Cranial Nerves
3rd Edition

Accessory XI

Description Labelled Unlabelled
Figure XI–1 Branchial motor component of cranial nerve XI demonstrating ipsilateral innervation to LMNs innervating the sternomastoid muscle (yellow) and contralateral innervation to LMNs innervating the upper fibers of the trapezius muscle (ochre). The brain stem is elevated. LMNs = lower motor neurons.
Branchial motor efferent (yellow)
Figure XI–2 Branchial motor component of the accessory nerve—C1 to C5 or C6.
Branchial motor efferent (yellow)
Figure XI–3 Overview of the accessory nerve.
Branchial motor efferent (yellow)
Figure XI–4 Action of the right sternomastoid muscle. A, the muscle pulls the mastoid process toward the clavicle resulting in B, the head rotating and the chin elevating to the opposite side.
Figure XI–5 Examination and palpation of the left sternomastoid muscle.
Figure XI–6 Left shoulder drop resulting from loss of action of upper fibers of the left trapezius muscle.
Figure XI–7 Patient shrugging his shoulders against resistance.