Muscles of Masstification Flashcards
what are the muscles of mastication?
- temporalis
- masseter
- medial pterygoid
- lateral pterygoid
what is the origin of the lateral pterygoid?
superior: lateral surface of greater wing of sphenoid
inferior: lateral surface of pterygoid plate
what is the insertion of the lateral pterygoid?
superior: articular disc and capsule of TMJ
inferior: superiomedial surface of ramus, and condylar process of mandible
what is the action of the lateral pterygoid?
bilateral: protrudes (protracts) mandible (pulls disc forward). depresses (abducts) mandible
unilateral: lateral movements (excursion) of mandible (chewing). if one side is injured the jaw will deviate toward the injured side.
what is the only muscle of mastication that does NOT elevate the mandible?
lateral pterygoid
what is the innervation of the lateral pterygoid?
CN V3
what is the origin of the medial pterygoid?
superficial: maxillary tuberosity
deep: medial surface of lateral pterygoid plate, lateral surface of medial pterygoid plate, pterygoid fossa
what is the insertion of the medial pterygoid?
both superficial and deep insert into the medial surface of the ramus and angle of the mandible
what are the actions of the medial pterygoid?
elevates (adducts) mandible
protrudes (protracts) mandible
unilateral: lateral movements (excursion) of mandible
what is the innervation of the medial pterygoid?
CN V3
what is unique about the medial pterygoid?
it is the deepest muscle of mastication
what are the different portions of the temporalis, and which types of fibers do they have?
anterior: vertical fibers
middle: oblique fibers
posterior: horizontal fibers
what is the origin of the temporalis?
inferior temporal line of the temporal fossa
temporal fascia
what is the insertion of the temporalis?
it travels UNDER the zygomatic arch and inserts into:
coronoid process of mandible
anterior border of ramus of mandible
what are the actions of the temporalis?
vertical: elevate (adduct) mandible
middle and posterior: retrude (retract) mandible
unilateral: lateral movement (excursion) of mandible
what is the innervation of the temporalis?
CN V3
what is unique about the temporalis?
it is the main postural muscle - maintains the mandible in the resting position
what are the portions of the masseter and how are their fibers oriented?
superficial: larger part, fibers run downward and slightly backward
deep: smaller part, fibers run vertically
what is the origin of the masseter?
superficial: anterior 2/3 of zygomatic arch
deep: posterior 1/3 of zygomatic arch
what is the insertion of the masseter?
superficial: lateral surface of angle and ramus of mandible
deep: ramus and coronoid process of mandible
what are the actions of the masseter?
elevate (adduct) mandible
protrude (protract) mandible - superficial head
unilateral: lateral movement (excursion) of mandible
what is the innervation of the masseter?
CN V3
what passes superficial to the masseter?
parotid duct
transverse facial artery
branches of CN VII
