A person receives a shallow knife wound just behind the sternocleidomastoid muscle and about 1 1/2 inches above the clavicle. There is an immediate numbness of the skin below the wound and over the acromion and clavicle. The nerve most likely severed is?

The supraclavicular nerve provides cutaneous sensation to the root of the neck, chest, and shoulder. Damage to this nerve would explain the numbness over the clavicle and acromion. The greater auricular nerve provides cutaneous sensation to the ear and the skin below the ear. The lesser occipital nerve provides cutaneous sensation to the skin behind the ear, and the transverse cervical nerve provides cutaneous sensation to the skin of the anterior surface of the neck. The suprascapular nerve has no cutaneous branches. It provides motor innervation to the supraspinatus and infraspinatus muscles. Ref: Moon D.A., Foreman K.B., Albeine K.H. (2011). Chapter 26. Triangles and Root of the Neck. In D.A. Moon, K.B. Foreman, K.H. Albeine (Eds), The Big Picture: Gross Anatomy.