M6S1 Peripheral Nervous System Flashcards
Peripheral nervous system
-all of the nerves outside of the brain and spinal cord
-PNS contains spinal and cranial nerves
Can be remembered as everything peripheral to, or outside of the brain and spinal cord
Cranial nerves arise from Brainstem, while spinal nerves arise from spinal cord
Divisions of the PNS
*refer to chart in goodnotes
Cranial nerves
-emerge in pairs from the brain and brain stem instead of the spinal cord
-12 pairs of cranial nerves
-some only carry sensory information or motor information, while others carry both sensory and motor information
-numbered using Roman numerals and referred to by their number or name
*refer to goodnotes for image
CN I - Olfactory Nerve
Information : sensory only
Function:
Sensory - smell
Motor - none
CN II - Optic Nerve
Information: sensory only
Function:
Sensory - vision
Motor - none
CN III - Oculomotor nerve
Information: motor only
Function:
Sensory - none
Motor - movement of eye (elevation of eye)
* one of the three cranial nerves that sends motor input to the muscles that move eye
CN IV - Trochlear Nerve
Information: motor only
Function:
Sensory - none
Motor - movement of eye (as if looking at nose)
* second of the three cranial nerves involved in eye movement
CN V - Trigeminal Nerve
Information: sensory and motor
Functions:
Sensory - forehead, eye, upper jaw, lower jaw
Motor - muscles of mastication (so innervate masseter muscle)
*as three divisions, therefore “tri” is logical
CN VI - Abducens Nerve
Information: motor only
Function:
Sensory - none
Motor - movement of eye (to abduct eyes, move them laterally)
* the third cranial nerve involved in eye movement
CN VII - Facial Nerve
Information: sensory and motor
Functions:
Sensory - taste for anterior 2/3 of tongue
Motor - muscles of facial expression, parasympathetic innervation of tear (aka lakeral) and salivary glands
CN VIII - Vestibulocochlear nerve
Information: sensory only
Functions:
Sensory - Equilibrium (vestibular apperatus responsible for that) and hearing (Conkia?, organ responsible for hearing)
Motor - none
CN IX - Glossopharyngeal Nerve
Information: sensory and motor
Functions:
Sensory - sensory innervation of the pharynx, taste from posterior 1/3 tongue
Motor - pharynx muscles, parasympathetic intervention of salivary glands
(Glosso=tongue)
CN X - Vagus nerve
Information: sensory and motor
Functions:
Sensory - sensory innervation of the larynx
Motor - pharynx and larynx muscles, parasympathetic innervation of the thoracic and abdominal organs (travelling through those cavities)
CN XI - (spinal accessory nerve according to video) Accessory Nerve
Information: motor only
Function:
Sensory - none
Motor - trapezius (strug shoulder) and sternocleidomastoid muscles (flex neck and turn head)
CN XII - Hypoglossal Nerve
Information: motor only
Function:
Sensory - none
Motor - muscles of the tongue
Mnemonic to remember cranial nerves
Once over one Tuesday, the actor finally voted good venue at hogwarts
Spinal nerves
-named as such because emerge from spinal cord
-31 pairs
-carry information through the PNS
-formed by union of posterior (sensory) and anterior (motor) roots of spinal cord
Classifying spinal nerves
-identified based on letter and number
Letter = region of spinal cord
Number = level
Within cervical region - spinal nerves emerge superior to corresponding vertebrae, Spinal nerve C8 exception , emerging between C7 and T1 (there is no C8 vertebra)
Below the neck - spinal nerves emerge inferior to corresponding vertebra
Nerve plexuses
-once spinal nerve exit vertebral column, fibres from anterior roots (motor) come together then redistribute into new networks of nerves (plexuses) that mostly innervate muscles of limb
- each plexus thus contains fibres (collection of axons) from a combination of spinal nerves
-functional important because in case of injury, contribution of multiple spinal nerves into nerve plexus ensures innervation to muscle
-main spinal nerve plexuses in body correspond to the enlargements of spinal cord
-cervical and brachial plexuses correspond to cervical enlargement
-lumbar and sacral plexuses correspond to lumbosacral enlargement
*refer to goodnotes for images