Afferent & Efferent Pathways

What is the process of swallowing?

It is the process by which saliva, food, and fluid is safely transported from the mouth to the stomach while the upper respiratory tract is simultaneously protected from pulmonary aspiration of the material being swallowed - a complex sensory-motor phenomenon

What are the 4 processes of eating?

transportation, salivation, mastication, & swallowing

Sensory pathways are ____________

afferent pathways

Motor pathways are ________________

efferent pathways

What is somatosensation?

It refers to the bodily experienced sensations of pain, temperature, touch, & proprioception. It begins with specialized receptors in the skin, muscles, joints & blood vessels that convert sensory stimuli to neural signals and transmits them to the CNS

Sensory pathways are made up of how many neurons? What are they?

3; first order, second order, & third order

Describe the sensory pathway neurons.

First order travels from periphery up to brainstem, second order neuron is inside CNS and first order synapses onto that and the neuron ascends or moved upwards and synapses onto the third order neuron which travels up to the cerebral cortex (parietal lobe) where our sensory cortex is.

What is a cell or neuron referred to as when it is outside of the CNS (AKA it is in the PNS)?

Ganglion (for example trigeminal ganglion)

What is an example of a sensory pathway?

Poking your cheek

What is an example of a motor pathway?

Wanting to wiggle your cheek

Describe motor control

Starts in CNS system. Generally brain puts together a motor plan and efferent impulses from the primary motor cortex (PMC) send out this message by activating spinal/cranial nerves and inducing contraction of specific muscles

What is the role of the PMC?

Controlling movement of the body, participating in sensory-motor transformation, and making sense of sensory information and using it to influence how the motor plan puts things together & sends out signals/impulses.

How is the motor cortex organized?

Contralateral to output and input, AKA right side of brain controls the left side of the body & vice versa. The corticobulbar efferent projections from the motor cortex cross the midline to innervate contralateral cranial nerve nuclei.

True or False - Most spinal nerves have bilateral innervation

False - spinal nerves do not have bilateral innervation, but most cranial nerves are bilaterally innervated

How many neurons are in the motor system? What are they?

2; upper & lower motor neurons

Why are internal capsule strokes bad?

Because a lot of upper motor neurons come together and pass through the internal capsule so internal capsule strokes can result in significant motor loss

True or false - the lower part of the face received bilateral innervation

False - only contralateral

What two cranial nerves are not completely bilaterally innervated?

Facial nerve and hypoglossal

True or false - the forehead will be spared in Bell's Palsy of CNVII after it exits the stylomastoid foramen

False - although the forehead is bilaterally innervated, at this point, the fibers from both sides have come together so the forehead would not be spared

True or false - all somatosensory inputs transmit impulses through three neurons with their fibers

True - first order neuron ganglion then second order sensory fibers decussate then third order fibers travel through the internal capsule and into the post central gyrus

In what part of our brain do we "plan" movement?

The premotor cortex (PMC) aka the supplementary motor area (prefrontal cortex also helps out)

What is another term for upper motor neurons?

Corticobulbar efferent projections

What is another term for lower motor neurons?

The actual cranial nerve