Somatic Nervous System Review

Flashcards created from lecture notes on the somatic nervous system, covering sensory perception, motor responses, pathways to the brain, and reflexes.

What is the somatic nervous system responsible for?

Our conscious perception of the environment and our voluntary responses to that perception by means of skeletal muscles.

What is sensation?

The activation of sensory receptor cells at the level of the sensory organs.

What is perception dependent on?

Experience, but not all sensations are perceived.

Where are free nerve endings located?

Dermis, cornea, tongue, joint capsules, visceral organs.

What types of stimuli do free nerve endings respond to?

Pain, temperature, mechanical deformation.

What stimuli do Merkel's discs respond to?

Low frequency vibrations (5-15 Hz).

What do Ruffini's corpuscles detect?

Stretch and deformation of the skin.

Where are Meissner's corpuscles located?

Papillary dermis, especially in the lips and fingertips.

What type of vibrations do Meissner's corpuscles respond to?

Light touch and vibrations below 50 Hz.

What do Pacinian corpuscles primarily detect?

Deep pressure and high-frequency vibrations (around 258 Hz).

What is a stretch reflex?

A reflex where a stretched muscle activates a spindle receptor, leading to contraction of the muscle.

What is an example of a common stretch reflex?

The knee jerk reflex, elicited by a rubber hammer struck against the patellar ligament.

What pathway does the sensory component of the corneal reflex travel through?

The trigeminal nerve.

Where does the motor response of the corneal reflex travel through?

The facial nerve innervating the orbicularis oculi muscle bilaterally.

What areas does sensory input to the brain enter through?

The spinal cord for somatosensory input or the brainstem for everything else except visual and olfactory systems.

What is the role of the thalamus in sensory pathways?

It is necessary for all sensory systems to reach the sensory cortex, except for olfactory.

What is the dorsal column system responsible for?

Carrying information about touch and proprioception.

What types of sensations does the spinothalamic tract primarily transmit?

Pain and temperature sensations.

What does the auditory pathway process?

Information from frequency stimuli in the brain stem.

How is visual information processed in the brain?

It segregates so that one half of the visual field projects to the opposite side of the brain.

What is the function of the dorsal visual stream?

It interacts with the somatosensory cortex and influences movements related to other stimuli.

Where do motor pathways project?

To the spinal cord to synapse with motor neurons.

What are lower motor neurons responsible for?

Connecting to skeletal muscle and causing contractions.

How many fibers can a single motor neuron connect to?

Varies based on the precision necessary for that muscle.

What is a withdrawal reflex?

A reflex from a painful stimulus that requires only one sensory and one motor neuron.

What is the corneal reflex?

Contraction of the orbicularis oculi muscle to blink when something touches the eye.

What is the role of the muscle spindle in stretch reflexes?

It senses the length of muscles and helps maintain a constant muscle length.