Infratemporal Fossa
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The infratemporal fossa is a region of the skull bounded by the maxilla anteriorly, styloid process posteriorly, lateral pterygoid plate medially, and ramus of mandible laterally. It contains the lateral and medial pterygoid muscles, branches of the mandibular nerve, maxillary artery and its branches, and the pterygoid venous plexus. The lateral pterygoid muscle has upper and lower heads and functions to open the mouth and move the mandible protrusively and laterally. The medial pterygoid muscle has deep and superficial heads and functions to elevate the mandible.
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Infratemporal Fossa
- 2. Boundaries • Anterior ▫ Posterior surface of the maxilla • Posterior ▫ Styloid apparatus, carotid sheath and deep part of the parotid gland • Medial ▫ Lateral pterygoid plate and the superior constrictor muscle of the pharynx • Lateral ▫ Ramus • Roof ▫ Greater wing of the sphenoid
- 3. Contents • The lateral and medial pterygoid muscles • The mandibular division of the trigeminal nerve • The chorda tympani branch of the facial nerve • The otic parasympathetic ganglion • The maxillary artery and branches • The pterygoid venous plexus • The deep ‘lobe’ of the parotid gland.
- 4. Lateral pterygoid relations • Deep to the muscle ▫ Branches of the mandibular nerve and the main origin of the medial pterygoid muscle. • Superficial to the lower head ▫ The maxillay artery • Between the two heads ▫ The buccal branch of the mandibular nerve • Below the inferior border ▫ Medial pterygoid muscle and the lingual and inferior alveolar nerves. • Upper border ▫ The deep temporal nerves and vessels. • Around and within the lateral muscle ▫ The pterygoid venous plexus.
- 6. The Masticatory Muscles • The four primary masticatory muscles ▫ Temporalis ▫ Media pterygoid ▫ Lateral pterygoid ▫ Masseter • Derived from the first branchial arch • Supplied by the mandibular nerve.
- 7. Lateral Pterygoid Muscle • Two heads ▫ Large Lower (pterygoid) ▫ Small upper (infratemporal) • Origin ▫ Lower head: lateral surface of pterygoid plate ▫ Upper head: infratemporal surface of greater wing • Insertion ▫ Lower: Pterygoid fovea (condyle) ▫ Upper: Capsule and articular disc • Innervation ▫ Anterior trunk of mandibular nerve • Vasculture ▫ Pterygoid branches of maxillary ▫ Ascending palatine from facial • Action ▫ Opening the mouth ▫ protrusion and in lateral movements of the mandible
- 8. Medial Pterygoid Muscle • Two heads ▫ Deep ▫ Superficial (tuberal) • Origin ▫ Deep head: Medial of the lateral pterygoid ▫ Superficial head: Maxillary tuberosity and pyramidal process • Insertion ▫ Roughened surface of the angle of the mandible on its medial aspect. • Innervation ▫ The mandibular nerve (trunk) • Vasculture ▫ Pterygoid branches of maxillary • Action ▫ Elevate the mandible ▫ Lateral and protrusive movements
- 9. Pterygoid Hiatus Sphenomandibular Muscle • Superiorly ▫ The inferior margin of the lower head of the lateral pterygoid muscle • Inferiorly ▫ The posterior margin of the medial pterygoid muscle. • In this space ▫ The lingual and inferior alveolar nerves, ▫ The first part of the maxillary artery ▫ Part of the pterygoid venous plexus ▫ The sphenomandibular ligament. • 5th masticatory muscle? • Origin: ▫ Greater wing of sphenoid • Insertion: ▫ Inner anterior coronoid ▫ Anterior ramus • Action ▫ Elevation (protrusion?) • Alternative explaination: ▫ Unidentified component of temporalis or medial pterygoid Contents
- 10. The Otic Ganglion • Below the foramen ovale • Parotid gland • The lesser petrosal nerve
- 11. The Maxillary Artery • Arises within the parotid gland ▫ At the level of the neck of the condyle • Enters the infratemporal fossa between the deep surface of the condyle and the sphenomandibular ligament. ▫ Below the auriculotemporal nerve and above the maxillary vein. • Firmly adherent to the
- 12. The Maxillary Artery • It lies near the inferior border of the muscle, crossing the inferior alveolar nerve.
- 13. The Maxillary Artery • 1st part: ▫ 5 branches ▫ Enter bone • 2nd part: ▫ 5 branches ▫ Not Entering • 3rd part: ▫ pterygopalatine fossa
- 14. Pterygoid Venous Plexus ▫ Within, the lateral pterygoid muscle and it surrounds the maxillary artery. ▫ Allows for the rapid take-up of blood ▫ Communicates with the cavernous sinus, the facial vein, the inferior ophthalmic vein and the pharyngeal plexus
- 15. Other contents ▫ Sphenomandibular ligament ▫ The tensor veli palatini muscle ▫ The insertion of the temporalis muscle ▫ The maxillary nerve As it passes from the pterygopalatine fossa into the inferior orbital fissure ▫ The posterior superior alveolar nerve(s), ▫ A loop of the facial artery ▫ The deep ‘lobe’ of the parotid gland
Editor's Notes
- The key to understanding the relationships of structures within the infratemporal fossa is the lateral pterygoid muscle. Thislies in the roof of the fossa, running anteroposteriorly in a horizontal plane from the region of the pterygoid plates to themandibular condyle. Deep to the muscleBranches of the mandibular nerve and the main origin of the medial pterygoid muscle. Superficial to the lower headThe maxillay artery Between the two headsThe buccal branch of the mandibular nerve Below the inferior border medial pterygoid muscle and the lingual and inferior alveolar nerves.Upper borderThe deep temporal nerves and vessels. Around and within the lateral muscle The pterygoid venous plexus.
- The pterygoid muscles lie within the infratemporalfossa. The masseter muscle arises from the zygomatic arch and is attached to the lateral surface of the ramus. The temporalis muscle arises from the floor of the temporal fossa and the overlying temporal fascia, passes behindthe zygomatic arch, and is attached to the anterior and medial surface of the coronoid process
- Some anatomists claim that the lateral pterygoid has threeheads—the upper head having two slips of muscle. t has been estimated that the upper head of the lateral pterygoid muscle can exert a tensileforce of about 40 N and the lower head a greater force of approximately 130 N.
- It has been estimated that the elevating force provided by thispterygoid masseter sling can be as great as 420 N
- It appears to take origin from the greater wing of the sphenoid bone (at the base of the temporal fossa) andextends downwards and backwards to be inserted onto the inner and anterior aspect of the mandibular coronoid process andthe anterior edge of the mandibular ramus. It would appear from its orientation that the muscle aids elevation (and perhapsprotrusion) of the mandible. An alternative explanation for the muscle is that it is a previously unidentified component of aknown muscle. Indeed, it may therefore be linked to the medial pterygoid muscle or be considered part of the temporal
- Immediately below the foramen ovale medial to mandibular trunk
- Terminal branch of carotidEnters the infratemporal fossa between the deep surface of the condyle and the sphenomandibular ligament.
- Its subsequent course is variable, although it usually passes superficial to the lower head of the lateral pterygoid before entering the pterygopalatine fossa through the pterygomaxillary fissure
- The maxillary artery has many branches. It is convenient to subdivide the artery into three parts: before the lateral pterygoidmuscle (first or (retro)mandibular part), on the lateral pterygoid muscle (second or pterygoid part), and in the pterygopalatinefossa (third or pterygopalatine part) (see page 52). The first branch is the deep auricular artery,supplying the skin of the external acoustic meatus and part of the tympanic membrane. anterior tympanic artery, passes through thepetrotympanic fissure to supply part of the lining of the middle ear. This is the companion artery to the chorda tympanic nerve The arterymay arise either directly from the first part of the maxillary artery or from a common trunk with the inferior alveolarartery.4,30 When the maxillary artery lies superficial to the lateral pterygoid muscle, the middle meningeal artery is usually thefirst branch of the maxillary arteryIA arises directly from the external carotid artery.
- The pterygoid venous plexus chiefly drains posteriorly into the maxillary vein. The maxillary vein runs with the first part ofthe maxillary artery, passing deep to the neck of the condyle of the mandible to enter the parotid gland. Here, it joins thesuperficial temporal vein to form the retromandibular vein.