Muscles of mastication

Question 1

What is it?

Answer 1

is the process by which food is crushed + ground by teeth. the muscles help in chewing food by moving the mandible in relation to the maxilla.

Question 2

1. Temporalis

Answer 2

Point of origin -attached to the temporal bone of cranium
Point of insertion- coronoid process of mandible, passing under zygomatic arch
Action - pulls mandible backwards + closed

Question 3

2. Masseter

Answer 3

Point of origin- attached to outer surface of zygomatic arch
Point of insertion -outer surface of mandibular ramus + angle (jaw bone area)
Action- closes the mandible

Question 4

3. Medial Pterygoid

Answer 4

Point of origin- medial pterygoid plate at base of cranium
Point of insertion -inner surface of mandibular ramus + angle
Action- closes the mandible

Question 5

4. Lateral Pterygoid

Answer 5

Point origin- lateral ptergoid plate at base of cranium
Point of insertion- head of mandibular condyle into TMJ meniscus
Action- both contracting brings mandible forwards to bite anterior teeth tip to tip, one contracting pulls mandible to opposite side

Question 6

Temporal + masseter

Answer 6

can be felt when teeth clench together - these form superficial layer of muscles of mastication whilst medial + lateral pytergoid form the deeper layer

Question 7

Acute inflammatory conditions

Answer 7

sometimes result in a protective spasm of the muscles of mastication, called truisms - affects the ability to open the mouth

Question 8

Most often occurs

Answer 8

in acute inflammation of gum surrounding an erupting lower wisdom tooth (pericorontitis)

Question 9

After surgical removal of these teeth

Answer 9

+ acute inflammation of parotid gland (mumps) - its purpose is to rest the inflamed part + prevent pain

Question 10

They receive nerve impulses

Answer 10

from the fifth cranial nerve (trigeminal nerve) which cause them to contract so that the length of the muscle shortens. this then causes various movements of mandible associated with closing, clenching + chewing

Question 11

The muscles of mastication do not

Answer 11

cause mouth opening - controlled by a different group of muscles called suprahyoid muscles. each set of muscles of mastication is connected to cranium or face at one end (point of origin) + at their other end to the mandible (point of insertion)