Unit 2 - Muscles of Mastication

What is the function of the masseter muscle?

-Elevation of the mandible

What is the function of the lower part of the TMJ?

Allows for the depression and elevation of the mandible, giving us the hinge-like action of the mandible

Which arteries supply the temporalis muscle?

Deep and middle temporal arteries

Which nerve innervates the temporalis muscle?

Deep temporal n. (Mandibular nerve [V3])

What type of joint is the TMJ?

Diarthritic joint

What is the insertion of the masseter muscle?

Lateral surface of the ramus of the mandible

What bony parts make up the TMJ? (3)

1. Condylar process of the mandible 2. Articular surface of the mandibular fossa 3. Articular tubercle of the temporal bone

What are the 4 main movements of the TMJ?

1. Depression 2. Elevation 3. Protrusion 4. Retraction

What are the muscles responsible for depression of the mandible? (3)

1. Digastric m. 2. Geniohyoid m. 3. Myloyoid m. Assisted by gravity

What are the muscles responsible for retraction of the mandible? (4)

1. Geniohyoid m. 2. Digastric m. 3. Temporalis m. 4. Masseter m.

What are the ligaments of the TMJ? (3)

1. Lateral ligament 2. Sphenomandibular ligament 3. Stylomandibular ligament

What are the muscles responsible for protrusion of the mandible? (2)

1. Lateral pterygoid m. 2. Medial pterygoid m.

Which muscles are responsible for elevating the mandible? (3)

1. Masseter m. 2. Temporalis m. 3. Medial pterygoid m.

What are the muscles responsible for elevation of the mandible? (3)

1. Temporalis m. 2. Masseter m. 3. Medial pterygoid m.

What is the function of the upper part of the TMJ?

Allows for protrusion of the head of the mandible forward into the articular tubercle and retraction into the mandibular fossa

Which nerve provides innervation to the lateral pterygoid muscle?

Nerve to lateral pterygoid m. (Mandibular n. [V3])

Which nerve innervates the medial pteryoid muscle?

Nerve to medial pterygoid m.(Mandibular n. [V3])

What is the function of the temporalis muscle?

- Elevation of the mandible -Side to side motion

Where is the articular disc located and what does it do?

- Inside the joint capsule - Creates 2 divisions of the TMJ

What is the function of the medial pterygoid muscle?

- Raises the mandible - Protrudes the mandible

What are the heads and attachments of the medial pterygoid muscles?

- Superficial head: attaches on palatine bone -Deep head: attaches on medial surface of the lateral pterygoid plate

Which direction do the lateral pterygoid muscle fibers run?

Horizontally

Where is the temporalis muscle located?

Lies in the temporal fossa of the skull and is covered by the fan-shaped temporal fascia

Which of the lateral pterygoid heads is larger?

Lower head

Which artery supplies blood to the masseter muscle?

Masoteric artery (branch of the maxillary artery)

Which nerve innervates the masseter muscle?

Masoteric n. (Mandibular nerve [V3])

What is the function of the lateral pterygoid muscle?

Protrude/protract the mandible

What are the heads of the lateral pterygoid muscles?

Upper head and Lower head

What are the 2 divisions of the TMJ?

Upper part & Lower part

What is the origin of the masseter muscle?

Zygomatic arch