Lecture 28 - Temporal fossae Flashcards
What does slicing involve?
Sharp edges coming together or shearing past each other
What does does grinding involve?
Sliding of rough or texture surfaces
What bony structures make up the TMJ?
Condyle of mandible
Mandibular fossa of temporal bone
What divides the TMJ into ventral and dorsal halves?
Cartilaginous articular disc
What does the dorsal half of the TMJ capsule do?
Allows mandibular condyle to slide rostrally or caudally back into place
What does the ventral half of the TMJ capsule do?
Permits hinge like opening and closing
What prevents lateral displacement of the TMJ?
Lateral ligament
What prevents posterior displacement of the TMJ?
Retroarticular process
What prevents ventral displacement of the TMJ?
Joint capsule
Surround muscles
What produces lateral movements of the mandible?
Retractors on same side
Protruders on opposite side
What is different about the mandible in most domestic animals?
Not fused; joined by a symphysis which allows lateral movement and torsional movement
What are the four muscles of mastication?
Temporalis - Masseter - Medial pterygoid - Lateral pterygoid
What nerve innervates the muscles of mastication?
CN V3 - Mandibular nerve
What muscles act across the TMJ but arent muscles of mastication?
Cranial digastric and Mylohyoid
Where does the temporalis muscle originate?
Temporal fossa - some dibers on the lateral nuchal crest
Where does the Temporalis muscle insert?
Coronoid process of the mandible
What is the bilateral action of the Temporalis muscle/?
Jaw closing
What is the unilateral action of the temporalis muscle?
Broad origin allows differences in action based on portion of muscle bring used but most cause retraction
What is the origin of the masseter muscle?
Zygomatic arch
What is the insertion of the masseter?
Masseteric fossa and angular process of the mandible
What is the bilateral action of the masseter?
Jaw closing
What is the unilateral action of the masseter?
Superficial fibers - Protract
Deep fibers - Draw mandible directly laterally or retract
Where does the medial pterygoid originate?
Pterygopalatine fossa
Where does the medial pterygoid muscle insert?
Medial surface of mandibular ramus and angular process
What is the bilateral action of the medial pterygoid?
Jaw closing
What is the unilateral action of the medial pterygoid?
Protraction
What is the origin of the lateral pterygoid muscle?
Pterygopalatine fossa
What is the insertion point of the lateral pterygoid?
Capsule of the TMJ and the articular disk
What is the action of the lateral pterygoid?
Control position of the articular disk during jaw movement
What are the general characteristics of animals who are mainly slicing and crushing during mastication?
Temporalis muscle is largest
Zygomatic arch flares laterally for larger coronoid
What is the general characteristics of animals who mainly are grinders during mastication?
Masseter and Medal pterygoid are largest
Zygomatic arch is smaller
What are the general characteristics of the TMJ in animals that are slicers and crushers?
Unilateral protraction and retraction are restriction due to hinge like TMJ
What are the general characteristics of the TMJ in animals who are grinders?
Unilateral protraction and retraction are very important
TMJ flatter and less restricted rostrally
What is the origin of the mylohyoid?
Along length of the medial aspect of the mandibular body
What is the insertion point of the mylohyoid?
Midline raphe with fibers from opposite muscles and the basihyoid
What nerve innervates the mylohyoid?
Mylohyoid nerve
What does the mylohyoid nerve come from?
CN V3
What is the action of the mylohyoid nerve?
Raises the floor of the oral cavity to support tongue and draws the basihyoid rostrally
What is the origin of the digastric muscle?
Paracondylar process
What is the insertion point of the digastric muscle?
Ventral and medial aspect of the mandible
What nerve innervates the digastric muscle?
Rostral - Mylohyoid N.
Caudal - Facial N.
What is the action of the digastric muscle?
Active depression of the mandible
What is the occipitomandibularis?
Accessory belly of the caudal digastric found in horses
What nerve is responsible for skin and mucosa sensory innervation in the mandibular region?
Mandibular nerve - CN V3
What is the mandibular nerve a branch of?
Trigeminal
What are the six sensory branches of the mandibular nerve?
Buccal n. - Auriculotemporal n. - Inferior alveolar n. - Mental n. - Mylohyoid n. - Lingual n.
What does the buccal nerve pass in relation to?
Rostrally passing dorsal to the lateral pterygoid
What does the buccal n. provide sensory to?
Skin of the cheek and underlying oral mucosa
What does the auriculotemporal n. supply sensory to?
Parts of the external ear and most of the skin overlying temporalis, masseter, and zygomatic arch
What is the path of the auriculotemporal n.?
Passes caudal to retroarticular process to emerge on the superficial surface of the face between the masseter and auricular cartilage
What sensory does the inferior alveolar n. provide?
Mandibular teeth
What sensory does the mental nerve provide?
Skin of the chin
What is the mental n. a branch of ?
Inferior alveolar n.
Where does the mental nerve exit?
Mental foramen
What sensory information does the mylohyoid n. provide?
Skin ventral to teh mandibular body
What motor actions does the mylohyoid n. provide?
Mylohyoid
Rostral digastric muscle
What could the mylohyoid nerve be a branch of?
Inferior avelolar
What sensory information does the lingual nerve provide?
Rostral two-thirds of the tongue and lingual mucosa
What is carried with the lingual n.?
Special sensory and preganglionic parasympathetic fibers from the facial n.
What is the path of the lingual nerve?
Runs parallel and rostral to the inferior alveolar n. passing medial to mandible to enter caudal aspect of the oral cavity
What is the maxillary a. divided into?
Mandibular - Pterygoid - Pterygopalatine
What are some things that the mandibular portion of the maxillary artery provide blood to?
Temporalis, Masseter, and some of pterygoid mass
TMJ and Ear
What are two main branches off the mandibular a.?
Inferior alveolar a.
Middle meningeal a.
Where does the middle meningeal a. go?
Through the oval foramen into the cranial cavity
What does the pterygoplatine a. provide blood to?
Orbit, palate, nasal cavity
Temporalis - and MOST of the pterygoid mass
What branch comes off the pterygoplatine?
Buccal artery
Where does the maxillary vein form?
caudal to the alar canal from union of veins from pterygoid plexus
What joins with the maxillary vein to form the external jugular?
Linguofacial v.
