Head & Neck Anatomy Lecture 13 PDF

Head & Neck Dr. Waleed Anatomy Lecture.13 Infratemporal fossa Is an irregularly shaped cavity, located below and deep to the zygomatic arch (deep to the ramus of the mandible). So...

Head & Neck Dr. Waleed Anatomy Lecture.13 Infratemporal fossa Is an irregularly shaped cavity, located below and deep to the zygomatic arch (deep to the ramus of the mandible). So, in order to reach the infratemporal fossa, we have to remove the ramus of mandible. Boundaries: Anteriorly: posterior surface of maxilla. Posteriorly: Styloid process. Laterally: Ramus of mandible. Medially: Lateral pterygoid plate. Superiorly (roof): Greater wing of sphenoid bone which contains open foramen ovale and foramen spinosum. Page | 1  Head & Neck Dr. Waleed Anatomy Lecture.13 Communication of infratemporal fossa: 1- To the orbit → via inferior orbital fissure. 2- To the middle cranial fossa → via foramen ovale and spinosum. 3- To the pterygopalatine fossa → via pterygomaxillary fissure. 4- To tympanic cavity → via petrotympanic fissure. Page | 2  Head & Neck Dr. Waleed Anatomy Type equation here. Lecture.13 Contents: 1-Three muscles of mastication (medial, lateral pterygoid & lower part of temporalis). 2- Mandibular nerve and its branches. 3- Chorda tympani nerve. 4- Maxillary artery and its branches. 5- Otic ganglia. 6- Pterygoid venous plexus. Muscles of Mastication: These mm move the mandible during mastication and speech, they are: 1. Masseter. (The strongest muscle in the body) 2. Temporalis. 3. Lateral pterygoid. 4. Medial pterygoid. Note: The masseter muscle is located outside the infratemporal fossa. The lower fibers of temporalis and lateral pterygoid and medial pterygoid within the infratemporal fossa Page | 3  Head & Neck Dr. Waleed Anatomy Lecture.13 Nerve supply: all muscles are supplied by the mandibular nerve. Page | 4  Head & Neck Dr. Waleed Anatomy Lecture.13 Mandibular division of trigeminal nerve Arises from the trigeminal ganglia (semilunar ganglia), it leaves the skull through the foramen ovale and just below the foramen ovale it joins the motor root of trigeminal nerve. *The mandibular division has main trunk, anterior division and posterior division. Branches of the trunk of mandibular division: 1-Meningeal branch: ascends upward and enters the cranial cavity through the foramen spinosum and shares in sensory supplying to the meninges. 2-Nerve to medial pterygoid: supplies the medial pterygoid muscle in addition it supplies the two muscles (tensor villi palatine and tensor tympani muscles). *After that the trunk divides into anterior division (mainly motor) and posterior division (mainly sensory). The anterior division is motor except the buccal nerve which is sensory. Page | 5  Head & Neck Dr. Waleed Anatomy Lecture.13 Branches of the anterior division: (supply the muscles of mastication): 1-Nerve to masseter (motor) 2-Deep temporal nerves which are 2 or 3 to temporal (motor). 3-Nerve to lateral pterygoid. 4-Buccal nerve to the skin and mucous membrane of the cheek (sensory) Page | 6  Head & Neck Dr. Waleed Anatomy Lecture.13 Branches of the posterior division: They are sensory except one branch which is motor (nerve to mylohyoid). 1-Auriculotemporal nerve: arises by two roots surrounding the middle meningeal artery. This nerve carries postganglionic parasympathetic from otic ganglia to the parotid gland, it also supplies sensory to the auricle and temporomandibular joint and the skin over the temple. it supplies sensory to the auricle, temporomandibular (TM) joint. 2-Lingual nerve: arises from the posterior division of mandibular nerve. It is directed downward forward supplying general sensation to the anterior 2/3 of the tongue. In the infratemporal fossa it receives the chorda tympani nerve which supplies special sensation to the anterior 2/3 of the tongue and supplies parasympathetic to the submandibular and sublingual salivary glands by means of submandibular ganglia. In the course of lingual nerve, it is in close relation with the third molar teeth. The lingual nerve crosses the duct of submandibular gland twice, lateral to the duct & then medial to the duct. 3-Inferior alveolar nerve: It passes downward to the mandibular foramen, before entering the foramen it gives nerve to mylohyoid which supplies mylohyoid and anterior belly of digastric. The inferior alveolar nerve then enters the mandibular foramen supplying the lower teeth and traverse through the mandible then it appears again through the mental foramen as mental nerve. Page | 7  Head & Neck Dr. Waleed Anatomy Lecture.13 Chorda Tympani nerve It is a branch from the facial nerve, arises above the stylomastoid foramen & enters the middle ear close to the posterior border of the tympanic membrane. It then runs forward over the TM. It leaves the middle ear through petrotympanic fissure which extends from the temporomandibular joint to the middle ear cavity. Chorda tympani nerve joins the lingual nerve in the infratemporal fossa supplying special sensation to the anterior 2/3 of the tongue and supplies parasympathetic to the submandibular and sublingual salivary glands through the submandibular ganglia. Page | 8