1. Infratemporal fossa
Dr A.Prasanna

2. Objectives The objective of the lecture :
Is to discuss infratemporal fossa
Muscles of mastication
Maxillary artery
Mandibular nerve
Temporomandibular joint.

3. Boundaries of infratemporal fossa
Roof:
Infratemporal surface of greater wing of sphenoid bone
A small part by sqamous part of temporal bone
Medial wall— Lateral pterygoid plate
Anterior wall—formed by posterior surface of body maxilla
Lateral wall—by medial surface of ramus of mandible.

4. Contents of infratemporal fossa
Lateral and medial pterygoid muscles
Maxillary artery
Mandibular nerve
Chorda tympani nerve
Maxillary nerve

5. Muscles of mastication

6. Muscles of mastication
There are 4 muscles
They are supplied by mandibular nerve
They develop from 1st pharyngeal arch
Muscles are :
Masseter
Temporalis
Lateral pterygoid
Medial prerygoid

7. Masseter Origin : lower border and deep surface of zygomatic arch
Insertion : lateral surface of ramus of mandible
Action : elevation and protrusion of mandible

8. Zygomatic arch & ramus of mandible

9. Temporalis Origin : temporal fossa Insertion :
Coronoid process apex
Anterior border of ramus of mandible
Action : elevation and retraction of mandible

10. Temporal fossa & coronoid process

11. Lateral pterygoid Origin : Upper head from roof of infratemporal fossa
Lower head from lateral surface of lateral pterygoid plate
Insertion :
Pterygoid fovea
Capsule of tempromandibular joint
Articular disc
Action : Depresion , protrusion and side to side movement

12. Infratemporal surface – lateral pterygoid plate & pterygoid fovea

13. Relations of Lateral pterygoid
It is triangular muscle
Base in the front and apex in the back attached to pterygoid fovea
From upper margin deep temporal nerves and vessels emerge
Buccal nerve emerges between the two heads of muscles
Maxillary artery lies superficial to the lower head of muscle
Lingual nerve and inferior alveolar nerve emerge from the lower margin of muscle
Middle meningeal artery and accessory middle meningeal artery passes deep to muscle

14. Lateral pterygoid relations

15. Medial pterygoid Origin : Superficial head from tuberosity of maxilla
Deep head from medial surface of lateral pterygoid plate
Insertion : medial side of angle of mandible
Action : Elevation , protrusion and side to side movement

16. Tuberosity of maxilla -Lateral pterygoid plate & pterygoid fovea

17. Maxillary artery

18. Maxillary artery parts

19. Maxillary artery
Beginning : posterior to the neck of mandible as a large terminal branch of external carotid artery
Three parts
First part: runs horizontally forwards between the neck of the mandible and sphenomandibular ligament
On the lower border of lateral pterygoid muscle

20. Maxillary artery
Second part : runs anterosuperiorly superficial to lower head of lateral pterygoid
Third part : turns medially between the heads of lateral pterygoid and ends in the pterygopalatine fossa

21. Maxillary artery The artery gives branches to :
External acoustic meatus
Middle ear
Muscles of the infratemporal region
Skull bones
Dura matter by middle meningeal artery
Its branches accompanies nerves into infratemporal and pterygopalatine fossa

22. Maxillary artery
The inferior alveolar artery descends with inferior alveolar nerve
To enter into mandibular foramen
It courses through the mandibular canal to supply teeth, gums and mandible
It also supplies skin over the chin and lip through the mental artery
It sends mylohyoid artery along with the mylohyoid nerve
The veins drain into pterygoid venous plexus

23. Branches of the maxillary artery

24. Mandibular nerve

26. Mandibular nerve It is a branch of trigeminal nerve
Arises from trigeminal ganglion
Passes through foramen ovale
It is joined by motor root in the foramen ovale and emerges as mixed nerve
It divides immediately as anterior ( mainly motor) and posterior ( mainly sensory) divisions

27. Branches from trunk
Meningeal branch enters skull with middle meningeal artery
Nerve to medial pterygoid

28. Branches from anterior division
Large sensory buccal nerve
Passes between the two heads of lateral pterygoid
Runs on the surface of buccinator muscle
It forms plexus with buccal branch of facial nerve
It supplies entire thickness of cheek from skin to mucous membrane
Motor branches of anterior division are :
Nerve to lateral pterygoid
Deep temporal nerves
Nerve to masseter

29. Branches from posterior division
Auriculotemporal nerve
Inferior alveolar nerve
Mylohyoid nerve
Lingual nerve

30. Auriculotemporal nerve
It arises by two roots
It receives post ganglionic parasympathetic fibers from otic ganglion for parotid gland
Preganglionic fibers reach from glossopharyngeal nerve
Roots surround middle meningeal artery

31. Inferior alveolar nerve
It is a large branch of the posterior division
It runs downwards with artery between the pterygoid muscles
They give rise to mylohyoid branch
Then enters mandibular foramen
In the body of the mandible it supplies teeth and gums
Sends mental branch which supplies skin of chin and lower lip
Mylohyoid nerve only motor of posterior division supplies mylohyoid and anterior belly of digastric muscles
The nerve is joined by submental artery in the digastric triangle
Mylohyoid branch

32. Ligual nerve
It is sensory to anterior two thirds of tongue , floor of mouth and gums
It is medial to mandible
It is in front of inferior alveolar nerve
The nerve is joined by chorda tympani nerve , a branch of facial nerve
Chorda tympani nerve brings preganglionic parasympathetic fibers to submandibular gland
And taste sensation for anterior 2/3rds of tongue

33. Mandibular nerve

35. Temporomandibular joint
Type :Synovial joint
Sub type : Hinge joint

38. Articular surfaces Head of the mandible
With mandibular fossa and articular tubercle of the temporal bone
They are separated by articular disc
Which divides joint cavity into upper and lower parts

39. Ligaments
Fibrous capsule : is attached to margins of articular surfaces
Laterally is thickened to form lateral ligament
It is triangular with base attached to zygomatic arch
With apex attached to lateral side of neck of mandible

40. Ligaments Articular disc is oval in shape
Fused with capsule around the periphery
The upper surface is concavoconvex to fit articular tubercle and mandibular fossa
Its concave inferior surface fits the head of he mandible

41. Ligaments
The capsule and the lateral ligament are the only proper ligaments
Sphenomandibular and the stylomandibular ligaments
Do not add any strength to the joint
Muscles of mastication provide the required strength
Similar to joints maintained by muscle strength- the joint is prone for dislocation

42. Ligaments
Sphenomandibular ligament extends from spine of sphenoid to lingula near the margin of the mandibular foramen
It is piercred by mylohyoid nerve
The ligament is the remnant of 1st pharyngeal arch

43. Relations Anterior Posterior Above Medially – Auriculotemporal nerve
Lateral pterygoid
Posterior
Parotid gland
Above
Floor of middle cranial fossa
Medially
– Auriculotemporal nerve

44. Blood supply
Blood supply
Superficial temporal artery
Maxillary artery

45. Nerve supply Nerve supply
Auriculo-temporal nerve – from the posterior division of mandibular nerve
Masseteric nerve – from anterior division of mandibular nerve

46. Movements of joint Protraction – pulling the jaw forwards
Retraction – it is reverse movement of protraction
Depression- lowering of jaw
Elevation – opposite of depresstion
Side to side and grinding movement

47. Muscles acting on the joint
Protraction – lateral and medial pterygoid
Retraction – posterior fibers of temporalis
Depression- lateral pterygoid, digastric and infrahyoid muscles
Elevation – temporalis, masseter and medial pterygoid
Side to side and grinding movement – produced by muscles of opposite side acting alternately

48. Clinical anatomy
Dislocation of joint

49. Learning Outcomes
At the end of the lecture, students should be able to:
Outline the boundaries and contents of the infratemporal fossa
Describe the origin,insertion,nerve supply and action of muscles of mastication.
Describe the origin,course, branches and distribution of maxillary artery
Describe the origin,course, branches and distribution of mandibular nerve.
Discuss the type,sub type of temperomandibular joint
Articular surfaces
Ligaments
Relations
Blood supply
Nerve supply
Movements
Muscles acting on temperomandibular joint
Outline the clinical anatomy of the temperomandibular joint