Infratemporal Fossa Boundaries of Infratemporal fossa Temporomandibular joint

Infratemporal Fossa

• Boundaries of Infratemporal fossa • Temporomandibular joint • Muscles of mastication • Maxillary artery • Mandibular nerve

Bony walls of infratemporal fossa - lateral view Infratemporal surface of sphenoid (roof) Styloid & Mastoid processes (posterior boundary) Body of maxilla (anterior wall) Ramus of mandible (lateral wall) ØIrregular shaped space inferior & deep to the zygomatic arch Øbelow the middle cranial fossa

• Masseter This quadrilateral muscle of mastication arises from the lower border of the zygomatic arch and is inserted into almost the whole of the lateral surface of the mandibular ramus. Most of its fibres slope downwards and backwards at 45�. The posteriormost fibres arise from the deep surface of the arch and pass vertically downwards to be inserted into the upper part of the ramus; these fibres blend with the lower fibres of temporalis. The upper anterior part of the muscle is covered by

• This muscle (one of the muscles of mastication) arises from the temporal fossa over the whole area between the inferior temporal line and the infratemporal crest, and from the deep surface of the temporalis fascia. The most anterior fibres are vertical and the most posterior are horizontal, turning downwards in front of the temporomandibular joint. The fanshaped muscle converges towards the coronoid process of the mandible, becomes tendinous, and is inserted into a bevelled

• Lateral pterygoid This muscle arises by two heads: the upper from the roof of the infratemporal fossa and the lower from the lateral surface of the lateral pterygoid plate. The two heads, lying edge to edge, converge and fuse into a short thick tendon that is inserted into the pterygoid fovea on the front of the neck of the mandible. The upper fibres of the tendon pass back into the capsule and the articular disc of the temporomandibular joint (Fig. 6. 20).

• Medial pterygoid This muscle also arises by two heads. The larger deep head arises from the medial (deep) surface of the lateral pterygoid plate. The muscle diverges down from the lateral pterygoid muscle at nearly a right angle from their common origin on either side of the lateral pterygoid plate (Fig. 6. 20). A small slip of muscle, the superficial head, arises from the tuberosity of the maxilla and the pyramidal process of the palatine

Infratemporal fossa - posterior view Infratempora l fossa Infratemporal Surface (roof) Lateral pterygoid Plate (medial wall) Ramus of mandible Attachment of medial pterygoid ( floor) (lateral wall)

S Z T Pterygomaxillary fissure (leads to pterygopalatine fossa) Body of maxilla lateral pterygoid plate

Articular tubercle (eminence) Mandibular fossa Articular Disc Condyle of mandible Neck of mandible Superior – Articular tubercle and mandibular fossa of the temporal bone Inferior – Head or condyle of the mandible Temporomandibular joint Dislocation if condyle rides too far anteriorly over eminence

TMJ Ligs Lateral Lig Sphenomandibular L 1 st. Arch capsule Styloid Process Lateral View Stylomandibular Lig [deep cervical fascia] Medial View

Movements of the joint 1. Elevation and depression [opening & closing the mouth] 2. Protrusion [protraction] and Retrusion [retraction] 3. Lateral or side-to-side movement In resting position small space [about 2 - 3 mm] exists between the upper and lower jaws; In occlusal position the teeth of both the jaws are in contact E R P D

Muscles of Mastication ØMasseter ØTemporalis ØLateral Pterygoid ØMedial Pterygoid • Act on the TMJ • Supplied by the Mandibular nerve [V 3] • Derived from the I pharyngeal arch

Temporal fascia Temporal fossa & fascia to coronoid process of mandible. Temporalis (elevates & retracts mandible) Medial pterygoid Muscles become prominent when teeth are clenched Coronoid process Masseter (elevates mandible) zygomatic arch to outer surface of the ramus of mandible

Infratermporal surface of the sphenoid [greater wing], lateral pterygoid plate Articular disc & neck of the mandible Lateral pterygoid Superior head Inferior head [Depression, protrusion & side to side] Articular disc Buccinator Medial pterygoid [Elevation, protrusion & side to side] Lateral pterygoid plate & maxilla Inner surface of the ramus

Maxillary Artery [larger terminal branch of ECA] Lateral pterygoid Neck of the mandible to the pterygopalatine fossa Three Parts: by the lateral pterygoid muscle Superficial temporal artery ECA 1 st - Mandibular 2 nd - Pterygoid 3 rd -

Maxillary Artery – Branches I part Accessory meningeal Middle meningeal Ant. tympanic V 3 Deep auricular Inferior alveolar

Middle Meningeal Artery [enters middle cranial fossa through foramen spinosum] Passes between duramater & bone [extradural]; can be damaged in head injury leading to extradural hemorrhage middle meningeal a. Hemorrhage / hematoma may cause cerebral compression – usually motor area of cerebral cortex

Maxillary Artery – Branches I part Ø Deep auricular artery – supplies external auditory meatus, tympanic membrane Ø Anterior tympanic artery – middle ear Ø Middle meningeal artery – meninges & cranial bones Ø Accessory meningeal artery - passes through foramen ovale Ø Inferior alveolar artery – to lower jaw [passes through mandibular foramen] Note: Branches from I & II parts mostly accompany the branches of mandibular nerve; from the III part branches course along with the branches of maxillary nerve

Maxillary Artery - Branches II Part Deep Temporal ant / post Branches are mostly muscular Buccal branch Pterygoid branches

Maxillary Artery - III part sphenopalatine Pharyngeal artery Pterygoid canal a. V 3 Posterior superior alveolar Infraorbital Descending palatine

Mandibular nerve • Largest branch of trigeminal - Motor & sensory roots • Passes through the foramen ovale to enter infratemporal fossa • Divides into anterior & posterior divisions

Mandibular nerve - distribution Motor to muscles of mastication, tensor tympani, tensor palatini, mylohyoid, anterior belly of digastric [I arch derivatives] Dorsal rami of cervical nerves • Sensory – duramater of middle cranial fossa, auricle [upper part], temporal area, cheek, lower jaw, anterior two thirds of the tongue, floor of oral cavity • Referred pain – from lower teeth / oral cavity to the temporal area Cervical plexus [ventral rami] V 1 V 3 V 2

Meningeal branch / nervus spinosus Branches from the trunk of V 3 Tensor tympani Tensor palatini Trunk of V 3 Medial petrygoid

Lateral pterygoid Motor branches Buccal sensory Buccinator muscle [Facial nerve] Medial pterygoid Branches of anterior division Anterior division – Buccal, masseteric, deep temporal and nerve to lateral pterygoid [all motor except buccal] Buccal nerve – sensory to the skin over and mucosa under the buccinator

Auriculotemporal nerve [sensory + para. V 3 sympathetic to parotid from otic ganglion] Posterior Division Lingual [sensory] Chorda tympani Inferior Alveolar [sensory] Submandibular ganglion Mental Nerve to Mylohyoid [motor]

Auriculotemporal nerve Posterior Division – medial veiw Lingual nerve Inferior alveolar nerve Mylohyoid nerve

CONNECTIONS TO OTHER NERVES Otic Ganglion [Parasympathetic] Chorda Tympani [CN VII] Facial Lingual Chorda tympani – parasympathetic fibers to submandibular & sublingual salivary glands & taste from anterior two thirds of tongue

Lesser Petrosal [CN IX] Preganglionic parasympathetic fibers Trunk of V 3 Otic ganglion Auriculotemporal nerve [Postganglionic pass to the parotid gland]

Mandibular nerve - Branches • From the trunk – Meningeal, nerve to medial pterygoid [supplies medial pterygoid, tensor tympani & tensor palati] • Anterior division – Buccal [sensory], masseteric, deep temporal and nerve to lateral pterygoid • Posterior division – Auriculo-temporal, lingual and Inferior alveolar [gives nerve to mylohyoid & anterior belly of digastric]