Point 9 Intro Pathway Deficit Note Gag Overview Problems Contents Anatomy

Cells in nucleus ambiguus contain motor neurons associated with three cranial nerves (rostral pole =C.N. IX=glossopharyngeal; middle part =C.N. X=vagus; caudal pole =C.N. XI=spinoaccessory). Axons arising from nucleus ambiguus pass laterally and slightly ventrally to exit the medulla just dorsal to the inferior olive. These axons then course with the three cranial nerves­­IX (glossopharyngeal), X (vagus) and XI (spinoaccessory)­­to innervate the striated muscles of the soft palate, pharynx, larynx, and upper part of the esophagus. Since these muscles have developed embryologically from branchial arches 3, 4 and 5, the cells that innervate them are called branchiomotor. Remember, NUC. AMBIGUUS is "SHARED" by three cranial nerves (IX, X, XI). The general pattern of motor innervation below does not have to be memorized. IX stylopharyngeus muscle X palatal muscles (with assistance from V for the tensor veli palatini; of little clinical significance), most of the pharyngeal muscles (with assistance from IX), laryngeal muscles and striated muscles of the esophagus-palatoglossus too! XI laryngeal muscles (cranial portion) THINK SOFT PALATE, PHARYNX, LARYNX