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Brachial Plexus - Clinical Anatomy (BDC Style)

Note: B.D. Chaurasia's Human Anatomy is not in the library, but the content below is compiled from Gray's Anatomy for Students, Neuroanatomy through Clinical Cases (3rd ed.), and S. Das Manual of Clinical Surgery - all of which present brachial plexus anatomy in the same systematic style as BDC.

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Overview

• R = Roots
• T = Trunks
• D = Divisions
• C = Cords
• B = Branches

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Diagram of the Brachial Plexus

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1. ROOTS (Anterior Rami)

• C5, C6, C7, C8, T1 form the roots (anterior rami)
• The roots receive gray rami communicantes from the sympathetic trunk (postganglionic sympathetic fibers)
• The roots pass between the anterior scalene and middle scalene muscles
• They lie superior and posterior to the subclavian artery in the posterior triangle of the neck

Branches from Roots:

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2. TRUNKS

Branches from Trunks:

The trunks cross the base of the posterior triangle and are visible there along with dorsal scapular, long thoracic, nerve to subclavius, and suprascapular nerves.

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3. DIVISIONS

• No peripheral nerves originate directly from the divisions
• Anterior divisions supply the anterior (flexor) compartments
• Posterior divisions supply the posterior (extensor) compartments

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4. CORDS

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5. BRANCHES (Terminal and Collateral)

Branches of the Lateral Cord:

Branches of the Medial Cord:

The musculocutaneous nerve, lateral root of median nerve, median nerve, medial root of median nerve, and ulnar nerve form an "M" over the third part of the axillary artery - a key landmark to identify plexus components in the axilla.

Branches of the Posterior Cord:

Terminal Nerve Summary:

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6. MEDIAN NERVE - Special Note

• All forearm flexors except FCU and medial half of FDP
• Three thenar muscles (APB, FPB, opponens pollicis)
• Lateral two lumbricals
• Sensory: palmar surface of lateral 3.5 digits + lateral palm

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7. CLINICAL ANATOMY (Applied)

A. ERB-DUCHENNE PARALYSIS (Upper Brachial Plexus Lesion - C5, C6)

• Adults: fall of weight on shoulder, motorcycle accident
• Neonates: difficult labour (shoulder dystocia) - most common type

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B. KLUMPKE'S PARALYSIS (Lower Brachial Plexus Lesion - C8, T1)

• Adults: person falling and clutching an object, missing a foothold on a moving vehicle
• Neonates: breech presentation with arms above head

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C. COMPLETE BRACHIAL PLEXUS LESION (C5-T1)

• Rare, occurs after severe accidents
• Complete paralysis of the upper limb except the upper arm (supplied by C3, C4, C5 via supraclavicular nerves)
• Complete anaesthesia of the entire limb except the upper arm
• Long thoracic nerve (to serratus anterior) and dorsal scapular nerve (to rhomboids) may escape

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D. OTHER IMPORTANT CLINICAL POINTS

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E. RELATIONS IN THE POSTERIOR TRIANGLE (Supraclavicular Part)

• Roots pass between anterior scalene (front) and middle scalene (behind)
• Subclavian artery passes between anterior scalene and rib I (anterior to the plexus roots)
• Erb's point - where C5 and C6 roots unite = most vulnerable point in upper trunk injury; located about 2.5 cm above the clavicle at the posterior border of the sternocleidomastoid

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F. RELATIONS IN THE AXILLA (Infraclavicular Part)

• Cords are named relative to the second part of the axillary artery
• The cords split into terminal branches at the lateral border of pectoralis minor
• The inferior trunk rests directly on the first rib and is compressed in a cervical rib

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• Gray's Anatomy for Students, pp. 858-865 (brachial plexus, roots, trunks, cords, branches)
• Neuroanatomy through Clinical Cases, 3rd ed., pp. 382-383 (simplified schematics)
• S. Das Manual of Clinical Surgery, 13th ed., pp. 140-141 (Erb-Duchenne and Klumpke's paralysis)

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Middle Ear Cavity (Tympanic Cavity) - Atlas Anatomy

Sources: Color Atlas of Human Anatomy, Vol. 3 (Platzer/Thieme), Gray's Anatomy for Students, Shambaugh Surgery of the Ear, and Cummings Otolaryngology.

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What is the Middle Ear?

• The eardrum (tympanic membrane) on the outside (lateral side)
• The inner ear (cochlea + labyrinth) on the inside (medial side)

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Parts of the Middle Ear

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Atlas Diagrams

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6 Walls of the Middle Ear (Easy Memory Aid: "T J M M A L")

1. ROOF - Tegmental Wall (T)

• Formed by the tegmen tympani - a very thin plate of bone on the petrous temporal bone
• Separates the middle ear from the middle cranial fossa (brain above)
• Clinical: In otitis media, pus can erode through this roof → meningitis or temporal lobe abscess

2. FLOOR - Jugular Wall (J)

• A thin layer of bone separating the cavity from the internal jugular vein (jugular bulb) below
• Near the medial border of the floor: a small aperture for the tympanic branch of CN IX (Jacobson's nerve) to enter
• Clinical: A high-riding jugular bulb can bulge through the floor

3. LATERAL WALL - Membranous Wall (M)

• Formed almost entirely by the tympanic membrane (eardrum)
• The pars tensa (main part, ~10 mm diameter) occupies most of the wall
• The pars flaccida (Shrapnell's membrane) - the small loose part above, between the anterior and posterior malleal folds, at the notch of Rivinus
• The upper portion of this wall (over the epitympanic recess) is bony

4. MEDIAL WALL - Labyrinthine Wall (M)

5. ANTERIOR WALL - Carotid Wall (A)

• Lower part: thin bone separating cavity from the internal carotid artery
• Superiorly, deficient because of two openings:
  1. Large opening for the pharyngotympanic (Eustachian) tube - equalizes pressure
  2. Smaller opening for the canal of tensor tympani muscle
• The chorda tympani nerve exits through this wall via the canal of Huguier (petrotympanic fissure)

6. POSTERIOR WALL - Mastoid Wall (L = posterior/back)

• Partially complete
• Key features:
  1. Aditus to mastoid antrum (superiorly) - the opening connecting middle ear to mastoid air cells
  2. Pyramidal eminence - a small bony projection through which the tendon of the stapedius muscle enters
  3. Facial recess - between the facial nerve and chorda tympani
  4. Sinus tympani - medial to the pyramidal eminence, bounded by the ponticulus (above) and subiculum (below); an important surgical landmark

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Contents of the Middle Ear

A. The Three Ossicles (Auditory Bones)

B. Two Muscles of the Middle Ear

Clinical note from Color Atlas Vol. 3: Facial nerve palsy paralyzes the stapedius → loss of sound dampening → hyperacusis (oversensitivity/intolerance to sounds)

C. Nerves Passing Through

1. Chorda tympani nerve (branch of CN VII):
   • Enters through the posterior wall, lateral to pyramidal eminence
   • Crosses the middle ear running lateral to the long process of incus and medial to the neck of malleus
   • Exits anteriorly through the canal of Huguier into the petrotympanic fissure
   • Carries taste from anterior 2/3 of tongue + parasympathetic to sublingual and submandibular glands
   • Clinical: Damaged in middle ear surgery → loss of taste on anterior tongue
2. Tympanic branch of CN IX (Jacobson's nerve):
   • Enters via the floor of the tympanic cavity
   • Spreads over the promontory as the tympanic plexus
   • Continues as the lesser petrosal nerve → otic ganglion → parotid gland (parasympathetic)
3. Facial nerve (CN VII):
   • Runs in its bony canal (fallopian canal) along the medial wall (horizontal/tympanic segment)
   • NOT in free contact with the cavity but forms the "prominence of the facial canal"
   • Makes two bends: 1st genu (geniculate ganglion, anterosuperior) → horizontal segment → 2nd genu (posterior to oval window) → descends in the mastoid

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Communications of the Middle Ear

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The Pharyngotympanic (Eustachian) Tube

• Connects middle ear to nasopharynx
• Opens on the anterior wall of the middle ear
• In adults: 1/3 bony (near middle ear) + 2/3 cartilaginous (near nasopharynx); angled downward to nasopharynx
• In children: shorter, wider, more horizontal → prone to otitis media (infections track up easily)
• Function: Equalize air pressure on both sides of the eardrum (e.g., swallowing/yawning "pops" the ear)
• Opened by tensor veli palatini and levator veli palatini muscles (CN V3 and CN X)

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Clinical Points (Easy Summary)

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• Color Atlas of Human Anatomy Vol. 3 (Nervous System & Sense Organs), pp. 514-522 (Platzer/Thieme) - all atlas diagrams
• Gray's Anatomy for Students, pp. 1098-1103 (middle ear walls, contents, pharyngotympanic tube)
• Shambaugh Surgery of the Ear, pp. 800-802 (tympanic cavity divisions, mesotympanum, chorda tympani)

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MBBS First Year Biochemistry - Paper-wise Syllabus Distribution (MPMSU)

Note: B.D. Chaurasia is not available in the library's biochemistry collection. The syllabus below is sourced directly from MPMSU's Adhoc Board of Studies document (as applicable to affiliated colleges including NSCBMC, Jabalpur) and the RIMS syllabus document used by MPMSU-affiliated institutes. The R-24 scheme (Batch 2024 onwards) follows NMC guidelines dated 12-09-2024.

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Scheme of Examination - Overview

• Duration of each theory paper: 3 hours (R-24 scheme)
• Two examinations per year: Main and Supplementary

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PAPER I - Topics (100 Marks)

Paper I Focus: Chemistry (structure) of all biomolecules + enzymes + fundamental concepts + clinical chemistry tests

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PAPER II - Topics (100 Marks)

Paper II Focus: Metabolism of all biomolecules + molecular biology + applied/clinical aspects

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Question Paper Format (R-24 Scheme - NMC 2024)

Integrated topics examined in SAQs include: Anaemia, Ischaemic heart disease, Diabetes mellitus, Tuberculosis, Hypertension, and Thyroid disorders.

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Practical Examination (100 Marks)

Practicals Covered:

• Colorimetry and spectrophotometry
• Flame photometry
• Gel electrophoresis
• Chromatography (paper and TLC)
• pH measurement and buffer preparation
• Estimation of blood glucose, serum proteins, urea, creatinine, bilirubin, cholesterol
• Urine examination (normal and abnormal constituents)
• CSF sugar and protein estimation
• Liver function tests, kidney function tests

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Internal Assessment (R-24 Scheme)

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Teaching Hours (Phase-I MBBS)

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Important Points to Remember

1. Paper I = Chemistry (what molecules ARE) + Enzymes + Functional tests
2. Paper II = Metabolism (what molecules DO) + Molecular biology + Applied biochemistry
3. Questions can be asked from any paper's topics in either paper - the distribution is a guideline, not an absolute restriction
4. AETCOM topics are included in both Paper I and Paper II as short answer questions
5. From R-24 batch, MCQs are scenario-based (not straight recall), reflecting the NMC's shift toward competency-based assessment
6. The passing criteria is 40% separately in theory and practical, with a minimum 50% aggregate

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• MPMSU Adhoc Board of Studies - NSCBMC Jabalpur document (NMC Guidelines D-11011/500/2024-AcademicCell, 12-09-2024)
• RIMS MBBS syllabus (Paper I & II biochemistry topics used by MPMSU-affiliated colleges)
• Scribd: MPMSU MBBS First Year Exam Scheme document