Muscles of mastication and muscles of facial expression

Question 1

Temporalis

Answer 1

MUSCLE of MASTICATION
Elevates the mandible (closes jaw) but its posterior fibres also retract jaw

Question 2

Masseter

Answer 2

MUSCLE OF MASTICATION
Main elevator of the mandible (closes jaw). Palpable when contracted

Question 3

Lateral pterygoid

Answer 3

MUSCLE OF MASTICATION
Laaaa!
Bilateral action protrudes the Mandible (pushes it forward!) Bilateral action assists in depressing mandible (opens jaw) Unilateral action produces the ‘side to side’ movement of the jaw (contralateral movement)

(gravity helps to open jaw too)

Question 4

Medial Pterygoid

Answer 4

MUSCLE OF MASTICATION

Bilateral contraction of this muscle assists with elevation of the mandible (closing the jaw) and assists in protruding the mandible

Question 5

Muscles of mastication motor innervation

Answer 5

mandibular division of the trigeminal nerve (cranial nerve V)

(Vc or V3)

Question 6

Occipitofrontalis

Answer 6

MUSCLE OF FACIAL EXPRESSION

Elevates eyebrows, wrinkles forehead

Question 7

Orbicularis Oris

Answer 7

MUSCLE OF FACIAL EXPRESSION

Brings lips together/ purses lips

Question 8

Platysma

Answer 8

MUSCLE OF FACIAL EXPRESSION

Depresses angles of mouth, tenses skin of neck

Question 9

Risorius

Answer 9

MUSCLE OF FACIAL EXPRESSION

Pulls corner of mouth laterally (bilateral contraction=smile)

Question 10

Zygomaticus (major and minor)

Answer 10

MUSCLE OF FACIAL EXPRESSION

Draws the angles of the mouth laterally and superiorly (smile)

Question 11

Orbicularis oculi (orbital and palpebral part)

Answer 11

MUSCLE OF FACIAL EXPRESSION

Palpebral part – gently closes the eyelids. (blinking, sleeping)

Orbital part – tightly closes the eyelids.

Question 12

Buccinator

Answer 12

MUSCLE OF FACIAL EXPRESSION

The buccinator pulls the cheek inwards against the teeth, preventing accumulation of food in that area (during mastication).

Trumpeters contract it against pursed lips

Question 13

Trapezius

Answer 13

Upper fibres elevate shoulders; also rotate scapula when abducting shoulder beyond 90degrees.

Therefore if affected, the person will struggle to abduct shoulder above 90degrees.

(movement of the scapula to accommodate the full range of motion of the arm)

Question 14

Sternocleidomastoid

Answer 14

Rotates the head to the contralateral side and laterally flexes neck

Question 15

Sternocleidomastoid site of attachment

Answer 15

Mastoid process of the temporal bone

Question 16

Muscles of facial expression innervated by which nerve

Answer 16

Innervated by extracranial branches of the Facial nerve (Cranial nerve VII)

FACIAL nerve cause FACIAL expressions

Near to parotid gland

Question 17

Cranial nerve XI innervates which two muscles?

Answer 17

The accessory nerve is the eleventh paired cranial nerve. It innervates the Sternocleidomastoid and trapezius on their respective side.

Question 18

If the Trapezius is affected due to an injury to the accessory nerve, how will the patient present?

Answer 18

The Trapezius stabilies the scapula. If the trapezius is no longer innervated (or adequately innervated) then the shoulder will drop.

Abduction of the shoulder beyond 90degrees will also be affected (impaired).

Over time get muscle wastage, atrophy