Oral Anatomy & Histology (Review: Outcome 11)

Question 1

Mastication

Answer 1

Act of chewing/grinding

Question 2

Elevation

Answer 2

Raising the mandible (closing the mouth)

Question 3

Protrusion

Answer 3

Forward movement of the mandible

Question 4

Retrusion

Answer 4

Process of moving the mandible backwards

Question 5

Depression

Answer 5

Lowering of the mandible

Question 6

Lateral excursion

Answer 6

Sideways movement

Question 7

Origin

Answer 7

A site from which something arises, the beginning

Question 8

Insertion

Answer 8

A site in which something inserts, the end

Question 9

What are the muscles of mastication?

Answer 9

Accomplish the movements of the jaw, opening of the mouth and depression of the mandible

1) Masseter
2) Temporal
3) Lateral (external) pterygoid
4) Medial (internal) pterygoid

Question 10

Muscles of Mastication - Masseter

Answer 10

Raises the mandible and closes the jaw

Question 11

Muscles of Mastication - Temporal

Answer 11

Raises the mandible and closes the jaw

Question 12

Muscles of Mastication - Medial (internal) pterygoid

Answer 12

Closes the jaw, pulls the mandible to one side

Question 13

Muscles of Mastication - Lateral (external) pterygoid

Answer 13

Depresses the mandible to open the jaw

Question 14

Hyoid Muscles - Floor of the mouth

Answer 14

• Muscles that accomplish the opening of the mouth
• Associated with the hyoid bone found beneath the mandible
• Divided into 2 groups:
  1) Suprahyoid (above)
  2) Infrahyoid (below)

Question 15

Muscles of the floor of the mouth

Answer 15

1) Digastric
2) Mylohyoid
3) Stylohyoid
4) Geniohyoid

Question 16

What are the suprahyoid muscles?

Answer 16

1) Digastric
- Elevation of the hyoid bone and depression of the mandible
- Anterior Digastric
- Posterior Digastric

2) Stylohyoid
- Assists in swallowing by raising the hyoid bone

3) Mylohyoid
- Forms the floor of the mouth (raises the tongue and depresses the lower jaw)

4) Geniohyoid
- Pulls the tongue and hyoid bone forward

Question 17

Infrahyoid Muscles

Answer 17

i. Depress the hyoid bone
- Omohyoid muscle*
- Sternohyoid muscle*
- Thyrohyoid muscle*

ii. Depresses the thyroid cartilage
- Sternothyroid muscle

Question 18

Muscles of Facial Expressions

Answer 18

• Usually symmetrical
• Originate in bone and insert on skin
• Loss of symmetry is an early sign of injury to facial nerve on one side
• Some are superficial and some are deep
• Usually function as a group

1) Orbicularis oris
2) Buccinator
3) Mentalis
4) Zygomatic major

Question 19

Muscles of Facial Expressions - Orbicularis oris

Answer 19

Closes and puckers the lips

Question 20

Muscles of Facial Expressions - Buccinator

Answer 20

Compresses the cheeks against the teeth and retracts the angle of the mouth

Question 21

Muscles of Facial Expressions - Mentalis

Answer 21

Raises and wrinkles the skin of the chin and pushes the lower lip up

Question 22

Muscles of Facial Expressions - Zygomatic major

Answer 22

Draws the angles of the mouth upward and backward, as in laughing

Question 23

Muscles of the neck

Answer 23

• Muscles found from the neck to the lower aspect of the mandible
• Muscles can become affected by improper posture while assisting the dentist or performing independent duties
• 3 muscles:
  1) Platysma
  2) Trapezius
  3) Sternocleidomastoid

Question 24

Muscles of the neck - Platysma Muscle

Answer 24

Function:
- grimacing
- raises the skin of the neck and pulls the corners of the mouth down

Question 25

Muscles of the neck - Trapezius

Answer 25

A large, flat triangular muscle that covers the back of the neck, the clavicle and shoulder

Function:
- lifts the clavicle and shoulder blade (shoulders are shrugged)

Question 26

Muscles of the neck - Sternocleidomastoid muscle

Answer 26

Function:
- if one SM is contracted the head turns to that side
- if both are contracted the head will flex at the neck and move forward and down
- serves as a landmark of neck during an extraoral examination

Question 27

Muscles of the Tongue

Answer 27

1) Intrinsic (within the tongue)
- responsible for shaping the tongue during speech, chewing, and swallowing

2) Extrinsic
- assist in the movement and function of the tongue

Question 28

Extrinsic Muscles

Answer 28

1) Genioglossus
- Depresses and protrudes the tongue

2) Hyoglossus
- Retracts and pulls down the side of the tongue

3) Styloglossus
- Retracts the tongue

Question 29

Major muscles of the soft palate

Answer 29

1) Palatoglossus
- elevates base of tongue, arching tongue against soft palate; depresses soft palate toward tongue

2) Palatopharyngeus
- forms posterior pillar of fauces; serves to narrow fauces and helps shut off nasopharynx