Quiz 2 Flashcards
Masseter
Superficial to mandible
elevates mandible
some protrusion
Creates muscular sling with medial pterygoid
Temporalis
3 Portions: Anterior - elevates mandible Middle - elevates and retrudes (opposite of protrude) mandible Posterior - retrudes mandible Runs under zygomatic arch
Medial Pterygoid
Creates muscular sling with masseter, sits deep to mandible
elevates and protrudes mandible
Unilateral contraction: mediotrusive movement (lateral and to opposite side)
Lateral Pterygoid
Inferior and Superior Body/Belly
Primary protruder of mandible
Contracts upon CLOSING, not opening
Inferior Lateral Pterygoid
Bilateral Contraction: protrusion
Unilateral Contraction: lateral movement to opposite side
Digastric
One muscle with a Posterior and Anterior belly separated by a tendon (Intermediate Tendon)
Both sit below mandible and attach to hyoid bone
Not considered a true muscle of mastication
Digastric Muscle Function - Fixed Hyoid
Mandible is depressed and brought backwards.
Fixed Hyoid happens via supra & infrahyoid muscles
Digastric Muscle Function - Fixed Mandible
Fixed mandible via digastric, infra and suprahyoid muscles which raises the hyoid bone = SWALLOWING
Digastric Muscle Function - Fixed Mandible
Fixed mandible via digastric, infra and suprahyoid muscles which raises the hyoid bone = SWALLOWING
Suprahyoid Muscles
muscles that span from mandible to hyoid
Infrahyoid Muscles
Muscles that span from hyoid to clavicle and sternum
Exteroceptors
provide info from exterior tissues of the body to inform CNS of conditions in the environment of that receptor
Nociceptors
Pain and discomfort
Proprioceptors
Position and movement of mandible and associated oral structures
Interoceptors
Internal organs and processes like blood flow, digestion, breathing
Primary / First Order Neurons
Carry input into dorsal horn. Synapse with second-order / secondary neurons or motor neurons
Secondary / Second Order Neurons
Carry information to different levels of the spinal cord
Trace Trigeminal Nerve Input
- Cell bodies of trigeminal n located in the gasserian ganglion (GG)
- Primary afferent neuron enters brainstem to synapse with the second-order neuron in the trigeminal spinal tract nucleus (STN of V).
- Second-order neuron to the thalamus for interpretation
- Thalamus sends information to cortex
Spinal Tract Nucleus of Trigeminal Nerve
Located in the brainstem
Broken into 3 parts
1. Subnucleus Oralis (sno) oral pain mechanisms
2. subnucleus interpolaris (sni)
3. subnucleus caudalis (snc) trigeminal nociceptive mechanisms
tooth pulp to all 3
Trigeminal Brainstem
- Spinal Tract Nucleus (sno, sni, snc)
- Main sensory nucleus of V (SN of V)
- Motor nucleus of V (MN of V)
Reticular Formation
monitors impulses that enter the brain via enhancing impulses or inhibiting impulses.
Thalamus
drives cortex to activity and enables communication between cortex and rest of the CNS. Without thalamus the cortex is useless!!
“keyboard” that controls functions and directs signals
Hypothalamus
Thirst
Hunger
Body Temperature
Limbic Structures
emotional and behavioral activities
Cortex
thinking process
muscle skills
special senses
Central Pattern Generator - CPG
pool of neurons that control rhythmic muscle activities such as breathing, walking, chewing.
Precise timing of activity between antagonistic muscles for special functions
Muscle Engrams
Learned & repeated pattern of chewing that minimizes damage to oral structures.
Superior Lateral Pterygoid
remains inactive during opening and active during closing
Especially active during power stroke and when teeth are held together
Mastication
An efficient chewing pattern that minimizes damage to structure Learned & Repeated (engram) Automatic and practically involuntary 2 phases -opening -closing (crushing & grinding)
Opening phase
Mandible is depressed and shifts 3-4 mm laterally
Closing Phase - Crushing
Majority of closing phase
At maximum opening begin to shift medial
Buccal cusps of mandibular teeth directly under buccal cusps of maxillary teeth which helps trap food between them.
Closing Phase - Grinding
Last bit of closing phase
Mandible guided by occlusal surfaces of teeth to IP
Cuspal inclines pass across each other= shearing & grinding of Bolus
Lateral Movements of Mandible
Depend on stage of Mastication -Early= more lateral movement -Late= less lateral movement Depends on food consistency -Hard=more lateral movement -Soft=less lateral movement
Forces of Mastication
Female average: ~80 lbs
Male average: ~120 lbs
Greatest: 975 lbs
Varies by teeth (first molars > incisors)
Varies by prosthetics (dentures 25% force)
Varies by pain (tooth/muscle pain reduce force)
Swallowing - Deglutition
Coordinated muscular contractions that move bolus to stomach
Voluntary, involuntary, and reflex muscular activity
Must have a stabilized mandible to allow movement of hyoid - different in adults and infants
Duration & Force of Swallowing
Takes 3x as long as tooth contact during mastication
7.8 lbs more than mastication
Somatic Swallow
adult uses teeth for mandibular stability
Visceral Swallow
Infant uses tongue forward and between dental arches to stabilize mandible to allow hyoid movement
