Inferior alveolar vein
- Clinical: Site of inferior alveolar nerve block (dental anesthesia)
Mental Foramen (on body of mandible):
- Location: Below 2nd premolar tooth (between 1st and 2nd premolar in some)
- Contents:
- Mental nerve (terminal branch of inferior alveolar nerve)
- Mental artery and vein
IBQ Key: Mandibular foramen = inferior alveolar nerve + vessels; lingula guards it; mental foramen below 2nd premolar = mental nerve exits.
📋 Quick Revision Table – All 16 Topics
| # | Topic | Key Point |
|---|---|---|
| 1 | Bowman capsule | Visceral layer = podocytes; pressure ≈ 18 mmHg opposes GFR |
| 2 | Corpus callosum | Largest commissure; parts: rostrum→genu→body→splenium |
| 3 | Dorsal interossei | DAB (Dorsal ABduct); deep ulnar nerve C8,T1 |
| 4 | Back muscles | Intrinsic = dorsal rami; erector spinae = main extensors |
| 5 | Esophageal constrictions | 15/25/40 cm; narrowest = cricopharyngeus (C6) |
| 6 | Wernicke's aphasia | Fluent, poor comprehension; posterior superior temporal |
| 7 | Anterior ventricular artery | LAD; supplies anterior 2/3 septum; widow maker |
| 8 | Cavernous sinus | III, IV, V1, V2 in wall; CN VI + ICA inside; VI palsy earliest |
| 9 | Chest X-ray | CT ratio <0.5; R hilum lower; left border = LV |
| 10 | Tragal pointer | Facial nerve 1 cm deep anteromedial to tragal tip |
| 11 | Submental triangle | Floor = mylohyoid; contents = submental lymph nodes |
| 12 | Lingual swelling | Anterior 2/3 = 1st arch; posterior 1/3 = copula (2nd–4th arch) |
| 13 | Ansa cervicalis | C1–C3 loop; innervates 3 strap muscles (not thyrohyoid) |
| 14 | Perforated bleeding ulcer | Posterior DU bleeds (GDA); anterior DU perforates |
| 15 | Great saphenous vein | Anterior to medial malleolus; drains into femoral vein |
| 16 | Mandible foramen content | Mandibular foramen = inferior alveolar nerve+vessels; mental foramen = mental nerve |
Sources: Gray's Anatomy for Students, Histology: A Text and Atlas (Ross), Neuroscience Exploring the Brain, Bradley & Daroff's Neurology, Cummings Otolaryngology, Schwartz's Principles of Surgery, Guyton & Hall Physiology.You've run out of free credits. Sign up for a free account to continue using Orris.
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