Infratemporal fossa and muscles of mastication

Infratemporal fossa and muscles of mastication

? Clinical case (review question)
A 20 year-old woman came back to her dentist few days after extraction of her lower third molar. She subsequently complained of numbness of the left side of her tongue and the floor of mouth. Her taste was also changed.
1- Which nerve is most likely injured in this case?
2- How it is related to lower third molar?
Lab check list
By the end of this lab students should be able to identify the following structures
1. Greater wing of sphenoid
2. Foramen ovale
3. Foramen spinosum
4. Lateral pterygoid plate
5. Pterygomaxillary fissure
6. Pterygopalatine fossa
7. Maxilla (Infratemporal surface)
8. Inferior orbital fissure
9. Lateral pterygoid
10. Medial pterygoid
11. Temporalis
12. Maxillary artery
13. Inferior alveolar artery
14. Mandibular nerve
15. Inferior alveolar nerve
16. Mental and incisive branches of inferior alveolar nerve
17. Lingual nerve
18. Chorda tympani nerve
19. Nerve to masseter

Lab Session objectives
By the end of this session students should be able to
1. List the boundaries, content of the infratemporal fossa
2. Define the cavities communicating with infratemporal fossa
3. Describe muscles of mastication (location, relations, nerve supply and action)

A- Infratemporal fossa (A space medial to ramus of mandible/lateral to pharynx)
? Boundaries (formed by bones of skull)
• Roof:
? Greater wing of sphenoid
? Foramen ovale & spinosum (to cranial cavity)
• Medial wall:
? Lateral pterygoid plate
? Pterygomaxillary fissure (to pterygopalatine fossa)
• Lateral wall:
? Ramus of the mandible
• Anterior wall:
? Maxilla (Infratemporal surface)
? Inferior orbital fissure
• Posterior wall
? Styloid process
? Communications
• Cranial cavity: through………………..
• Temporal fossa: Deep to …………………arch
• Pterygopalatine fossa: through ……………………… fissure
• Orbital cavity: through …………………………… fissure
? Content
• Muscles:
1. Lateral pterygoid
2. Medial pterygoid
3. Temporalis (tendon)
• Vessels:
1. Maxillary artery
2. Maxillary vein
3. Pterygoid venous plexus
• Nerves:
1. Mandibular nerve and branches
2. Chorda tympani nerve
3. Otic ganglion
? Important vessels:
• Maxillary artery
? A branch of ………………..
? Enter the fossa by passing medial to ……………….
? Pass through a gap between the fibers of lateral pterygoid muscle
? Leave the infratemporal fossa through …………………… to reach ……………..
• Inferior alveolar artery
? A branch of ……………………
? Reach the mandibular foramen with the inferior alveolar nerve
? Supply …………………..
? Important nerves:
• Nerve to masseter
? A branch of ……………
? Reach the mandibular notch

• Inferior alveolar nerve (a branch of mandibular nerve)
? Emerge at the lower border of lateral pterygoid
? Reach the …..……………. foramen to enter the mandibular canal
? Terminates by dividing into mental and incisive branches
? It supply ……………….
• Lingual nerve (a branch of mandibular nerve)
? Joined by chorda tympani nerve at the lower border of lateral pterygoid muscle
? Run medial to ramus of mandible/medial to the socket for last molar tooth
? Enters the mouth above the mylohyoid
? It supply ……………….

B- Muscles of mastication
? Lateral pterygoid (Key muscle of infratemporal fossa)
• Origin: lateral pterygoid plate (medial wall of the fossa)
• Insertion: Pterygoid fovea (neck of mandible), Articular disc and capsule of TMJ
• Action: ………………………(Note: It is the only muscle of mastication which opens the mouth)
• Maxillary artery lies superficial to it
• Deep to it lies:
1. Mandibular nerve
2. Sphenomandibular ligament.
? Medial pterygoid
• Origin: medial surface of lateral pterygoid plate
• Insertion: angle of mandible (medial aspect)
? Temporalis (tendon)
• Origin: temporal fossa
• Pass deep to zygomatic arch
• Insertion: Coronoid process of mandible
? Masseter
• Origin: ……………………..
• Insertion: ………………………………..
• Important structures related to it include:
1. ……………………………………. nerve
2. ……………………………………. artery
3. ……………………………………. duct

Exercise: Regarding the temporalis and masseter muscles
1- How they are related to zygomatic arch?
2- If you are asked to palpate them, what will you ask the patient to do?
3- What is the nerve supplying both muscles?