Brachial Plexus Structures Flashcards
7 cards from real Anatomy Exam practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Brachial Plexus Structures flashcards as text
Which structure separates the anterior and posterior divisions of the brachial plexus trunks?
Answer: First rib
The divisions form as the trunks cross over the first rib, passing between the clavicle and the first rib.
In thoracic outlet syndrome, which trunk of the brachial plexus is most commonly compressed?
Answer: Lower trunk
The lower trunk (C8–T1) is most often compressed in neurogenic thoracic outlet syndrome, causing intrinsic hand weakness.
The dorsal scapular nerve innervates the rhomboids and arises from which root?
Answer: C5
The dorsal scapular nerve arises from the C5 root (with a small C4 contribution) and innervates the rhomboids and levator scapulae.
The medial root of the median nerve arises from which cord?
Answer: Medial cord
The medial cord gives rise to the medial root of the median nerve (C8–T1), which joins the lateral root from the lateral cord.
Which statement best describes the relationship of the brachial plexus to the scalene muscles?
Answer: Roots emerge between anterior and middle scalenes
The ventral rami (roots) of the brachial plexus pass between the anterior and middle scalene muscles in the posterior triangle.
A patient cannot abduct the arm past 15 degrees and has numbness over the lateral shoulder. Which nerve is injured?
Answer: Axillary nerve
Axillary nerve injury paralyzes the deltoid (abduction 15–180°) and causes sensory loss over the regimental badge area of the lateral shoulder.
Anterior divisions of the brachial plexus trunks combine to form which cords?
Answer: Lateral and medial cords
The anterior divisions of the upper and middle trunks form the lateral cord; the anterior division of the lower trunk forms the medial cord.