Anatomy Brachial Plexus Structures Questions and Answers

Question 1

A patient presents with a 'winged scapula,' where the medial border of the scapula protrudes posteriorly.
This is most likely caused by an injury to which nerve that originates from the roots of the brachial plexus?

Accepted Answer

Long thoracic nerve

Answer

Axillary nerve

Answer

Dorsal scapular nerve

Answer

Suprascapular nerve

Question 2

Which of the following structures of the brachial plexus is formed by the union of the anterior divisions of the superior and middle trunks?

Accepted Answer

Lateral cord

Answer

Posterior cord

Answer

Medial cord

Answer

Inferior trunk

Question 3

A patient suffers a fracture of the surgical neck of the humerus. Which terminal branch of the posterior cord is most at risk, potentially leading to weakness in abducting the arm and loss of sensation over the 'regimental badge' area?

Accepted Answer

Axillary nerve

Answer

Musculocutaneous nerve

Answer

Radial nerve

Answer

Median nerve

Question 4

A newborn is diagnosed with Erb's palsy following a difficult delivery. This condition, characterized by a 'waiter's tip' posture, involves damage to which part of the brachial plexus?

Accepted Answer

The superior trunk (C5, C6)

Answer

The posterior cord

Answer

The lower trunk (C8, T1)

Answer

The medial cord

Question 5

Which terminal nerve of the brachial plexus characteristically pierces the coracobrachialis muscle before continuing down the arm to innervate the anterior compartment muscles?

Accepted Answer

Musculocutaneous nerve

Answer

Median nerve

Answer

Ulnar nerve

Answer

Radial nerve

Question 6

An injury resulting from a sudden and forceful hyper-abduction of the arm, such as when grabbing onto something to break a fall, is most likely to damage which structure of the brachial plexus, leading to a 'claw hand' deformity?

Accepted Answer

Inferior trunk

Answer

Superior trunk

Answer

Lateral cord

Answer

Middle trunk