PNS 6 - Brachial Plexus

Question 1

What spinal nerve roots form the brachial plexus?

Answer 1

The ventral rami of C5 to T1 spinal nerve roots.

Question 2

What is the sequence of structures in the brachial plexus?

Answer 2

Roots → Trunks → Divisions → Cords → Individual peripheral (post-plexus) nerves (e.g., axillary, radial, ulnar, median, musculocutaneous).

Question 3

What is the function of the brachial plexus?

Answer 3

Motor innervation to most upper limb muscles and cutaneous innervation of the upper limb.

Question 4

What is the range of severity in brachial plexus injuries?

Answer 4

From mild neuropraxia with early recovery to complete avulsion of spinal nerve roots with minimal recovery potential.

Question 5

What is Erb’s Palsy?

Answer 5

The most common birth-related brachial plexus injury involving the upper trunk (C5 and C6, occasionally C7).

Question 6

What causes Erb’s Palsy?

Answer 6

Widening of the head-shoulder interval, often due to birth trauma (especially difficult or breech births, large neonates, twin pregnancies, shoulder dystocia).

Question 7

Which nerve roots are affected in Erb’s Palsy?

Answer 7

C5 and C6 (occasionally C7 in severe cases).

Question 8

What muscles are paralyzed in Erb’s Palsy (SOLE C5/C6)?

Answer 8

• Deltoid
• Biceps brachii
• Brachialis
• Supinator
• Brachioradialis

Question 9

What actions are affected in Erb’s Palsy due to paralysis?

Answer 9

• GH abduction
• Elbow flexion
• Supination

Question 10

What functions are most impaired in Classic Erb’s Palsy?

Answer 10

• Shoulder abduction
• Elbow flexion
• Forearm supination
• Shoulder external rotation*

Question 11

What functions are significantly impaired in Erb’s Palsy?

Answer 11

• Scapular elevation*
• Scapular retraction*
• Shoulder flexion*
• Shoulder extension*

Question 12

Why is the shoulder often held in adduction in Erb’s Palsy?

Answer 12

Due to paralysis of abductors like deltoids (C5-C6), while adductors (pec major/minor, latissimus dorsi, subscapularis, teres major) retain stronger function.

Question 13

What are common complications of shoulder involvement in Erb’s Palsy?

Answer 13

Chronic internal rotation, adduction contracture, arthritis, posterior subluxation, thoracic outlet syndrome, adhesive capsulitis.

Question 14

What is the result of elbow flexion and supination loss in Erb’s Palsy?

Answer 14

Pronation contracture and major functional impairments in ADLs.

Question 15

Is hand and finger function usually affected in Erb’s Palsy? Why or why not?

Answer 15

No, because hand muscles are mostly innervated by C8 and T1.

Question 16

What sensory deficits occur in Erb’s Palsy?

Answer 16

Cutaneous deficits in the C5 and C6 dermatomes, including loss of proprioception in the shoulder and lateral elbow.

Question 17

Is the autonomic nervous system (ANS) involved in Erb’s Palsy?

Answer 17

No

Question 18

Why is the shoulder highly susceptible to subluxation and chronic damage in Erb’s Palsy?

Answer 18

Due to impairment of the rotator cuff’s “dynamic ligament” function, proprioception, and tissue sensation.

Question 19

What treatment precautions should be taken in recent Erb’s Palsy cases?

Answer 19

Neck immobilization/stabilization and careful shoulder handling.

Question 20

What happens if C7 is involved in severe Erb’s Palsy?

Answer 20

Added impairment of wrist and finger extension → forearm flexor contracture → “Waiter’s Tip” posture.

Question 21

What is Klumpke’s Palsy?

Answer 21

A lower trunk brachial plexus injury involving C8 and T1 (with possible C7 involvement).

Question 22

What causes Klumpke’s Palsy?

Answer 22

Forceful shoulder abduction (e.g. pulling the arm during birth, falling, tractioning).

Question 23

What nerve roots are affected in Klumpke’s Palsy?

Answer 23

T1 completely, C8 partially (C7 in severe cases).

Question 24

What muscles are paralyzed in Klumpke’s Palsy (SOLE C8/T1)?

Answer 24

• Opponens Pollicis
• Adductor Pollicis
• Lumbricals
• Interossei
• Abductor digiti minimi

Question 26

What functions are most impaired in Classic Klumpke’s Palsy?

Answer 26

• Thumb opposition, flexion, adduction • Finger flexion • 5th digit opposition • Finger abduction/adduction

Question 27

What functions are significantly impaired in Klumpke’s Palsy (especially with edema)?

Answer 27

• Wrist flexion • Forearm pronation • Thumb extension and abduction

Question 28

What is the shoulder and elbow function like in Klumpke’s Palsy?

Answer 28

Normal.

Question 29

What is "Garden Rake Hand" and how does it present?

Answer 29

• Wrist pulled into extension (due to impaired FCU, FDP, FDS) • Fingers extended by long finger extensors • Thumb lies flat in the plane of the hand • Atrophy of interossei, adductor pollicis, and thenar eminence muscles

Question 30

What sensory deficits occur in Klumpke’s Palsy?

Answer 30

Impairment in C8 and T1 dermatomes—medial arm, forearm, and hand.

Question 31

Is the autonomic nervous system (ANS) involved in Klumpke’s Palsy?

Answer 31

Yes—vasomotor deficits due to damage to the proximal sympathetic chain at T1.

Question 32

What happens with severe C7 involvement in Klumpke’s Palsy?

Answer 32

Weakness in wrist and finger extensors, wrist may shift from extended to neutral.

Question 33

What syndrome may occur with T1 nerve root injury in Klumpke’s Palsy?

Answer 33

Horner’s Syndrome.

Question 34

What are the 4 classic symptoms (tetrad) of Horner’s Syndrome?

Answer 34

• Enophthalmos (sunken eyeball) • Ptosis (drooping eyelid) • Miosis (pupil constriction) • Anhidrosis (lack of sweating on face/neck)