[UW Anatomy | Contents]

Function:
Motor innervation of IPSI. muscles of the soft palate, pharynx, larynx and upper esophagus.

Pathway:
Axons of motor neurons in the nucleus ambiguus course with three cranial nerves: C.N. IX (glossopharyngeal), C.N. X (vagus), C.N. XI (rostral or cranial portion of spinoaccessory) to innervate striated muscles of the soft palate, pharynx, larynx and upper esophagus.

Deficits:
Lesion of nucleus ambiguus results in atrophy (lower motor neuron) and paralysis of innervated muscles, producing nasal speech, dysphagia, dysphonia, and deviation of the uvula toward the CONTRA. side (strong side). NO PROBLEM WITH THE STERNOCLEIDMASTOID OR TRAPEZIUS. These muscles are innervated by cells in the rostral spinal cord (caudal portion C.N. XI).

Other Note:
Bilateral corticobulbar input to nucleus ambiguus. Good! Remember, uvula deviation to the contra. side only follows a lesion of nucleus ambiguus, NOT the corticobulbar input. Nucleus ambiguus does NOT innervate the STERNOCLEIDMASTOID and TRAPEZIUS. NUC. AMBIGUUS RECEIVES BILATERAL INPUT FROM T.T.T. FOR GAG REFLEX.