Temporal & infratemporal fossae

1. Temporal & infratemporal fossae • Temporal fossa :extends above by the sup.temporal line and below by zygomatic arch. • Infratemporal fossa : lies beneath the base of the skull, between the pharynx (medially) & ramus ofmandible (laterally). or the space lying below the temporal fossa and behind the maxilla.

2. Muscles of mastication:1-Temporalis • It lies in the temporal fossa. • Origin:floor of temporal fossa & temporal fascia. • Insertion:by a tendon into the coronoid process of the mandible. • N.supply: deep temporalnerves from the ant.division ofmandibular N. • Action: anterior fibers --- elevate the mandible.posterior fibers--- retract themandible.

3. Muscles of mastication • 2-Masseter muscle : • Origin :lower border & inner surface of zygomatic arch. • Insertion : lateral (outer) surface of ramus of the mandible. • N.supply :masseteric N. from anterior division ofmandibular N. • Action : raises the mandible.

4. Muscles of Mastication attached to mandible : Medial Surface Lateral Surface

5. Contents of the temporal fossa 1-Temporalis muscle. 2-Temporal fascia---- covers temporalis muscle, attached above to sup.temporal line and below to upper border of zygomatic arch. 3-Deep temporal nerves :from the ant. division ofmandibularN., emerge from upper border of lateral pterygoid, enter the deep surface of temporalis .

6. Contents of the temporal fossa 4-Auriculotemporal nerve : arise from the posterior division of mandibular N.It emerges from upper border of parotid gland ,It liesbehind superficial temporal artery & TMJ, in front of the auricle. It supplies skin of auricle , ext.auditory meatus and the scalpe over the temporal region.

7. Contents of the temporal fossa 5-Superficial temporalartery : it is a terminal branch of ext.carotid artery. • It Emerges from upper border of parotid gland, behind T.M.J. • It crosses root of zygomatic arch in front of auriculo-temporal N. & auricle ,here its pulsation can be easily felt.

8. Contents of Infratemporal fossa • Lateral & medial pterygoid muscles (muscles of mastication) • Branches of the mandibular N. • Otic ganglion. • Chorda tympani. • Maxillary artery. • Pterygoid venous plexus.

9. Lateral pterygoid • Origin :upper head---- from the infratemporal surface of the greater wing of sphenoid.Lower head---- from the lateral surface of lateral pterygoid plate. • Insertion :neck of mandible (pterygoid fovea) & articular disc of T.M.J. • N.supply :anterior division.of mandibular N. • Action:1-Pulls the neck of mandible forward with the articular disc to depress mandible during opening of mouth. 2-Acting with medial pterygoid of the same side during movement of chewing. 3-Acting with medial pterygoid to protrude the mandible.

10. Medial pterygoid • Origin:superficial head----- from the tuberosity of themaxilla.Deep head----- from the medial surface of the lateral pterygoid plate. • Insertion: angle of mandible (medial surface). • N.supply : main trunk ofmandibular N. • Action : 1-elevates the mandible. 2-Acting with lateral pterygoid duringmovement of chewing.

11. Tempromandibular joint (TMJ) • Articlation :between the articular tubercle & mandibular fossa of temporal bone, and the head of mandible (condyloid process). • Type :condyloid synovial joint. • Capsule :it surrounds the joint. • Synovial membrane--- lines the capsule in upper & lower cavities.

12. Ligaments of Temperomandibular joint : • Lateral temporomandibular ligament : lies on the lateral side of joint ,between the tubercle and lateral surface of the neck of mandible. • Sphenomandibular ligament : lies on the medial side of the joint ,it connects the spine ofsphenoid to the lingula of mandibular foramen. • Stylomandibular ligamentbehind& medial .to the joint. it is a band ofthickened deep cervical fascia, from apex of styloid process to angle of mandibule.

13. Intracapsular articular disc • It is a plate offibro-cartilage, it divides the joint into upper & lower cavities. • It is attached in front to the tendon of lat. pterygoid , and by fibrous bands to head ofmandible. • Its upper surfaceis concavo-convexto fit the articular tubercle & mandibular fossa , while its lower surface is concave to fit the head of mandible.

14. N.supply-auriculotemporal & masseteric branches ofmandibular N. Movements: • Depression of mandibule : by lat.pterygoid, helped bydigastric,geniohyoid & mylohyoid muscles. • Elevation :by temporalis,masseter, and medial pterygoid. • Protrusion : by lateral + medial pterygoids of both sides. • Retraction :by post.fibers of temporalis . • Lateral chewing movement:by lat.& med. Pterygoids of both sides acting alternately.

15. Relation of the Temporomandibularjoint (TMJ) : • Anteriorly :mandibular notch and masseteric N. & artery (structures passing through mandibular notch). • Posteriorly :ext.auditorymeatus, glenoid process of parotid gland., auriculotemporal N., & superficial temporal artery. • Laterally :parotid gland, fascia & skin. • Medially :maxillary vessels.

16. Clinical significance of the TMJ : • The great strength of the Lat.TM ligamentprevents head of mandible from passing backward to cause fracture of the tympanic plate in case of severe blow on the chin. • The articular disc may be partially detached causing noisy & audibleclick, during movements of the joint.

17. Dislocation of the TMJ • Sometimes occurs when themandible is depressed. • In case of minor blow on chin or sudden contraction of lateral pterygoids as in yawning, leads to pull the head of mandible & articular disc forward beyond the summit of tubercle. • Reduction of disloction : by pressing the thumbs downward on the lower molar teeth and pushing the jaw backward.