UE Functional Neuroanatomy Flashcards
1
Q
Long Thoracic Nerve (C5-C7)
A
- Innervates Serratus Anterior
- Serratus Anterior does protraction, stabilizes medial border of scap, and does upward rotation of scapula (because it assists with shoulder flexion and abduction)
- Motor nerve ONLY
2
Q
Long Thoracic Nerve Palsy (C5-C7) Pathology
A
- Long thoracic nerve palsy (common in backpackers or repetitive overhead movements)
- Medial scapula winging (prominent when pushing against a wall)
- Difficulty raising arm above 90 degrees
- Weakness in shoulder flexion and abduction (because SA assists with upward rotation of scap which is needed for shoulder flex and abd)
3
Q
Radial Nerve (C5-T1) & Posterior Interosseous Nerve (C7-C8)
A
- Triceps brachii — elbow extension
- Wrist extensors (ECRL, ECRB, ECU, ED, EPL, APL)
- Wrist and finger extensors will be posterior interosseous nerve (PIN) which is motor ONLY
- Superficial branch of radial nerve does sensation ONLY
4
Q
Radial Nerve (C5-T1) & Posterior Interosseous Nerve (C7-C8) Pathology
A
- Radial nerve compression (saturday night palsy, humeral shaft fracture) and wrist drop
- Wrist drop = compression of PIN
- Sensory loss = compression of superficial branch of radial nerve
- Weak elbow extension
- No grip strength — wrist instability impairs finger flexors
5
Q
Axillary Nerve (C5-C6)
A
- Deltoid — shoulder abduction, flexion, and extension
- Teres Minor — ER
6
Q
Axillary Nerve (C5-C6) Pathology
A
- Anterior shoulder dislocation
- Humeral neck fracture
- Flat deltoid appearance
- Weakness in abduction (0-30 degrees intact via supraspinatus, beyond that is axillary nerve)
- Sensory loss over “patch area” where a patch would go on the side of arm/shoulder area
7
Q
Median Nerve (C6-T1) & Anterior Interosseous Nerve (C8-T1)
A
- Forearm flexors — FCR, PL, FDS, lateral FDP
- Thenar muscles — “2 pieces of L.O.A.F” (lumbricals 1 and 2, opponens pollicis, APB, superficial head of FPB)
8
Q
Median Nerve (C6-T1) & Anterior Interosseous Nerve (C8-T1) Pathology
A
- Carpal Tunnel Syndrome — compression at wrist, median nerve (which does 1/2 of lateral ring finger, index finger, and thumb)
- Pronator Teres Syndrome — compression at forearm
- Anterior Interosseous Nerve Syndrome — cannot make the “ok” sign due to FPL and FDP (index/middle finger) weakness
- Thenar atrophy (ape hand deformity)
- Weak grip and pinch strength (FDS and thenar muscles affected)
- Positive Phalens and Tinels tests
9
Q
Musculocutaneous Nerve (C5-C7)
A
- Biceps brachii — elbow flexion and supination
- Brachialis — elbow flexion
- Coracobrachialis — shoulder flexion and adduction
10
Q
Musculocutaneous Nerve (C5-C7) Pathology
A
- Compression in coracobrachialis
- Trauma (shoulder dislocation, entrapment in weightlifters)
- Weak elbow flexion (brachioradialis intact via radial nerve)
- Weak supination (biceps brachii)
- Sensory loss over lateral forearm
11
Q
Thoracodorsal Nerve (C6-C8)
A
- Motor ONLY
- Latissimus Dorsi — shoulder extension, adduction, and IR
12
Q
Thoracodorsal Nerve (C6-C8) Pathology
A
- Nerve injury during axillary lymph node dissection (masectomy)
- Weak shoulder extension and adduction (difficulty with pull ups)
- Inability to use crutches — lats needed for weight bearing
- Push up from chair — lats needed for push off
13
Q
Ulnar Nerve (C8-T1)
A
- Lumbricals 3 and 4 (MCP flexion and PIP extension)
- Medial FDP (digits 4-5, FCU)
- Hypothenar muscles (ADM, FDM, ODM)
- Interossei (finger abduction/adduction)
- Adductor pollicis and flexor pollicis brevis (deep head)
14
Q
Ulnar Nerve (C8-T1) Pathology
A
- Cubital Tunnel Syndrome — elbow compression
- Guyons Canal Syndrome — compressed between pisiform and hamate on medial wrist (cyclists commonly get this)
- Claw Hand — hyperextension of MCP, flexion of PIP/DIP in digits 4-5
- Weak finger abduction/adduction — loss of interossei
- Positive fromets sign — compensation by FPL in thumb adduction
