Mastication and muscles of mastication

Question 1

What are the chief muscles of mastication

Answer 1

• Masseter muscle
• Temporalis muscle
• Medial pterygoid muscle
• Lateral pterygoid muscle

Question 2

Which is the larger head of the masseter muscle

Answer 2

Superficial

Question 3

What is the origin and insertion point of the superficial masseter

Answer 3

Origin - anterior two-thirds of the lower border of the zygomatic arch.
Insertion - the angle and lower half of the lateral surface of the ramus of the mandible.

Question 4

Which direction do the fibres of the superficial masseter run

Answer 4

downwards and backwards

Question 5

What is the origin point of the deep masseter

Answer 5

Origin: it arises from the posterior third of the lower border and from the whole of the medial surface of the zygomatic arch.

Question 6

What is the insertion point of the deep masseter

Answer 6

the upper half of the ramus

Question 7

Which direction do the fibres of the deep masseter run

Answer 7

down and forwards

Question 8

Anteriorly and posteriorly what is the deep masseter related to

Answer 8

Ant: superficial portion
Post: the parotid gland

Question 9

What are the actions of the masseter

Answer 9

elevates and protrudes the mandible thus

closing the mouth; deep fibers retrudes it.

Question 10

What innervates the masseter

Answer 10

Mandibular division (V3) of trigeminal nerve through masseteric branch.

Question 11

What is the blood supply of the masseter

Answer 11

masseteric artery from maxillary

artery

Question 12

What is the origin point of the temporalis

Answer 12

the whole of the temporal fossa and the deep surface of temporal fascia

Question 13

What is the insertion point of the temporalis

Answer 13

the medial surface, apex, and anterior border of the coronoid process, and the ant. Border of mandibular ramus

Question 14

What is the action of the temporalis muscle

Answer 14

its anterior and middle fibers elevate the mandible thus closing the mouth; its posterior fibers retrudes it.

Question 15

What innervates the temporalis muscle

Answer 15

Deep temporal branches of mandibular nerve.

Question 16

What supplies blood to the temporalis muscle

Answer 16

Deep temporal branches of maxillary artery.

Question 17

What are the 2 heads of the lateral pterygoid muscle

Answer 17

superior and inferior

Question 18

What is the origin point of the lateral pterygoid muscle

Answer 18

the superior head arises from greater wing of sphenoid bone while the inferior head arises from the lateral surface of the lateral pterygoid plate

Question 19

What is the insertion point of the lateral pterygoid muscle

Answer 19

fibers pass backward to be inserted into the neck of mandible and articular disc of TMJ.

Question 20

What innervates the lateral pterygoid muscle

Answer 20

Ant. division of mandibular nerve through lateral pterygoid nerve

Question 21

What supplies blood to the lateral pterygoid muscle

Answer 21

maxillary artery through the pterygoid branch.

Question 22

What is the action of the lateral pterygoid muscle

Answer 22

acting together they protrude and
depress the mandible;
acting alone and alternatively they produce side to side movements of the mandible.
(rotates the mandible to the opposite side)

Question 23

What are the heads of the medial pterygoid muscle

Answer 23

superficial and deep

Question 24

What is the origin point of the medial pterygoid muscle

Answer 24

the superficial head arises from the maxillary tuberosity. The deep head arises from medial surface of the lateral pterygoid plate

Question 25

What is the insertion point of the medial pterygoid muscle

Answer 25

the medial surface of the angle of the mandible

Question 26

Which direction do the fibres of the medial pterygoid muscle run

Answer 26

backward, laterally and downwards

Question 27

What innervates the medial pterygoid muscle

Answer 27

main trunk of mandibular nerve through nerve to medial pterygoid

Question 28

What supplies blood to the medial pterygoid muscle

Answer 28

Maxillary artery through the medial pterygoid artery

Question 29

What is the action of the medial pterygoid muscle

Answer 29

Assists in elevating and protrusion
of the mandible
Acts together with lat. Pterygoid of the same side in rotating the mandible

Question 30

What are the origin and insertion points of the digastric muscles

Answer 30

origin = mandible process
insertion =  mastoid process