Point
9
Intro
Point: 9. Nucleus Ambiguus
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.