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NEUROANATOMY Lecture : 11

NEUROANATOMY Lecture : 11 Anatomy of the Glossopharyngeal (IX), Vagus (X), & Hypoglossal (XII) Nerves. Prepared and presented by: Dr. Iyad Mousa Hussein, MD, Ph.D in Neurology Head of Neurology Department Nasser Hospital. LECTURE OBJECTIVES:.

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NEUROANATOMY Lecture : 11

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  1. NEUROANATOMY Lecture : 11 Anatomy of the Glossopharyngeal (IX), Vagus (X), & Hypoglossal (XII) Nerves Prepared and presented by: Dr. Iyad Mousa Hussein, MD, Ph.D in Neurology Head of Neurology Department Nasser Hospital

  2. LECTURE OBJECTIVES: Origin, Nuclei, and Functions of Glossopharyngeal Nerve. Course, and Relations, and branches of Glossopharyngeal Nerve. Lesion of Glossopharyngeal Nerve. Origin, Nuclei, and Functions of Vagus Nerve. Course, and Relations, and branches of Vagus Nerve. Lesion of the Vagus Nerve. Origin, and Functions of Hypoglossal Nerve. Course, and Relations, and branches of Hypoglossal Nerve. Lesion of Hypoglossal Nerve.

  3. The Glossopharyngeal Nerve (IX) • The glossopharyngeal nerve is a mixed nerve containing: a. Sensory fibers. • b. Parasympathetic fibers • c. Motor fibers. • It is more important as sensory than as a motor nerve. • Origin:from posterolateral sulcus of medulla.

  4. Nuclei of Glossopharyngeal Nerve It has three nuclei: The upper part of nucleus ambiguous:it lies in the medulla (motor function). The inferior salivary nucleus:it lies in the medulla (parasympathetic function). The solitary nucleus:it lies in the medulla (sensory function).

  5. Functions of the Glossopharyngeal Nerve • 1. Sensory function: supplies the: • a. Posterior 1/3 rd of the tongue (taste and general • sensation). • b. Mucous membrane of the pharynx and tonsil. • c. Carotid sinus and the carotid body. • 2. Parasympathetic function: supplies the parotid gland. • 3. Motor function: supplies one muscle only the • stylopharyngeus muscle.

  6. Course of Glossopharyngeal Nerve The glossopharyngeal nerve arises by 4-5 rootlets from the posterolateral sulcus of medulla. It leaves the skull through the jugular foramen. While it lies in jugular foramen it has 2 small sensory ganglia (superior and inferior). It descends downwards inside the upper carotid sheath superficial to vagus nerve and between IJV & ICA lying deep to the styloid process and muscle attached to it. Then it leaves the carotid sheath and passes forwards with stylopharyngeus muscle between the ICA & ECA. Ascends deep to hyoglossus to reach the tongue. Termination:it ends into terminal branches supplying the mucous membranes of pharynx, tonsil and the posterior 1/3 of tongue.

  7. Branches of the Glossopharyngeal Nerve Meningeal branch (sensory). Tympanic branch (Jacobson's Nerve- parasympathetic nerve). Nerve to stylopharyngeus muscle (motor). Tonsillar branches (sensory). Lingual branches (sensory).

  8. Branches of the Glossopharyngeal Nerve • 1. Meningeal branch (sensory): • Arises from the intracranial part of the glossopharyngeal • nerve. • Sensory nerve supplies meninges of posterior cranial • fossa.

  9. Branches of the Glossopharyngeal Nerve • 2. Tympanic branch (Jacobson's Nerve- parasympathetic nerve): • Preganglionic parasympathetic nerve to parotid gland. • Arises from the inferior ganglion of the glossopharyngeal nerve in • the jugular fossa. • Course of the tympanic nerve: • It passes through the tympanic canaliculus. • It reaches the middle ear cavity where it breaks to form the • tympanic plexus. • Lesser superficial petrosal nerve arises from the tympanic plexus • and reaches the middle cranial fossa. • Then lesser superficial petrosal nerve passes through the foramen • ovale to reach infratemporal fossa to relay in the otic ganglion. • The postganglionic fibers joint the auriculotemporal to supply the • parotid gland.

  10. Branches of the Glossopharyngeal Nerve 3. Carotid branch (sensory): sensory nerve to the carotid sinus and carotid body. 4. Nerve to stylopharyngeus muscle (motor): motor nerve to stylopharyngeus muscle.

  11. Branches of the Glossopharyngeal Nerve 5. Pharyngeal branches (sensory): they enter the formation of the pharyngeal plexus and supplies the mucous membrane of pharynx. The pharyngeal plexus receives also: a. Motor fibers (the pharyngeal branches of vagus nerve). b. Sympathetic fibers(the pharyngeal branches of the superior cervical ganglion)

  12. Branches of the Glossopharyngeal Nerve 6. Tonsillar branches (sensory):to the palatine tonsil. 7. Lingual branches (sensory):terminal branches to mucous membrane of the posterior 1/3 rd of the tongue (taste and general sensation).

  13. Lesion of the Glossopharyngeal Nerve: Loss of taste and general sensation from the posterior 1/3 of the tongue. Loss of sensation in the pharynx. Some pharyngeal weakness. Loss of salivation from the parotid gland.

  14. The Vagus Nerve (X) • The vagus nerve is the longest of the cranial nerve. • Its name is derived from Latin meaning "wandering". True • to its name the vagus nerve wanders from the brain stem • through organs in the neck, thorax and abdomen. • It is a mixed nerve with: • a. Motor fibers. • b. Parasympathetic fibers • c. Sensory fibers. • It is the most important parasympathetic nerve in the body. • Origin:the vagus nerve leaves the brain by about 10 rootlets from the posterolateral sulcus of the medulla.

  15. Nucleus of the vagus nerve It has three nuclei: Dorsal motor nucleus of vagus:give parasympathetic fibers to respiratory system, digestive tract and the heart. Main part of nucleus ambigus:give motor fibers to the muscles of the larynx, pharynx and palate. Solitary nucleus:receives taste sensation from the epiglottis and general sensation from the areas supplied by the parasympathetic fibers.

  16. Function of the vagus nerve 1. The motor fibers supply: a. All the muscles of the larynx. b. All the muscles of the pharynx except the stylopharyngeus. c. All the muscles of the palate except the tensor palati muscle. 2. The parasympathetic fibers supply: a. The smooth muscles and glands digestive system. b. The smooth muscles and the glands of the respiratory system. c. The heart. 3. The sensory fibers:receive sensation from the mucous membrane of the respiratory and digestive system mainly.

  17. Course and Relations of Vagus Nerve in the Neck It leaves the skull through the jugular foramen. Here it has two sensory ganglia: a. Superior ganglion in the jugular foramen. b. Inferior ganglion just below the jugular foramen. 2. The cranial root accessory nerve joins the inferior ganglion of vagus nerve. 3. The vagus nerve descends vertically downwards inside the carotid sheath, first between IJV and ICA, then it descends between IJV and CCA. 4. At the root of the neck, the vagus nerve crosses infront of first part of subclavian artery to enter the thorax.

  18. Branches of the Vagus Nerve • I. Branches from the superior ganglia: • Meningeal nerve. • Auricular nerve. • II. Branches from the inferior ganglia: • Pharyngeal branch. • Superior laryngeal branch: • a. Internal laryngeal branch. • b. External laryngeal branch. • III. Branches in the neck: • Upper and lower cardiac nerve. • Recurrent laryngeal nerve. • IV. Branches in the thorax: • Pulmonary branches of vagus nerve. • Esophageal branches of vagus nerve. • V. Branches in the abdomen: • Abdominal branches of vagus nerve to abdominal viscera.

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