14 - Infratemporal Fossa + TMJ.docx

BMS 133: Infratemporal Fossa + TMJ Parotid gland Around the masseter, ramus, and medial pterygoid Produces ¼ of salivary volume Serous production Submandibular gland makes the most saliva Traversing the gland CN VII External carotid artery Retromandibular vein Superficial temporal vein + Maxillary v...

BMS 133: Infratemporal Fossa + TMJ Parotid gland Around the masseter, ramus, and medial pterygoid Produces ¼ of salivary volume Serous production Submandibular gland makes the most saliva Traversing the gland CN VII External carotid artery Retromandibular vein Superficial temporal vein + Maxillary vein Anterior branch joins the facial vein = interior jugular Posterior branch joins the posterior auricular vein = external jugular Auriculotemporal nerve (V3) Parotid GSA Auriculotemporal nerve (V3) Great auricular nerve (C2+C3) Parotid GVE Sympathetic Synapse in the superior cervical ganglion Post ganglionic fiber plexus follows the arteries Parasympathetic From CN IX → Tympanic nerve → Middle cranial fossa = lesser petrosal nerve → Through foramen ovale → Synapse in Otic ganglion by V3 Postganglionic fibers follow the auriculotemporal nerve Masticator space Temporal + Infratemporal fossa Infratemporal Fossa Muscles of mastication Mandibular division of Trigeminal nerve (V3) Chorda tympani branch of Facial nerve Maxillary artery and vein Fascial compartment Fascia from investing and deep cervical fascia splits at the mandible Deep layer comes over base of skull Superficial layer comes over superficial face and temporalis Continuous with Galen aponeurosis of the scalp Envelopes the mandible and the muscles of mastication Investing layer forms parotid and submandibular gland capsule Includes branches of CN V, maxillary artery, and maxillary vein Temporalis Superficial muscle Inferior temporal line to the coronoid process Superior temporal line gives rise to fascia Tendon continues down the ramus Attaches to medial side of the occlusal plane Don’t want to give anesthetic injections into the tendon Closes and pulls the jaw back Both vertical and horizontal muscle fibers Masseter Superficial muscle Anterior border of zygomatic arch to anterior mandible Origin is more lateral than its insertion 2 heads Closes the jaw Medial pterygoid Deep muscle Medial surface of lateral plate of the sphenoid to medial surface of the ramus Origin is more medial than its insertion Closes the jaw Lateral pterygoid Deep muscle Lateral surface of the lateral plate of the sphenoid bone to articular disc and TMJ capsule 2 heads Inferior head to neck of condyle Moves jaw forward Superior head to the disc capsule of the TMJ V3 emerges between lateral and medial pterygoid muscles Lingual nerve + Inferior alveolar nerve Pterygomandibular raphe Common origin for: Buccinator muscle (anterior) Pharyngeal constrictor muscle (posterior) Pterygomandibular triangle Between the lateral pterygoid muscle and medial pterygoid muscle Lingual nerve at the floor + Inferior alveolar nerve Buccal fat anterior Parotid gland may be in the area Buccinator Keeps food on occlusal plane Assists mastication but not involved in mastication Superficial face innervation Sensory CN V innervation From 1st branchial arch Ophthalmic (V1) Maxillary (V2) Mandibular (V3) Both sensory and motor Motor of muscles of mastication Motor CN VII innervation From 2nd branchial arch Trigeminal ganglion Equivalent to a dorsal root ganglion Only contains pseudounipolar nerve cell bodies No synapse Primary sensory nerve fibers from the face Trigeminal nuclei Motor nucleus Motor to masticatory muscles, mylohyoid, anterior belly of digastric, tensor tympani, … Receives some proprioceptive fiber synapses going to the brain = Reflex arc Ex: jaw jerk reflex when biking cheek/tongue Cell bodies of motor fibers in the motor root Mesencephalic Proprioception from muscles of mastication, TMJ, and PDL Cell bodies of proprioceptive fibers in the motor root Principal/main (pontine) Touch from face, mouth, … Cell bodies of the trigeminal ganglion Spinal trigeminal Touch, pain, and temperature from face Extends to C3 Cell bodies of the trigeminal ganglion Trigeminal stem Medial pterygoid nerve Tensor tympani nerve Contracts for loud sounds to protect the eardrum Tensor palatini nerve Meningeal branch V3 anterior division Motor branches Deep temporal nerves (2) Masseteric nerve Lateral pterygoid nerve Sensory branch Long buccal nerve Penetrates the buccinator but does not innervate V3 posterior division Sensory branches Auriculotemporal nerve Parotid gland, TMJ, and lateral scalp Lingual nerve Lingual gingiva and anterior 2/3 of the tongue Medial to the inferior alveolar nerve Inferior alveolar nerve Mylohyoid Mental Terminal branch passes through the mental foramen Sensory to lower lip, skin, and mucosa Incisive Terminal branch stays in bone at the 2nd bicuspid Innervates bicuspids, canines, and incisors Molars innervated prior to split Motor branches Mylohyoid branch Motor innervation to the anterior digastric and the mylohyoid Primarily a motor nerve but also has sensory branches In the mylohyoid groove of the mandible Branches may dive into the bone and attach to the IA nerve Chorda tympani Branch of CN VII Carries SSA taste fibers from anterior tongue Secretomotor fibers to salivary glands Submandibular and Sublingual glands Joins lingual nerve of V3 in intertemporal fossa Infratemporal fossa blood supply Maxillary artery Mandibular (DAM AI) External carotid to inferior border of the lateral pterygoid muscle Deep auricular Anterior tympanic Middle meningeal Accessory meningeal Not present in everyone Enters the skull through the foramen ovale Inferior alveolar Primary blood supply to the mandible Gives rise to the mylohyoid, mental, and incisive branches Pterygoid (DM Less Big Ladies Man) Portion that crosses the lateral pterygoid muscle Deep temporal (2) Medial pterygoid Lateral pterygoid Buccal Lingual Masseteric Pterygopalatine (SPPAID) Portion in the pterygopalatine fossa Follows branches of V2 Sphenopalatine Posterior superior alveolar Pharyngeal branch Artery of pterygoid canal Infraorbital Descending palatine Infratemporal fossa blood supply Pterygoid Venous Plexus Cavernous sinus Facial vein Inferior ophthalmic vein Pharyngeal plexus Primary drainage to Maxillary vein TMJ Mandibular fossa roof is thin bone Area can’t withstand occlusal forces Articular eminence helps withstands forces Made of dense bone Articular disc Made of dense fibrous connective tissue Greater regeneration, deformation, wear, and elasticity vs Hyaline Not great at load bearing Between the temporal and mandibular bones TMJ layers Temporal bone Fibrocartilaginous zone Proliferative zone Articular zone Articular disc Capsular / Temporomandibular ligament Lateral surface is thicker Outer oblique + Inner horizontal portions Ligaments Limits movement towards disarticulation Joint spaces Separated by the articular disc 2 synovial spaces with different movements Upper joint space: translation (sliding) of the disk and bone Lower joint space: rotation of condyle against the disk Articular disc Biconcave shape Thinnest in center Thickest posteriorly Thicker medially than laterally Attached to poles of the mandible by the medial and lateral discal ligaments Disc moves with the mandibular condyle Posterior of the articular disc Bilaminar zone Retrodiscal tissue sandwiched between two lamina Superior lamina Made of elastic fibers Inferior lamina Made of collagen fibers TMJ innervation Primarily from the auriculotemporal nerve Secondarily by the masseteric nerve (anterior) TMJ blood supply Superficial temporal + Deep auricular artery Primarily to retrodiscal tissue Draining vias pterygoid venous plexus Closed position Condyle rests on the thinnest part of the disc (intermediate zone) Held by muscle tone of the muscles of mastication Disc against the posterior slope of the articular eminence Jaw movements Elevation Depression Retrusion Protrusion Lateral excursions Right & Left Accessory muscles of mastication Suprahyoid and Infrahyoid muscles Minor assistance in jaw movements TMJ opening 1st movement is rotation Hinging Within the inferior joint space Only achieves limited opening 2nd rotation is translation Sliding/Translation Within the superior joint space Allows maximum opening Lateral movements Superficial muscle contraction on side of movement + Deep muscle contraction of opposite side Opening Disc translates forward with the mandible Condyle rotates posteriorly over its head Superior retrodiscal lamina stretches Allows disc to move forwards Inferior head of lateral pterygoid muscle contracts Superior head is quiet Closing Superior head of lateral pterygoid muscle contracts Inferior head is quiet Balances posterior pull of elastic superior retrodiscal lamina Keeps the disc positioned between the two bones Condyle can move off the articular eminence when force is applied Ex: biting into food Anterior displacement Pops and clicks Caused by reduction (condyle back on disc) Disc may not slide all the way back to its normal position Head of the condyle rests on the posterior border of the disc Should be in the intermediate zone Causes of abnormal cycle Superior head of the lateral pterygoid muscle never fully relaxes Superior retrodiscal lamina loses its elasticity Joint ligaments become loose Joint pain from posterior compression Blood supply and nerves in the retrodiscal tissue Can cause tissue degeneration Birdbeak of bone Caused by condyle bone degeneration TMJ treatment Splint to hold the jaw open in a natural resting position For people that clench and grind Relax