mastication

temporomandibular joint

• what is it

• what prevents caudal dislocation of the TMJ

• articulation between condylar process of mandible and mandibular process of skull

• left and right temporomandibular joint have been considered a single joint

• caudal dislocation of the TMJ is prevented by a prominent retro articular process

mandibular symphysis

• what is it

• what type of joint is it

• what does it do to each mandibular bone

• where left and right mandible join

• fuse in majority of mammals

• fibrous joint

• precise occlusion

• independent rotation of each mandibular bone

temporal masticatory muscle

origin- which surface

insertion

which direction does it pull the mandible

• origin on cranium lateral surface

• insertion on coronoid process

• pulls mandible dorsally

• some fibres pull mandible rostrally some caudally

innervation and origin of masticatory muscles

• 1st pharyngeal arch

• mandibular branch of CN V

masseter masticatory muscle

• where

• insertion- what side of the manduble?

• what sort of contraction

• movement of jaw

• maxillary region of skull and zygomatic arch

• insertion on wide area of caudal side of mandible

• several divisions

• participates both unilateral and bilateral contracion

• protudes jaw

medial pterygoid muscle

• origin

• insertion

• what does it do to the jaw

• origin is pterygopalatine region of skull

• insert into medial aspect of mandible

• close jaw

lateral pterygoid muscle

• origin

• insertion

• what does it do to the jaw

• origin on pterygopalatine region of skull

• insert into medial aspect of mandible

• closes and protudes jaw

what is the digastricus

• origin

• insert

• 2 parts and innervation

• jaw opening muscle

• origin is paracondular process of occipal bone

• inserts into angle of mandible

• caudal belly- CN VII

• cranial belly CNV

nasal cavities

• what do they contain

• what thickens some bones bordering the nasal cavity

• twinned pair of cavity

• head conformation gauges size

• nasal cavity contains turbinate bones - covered by mucous forming conchae

• features of neighbouring anatomy reduce size

• certain bones bordering the nasal cavity are thickened by air spaces- the paranasal sinuses. (not part of nasal cavity but comminicate with it)

what features reduce size of nasal cavity

• paranasal sinuses in neighbouring bones

• roots of upper cheek teeth occupy space

• turbinate bones

• mucosal covering of turbinate bones

conchae

what are they

what do they compartmentalise

foldings of inner nasal wall towards nasal sepum that compartmentalise the nasal cavity

meatus

nasal cavity compartments

rostrally the dorsal and ventral meatus are very large but middle meatus is small, which expands as you move back

3 examples of jaw closing muscles

• temporal

• masseter

• lateral and medial pterygoids