Lecture 24: Temporal and Infratemporal fossa Flashcards
mastication
mechanical breakdown of food within the oral cavityw
what are the two types of mastication
slicing/puncture and grinding
what bones make up the temporomandibular joint
condyle of the mandible and the mandibular fossa of the temporal bone
what divides the TMJ into dorsal and ventral halves
thin cartilaginous disc
what does the dorsal half of TMJ allow
permits mandibular condyle to slide rostrally or caudally back into place
what does ventral half of TMJ allow
permits a hinge-like opening and closing
what ligament in TMJ prevents lateral displacement of condyle and when the mouth is open, excessive rostral displacement
lateral ligament
what prevents posterior displacement of TMJ
retroarticular prodcess
what prevents ventral displacement of TMJ
joint capsule and surrounding muscles
what cranial nerve innervates all muscles of mastication
CN V3- mandibular branch of trigeminal
what are the four major muscles of mastication
temporalis, lateral pterygoid, medial pterygoid and masseter
temporalis OINA
O: temporalis fossa (some fibers from nuchal crest)
I: coronoid process on mandible
N: CN V3- mandibular
A: bilateral- jaw closing
Masseter OINA
O: zygomatic arch
I: angular process and masseteric fossa of mandible
N: CN V3- mandibular
A: bilateral- jaw closing, unilateral- superficial fibers protract and deep fibers retract or move laterally
medial pterygoid OINA
O: pyterygopalatine fossa
I: medial aspect of mandibular ramus and angular process
N: CN V3- mandibular
A: bilateral- jaw closing, unilateral- protraction
lateral pterygoid OINA
O: pterygoidpalatine fossa
I: capsule of TMJ and the articular disk
N: CN V3- mandibular
A: control the position of the articular disk during jaw movement
what muscles are the predominant muscles for mastication in carnivores and omnivores
temporalis muscle
what is the difference between the zygomatic arch and coronoid process in carnivores and omnivores vs herbivores
carnivores and omnivores- zygomatic arch flares laterally to accommodate for larger coronoid process and muscle mass
herbivores: zygomatic arch is usually less prominent and coronoid process is greatly reduced
what are the predominant muscles for mastication in herbivores
masseter and medial pterygoid
how is the TMJ restricted in species where slicing and crushing are primary mastication functions
unilateral protraction and retraction are restricted by a more hinge-like TMJ
how is the TMJ restricted in a species where grinding is more important
unilateral protraction and retraction is very important therefore TMJ is less restricted rostrally
mylohyoid OINA
O: along the length of the medial aspect of the mandibular body
I: midline raphe with fibers from opposite muscle and basihyoid
N: myloyhoid nerve from CN V3
A: raises the floor of oral cavity to support the tongue and draws basihyoid rostrally
diagastric muscle OINA
O: paracondylar process
I: medial and ventral aspect of the mandible
N: rostral-mylohyoid CN V3 and facial CN VII
A: active depression of mandible
occipitomandularis
accessory belly of caudal diagastric found in horses
what nerve provides motor innervation to muscles of mastication and sensory innervation to ear, cheek, jawline, lower lip, tongue, and mandibular teeth
mandibular nerve
