Human Anatomy Lecture 9: Neuro Anatomy and Facial & Glossopharangeal Nerve (Almaagal University, 2022-2023) PDF

Academic year 2022-2023 ‫فرع جراحة الفم والوجه والفكين‬ ‫كلية طب االسنان‬ 2ed year Human Anatomy Lecture 9...

Academic year 2022-2023 ‫فرع جراحة الفم والوجه والفكين‬ ‫كلية طب االسنان‬ 2ed year Human Anatomy Lecture 9 Neuro anatomy Facial &Glossopharangeal nerve By:Dr.Nada hashim AL JASSIM Snell R.S. Clinical Anatomy by regions, 9th Edition, Lippincott Williams & Wilkins, [2012 For more detailed instructions, any question, cases need help please post to the telegram group of the session  Facial nerve The facial nerve is the seventh cranial nerve. It has both a motor root and sensory root. The motor root supplies the muscles of facial expressions, includingthe superficial muscle of the neck, aurbicularis muscles, scalp muscles and certain other muscles derived from the second pharyngeal arch. The sensory root, which leave the facial nerve while it is in the facial canal, is responsible for the supply of special sensory innervations ( taste )to the anterior two third of the tongue The facial nerve exits the skull through the stylomastoid foramen and runs anteriorly and passes through the parotid gland and divided into five branches: ▪ Temporal branch. ▪ Zygomatic branch. ▪ Buccal branch. ▪ Mandibular branch. ▪ Cervical branch.  Origin and intracranial course It has 6 nuclei of origion(1 motor ,2 sensory ,and 3 parasympathetic) lying in the lower Part of pons. The nerve emerges at the lower border of pons as 2 roots: Motor root :formed by the axons of the motor nucleus and appears At the cerebellopontine angle. Nerves intermedius :formed by all sensory and parasympathetic fibers.It emerges lateral to the motor root (between motor root and vestibulocochlear Nerve) The nerve has 2 major parts; ✓ Intra –petrous part: the 2 roots pass Through the internal acoustic meatus to reach the facial canal(in the ear ). It passes laterally in the inner ear to reach its geniculate (sensory) ganglion. Then it turns backward in the medial wall of the middle ear. Finally it descends vertically to exit from the skull via the stylomastoid foramen. ✓ Extra cranial part : it enters the postero- medial surface of the parotid gland and divides into temporo- facial and cervico- facial divisions. These divisions form the (pes anserinus plexus) within the parotid gland. -it ends by giving 5 terminal branches which pierce the antero-medial surface of the parotid gland to reach the face. Applied anatomy The Facial Artery: The facial artery which is a branch of the external carotid artery is the main artery of the face. it runs a sinuous course to accommodate to the mobility of the structures through which it passes. We can palpate the artery against the mandible, at the antero-inferior border of the masseter muscle. On the face it runs antero- superiorly to a point 1.5 cm. from the angle of the mouth, and then ascends more vertically to end near the medial angle of the eye. Branches of the Facial Artery: The facial artery supplies the lips, and the external nose by means of the following branches: 1-The inferior labial artery penetrates the orbicularis oris, supplies the skin, muscle, and mucous membrane of the lower lip. 2-The superior labial artery which is larger, and more tortuous than the inferior labial artery, has a similar course and distribution in the upper lip. It gives septal and alar branches to the nose. 3-The lateral nasal branch supplies the ala and the dorsum of the nose. 4-The angular artery is the termination of the facial artery. At the medial angle of the eye it anastamoses with the dorsal nasal and palpebral branches of the ophthalmic artery, and thereby establishes a communication ultimately between the external and internal carotid arteries. The Facial Vein: The facial vein lies behind the facial artery and pursues a straighter course across the face. It begins at the medial angle of the eye as the angular vein, by the union of the supra-orbital and supra-trochlear veins. It communicates freely with the superior ophthalmic vein and thereby with the cavernous sinus. The facial vein descends behind the facial artery and usually ends directly or indirectly in the internal jugular vein. In the cheek, the facial vein receives the deep facial vein from the ptrygoid venous plexus. The facial vein has no valves. Because of its connection with the cavernous sinus and the pterygoid venous plexus, and the consequent possibility of spread of infection. The territory of the facial vein around the nose and the upper lip is frequently termed as the danger area of the face. The External Jugular Vein: The superficial temporal vein unites with the maxillary vein to form the retromandibular vein which is previously known as the posterior facial vein. The retromandibular vein divides into anterior and posterior branches. The anterior branch unite with the facial vein to form the common facial vein, and the posterior branch unite with the posterior auricular vein to form -the external jugular vein. The external jugular vein descends vertically downwards in the superficial fascia, deep to the platysma and pierces the investing fascia on the posterior triangle of the neck at the posterior border of sternocleidomastoid ,2-3 cm. above the calvicle. In the posterior triangle beside the sternocleidomastoid, crosses the lower roots of the brachial plexus and the third part of the subclavian artery to enter the subclavian vein behind the clavicle It receives: 1- The transverse cervical vein. 2- Suprascapular vein. 3- The anterior jugular vein.  GLOSOPHARYNGEAL NERVE The glossopharyngeal nerve, known as the ninth cranial nerve (CN IX), is a mixed nerve that carries afferent sensory and efferent motor information. It exits the brainstem out from the sides of the upper medulla, just anterior to the vagus nerve. sensory: Provides taste sensation to the posterior 1/3 of the tongue. Parasympathetic: Provides parasympathetic innervation to the parotid gland. Motor: Innervates the stylopharyngeus muscle of the pharyna Course of glosso- pharyngeal nerve (9th cranial nerve) -emerge bet Olive & inf. Cerebellar peduncle in the medulla Nuclei ❖ Nucleus ambigus— ❖ Nucleus dorsalis ❖ Nucleus solitarius ❖ Inferior salivary nucleus -leave the skull through the jugular foramen -it acompany the stylopharyngous muscle between Ext. & int. Carotid artery till it disappear behind hypoglossus muscle Where it enter between the sup. & middle consterictor Muscles of pharynx - The glossopharyngeal nerve originates in the medulla oblongata of the brain. It emerges from the anterior aspect of the medulla, moving laterally in the posterior cranial fossa. The nerve leaves the cranium via the jugular foramen. At this point, the tympanic nerve arises. It has a mixed sensory and parasympathetic composition. Immediately outside the jugular foramen lie two ganglia (collections of nerve cell bodies). They are known as the superior and inferior (or petrous) ganglia – they contain the cell bodies of the sensory fibres in the glossopharyngeal nerve. Now extracranial, the glossopharyngeal nerve descends down the neck, anterolateral to the internal carotid artery. At the inferior margin of the stylopharyngeus, several branches arise to provide motor innervation to the muscle. It also gives rise to the carotid sinus nerve, which The nerve enters the pharynx by passing between the superior and middle pharyngeal constrictors. Within the pharynx, it terminates by dividing into several branches – lingual, tonsil and pharyngeal. CLINICAL RELEVANCE :  Examination : Damage : The clinical tests used to Damage to the glossopharyngeal determine if the glossopharyngeal nerve can result in loss of taste nerve has been damaged include sensation to the posterior one third of testing the gag reflex of the the tongue, and impaired swallowing mouth, asking the patient to swallow or cough, and evaluating for speech impediments  Maxillary artery The maxillary artery is the larger of the two terminal branches of the external carotid artery; arises posterior to the neck of the mandible. Then it runs forward medial to the neck of the mandible and enters the pterygopalatine fossa of the skull. It is divided into three parts based on its relation to the lateral pterygoid muscle: (Retro)mandibular: arteries enter foramina and supply dura, mandibular teeth and gums, ear, and chin. Pterygoid: branches supply muscles of mastication and buccinator. Pterygopalatine: branches enter foramina and supply maxillary teeth and gums, orbital floor, nose, paranasal sinuses, palate, auditory tube, and superior pharynx. The three parts of the maxillary artery and their branches are illustrated in their courses and distributions are listed below TABLE 1: Parts and branches of maxillary artery. Pterygoid Venous Plexus The pterygoid venous plexus is located partly between the temporalis and pterygoid muscles. It is the venous equivalent of most of the maxillary artery, that is, tributaries from each of the areas supplied by the branches of the maxillary vein ultimately drain into the pterygoid venous plexus and/or its principal anastomotic veins. These veins are valve-less, so flow can go in either direction based on gravity and pressure The plexus communicates with the cavernous sinus, the facial vein, the inferior ophthalmic vein and the pharyngeal plexus. The connections with the cavernous sinus are via emissary veins. The communication with the facial vein is via the deep facial vein. The inferior ophthalmic vein communicates with the pterygoid plexus through a branch passing through the inferior orbital fissure. The pterygoid venous plexus chiefly drains posteriorly into the maxillary vein. The maxillary vein runs with the first part of the maxillary artery, passing deep to the neck of the condyle of the mandible to enter the parotid gland. Here, it joins the superficial temporal vein to form the retromandibular vein. THANK YOU