A: Innervations

Question 1

A patient falls from a bike and injures the upper trunk of the brachial plexus. What are the consequences for the patient? Explain.

Answer 1

Muscles supplied by C5 & C6 affected:
UL hangs limply by the side (shoulder adducted),
UL medially rotated at shoulder jt (unopposed action of pectoralis major)
Elbow extended & Forearm pronated (loss of action of biceps & brachialis) Loss of sensation to lateral side of arm (C5, C6 dermatomes)

Question 2

A builder fell from a ladder. As he fell, he clutched to the lower steps of the ladder which resulted in excessive abduction of his arm and he injures the lower trunk of the brachial plexus. What are the consequences for the patient? Explain.

Answer 2

Muscles supplied by C8 & T1 affected:
All small muscles of the hand affected (T1 in ulnar and median nerves)
→ claw hand deformity Loss of sensation of:
medial side of arm (T1 dermatome),
medial side of forearm & hand & medial 11⁄2 fingers (C8 dermatome).

Question 3

Identify this nerve + what spinal nerves contribute to it

Answer 3

Phrenic nerve
C3,4,5