This document provides information on the 9th, 10th, 11th, and 12th cranial nerves: - The glossopharyngeal nerve (CN IX) carries sensory and parasympathetic fibers and has branches that innervate the ear, pharynx, and tongue. It exits the skull through the jugular foramen. - The vagus nerve (CN X) is a mixed nerve that innervates the pharynx, larynx, heart, lungs, and gastrointestinal tract. It exits the skull through the jugular foramen and has ganglia in the jugular fossa and inferiorly. - The spinal accessory nerve (CN XI) innervates muscles of the neck and exits

1. 9TH 10TH 11TH 12TH CRANIAL
NERVES

2. GLOSSOPHARYNGEAL NERVE
• Upper motor neuron influences on CN IX arise from the primary
motor cortex and descend in the corticobulbar tracts to synapse in
the rostral portion of the nucleus ambiguus in the dorsolateral
medulla. The cortical innervation is bilateral. The cells in the nucleus
ambiguus are branchiomotor and innervate muscles derived from the
third, fourth, and sixth branchial arches. The nerve emerges from the
medulla as three to six rootlets in the groove between the inferior
olive and the inferior cerebellar peduncle, between and in line with
the emerging fibers of CN VII above and CN X. These rootlets unite to
form a single nerve, which leaves the skull through the jugular
foramen.

5. • CN IX exits the skull through the jugular foramen, lateral and anterior
to CNs X and XI within a separate dural sheath. After leaving the skull,
CN IX enters the carotid sheath, descends between the internal
jugular vein and internal carotid artery, dips beneath the styloid
process, and then passes between the internal and external carotid
arteries. It curves forward, forming an arch on the side of the neck to
reach the lateral pharyngeal wall, and then disappears under the
hyoglossus muscle to divide into its terminal branches.

6. • Two ganglia lie on the nerve just caudal to the jugular foramen: the
superior (jugular) and inferior (petrosal) glossopharyngeal ganglia.
The superior glossopharyngeal ganglion is small, is inconstant, has no
branches, and is often fused with the inferior ganglion.

8. • CN IX has six terminal branches: (a) the tympanic nerve (Jacobson’s
nerve), (b) carotid, (c) pharyngeal, (d) muscular, (e) tonsillar, and (f)
lingual branches

10. EXAMINATION OF 9TH NERVE
• The pharyngeal reflex is the more active.
• The reflex occurs with touching the base of the tongue or posterior
pharyngeal wall.
• The afferent limb of the reflex is mediated by CN IX and the efferent limb
through CNs IX and X. The reflex center is in the medulla. The motor
response is constriction and elevation of the oropharynx. This causes the
midline raphe of the palate and the uvula to elevate and the pharyngeal
constrictors to contract. The activity on the two sides is compared. There
are three motor components: elevation of the soft palate to seal off the
nasopharynx, closure of the glottis to protect the airway, and constriction
of the pharynx to prevent entry of the substance

11. DISORDERS OF FUNCTION
• Nuclear and infranuclear processes that may affect CN IX include
intramedullary and extramedullary neoplasms and other mass lesions
(e.g., glomus jugulare tumor), trauma (e.g., basilar skull fracture or
surgical dissection), motor neuron disease, syringobulbia,
retropharyngeal abscess, demyelinating disease, birth injury, and
brainstem ischemia

12. • GLOSSOPHARYNGEAL NEURALGIA ALSO CALLED AS TIC DOULOUREUX
OF NINTH NERVE – CAUSES AND AGGREVATING FACTORS
• JACOBSONS NEURALGIA

13. VAGUS NERVE
• The vagus emerges from the medulla as a series of rootlets just below
those of the glossopharyngeal. CN X leaves the skull through the
jugular foramen in the same neural sheath as the cranial root of CN XI
and behind CN IX. In the jugular foramen, the nerve lies close to the
jugular bulb, a dilatation of the internal jugular vein that houses the
glomus jugulare (tympanic body). The glomus jugulare has functions
similar to the carotid body. CN X descends the neck in the carotid
sheath, lying between the carotid artery and internal jugular vein to
the upper border of the thyroid cartilage and then between the vein
and common carotid to the base of the neck.

15. • Branches leave in the jugular foramen to supply the meninges and
ear; other branches leave distal to the foramen to supply the pharynx
and larynx. The major portion of the nerve enters the thorax. The
vagus has two sensory ganglia. The superior (jugular) vagal ganglion is
located in the jugular fossa of the temporal bone; the inferior
(nodose) ganglion is located just distal to the jugular foramen. There
are 10 major terminal branches that arise at different levels: (a)
meningeal, (b) auricular, (c) pharyngeal, (d) carotid, (e) superior
laryngeal, (f) recurrent laryngeal, (g) cardiac, (h) esophageal, (i)
pulmonary, and (j) gastrointestinal.

18. • A unilateral vagal lesion causes weakness of the soft palate, pharynx,
and larynx. Acute lesions may produce difficulty swallowing both
liquids and solids and hoarseness or a nasal quality to the voice. The
only definite sensory change is anesthesia of the larynx because of
involvement of the superior laryngeal nerve. The gag reflex is absent
on the involved side. Autonomic reflexes (vomiting, coughing, and
sneezing) are not usually affected. Tachycardia and loss of the
oculocardiac reflex on the involved side may occur.

20. • . Bilateral complete vagal paralysis is incompatible with life. It causes
complete paralysis of the palate, pharynx, and larynx, with marked
dysphagia and dysarthria; tachycardia; slow, irregular, respiration;
vomiting; and gastrointestinal atonia. Lesions of individual vagal
branches are rare except for involvement of the recurrent laryngeal
nerve

22. REFLEXES OF 10TH NERVE
• OCULOCARDIAC REFLEX
• VOMITING REFLEX
• CAROTID SINUS REFLEX
• VASO VAGAL ATTACK

23. SPINAL ACCESSORY NERVE

24. • CN XI emerges from the skull posteromedial to the styloid process
and then descends in the neck near the internal jugular vein, behind
the digastric and stylohyoid muscles, to enter the deep surface of the
upper part of the SCM muscle. It passes through the SCM, sending
filaments to it, and then emerges at its posterior border near the
midpoint, coursing near the great auricular nerve. CN XI then runs
obliquely across the posterior triangle of the neck on the surface of
the levator scapula muscle, superficially and in close proximity to the
lymph nodes of the posterior cervical triangle. About three
fingerbreadths above the clavicle, the nerve enters the deep surface
of the anterior border of the upper trapezius muscle.

27. HYPOGLOSSAL NERVE
• The hypoglossal nerve (CN XII) is a purely motor nerve, supplying the
tongue. Its cells of origin are in the hypoglossal nuclei, which are
upward extensions of the anterior gray columns of the spinal cord;
they consist of large, multipolar cells, similar to the anterior horn
motoneurons. The paired nuclei extend almost the entire length of
the medulla just beneath the floor of the fourth ventricle, close to the
midline
• The hypoglossal fibers gather into two bundles, which perforate the
dura mater separately, pass through the hypoglossal canal, and then
unite. The nerve descends through the neck to the level of the angle
of the mandible and then passes forward under the tongue (hence its
name) to supply its extrinsic and intrinsic muscles

30. • ALL MUSCLES OF PALATE
• ALL MUSCLES OF PHARYNX
• ALL MUSCLES OF LARYNX
• ALL MUSCLES OF TONGUE

31. •THANK YOU