VISUAL ANATOMY MODULE
Brachial Plexus
Stop memorising disconnected nerves. See the full pathway from C5–T1 roots to terminal branches, then attach the lesion patterns that NEET PG repeatedly tests.
The one-line framework
Roots → Trunks → Divisions → Cords → Branches. The plexus is formed primarily by the anterior rami of C5, C6, C7, C8 and T1.
How to decode the map
Three trunks
- Upper: C5–C6
- Middle: C7
- Lower: C8–T1
Every trunk splits
- Each trunk gives an anterior and a posterior division.
- Remember the pattern before learning individual branches.
Named around the artery
- Lateral: anterior divisions of upper + middle trunks
- Medial: anterior division of lower trunk
- Posterior: all three posterior divisions
Exam anchor: cords are named by their relation to the second part of the axillary artery.
Lateral cord → musculocutaneous + lateral root of median. Medial cord → ulnar + medial root of median. Posterior cord → axillary + radial.
Branches that need to be automatic
Early branches
- Dorsal scapular (C5): rhomboids, levator scapulae
- Long thoracic (C5–7): serratus anterior
Two favourites
- Suprascapular (C5–6): supraspinatus, infraspinatus
- Nerve to subclavius (C5–6)
Do not miss
- Upper subscapular, thoracodorsal, lower subscapular
- Terminal: axillary and radial
Lesion patterns: make anatomy clinical
Upper trunk — Erb pattern
Roots: C5–C6. Classic mechanism is traction increasing the angle between neck and shoulder. Think weakness of shoulder abduction/lateral rotation and elbow flexion/supination; the classic posture is remembered as “waiter’s tip.”
Lower trunk — Klumpke pattern
Roots: C8–T1. Think intrinsic hand weakness and clawing tendency. T1 sympathetic involvement may be associated with Horner syndrome in an appropriate proximal lesion context.
Long thoracic nerve
C5–7 → serratus anterior. Injury produces winging of scapula; upward rotation is impaired, affecting overhead abduction.
Axillary nerve
C5–6 → deltoid, teres minor. Test association: surgical neck fracture or anterior shoulder dislocation; assess deltoid function and “regimental-badge” area sensation.
Rapid-revision MCQs
1. The lateral cord is formed by which divisions?
Answer: Anterior divisions of the upper and middle trunks.
2. Which cord gives both axillary and radial nerves?
Answer: Posterior cord.
3. The median nerve receives roots from which cords?
Answer: Lateral and medial cords.
4. Winged scapula after axillary surgery suggests injury to?
Answer: Long thoracic nerve supplying serratus anterior.
5. Upper trunk lesion primarily involves which roots?
Answer: C5–C6.
6. Which nerve arises from the upper trunk?
Answer: Suprascapular nerve (also nerve to subclavius).
7. In relation to which vessel are the cords named?
Answer: The second part of the axillary artery.
8. Ulnar nerve is a terminal branch of which cord?
Answer: Medial cord.
How to use this module tonight
First trace the visual map twice without looking at labels. Then close it and reproduce: C5–T1 → 3 trunks → 6 divisions → 3 cords → 5 terminal branches. Finally, revise the four lesion cards. Cross-check fine details in your preferred standard anatomy text; an open evidence reference is available through NCBI PubMed Central.