1. Muscles of Mastication

2. Muscles of mastication:
The muscles of mastication moves the mandible during mastication and speech. They are:
1) Masseter
2) Temporalis
3) Lateral pterygoid
4) Medial pterygoid
Lateral pterygoid
Temporalis
Masseter
Medial pterygoid

3. Masseter:
It is a quadrilateral muscle which covers lateral surface of the Ramus of the mandible.
Origin:
It arises from lower border of Zygomatic arch and from Zygomatic process of maxilla.
Insertion:
The fibres are inserted into coronoid process and lateral surface of Ramus of mandible
Zygomatic arch
Masseter

4. Nerve supply: Masseteric nerve, a branch of the anterior division of the Mandibular nerve

5. Action:
It elevates the mandible to close the mouth and clenches the teeth
Clenching of the teeth
Elevation

6. Temporalis: The muscle fills the temporal fossa
Origin:
Arises from temporal fossa, excluding zygomatic bone and from temporal fascia.
Insertion:
The margins and deep surface of the coronoid process and anterior border of the ramus of the mandible
Temporal fascia
Temporalis
Coronoid process

7. Nerve supply:
Deep temporal branches from anterior division of the Mandibular nerve
Temporalis muscle
Deep temporal nerve
Mandibular nerve

8. Action: Retraction Elevation 1) It elevates the mandible
2) Posterior fibres retract the potruded mandible:
Retraction
Elevation

9. Lateral pterygoid: The muscle has upper head and lower head. Origin:
It arises from the infratemporal surface and crest of the greater wing of sphenoid bone
Lower head:
It arises from the
lateral pterygoid plate.
Upper head
Lower head

10. Capsule of Temporomandibular joint
Insertion:
The fibres get inserted into:
a) Pterygoid fovea on the anterior surface of the neck of the mandible and to
b) The anterior margin of the articular disc and capsule of the temporomandibular joint
Articular disc
Capsule of Temporomandibular joint

11. Nerve to lateral pterygoid
Nerve supply:
A branch from anterior division of Mandibular nerve.
Nerve to lateral pterygoid

12. Depression Action: 1) Depresses the mandible to open the mouth.
2) The lateral and medial pterygoid acting together protrude the mandible.
3) Alternate contraction of lateral and medial pterygoid produces side to side movements.
Depression

13. Lateral pterygoid plate
Medial pterygoid:
This is a quadrilateral muscle having small superficial head and a large deep head.
Origin:
Superficial head: From tuberosity of maxilla and adjoining bone
Deep head: From medial surface of lateral pterygoid plate and adjoining part of palatine bone.
Lateral pterygoid plate
Deep head
Superficial head

14. Insertion:
The fibres are inserted into the medial surface of the angle of the mandible and adjoining part of the ramus of the mandible.
Medial pterygoid muscle

15. Nerve to Medial pterygoid Medial pterygoid muscle
Nerve supply:
Nerve to Medial pterygoid, which is a branch of the main trunk of the Mandibular nerve
Nerve to Medial pterygoid
Medial pterygoid muscle

16. Protrusion Elevation Action: 1) Elevates the mandible:
2) Helps in protrude the mandible
3) Alternate contraction of Medial and Lateral pterygoid muscles produce side to side movements
Protrusion
Elevation

17. TEMPOROMANDIBULAR JOINT

18. Variety: It is a synovial joint of the condylar variety.
Bones forming the joint:
Above:
Articular tubercle and anterior articular part of the mandibular fossa of the temporal bone.
Below:
Head (or) Condyle of the mandible.
Mandibular fossa
Head of mandible
Articular tubercle

19. Menisco-mandibular compartment Menisco-temporal compartment
Articular surfaces of both bones are covered with fibro-cartilage.
The joint is completely divided by an articular disc into upper menisco-temporal compartment and a lower menisco-mandibular compartment.
Articular disc
Menisco-mandibular compartment
Menisco-temporal compartment
Fibro-cartilage

20. Ligaments: Capsular ligament with synovial membrane Articular disc
The joint presents the following ligaments:
Capsular ligament with synovial membrane
Articular disc
Lateral (or) Temporomandibular ligament
Accessory ligaments:
a) Sphenomandibular and
b) Stylomandibular ligaments

21. Squamo-tympanic fissure
1) Capsular ligament:
It envelops the joint and presents the following attachments:
Above:
Infront: To the articular tubercle
Behind: To the Squamo-tympanic fissure
And periphery of articular fossa between them
Below: Attached around the neck of the mandible
Above the disc the capsule is loose and below the disc it is tight
Squamo-tympanic fissure
Neck of the mandible
Articular tubercle

22. Synovial membrane:
It lines the inner aspect of the capsule of each compartment of the joint, but fails to cover the articular cartilages and articular disc.
Synovial membrane

23. 2) Articular disc:
It is an oval plate of fibro-cartilage which caps the head of mandible and divides the joint cavity into two compartments.

24. 3) Lateral (or) Temporomandibular ligament:
It reinforces and strengthens the lateral part of the capsular ligament and extends downwards and backwards from the articular tubercle to the posterolateral aspect of neck of mandible.
Lateral ligament
Articular tubercle

25. Sphenomandibular ligament
Accessory ligaments:
Sphenomandibular ligament:
It is situated medial to the capsule and is attached superiorly to the spine of sphenoid and inferiorly to the lingula of the mandibular foramen.
Lingula
Spine of sphenoid
Sphenomandibular ligament

26. Sylomandibular ligament
2) Stylomandibular ligament:
It is formed by the thickening of deep cervical fascia and extends from the tip of styloid process of temporal bone to angle of mandible.
Sylomandibular ligament

27. Arterial supply: Nerve supply:
Branches from superficial temporal and maxillary arteries
Nerve supply:
By Auriculo temporal and Masseteric nerves

28. Movements: Movements permitted at the Temporamandibular joints are
Protrusion
Retraction
Depression
Elevation
Side-side movements
(chewing movements)
Protrusion
Retraction
Elevation
Depression

29. Muscles Producing Movement
Muscles producing movements:
Movement
Muscles Producing Movement
Protrusion
Lateral pterygoid & Medial pterygoid muscle
Retraction
Posterior fibres of Temporalis, Masseter & Digastric
Depression
Lateral pterygoid muscle
Wide opening
Digastric, Geniohyoid, Mylohyoid
Elevation
Masseter, Temporalis, Medial pterygoid of both sides
Side to Side Movements
Medial & Lateral pterygoids of both sides acting alternately

30. Applied anatomy: Dislocation of Mandible:
During excessive opening of the mouth, the head of mandible of one (or) both sides may slip anteriorly into the infratemporal fossa, as a result of which there is inability to close the mouth.
Reduction is done by depressing the jaw with the thumbs placed on the last molar teeth and at the same time elevating the chin

31. SUBMANDIBULAR GLAND

32. Submandibular salivary gland:
It is one of the three paired salivary glands
Situation:
It is situated in digastric triangle and lodges partly in submandibular fossa of the mandible upto Mylohyoid line opposite the molar and premolar teeth.
Mylohyoid line
Submandibular fossa

33. It weights about 10-20gms and appears like walnut
Divisions of the gland:
The gland consists of a large superficial part and a small deep part, both the parts are continuous with each other around posterior border of Mylohyoid muscle.
Deep part
Mylohyoid muscle
Superficial part

34. Superficial part: It presents Two ends: 1) Anterior end
2) Posterior end
Three surfaces:
1) Inferior
2) Lateral
3) Medial
Lateral surface
Anterior end
Medial surface
Posterior end

35. Anterior belly of digastric
Parts:
Anterior end:
it extends upto anterior belly of digastric
Posterior end:
It extends upto Stylomandibular ligament and separates Sumbandibular from parotid gland.
Anterior belly of digastric

36. f a b c e d Surfaces of superficial part:
The surfaces are covered by investing layer of deep cervical fascia
1) Inferior surface: It presents the following relations:
Skin,
Platysma,
Cervical branch of facial nerve,
Deep cervical fascia
Facial vein,
Submandibular lymph node. f a b c e d

37. 2) Lateral surface: It is related to
Submandibular fossa on the mandible
Insertion of Medial pterygoid muscle
Facial artery
Facial artery

38. c b a 3) Medial surface: It is related to
a. Mylohyoid muscle, nerves and vessels
b. Hyoglossus and Styloglossus
c. Lingual and Hypoglossal
d. Stylohyoid ligament, Glossopharyngeal Nerve(IX)
e. Wall of the pharynx b c a

39. Anteriorly it extends upto the posterior end of sublingual gland
Deep part :
It is small in size and lies deep to Mylohyoid and superficial to Hyoglossus and styloglossus
Anteriorly it extends upto the posterior end of sublingual gland
Posteriorly it continuous with the superficial part around the posterior border of Mylohyoid.
Styloglossus
Hyoglossus
Mylohyoid

40. Submandibulat Duct (or) Wharton’s duct:
It is thin walled and is about 5 cm long and emerges at the anterior end of the deep part of the gland
Submandibular duct
Hypoglossal nerve
Lingual nerve

41. Supplied by facial artery
Arterial Supply
Supplied by facial artery
Venous Drainage
Drains into common facial
(or) lingual vein
Lymphatic Drainage
Submandibular lymph nodes

42. Nerve supply:
The Secreto-motor supply of gland is supplied by both Parasympathetic and Sympathetic nerves.

43. Superior salivatory nucleus of Pons Submandibular Ganglion
Facial Nerve
Chorda Tympani
Lingual Nerve
Submandibular Ganglion
Submandibular Gland
Parasympathetic
Preganglionic
Fibers
Parasympathetic
Postganglionic
Fibers

44. Sympathetic fibres:
Sympathetic fibers reach the gland around the facial artery and convey postganglionic fibers from the superior cervical ganglion of the sympathetic trunk

45. Nerve supply: Preganglionic parasympathetic fibres
Postganglionic parasympathetic fibres
Sympathetic fibres

46. THANK YOU