Anatomy of the Temporal region & Temporomandibular joint

Provides a detailed description of the gross anatomy of the temporal fossa, infratemporal fossa & temporomandibular joint. The boundaries & the structures present in the temporal & infratemporal fossa, the formation & movements of the TMJ & also includes branches of the mandibular nerve & maxillary artery.

1. Temporal Region Card-5 Item-3

2. Introduction The Temporal region constitutes of the temporal and infratemporal fossae which are interconnected spaces on the lateral side of the head. Temporal fossa : lies superiorly above the zygomatic arch I nfratemporal fossa : lies inferiorly below the zygomatic arch

3. Bones of Temporal Region

4. Temporal Fossa: Borders The temporal fossa is a narrow fan-shaped space that covers the lateral surface of the skull Borders: Superiorly and posteriorly - superior temporal line Inferiorly - zygomatic arch Anteriorly - frontal process of the zygomatic bone and zygomatic process of the frontal bone

5. Temporal Fossa: Contents Contents : Temporalis muscle Deep temporal arteries Middle temporal artery Zygomaticotemporal nerve from (CN-V2) A nterior and Posterior branches of the deep temporal nerve Auriculotemporal nerve from (CN-V3) Temporal branches of the   Facial Nerve (CN-VII) Temporalis muscle: The temporalis muscle is a large, fan-shaped muscle that fills much of the temporal fossa Origins: from the bony surfaces of the fossa superiorly to the inferior temporal line and is attached laterally to the surface of the temporal fascia . Insertion: attaches down the anterior surface of the coronoid process and along the related margin of the ramus of the mandible , almost to the last molar tooth Actions: powerful elevator of the mandible. retracts the mandible side-to-side mandible movement Innervation : deep temporal branches of Mandibular Nerve (CN-V3)

6. Temporal Fossa: Contents Deep temporal arteries Normally 2 in number, these vessels originate from the maxillary artery in the infratemporal fossa Middle temporal artery The middle temporal artery originates from the superficial temporal artery just superior to the root of the zygomatic arch Auriculotemporal nerve   branch of the mandibular nerve [CN V3] Zygomaticotemporal nerve The zygomaticotemporal nerve is a branch of the zygomatic nerve which is a branch of the maxillary nerve [V2 ] Deep temporal nerves 2 deep temporal nerves , originate from the anterior trunk of the mandibular nerve [V3] in the infratemporal fossa Temporal branches of Facial nerve (CNVII) Arises from the facial nerve when it divides into its 5 branches in the parotid gland

7. Temporomandibular joint (TMJ) Articulating Surfaces: The temporomandibular joint consists of articulations between   3   surfaces ; 2 from the squamous part of the  temporal bone mandibular fossa articular tubercle 3)   head of mandible . A unique feature of the TMJ is the fibrocartilaginous articular disc , located within the joint capsule between the mandibular fossa and condyle. The disc divides the joint capsule into 2 distinct compartments : Lower compartment: During the first 2 cm of opening the mouth (depression) it enables the hinge-like rotation of the mandibular condyle . Upper compartment : For the mouth to be opened >2cm , the upper compartment within the joint capsule enables both the mandibular condyle and the articular disc to slide anteriorly (protrusion ).

8. (TMJ): Ligaments Extracapsular   ligaments There are 3  extracapsular   ligaments . They act to stabilise the temporomandibular joint. Lateral ligament   – runs from the beginning of the articular tubule to the mandibular neck . It is a thickening of the joint capsule , and acts to prevent posterior dislocation of the joint. Sphenomandibular ligament  – originates from the sphenoid spine , and attaches to the mandible at the lingula . Stylomandibular ligament  – It passes from the styloid process of the temporal bone to the posterior margin and angle of the mandible.

9. (TMJ): Muscles of Mastication

10. (TMJ): Muscles of Mastication

11. (TMJ): Muscles of Mastication

12. (TMJ): Actions Clinical : TMJ Dislocation: A  dislocation  of the temporomandibular joint can occur via a blow to the side of the face , yawning , or taking a large bite . The head of the mandible ‘slips ’ out of the mandibular fossa , and is pulled anteriorly . The patient becomes unable to close their mouth . The facial and   auriculotemporal nerves  run close to the joint, and can be damaged if the injury is high-energy. Clinical : TMJ disorder: TMJ disorder is associated with painful and limited movement of the jaw. Symptoms of TMJ disorder include: Pain and tenderness in and around the jaw , Difficulty and painful chewing Headache Clicking sounds when the jaw opens and closes . TMJ disorder can occur when the articular disc is damaged, eroded , or slipped out of alignment .

13. Infratemporal fossa: Borders Description: The wedge-shaped infratemporal fossa is inferior to the temporal fossa and between the ramus of the mandible laterally and the wall of the pharynx medially. Borders: Lateral  – coronoid process and ramus of the mandible bone Medial  – lateral pterygoid plate ; tensor veli palatine , levator veli palatine and superior constrictor muscles Anterior   – posterior border of the maxillary sinus Posterior  – carotid sheath , styloid and condylar processes Roof   – inferior surfaces of the greater wing of the sphenoid bone and temporal bone Floor   – medial pterygoid muscle

14. Infratemporal fossa: Borders

15. Infratemporal fossa: Contents Ligaments : sphenomandibular ligament Muscles: temporalis, lateral pterygoid, medial pterygoid

16. Infratemporal fossa: Contents Arterial Supply Maxillary artery :   The terminal branch of the external carotid artery. It travels through the infratemporal fossa. Important branches here are: Middle meningeal artery: Ascends through the foramen spinosum , coursing between the roots of the auriculotemporal nerve ; provides the principal blood supply to intracranial dura mater. Inferior alveolar artery. Accompanies the inferior alveolar nerve into the mandibular foramen .

17. Branches of Maxillary artery

18. Branches of Maxillary artery The main trunk of the maxillary artery is divided into 3 parts. These three parts are the: Mandibular part (1st part) – named as such because it winds around deep to the neck of the mandible . Branches here: D – deep auricular artery  A – anterior tympanic artery M – middle meningeal artery I – inferior alveolar artery A – accessory meningeal artery Pterygoid part (2nd part ) – it has this name because it travels between the two heads of the lateral pterygoid muscle  . Branches here: M – masseteric artery P – pterygoid artery D – deep temporal artery B – buccal or buccinator artery   Pterygopalatine part (3rd part) – this part derived its name from the  pterygopalatine fossa , into which it enters . Branches here: S – sphenopalatine artery D – descending palatine artery I – infraorbital artery P – posterior superior alveolar artery M - middle superior alveolar artery P – pharyngeal artery A - anterior superior alveolar artery A – artery of the pterygoid canal MNEMONIC:     DAM n  I AM   P iss  D runk  B ut  S tupid  D runk  I   P refer,  M ust  P hone  A lcoholics  A nonymous

19. Infratemporal fossa: Contents Venous Drainage Pterygoid venous plexus   –  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. Maxillary vein Middle meningeal vein

20. Infratemporal fossa: Contents Nerves of the Infratemporal fossa: Mandibular nerve [CN-V3]   Posterior superior alveolar nerve- branch of Maxillary nerve [CN-V2]   Otic ganglion- ganglion where lesser petrosal synapses Chorda tympani- branch of Facial nerve [CN-IX] hitch-hikes Lingual nerve from CN-V3 Lesser petrosal nerve- branch of Glossopharyngeal nerve [CN-IX] hitch-hikes Auriculotemporal nerve from CN-V3

21. Mandibular Nerve- Trunk &Anterior Division The sensory and motor roots of [CN V-3] fuse together as a trunk and descend into the infratemporal fossa via the foramen ovale . Trunk (pre-division): Branches arising are Meningeal branch- (General Sensory) from dura mater , mainly of the middle cranial fossa, and the mastoid cells. Nerve to the medial pterygoid – ( Motor) Medial pterygoid muscle Tensor veli palatini muscle Tensor tympani muscle Anterior division : Deep temporal nerves- (Motor) Temporalis muscle Masseteric nerve- (Motor) Masseter muscle Nerve to lateral pterygoid- (Motor) Lateral pterygoid muscle Buccal nerve- (General Sensory) skin of the cheek

22. Mandibular Nerve- Posterior Division Posterior division : Auriculotemporal nerve- ( General Sensory) to the temporal region of the face and scalp , and external ear . postganglionic parasympathetic nerves from the lesser petrosal nerve [CN IX] to the parotid gland. Lingual nerve- (General sensory) from the anterior 2/3s of the tongue Inferior alveolar nerve- ( General sensory ) all lower teeth and much of the associated gingivae, it also supplies the mucosa and skin of the lower lip and skin of the chin . Nerve to the mylohyoid : (Motor) Mylohyoid muscle Anterior belly of the digastric muscle.

23. Chorda Tympani & Lesser Petrosal Chorda tympani nerve [CN VII]: Enters the infratemporal fossa via the petrotympanic fissure , where it joins with the lingual nerve . The chorda tympani nerve provides: ( Special sensory) taste from the anterior 2/3 s of the tongue , Visceral motor parasympathetic innervation to the submandibular and sublingual salivary glands. Submandibular ganglion : Suspended from the lingual nerve, where preganglionic and postganglionic parasympathetic neurons from the chorda tympani nerve (CN VII) synapse en route to innervating the submandibular and sublingual salivary glands. Lesser petrosal nerve [CN IX] : The lesser petrosal nerve carries mainly parasympathetic fibers destined for the parotid gland . Enters the infratemporal fossa via the foramen ovale , where it synapses in the otic ganglion . Otic ganglion : Preganglionic parasympathetic neurons from lesser petrosal nerve [CN IX] exit the middle ear and synapse in the otic ganglion. Postganglionic parasympathetic neurons "hitch-hike " along with the auriculotemporal nerve and innervate the parotid gland

24. Chorda Tympani & Lesser Petrosal