A person receives a laceration along the anterior border of the trapezius muscle in the neck and subsequently the point of his shoulder (scapula) sags and he has some difficulty fully abducting his arm. What nerve appears to have been severed?
If the accessory nerve is damaged and the trapezius is denervated, a person will no longer be able to raise the acromion of the shoulder. The dorsal scapular nerve innervates rhomboid major, rhomboid minor, and levator scapulae. If the dorsal scapular nerve is damaged, the rhomboids will be denervated, and retraction of the scapula will be weakened. An injury to the greater occipital nerve will result in a loss of sensation on the posterior scalp but no muscular deficit. The axillary nerve and suprascapular nerve will be covered with the upper limb, but for completeness, note that the axillary nerve innervates the deltoid muscle. If this nerve is damaged, the deltoid may atrophy, and the person will be unable to abduct the arm.
Accessory (Cr. N. XI)
Axillary
Dorsal scapular
Greater occipital