Oral Anatomy & Histology (Review: Outcome 11) Flashcards
Mastication
Act of chewing/grinding
Elevation
Raising the mandible (closing the mouth)
Protrusion
Forward movement of the mandible
Retrusion
Process of moving the mandible backwards
Depression
Lowering of the mandible
Lateral excursion
Sideways movement
Origin
A site from which something arises, the beginning
Insertion
A site in which something inserts, the end
What are the muscles of mastication?
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
Muscles of Mastication - Masseter
Raises the mandible and closes the jaw
Muscles of Mastication - Temporal
Raises the mandible and closes the jaw
Muscles of Mastication - Medial (internal) pterygoid
Closes the jaw, pulls the mandible to one side
Muscles of Mastication - Lateral (external) pterygoid
Depresses the mandible to open the jaw
Hyoid Muscles - Floor of the mouth
- 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)
Muscles of the floor of the mouth
1) Digastric
2) Mylohyoid
3) Stylohyoid
4) Geniohyoid
What are the suprahyoid muscles?
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
Infrahyoid Muscles
i. Depress the hyoid bone
- Omohyoid muscle*
- Sternohyoid muscle*
- Thyrohyoid muscle*
ii. Depresses the thyroid cartilage
- Sternothyroid muscle
Muscles of Facial Expressions
- 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
Muscles of Facial Expressions - Orbicularis oris
Closes and puckers the lips
Muscles of Facial Expressions - Buccinator
Compresses the cheeks against the teeth and retracts the angle of the mouth
Muscles of Facial Expressions - Mentalis
Raises and wrinkles the skin of the chin and pushes the lower lip up
Muscles of Facial Expressions - Zygomatic major
Draws the angles of the mouth upward and backward, as in laughing
Muscles of the neck
- 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
Muscles of the neck - Platysma Muscle
Function:
- grimacing
- raises the skin of the neck and pulls the corners of the mouth down
Muscles of the neck - Trapezius
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)
Muscles of the neck - Sternocleidomastoid muscle
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
Muscles of the Tongue
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
Extrinsic Muscles
1) Genioglossus
- Depresses and protrudes the tongue
2) Hyoglossus
- Retracts and pulls down the side of the tongue
3) Styloglossus
- Retracts the tongue
Major muscles of the soft palate
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
