Muscles of Mastication Temporal and Infratemporal Fossae

Muscles of mastication Temporal and Infratemporal fossae Depression Elevation Protraction Retraction Temporalis muscle Origin: from the bony surfaces of the temporal fossa Insertion: coronoid process And anterior border of the ramus of the mandible Action: Temporalis is a powerful elevator of the mandible, closing jaws Retraction of the mandible Temporalis is innervated by deep temporal nerves (mandibular nerve) Masseter muscle Origin: the zygomatic arch, maxillary process of zygomatic bone. Insertion: into the lateral surface of the ramus of the mandible Action: elevation of the mandible, closing jaws The masseter is innervated by the masseteric nerve from the mandibular nerve [V3] The masseter muscle is quadrangular in shape Medial pterygoid Origin: medial surface of the lateral plate of the pterygoid process Insertion: medial surface of the ramus of mandible near the angle Action: The medial pterygoid mainly elevates the mandible, closing jaws The medial pterygoid is innervated by the nerve to medial pterygoid from the mandibular nerve [V3]. The medial pterygoid muscle is quadrangular in shape and has deep and superficial heads Note: the fibers of the medial pterygoid are oriented almost vertically Lateral pterygoid The upper head originates from the roof of the infratemporal fossa (inferior surface of the greater wing of the sphenoid and and the infratemporal crest) The lower head is larger and originates from the lateral surface of the lateral plate of the pterygoid process Insertion: into the neck of mandible (pterygoid fovea), into the capsule of the Temporomandibular joint Action: The lateral pterygoid is the major protruder of the lower jaw The lateral pterygoid is innervated by the nerve to lateral pterygoid from the mandibular nerve [V3]. The lateral pterygoid is a thick triangular muscle and has two heads Note: the fibers of the lateral pterygoid are oriented almost horizontally The upper head The lower head Lateral Infratemporal crest lateral pterygoid plate Pterygoid fovea Lateral pterygoid The upper head The lower head Medial pterygoid Masseter/ Superficial part Masseter/ deep part Temporal and infratemporal fossae are interconnected spaces on the lateral side of the head Temporal fossa is superior to the infratemporal fossa above the zygomatic arch Temporal fossa Pterygo-palatine fossa Lies below the apex of the orbit Of the four muscles of mastication (masseter, temporalis, medial pterygoid, and lateral pterygoid) that move the lower jaw at the TMJ One (masseter) is lateral to the infratemporal fossa Two (medial and lateral pterygoid) are in the infratemporal fossa One fills the temporal fossa (temporalis) Temporal fossa is a narrow fan shaped space that covers the lateral surface of the skull Temporal fossa Contents Temporalis muscle Temporal fascia Zygomaticotemporal nerve The infratemporal fossa is an irregularly shaped cavity, situated below the zygomatic arch, deep to the ramus of the mandible The infratemporal fossa acts as a pathway for neurovascular structures passing to and from the cranial cavity, pterygopalatine fossa and temporal fossa. It also contains some of the muscles of mastication Infra temporal fossa Anterior wall: back of the maxilla Medial wall: lateral pterygoid plate Roof: greater wing of sphenoid bone Lateral wall: ramus of mandible Communications Temporal fossa: through the gap deep to the zygomatic arch Orbit: through the inferior orbital fissure Pterygo-palatine fossa: through the pterygo-maxillary fissure Middle cranial fossa: through foramen ovale and spinosum Note: the infratemporal fossa lies between the ramus of the mandible laterally and the wall of pharynx medially greater wing of sphenoid bone Back of the maxilla lateral pterygoid plate Infratemporal fossa The roof of Infratemporal fossa Inferior view of the skull Inferior orbital fissure Foramen ovale (Mandibular nerve) Foramen spinosum (Middle meningeal artery) Note: The foramen ovale and foramen spinosum open on its roof Pterygo-palatine fossa Inferior orbital fissure Communication with the orbit Maxilla Lat Pterygoid plate The medial and anterior walls of Infratemporal fossa Pterygo-maxillary fissure Communication with Pterygo-palatine fossa Greater wing of sphenoid Lateral wall is formed by the medial surface of the ramus of mandible Which contains the mandibular foramen The lateral wall of Infratemporal fossa Lateral pterygoid plate Mandibular foramen: an opening to the mandibular canal Transmits inferior alveolar nerve (mandibular nerve) Contents of infratemporal fossa Lateral pterygoid muscle Medial pterygoid muscle Sphenomandibular ligament Maxillary artery (and its branches: ☺Middle meningeal artery Deep temporal arteries Buccal artery Inferior alveolar artery Mandibular nerve (and its branches: Auriculotemporal nerve Buccal nerve Lingual nerve Inferior alveolar nerve Chorda tympani Pterygoid venous plexus Maxillary vein Middle meningeal vein Otic ganglion Temporalis Lateral pterygoid muscle Medial pterygoid muscle Maxillary artery Buccinator Masseter Maxillary artery the terminal branch of the external carotid artery. It travels through the infratemporal fossa. Within the fossa, it gives rise to the middle meningeal artery, which passes through the foramen spinosum. Foramen spinosum Deep temporal arteries Infraorbital artery Buccal artery Masseteric artery Maxillary artery Middle meningeal artery Superficial temporal artery External carotid artery Inferior alveolar artery Mandibular Nerve (V3) The mandibular nerve is both motor and sensory The sensory root leaves the trigeminal ganglion and passes out of the skull through the foramen ovale to enter the infratemporal fossa. The motor root of the trigeminal nerve also leaves the skull through the foramen ovale and joins the sensory root to form the trunk of the mandibular nerve Then divides into a small anterior and a large posterior division . foramen ovale Branches From the Main Trunk of the Mandibular Nerve: 1- Meningeal branch 2- Nerve to the medial pterygoid muscle Branches From the Anterior Division of the Mandibular Nerve 1- Masseteric nerve (to masseter muscle) 2- Deep temporal nerves (to temporalis muscle) 3- Nerve to the lateral pterygoid muscle 4- Buccal nerve Branches From the Posterior Division of the Mandibular Nerve 1- Auriculotemporal nerve 2- Lingual nerve 3- Inferior alveolar nerve Foramen spinosum Foramen ovale Meningeal branch Posterior Division Auriculotemporal nerve Lingual nerve Nerve to the medial pterygoid Anterior Division Masseteric nerve Deep temporal nerve Nerve to the lateral pterygoid Inferior alveolar nerve Buccal nerve Deep temporal nerves Meningeal branch Auriculotemporal nerve Buccal nerve Lingual nerve Inferior Alveolar nerve Masseteric nerve Nerve to the medial pterygoid muscle supplies: 1- The medial pterygoid muscle 2- The tensor veli palatini muscle 3- The tensor tympani muscle Lingual nerve It supplies the mucous membrane of the anterior two thirds of the tongue and the floor of the mouth (general sensations)  It is joined by the chorda tympani nerve  It gives off preganglionic parasympathetic secretomotor fibers to the submandibular ganglion. It carries taste information from the anterior two thirds of the tongue, via the chorda tympani The buccal nerve is the only sensory branch of the anterior division of the mandibular nerve. Note: The buccal nerve of mandibular nerve is SENSORY and does not supply the buccinator muscle (which is supplied by buccal branch of facial nerve MOTOR) Buccal nerve supplies the skin and the mucous membrane of the cheek Auriculotemporal nerve conveys postganglionic parasympathetic secretomotor fibers from the otic ganglion to the parotid salivary gland. The inferior alveolar nerve (inferior dental nerve) is a branch of the mandibular nerve It supplies sensation to the lower teeth, lower lip and chin Mental nerve is a branch of inferior alveolar nerve to supply the skin and mucous membrane of the lower lip and chin (Passes through mental foramen) Sphenomandibular ligament is an extra-capsular ligament of TMJ . It runs between the spine of sphenoid and the lingula of the mandible Lingula Spine of sphenoid Greater wing Foramen spinosum Spine of sphenoid Temporomandibular joint Sphenomandibular ligament It is the primary passive support of the mandible, along with the muscles of mastication. Superior and inferior ophthalmic veins Cavernous sinus Pterygoid venous plexus It is a valveless venous plexus of considerable size, and is situated on the lateral aspect of medial pterygoid within the infratemporal fossa It drains the eye and is directly connected to the cavernous sinus. It provides a potential route by which infections of the face can spread intracranially. Facial vein It receives tributaries corresponding with the branches of the maxillary artery deep facial vein It forms the maxillary vein Pterygoid venous plexus The maxillary vein consist of a short trunk Superficial temporal vein It is formed by a confluence of the veins of the pterygoid plexus Posterior auricular vein It unites with the superficial temporal vein to form the retromandibular vein Maxillary vein Facial vein Retromandibular vein Ant. division of retromandibular vein Post. division of Retromandibular vein Common facial vein Internal jugular vein External jugular vein Note: Pterygoid venous plexus lies around lateral pterygoid muscle Superficial temporal vein Facial vein Maxillary vein Retromandibular vein Pterygoid venous plexus Deep facial vein The otic ganglion is a small parasympathetic ganglion located immediately below the foramen ovale in the infratemporal fossa and on the medial surface of the mandibular nerve. It is functionally associated with the glossopharyngeal nerve and innervates the parotid gland for salivation. The preganglionic parasympathetic fibers originate in the glossopharyngeal nerve, and they reach the ganglion via the lesser petrosal nerve The postganglionic parasympathetic (secretomotor) fibers reach the parotid salivary gland via the auriculotemporal nerve. The lesser petrosal nerve is a branch from glossopharyngeal nerve (CN IX), carrying parasympathetic preganglionic fibers from the tympanic plexus to the parotid gland. It synapses in the otic ganglion, from where the postganglionic fibers emerge Tympanic nerve IJV Glossopharyngeal nerve Medial wall Lesser petrosal nerve Tympanic nerve IJV Glossopharyngeal nerve Middle meningeal artery Lesser petrosal nerve Foramen spinosum Foramen ovale Auriculotemporal nerve Mandibular nerve Otic ganglion Auriculotemporal nerve Anatomically its connected to mandibular nerve Functionally its associated with the glossopharyngeal nerve Mandibular nerve Sensory root Does not relay Lesser petrosal nerve Parasympathetic root Sympathetic root Does not relay Sympathetic plexus Around MMA Otic ganglion Foramen ovale transmits: Mandibular nerve Accessory meningeal artery Lesser petrosal nerve Emissary vein MALE Cavernous sinus Foramen ovale Emissary vein Pterygoid venous plexus in Infratemporal fossa