Biceps brachii

Question 1

how roots to biceps brachii damaged?

Answer 1

1. root damage: Nerve-root compression (while sleeping) Trauma to roots which produces paralysis (puncturing or stabbing)

Winged scapula due to innervation of long thoracic nerve which paralyzed serratus anterior muscle

2. Damage to vertebra or congenital disorders like cervical spondylosis (wear and tear to cervical spine)

Question 2

how is the superior trunk to biceps brachii damaged?

what are the signs?

Answer 2

1. Superior trunk: Erb-duchenne paralysis: most common, downward displacement of arm (violent), tear of C5-C6 roots
   effect: lose fx of all nerve that receive contributions from anterior + posterior divisions of the upper trunk. Loss of abduction, external rotation, radial flexion.

Damage to lateral pectoral nerve. Cause waiters tip position

Question 3

how is the middle trunk to biceps brachii damaged?

Answer 3

very rare

Question 4

how is the inferior trunk to biceps brachii damaged?
what is it called?
what are the signs/effects?

Answer 4

Klumpke paralysis: RARE

Cause: Violent upward displacement of arm during breached delivery causing Shoulder dislocation OR Apical tumor: Tumor of lungs pushing on trunk
➢ Cervical rip C7

Effect: loss of fx from all nerves that derive from anterior + posterior divisions of lower trunk
Loss of ulnar flexion of wrist, intrinsic muscles of the hand + wrist

Question 5

how are the cords to the biceps brachii damaged?

Answer 5

Mostly posterior cords bc they stand alone
• Injury to entire posterior cord: Saturday night palsy
• Effects:
➢ Axillary nerve injury
➢ Thoracodorsal nerve injury
• Effect: loss of extension of all posterior arm muscles

Question 6

origin of biceps brachii

Answer 6

long head: supra glenoid tubercle of the humerus

short head: coracoid process of the scapula

Question 7

insertion of the biceps brachii

Answer 7

biccipital aponeurosis (medial) + radial tuberosity (lateral)