Chapter 14- Peripheral Nervous System Flashcards
Peripheral Nervous system made of?
Mixed nerves (contain afferent and efferent axons)- all spinal nerves are mixed nerves Motor nerves (only efferent axons) Sensory nerves (only afferent axons)
How many pairs of cranial nerves are there?
12
Cranial nerves are…
Attached to the brain and pass through the skull foramina; numbered with roman numerals from rostral to caudal; each nerve is either motor, sensory or mixed
Identify all 12 cranial nerves from top view of brain
:(
CN I: Olfactory
Composed of very short fibers; sensory; doesn’t form tight nerve; bipolar neurons that are olfactory neurons; olfactory bulb is not cranial nerve I it is where olfactory nerve synapses
CN II: Optic
Axons of the retina converge to form the optic nerve; passes through the optic foramen into the brain; from eye to chiasma; sensory- vision
CN III: oculomotor
Motor- moves the eyeball and eyelid; parasympathetic; activates skeletal muscles that move eyeball
Palpebrae=
eyelid
CN IV: trochlear
Motor- moves the eyeball; smallest CN; only cn from DORSAL brainstem; innervates the superior oblique muscle and that’s all
CN V: trigeminal
MIXED
- Motor: muscles of mastication (chewing only)
- Sensory: All facial sensations
CN VI: Abducens
Motor- moves the eyeball
runs along the middle of pons; activates lateral rectus muscles (ABDUCTS the eyeball)
CN VII: facial
MIXED
- Motor: Facial expression
- Sensory: taste in anterior 2/3rds of tongue
NOT FOR CHEWING
CN VIII: Vestibulocochlear
Sensory- equilibrium and audition
CN IX: Glossopharyngeal
MIXED
- Sensory: taste for the posterior 1/3 of the tongue
- Motor: swallowing muscles
CN X: Vagus
BIGGEST CN Nerve; only one that goes past the neck (fibers innervate most organs of ventral body cavity); MIXED
- Sensory: visceral sensation and taste from throat region
- Motor: supplies muscles of the pharynx, larynx and soft palate that are involved in swallowing and vocalization
Effector tissues of the Vagus Nerve
Lung, heart, spleen, liver, stomach, kidney, small intestine, colon
CN XI: Accessory
MOTOR- coordinates head movements
activates sternocleidomastoid and trapezius; through foramen magnum, exit out jugular foramen
CN XII: Hypoglossal
Underneath tongue, activates tongue; motor tongue movement
Internal muscles change shape of tongue; external muscles are skeletal muscles
Mnemonic
Oh Oh Oh To Touch And Feel Very Good Velvet Ah
Functions: Some Say Marry Money But My Brother Says Big Brains Matter More
Is cranial nerve XI attached to the brain?
NO
How many pairs of MIXED nerves are attached to the spinal cord?
31
How are spinal nerves named?
For their point of issue from the vertebral column
of spinal nerves at each segment corresponds to the number of vertebra except
Cervical
Below cervical region, all spinal nerves exit ___ their respective vertebra
Below
If coming from your limbs it will follow what route?
Ventral Ramus
If coming from your back it follows what route?
Dorsal route; sensory must go in dorsal route
The _____ of all spinal nerves (except ___) branch and join one another forming an interlacing network of axons
Ventral rami; T2-T12
The ventral rami primarily serve…
the limbs
Because of the arrangement of the ventral rami, if a single spinal nerve is damaged does it completely paralyze the limb muscle?
NO
Back and thorax innervation=
Spinal nerves T2-T12
The dorsal rami supply the back of the trunk in a segmented fashion;
The ventral rami of the thorax supplies the remainder of the thorax in a segmented fashion via the intercostal nerves
Cervical plexus=
C1-C5 spinal nerves; located deep in the neck under the SCM muscle; phrenic nerve (innervation of the diaphragm)
What does spinal cord damage superior to C3 to C5 result in?
respiratory arrest
The brachial plexus
Arises from C4-T1; located in neck and axilla region; innervates the shoulders and arms; Ulnar nerve
The lumbar plexus
Femoral nerve supplies the anterior thigh; obturator nerve supplies the medial thigh (adductors)
Arises from L1-L4; located in psoas major
The sacral plexus
Arises from L4-S4 spinal nerves; supplies buttocks, hamstrings, and leg; Sciatic nerve= largest in the body, innervates all of lower limb except anterior and medial thigh
Coronial is also known as…
Fibular
What are dermatomes?
An area of the skin that provides sensory input to the CNS via one pair of spinal nerves;
Clinical relevance? Nerve blocks, localization of injuries