Anatomy Exam Brachial Plexus Structures 5

Question 1

Which structure separates the anterior and posterior divisions of the brachial plexus trunks?

Accepted Answer

First rib

Answer

The divisions form as the trunks cross over the first rib, passing between the clavicle and the first rib.

Question 2

In thoracic outlet syndrome, which trunk of the brachial plexus is most commonly compressed?

Accepted Answer

Lower trunk

Answer

The lower trunk (C8–T1) is most often compressed in neurogenic thoracic outlet syndrome, causing intrinsic hand weakness.

Question 3

The dorsal scapular nerve innervates the rhomboids and arises from which root?

Accepted Answer

C5

Answer

The dorsal scapular nerve arises from the C5 root (with a small C4 contribution) and innervates the rhomboids and levator scapulae.

Question 4

The medial root of the median nerve arises from which cord?

Accepted Answer

Medial cord

Answer

The medial cord gives rise to the medial root of the median nerve (C8–T1), which joins the lateral root from the lateral cord.

Question 5

Which statement best describes the relationship of the brachial plexus to the scalene muscles?

Accepted Answer

Roots emerge between anterior and middle scalenes

Answer

The ventral rami (roots) of the brachial plexus pass between the anterior and middle scalene muscles in the posterior triangle.

Anatomy Exam Practice Test