TMJ and Muscles Flashcards
What are the three major parts of the TMJ?
Mandibular condyle, articular fossa and eminence (of the temporal bone), and articular disc
What are the four ligaments of the TMJ?
Fibrous capsule (capsular ligament), lateral ligament, stylomandibular ligament, sphenomandibular ligament
What are the four muscles of mastication?
Masseter, temporalis, medial pterygoid, and lateral pterygoid,
What is the function of the masseter muscle?
To elevate mandible (close teeth together)
What is the origin and insertion of the masseter muscle?
Origin: zygomatic arch
Insertion: lateral surface of rami and angle of mandible
What is the function of the temporalis muscle?
To elevate and position (retrude) mandible
The anterior part of the temporalis muscle generally moves the mandible in what way?
Elevates the mandible (closes teeth), these are mostly vertical fibers
The posterior part of the temporalis muscle generally moves the mandible in what way?
Retrude the mandible, these fibers are more horizontal
Where is the origin and insertion of the temporalis muscle?
Origin: temporal fossa on cranium
Insertion: coronoid fossa, anterior border of ramus, and temporal crest
What is the function of the medial pterygoid muscle?
To elevate mandible (close teeth together)
What is the origin and insertion of the medial pterygoid muscle?
Origin: pterygoid fossa (sphenoid)
Insertion: medial angle of mandible
What is the function of the lateral pterygoid muscle?
One alone moves mandible laterally, together they protrude and depress mandible
What is the origin and insertion of the lateral pterygoid muscle?
Origin: lateral pterygoid plate (sphenoid) and greater wing
Insertion: pterygoid fovea (condylar process) and anterior part of articular disc
What are the three suprahyoid muscles?
Geniohyloid, mylohyoid, and digastric
What are the two infrahyoids?
Omohyoid and sternohyoid
Together the suprahyoids and infrahyoids move the mandible in what way?
Open mouth and depress mandible
What is the muscle that immediately surrounds the lips?
Orbicularis oris
What are the three muscles of the upper lip?
Zygomaticus, levator labii superior, levator anguli oris
What are the three muscles of the lower lip?
Depressor labii inferior, depressor anguli oris, mentalis
What muscles are involved in elevation of the mandible?
Masseters, medial pterygoids, temporalis (anterior vertical and middle fibers)
What muscles are involved in depression of the mandible?
Supra- and infra hyoids together, and both lateral pterygoids
What muscles are involved in the retrusion of the mandible?
Temporalis (posterior horizontal fibers) and suprahyoids (with help from infrahyoids)
What muscle is involved in protrusion of the mandible?
Both lateral pterygoids together
What muscle is involved in lateral excursion of the mandible?
Right lateral pterygoid moves the mandible to the left and left lateral pterygoid moves the mandible to the right
What cranial nerve supplies the muscles of mastication?
Trigeminal (CN V) division III mandibular branch
What cranial nerve supplies the muscles of facial expression?
Facial (cranial nerve VII)
