Control Of Mastication Flashcards
What synaptic is the stretch reflex
Monosynaptic
What is the pathway of the stretch reflex knee jerk reflex
Activation of Sensory afferent neuron from spindle in the muscle - dorsal horn or spinal cord - ventral horn where they synapse to efferent nerves to the muscle and excite those muscle fibre relaxing the muscle
Inhibitory leads to contracting muscle
What does monosynaptic mean
One synapse involved in knee jerk and excitatory one
What synaptic is the withdrawal reflex
Disynaptic (2 synapses)
What is the pathway of the withdrawal reflex (pain hot)
Impulse sent down afferent sensory neuron - dorsal horn of spinal cord - synapse onto an excitatory interneuron - in ventral horn and affects efferent or motor neurons to the flexor muscle
What is different with the crossed extensor reflex
There is a secondary input on the same line which crosses the middle and goes to the opposing limb
What is the Golgi tendon reflex
Activation of the Golgi tendon releases excitation of an inhibitory inter neuron which reduces the force of contraction in the muscle
What is the Golgi tendon reflex also referred to as
Inverse myototactic reflex
What are muscle spindles
Consists of specialised muscle fibres
What are interfusal fibres
Muscles fibres of muscle spindle
What are extrafusal fibres
Muscles fibres not in correlation to the spindles
What happens to the spindles when the muscle is stretched
Activates the anulospiral endings resulting in an increase in the firing rate
In relation to muscle rate of firing which is higher to lower
Stretched
Relaxed
Contracted - nearly zero
What is the primary ending
Annulospiral endings
What do secondary endings respond to
Purely the length of the muscle and have no affect on the rate
What are Ruffini endings
Pressure slowly adapting
What are pacinian corpuscles
Vibration rapidly adapting
Which muscles help with depression (opening mouth)
Digastric, geniohyoid, lateral pterygoid and mylohyoid assisted by gravity
Which muscles help with elevation (closing the mouth)
Temporalis, massater and medial pterygoid
Which muscles help with protraction (protrusion)
Lateral pterygoid and some assistance by medial pterygoid
Which muscles help with retraction (retrusion)
Geniohyoid, digastric and posterior and deep fibres of Temporalis and masseter
What are 2 examples for free nerve endings
Mechanoreceptors
Nociceptors
What receptors does the PDL have
Mechanoreceptors
What nerve endings does the oral mucosa have
Innervated with free nerve endings for mechanical, thermal and nociceptive inputs
What are the TMJ capsule receptors
Innervated by free nerve endings, Ruffini endings (slowly adapting to pressure) and pacinian corpuscles (vibration - rapidly adapting to pressure)
Where does the afferent and efferent nerves of the jaw travel through
Trigeminal mesencephalic nucleus not the spinal cord like other muscles
What is the chewing cycle
Initiated by bolus presence opening of the jaw
Activation of stretch reflex closing of the jaw
Presence of food between teeth results in loading
Collapse of the food or teeth coming into contact results in unloading and inhibition of the jaw opening muscles
What influences the rhythmic control of chewing
Brain stem
Reticular formation, amygdala (basal ganglia), lateral hypothalamus, cerebellum, pre and post central gyrus of the motor cortex
What is the freeway space
The difference between the OVD and RVD when mouth is closed as teeth do not touch when closed
What is the freeway space determined by
Muscle tone
Elasticity of surrounding structures
Posture
Exercise
Anxiety
Stress
