Brachial Plexus

Question 1

General innervation of antebrachium.

Answer 1

anterior: ulnar and median nerves
posterior: radial nerve

Question 2

What injuries can result from injuries to the superior trunk (C5-C6)? How can this occur?

Answer 2

-result from excessive, forceful increase in angle between neck and shoulder

-Erb’s palsy
+sensory deficit in lateral aspect of upper limb
+loss of arm abduction, loss of elbow flexion, loss of forearm supination, weakness of wrist extension
+presented as the “waiter’s tip,” upper limb adducted, medially rotated and elbow extended and wrist flexed

Question 3

What results from injuries to the inferior trunk (C8 and T1)? What causes this?

Answer 3

-limb is suddenly and forcefully pulled in superior direction

-Klumpke’s palsy
+medial aspect of upper limb except axilla has sensory deficit
+loss of precise finger movements, weakness in forearm protonation, weakness of wrist and finger extension, weakness of wrist and finger flexion

+presents as “claw hand”, with possible wasting of intrinsic hand muscles, 4th and 5th digits can’t flex

Question 4

What can result from the radial nerve? What can causes this?

Answer 4

• can occur with mid shaft fractures of the humerus, improper use of crutches
• extensors affected -> wrist drop
• “Saturday night palsy,” nerve pinched due to pinching of nerve
• paresthesia and/or pain along course of nerve

Question 5

What results from an injury to the axillary nerve? Causes?

Answer 5

• can occur with fractures to the surgical neck of the humerus or dislocation of glenohumeral joint
• improper use of backpack -> quandrangular space syndrome
• can result in impaired or lost function of deltoid and teres minor
• patient would be unable to fully abduct their arm and diminished ability to laterally rotate

Question 6

What can result from injuries to the long thoracic nerve? Causes?

Answer 6

• can be damaged during surgical removal of lymph nodes or other tissues in axillary region, penetrating trauma
• serratus anterior affected
• “winged scapula”, inability to raise arms above 90 degrees

Question 7

Affects of ulnar nerve damage? Causes?

Answer 7

• fracture of medial epicondyle or proximal ulna, slashed wrist
• damage will involve flexors of wrist, digits, and intrinsic hand muscles
• radial deviation at wrist joint, loss of ab and adduction of fingers, weak wrist flexion and some loss of flexion digits

Question 8

Affects of median nerve damage? Causes?

Answer 8

• fracture of humerus above condyles, slashing of wrist, or carpal tunnel syndrome
• flexors of wrist and digits affected and intrinsic hand muscles
• “Pope’s blessing”
• “ape hand”

Question 9

General innervation of brachium.

Answer 9

anterior: musculocutaneous (flexors of elbow)
posterior: radial nerve (extensors of elbow)