Lecture 2- muscles of mastication Flashcards
How many maxillary bones are present in the skull?
2
The 2 maxillary bones are fused together at the:
mid-palatal suture
The superior border of the maxilla is the:
floor of the nasal cavity and orbit
The inferior border of the maxilla is the:
palate and alveolar ridge
Components of the maxilla: (2)
Body & Procresses
What processes are fun din the maxilla?
zygomatic, frontal, alveolar, palatine
What is the largest and strongest bone of the skull?
mandible
What components make up the mandible?
body and ramus
The superior aspect of the mandible:
alveolar crest and teeth
The body of the mandible makes up the posterior aspect including:
mandibular angle, and asending ramus
What two parts make up the ascending ramus?
coronoid process and condyle
In the TMJ, the condyle articulates with the:
cranium
What poles are present in the condyle?
medial and lateral poles
The mediolateral length of the condyle is:
15-20mm
The anterior-posterior width of the condyle is:
8-10mm
The squamous portion of the temporal bone articulates with the:
mandibular condyle
The _____ articulates with the mandibular condyle
Squamous portion of temporal bone
The thick dense bone to tolerate heavy forces (on temporal bone)
articular eminence
What are the muscles of mastication?
lateral pterygoids, medial pterygoid, masseter and temporalis
The masseter has ___ heads
2
The two heads of the masseter:
superficial head and deep head
In the ____ head of the masseter, fibers run downward and backward
superficial
In the ____ head of the masseter, the fibers run in a vertical direction
deep
How do the muscle fibers run in the superficial head of the masseter?
fibers run downward and backward
How do the fibers run in the deep head of the masseter?
fibers run in a vertical direction
Where is the origin of the masseter?
zygomatic arch
Where is the insertion of the masseter? (2)
lateral surface of ramus and angle of mandible
Function of the masseter:
elevate the mandible
The masseter is a ____ muscle providing the force for ____.
powerful; chewing
Portion of the masseter that aids in protrusion:
superficial head
Function of the superficial head of the masseter:
aids in protrusion
Portion of the masseter that stabilizes the condyle against the eminence
deep head
Function of the deep head of the masseter:
stabilzes the condyle against the eminence
The origin of the superficial portion of the masseter:
The origin of the deep portion of the masseter:
anterior 2/3 of lower border of zygomatic arch
medial surface of the zygomatic arch
The insertion of the masseter is the:
lateral surface of ramus coronoid process and angle of mandible
The function of the masseter is to:
elevate jaw and clench teeth
The blood supply to the masseter:
a muscular branch of the maxillary artery
The nerve supply to the masseter:
masseteric nerve of mandibular division of the trigeminal nerve
The temporalis can be divided into ____ distinct divisions:
3
The 3 distinct divisions of the temporalis include:
anterior, middle, posterior
Portion of the temporalis characterized by the vertically directed fibers
anterior
Portion of the temporalis characterized by fibers running obliquely across the lateral aspect of the skull
middle
Portion of the temporalis characterized by horizontal fibers coming forward above the ear to join other temporalis fibers
posterior
Origin of the temporalis:
termporal fossa and lateral surface of the skull
Insertion of the temporalis: (2)
coronoid process and anterior border of ascending ramus
Action of the anterior temporalis:
vertical raising of mandible
Action of the middle temporalis:
elevates and retrudes the mandible
action of the posterior temporalis:
aids in recursion of the mandible
Blood supply to the temporalis:
a muscular branch of the maxillary artery
Nerve supply to termporalis:
deep temporal nerve of the mandibular division of trigeminal nerve
How many heads are present in the lateral pterygoid?
2
The lateral pterygoid may also be referred to as:
external pterygoid
The two heads of the lateral pterygoid are almost:
almost two separate muscles
What are the two heads of the lateral pterygoid?
superior lateral pterygoid and inferior lateral pterygoid
The origin of the inferior lateral pterygoid:
outer surface of lateral pterygoid plate
The insertion of the inferior lateral pterygoid:
neck of condyle
The inferior lateral pterygoid extends:
backward, upward, and outward
The action of the inferior lateral pterygoid includes both:
bilateral contraction and unilateral contraction
“causes the condyles to be pulled down and the articular eminences and the mandible is protruded” would be describing what action of the inferior lateral pterygoid?
bilateral contraction
“causes mediotrusive movement (downward, forward, and medially)” would be describing what action of the inferior lateral pterygoid?
unilateral contraction
Which is the smallest of the 2 bellies of the lateral pterygoids?
superior lateral pterygoid
The origin of the lateral pterygoid:
infratemporal surface of the greater sphenoid wing
The insertion of the superior lateral pterygoid:
disk, capsule, and neck of the condyle
The superior lateral pterygoid action is ____ during mandibular opening
inactive
The superior lateral pterygoid is active only with:
elevator muscles
The superior lateral pterygoid is active only with elevator muscles - meaning
closure of the mandible
The superior lateral pterygoid is involved in a ______: this muscle is active during mandibular closure against resistance (chewing or clenching)
power stroke
Muscle involved in the power stroke
superior lateral pterygoid
The superior lateral pterygoid is active during:
mandibular closure against resistance (chewing or clenching)
mandibular closure against resistance=
chewing or clenching
blood supply to lateral pterygoid:
a muscular branch of the maxillary artery
nerve supply to lateral pterygoid:
a branch of the masseteric or buccal nerve of the mandibular division of the trigeminal nerve
Origin of the medial (internal) pterygoid:
pterygoid fossa
What is another name for the medial pterygoid?
internal pterygoid
The insertion of the medial (internal) pterygoid:
medial surface of the mandibular angle
What are the 3 functions of the medial (internal) pterygoid:
- elevates the mandible
- protrudes the mandible
- unilateral contraction (results in mediotrusion)
The unilateral contraction function of the medial pterygoid results in:
mediotrusion