LECTURE: Muscles of Mastication Flashcards
The primary muscles of mastication
temporalis, masseter and pterygoids
the boundaries of the temporal fossa
- Posteriorly and superiorly by the temporal lines.
- Anteriorly by the frontal and zygomatic bones
- Laterally by the zygomatic arch.
- Inferiorly by the infratemporal crest.
What makes up the floor of the temporal fossa?
lateral skull
What makes up the roof of the temporal fossa?
temporal fascia
The temporal fascia covers the ______ muscle
temporalis
Action of temporal fascia during chewing
pulling up on the zygomatic arch
Action of the masseter during chewing
inferior pull by masseter
What is the infratemporal fossa?
an irregularly shaped space deep and inferior to the zygomatic arch and deep to the ramus of the mandible
What does the infratemporal fossa communicate with?
the temporal fossa under the zygomatic arch
The boundaries of the infratemporal fossa
- Laterally: the ramus of the mandible.
- Medially: the lateral pterygoid plate.
- Anteriorly: the posterior aspect of the maxilla.
- Posteriorly: the mastoid and styloid processes of temporal bone.
The infratemporal fossa opens into the
pterygomaxillary fissure
The pterygomaxillary fissure leads to the
pterygopalatine fossa
In the medial wall of the pterygopalatine fossa is an opening called the
sphenopalatine foramen
The sphenopalatine foramen leads to the
nasal cavity
O/I/A/N of temporalis muscle
- O: temporal fossa
- I: coronoid process and anterior ramus of mandible
- A: elevate mandible with chewing, the posterior part of muscle retract mandible
- N: mandibular division of V3 (via deep temporal nerves)
O/I/A/N of masseter muscle
- O: zygomatic arch (superficial portion above the arch, the posterior portion of muscle at the posterior part of the arch)
- I: angle and lateral aspect of ramus of mandible
- A: elevate mandible with chewing, the posterior part of muscle protrude the mandible
- N: mandibular division of V3 (via deep temporal nerves)
Which muscle of mastication has a superior and inferior head?
lateral pterygoid
O/I/A/N of the inferior head of lateral pterygoid
- O: lateral surface of the lateral pterygoid plate
- I: neck of mandible, articular disc and capsule of TMJ (same as superior head)
-
A: two actions (same as superior head)
- bilaterally: protraction of condyle
- unilaterally: moves mandible laterally
- N: lateral pterygoid branches of V3
O/I/A/N of the superior head of lateral pterygoid
- O: infratemporal surface of greater wing of sphenoid
- I: neck of mandible, articular disc and capsule of TMJ (same as inferior head)
-
A: two actions (same as inferior head)
- bilaterally: protraction of condyle
- unilaterally: moves mandible laterally
- N: lateral pterygoid branches of V3
O/I/A/N of the superficial head of medial pterygoid
- O: maxillary bone
- I: medial aspect of the angle of the mandible (same as deep head)
-
A: two actions (same as deep head)
- bilaterally: elevates and protrudes the mandible (working with masseter)
- unilaterally: moves the mandible contralaterally (grinding movements)
- N: V3
O/I/A/N of the deep head of medial pterygoid
- O: medial surface of lateral pterygoid plate
- I: medial aspect of the angle of the mandible (same as superficial head)
-
A: two actions (same as superficial head)
- bilaterally: elevates and protrudes the mandible (working with masseter)
- unilaterally: moves the mandible contralaterally (grinding movements)
- N: medial pterygoid branches of V3
With damage to the lateral pterygoid on one side, the mandible will be …
deviated to the side that is damaged
With a subcondylar fracture on the left, only the right lateral pterygoid is functional and will pull the mandible to the …
left (contralateral)
The ____ is a hinge-like synovial joint.
temporomandibular joint (TMJ)
The articular surfaces involved are
- condyle of the mandible
- articular tubercle of the temporal bone
- mandibular fossa
The TMJ is surrounded by a
capsule
What divides the joint cavity into a superior and inferior joint space of the TMJ?
an articular disc
The TMJ comprises what 2 types of synovial joints?
hinge and sliding
Structural Components of TMJ
- Squamous portion of the temporal bone
- Articular disc
- Condyle of the mandible
- TMJ compartments
- capsule
- superior and inferior lamina
Which structural component of the TMJ is responsible for providing an important articular surface that includes the articular eminence and glenoid fossa?
squamous portion of the temporal bone
Which structural component of the TMJ is biconcave and made of dense fibrous connected tissue?
articular disc
Which structural component of the TMJ is located between squamous portion of temporal bone and the condyle?
articular disc
What part of the articular disc is avascular and vascular?
central part is avascular
periphery is vascular
What anchors the articular disc to the condyle?
strong medial and lateral collateral ligaments
Which structural component of the TMJ articulates with the articular disc?
condyle
The articular surface of the condyle of the mandible is _____________ instead of hyaline cartilage.
avascular fibrous connective tissue
The TMJ superior and inferior compartments are what type of joints?
synovial joints
Which structural component of the TMJ encloses the articular surface of the temporal bone and the condyle?
capsule
Which structural component of the TMJ is strengthened medially and laterally by the collateral ligaments?
articular disc and the capsule
Which structural component of the TMJ anchor the posterior aspect of the disc to the temporal bone and condylar neck?
superior and inferior lamina
Which structural component of the TMJ serve as the borders for the retrodiscal pad?
superior and inferior lamina
What structural component of the TMJ is the highly vascular and neural part of the TMJ?
retrodiscal pad
Which TMJ ligament provide strong attachment for disc (to condyle)?
medial and lateral collateral ligaments
The medial and lateral collateral ligaments are made of collagenous connective tissue which prevents them …
from stretching