peripheral nervous system Flashcards
the PNS can be broken down into which two systems
autonomic NS and somatic NS
the autonomic nervous system can be broken down into which two systems
sympathetic and parasympathetic
what does the CNS contain
brain and spinal cord
what does the PNS contain
nerves and ganglia outside of the CNS
How many pairs of spinal nerves do we have?
31 pairs
where do spinal nerves originate from
the spinal cord
describe somatic nervous system
voluntary! Has both sensory and motor neurons
where do sensory neurons convey input from?
receptors for somatic and speical senses `
are sensory neurons afferent or efferent
afferent!
where do somatic motor neurons innervate?
skeletal muscle cells
describe the autonomic nervous system
it is involuntary! The autonomic nervous system regulates cardiac muscle tissue, smooth muscle, and glandular tissue. It also regulates visceral activities by exciting or inhibiting activities in effector tissues. It can also be broken down into the SNS (fight or flight) and the PNS (rest and digest_
what are the two portions of the afferent PNS
somatic sensory (carrying signals from receptors in skin, muscles, bones, and joints) and visceral sensory (carrying signals from organs in thoracic and abdominal cavities)
how many neurons in a pathway does the somatic NS have?
the somatic NS is a 1 neuron system
how many neurons in a pathway does the autonomic nervous system have?
the autonomic nervous system is a 2 neuron system
what does the autonomic nervous system innervate?
smooth muscle, glands, and cardiac muscle
what does the somatic nervous system innervate?
skeletal muscles
what sensory receptos are part of the somatic sensory division
vision, hearing, equilibrium
what sensory receptors are part of the autonomic nervous system
smell and taste
where are free nerve endings of sensory neurons located?
most body tissues - especially connective tissues
what is the functional class of free nerve endings of sensory neurons
nociceptrs, thermoreceptors, mechanoreceptors, chemoreceptors
where are merkel discs (modified free nerve endings) located?
deepest layer of the epidermis (very superficial)
what is the functional class of merkel discs?
mechanoreceptors
what is the functional class of hair follicle receptors
mechanoreceptors
where are hair follicle receptors located
in and surrounding hair follicles
what are the 3 different types of sensory receptors
free nerve endings, encapsulated, proprioceptors
type of sensory receptors are merkel discs?
free nerve endings
what type of sensory receptors are hair follicle receptors
free nerve endings
what is the functional class of tactile corpuscles?
mechanoreceptors - sensitive to light pressure, discriminative touch, vibrations of low frequencyy
where are tactile corpuscles located
hairless skin (ie nipples, external genitalia, fingertips, eyelids)
what is the functional class of lamellar corpuscles
mechanoreceptors (sensitive to deep pressure, stretch, vibration of high frequency)
where are lamellar corpuscles located?
dermis and hypodermis - abundent in fingers, soles of feet, external genitalia, nipples
what is the functional class of ruffini corpuscles
mechnoreceptors (sensitive to deep pressure and strecth - espically of tendons)
where are ruffini corouscles located?
deep in the dermis, hypodermis, and joint capsules
what are the 3 types of encapsulated sensory receptors?
tactile corpuscles, lamellar corpuscles, ruffini corpuscles`
what is the functional class of muscle spindles?
mechanoreceptors (detect muscle stretch)
where are muscle spindles located?
skeletal muscles (particularly extremities)
what is the functional class of tendon organs
mechanoreceptors - detect tendon stretch
where are tendon organs located?
tendons
what are the two different types of proprioceptors
muscle spindles and tendon organs
where is the lateral horn of the spinal cord located?
ONLY throacic region, lumbar region, and sacral region
what is the lateral horn of the spinal cord responsible for
sympathetic division
what is the anterior horn of the spinal cord responsible for
motor neurons
purpose of spinal nerves
comminication btw brain and body parts, voluntary and involuntary actions, highway for sensory and motor integrations, rapid autonomic responses via reflex
what does the epineurium encapsulate in spinal nerves
the entire nerve itself
what does the perineurium encapsulate in spinal nerves
fassicles (bundles of nerve axons)
what does the endoneurium encapsulate in spinal nerves
the individual nerve fibers
how many cervical spinal nerves?
8 (7 of which leave spinal cord above corresponding vertebral level)
how many pairs of lumbar spinal nerves?
5
how many pairs of sacral spinal nerves
5
how many pairs of coccygeal nerves
1
what do the dorsal roots of the spinal nerves contain?
axonal processes of sensory neurons coming from the posterior horn
what is the dorsal root ganglion?
an enlargement of the dorsal roots containing clusters of cell bodies of sensory neurons
what is the function of the dorsal root ganglion?
sensory motor relay station by processing and modulating sensory signals before reaching CNS
what do the ventral roots of the spinal nerve contain?
axonal processess of motor neurons whose cell bodies are located in the anterior horn of the spinal cord
what region do the dorsal and ventral rami supply?
somatic region of the body
what kind of fibers do the dorsal and ventral rami contain?
both sensory and motor
where does the dorsal rami supply
the dorsum of the neck and back
where does the ventral rami supply
anterior and lateral regions of neck and trunk, all regions of the limbs
how many primary nerve plexuses come from the ventral rami
4 - cervicle plexus
which spinal nerves contribute to the cervicle plexus
C1-C4
what does the cervicle plexus supply
sensory and motor innervation to neck and head
what spinal nerves contribute to the brachial plexus
C5-T1
what does the brachial plexus supply
sensory and motor innervation to shoulder and upper limbs
what spinal nerves contribute tot eh lumbar plexus
L1-L4
what does the lumbar plexus supply
nerves to the lower back, abdominal wall, and lower limb
what spinal nerves contribute to the sacral plexus
L4-S5
what does the sacral plexus supply
innervates buttocks, pelvic structures, and remainder of lower limb
what is the motor reflex arc?
a neural pathway that mediates rapid involunatry actions, it integrates sensory inputs and motor outputs, and it provides physiological and neural response against potential harmful stimuli
what are dermatomes
sections of skin innervated by a single nerve
