CH. 14 Flashcards
How many pairs of cranial nerves do we have?
12 pairs, 24 total
The dots in the olfactory buld represent what?
The cross sections of CNI.
Olfactory bulb is NOT CNI.
SEVERED WHEN BRAIN IS TAKEN OUT
Which cranial nerve comes off of the dorsal aspect of the brain stem?
CNIV
CNI
OLFACTORY NERVE
CN2
OPTIC NERVE
CNIII
OCULOMOTOR NERVE
CNIV
TROCHLEAR NERVE
CNV
TRIGEMINAL NERVE
CNVI
ABDUCENS NERVE
CNVII
FACIAL NERVE
CNVIII
VESTIBULOCOCHLEAR NERVE
CNIX
GLOSSOPHARYNGEAL NERVE
CNX
VAGUS NERVE
CNXI
ACCESSORY NERVE
CNXII
HYPOGLOSSAL NERVE
Why is CNI not a common nerve structure?
It is not ensheathed by CT tissue.
Just a collection of axons running up the nasal cavity and synapsing with neurons on the olfactory bulb
What is the sensory function, origin and pathway of CNI?
Olfactory
Sensory Function: special visceral sensory, sense of smell
Origin: Olfactory receptor cells (BIPOLAR NEURONS–RARE) in the olfactory epithelium of the nasal cavity
Pathway: it travels through the cribiform foramina of the ethmoid bone to synapse in the olfactory bulb. Fibers of the olfactory bulb neurons then extend posteriorly beneath the frontal lobe as the olfactory tract. They terminate in the primary olfactory cortex of the cerebrum.
Sensory function and origin of CNII?
Optic nerve
Sensory function: special somatic sensory; vision
Origin: Retina of the eye
Pathway: comes back to the optic chiasm and those axons continue as the optic tract
Somatic motor function and visceral motor function and what branch of the ANS for CNIII.
Oculomotor Nerve
Somatic motor function: innervates the muscles that Direct the eyeball–>superior rectus, inferior rectus, medial rectus, inferior oblique muscle. Also innervates the levator palpebrae superioris muscle.
Visceral motor function (PARASYM): constrictor muscles of the iris to constrict the pupil and ciliary muscle controls lens shape.
WHAT IS LR6 SO4
Lateral rectus muscle is controlled by CNVI and Superior oblique is controlled by CNIV
what is the smalled cranial nerve
Trochlear nerve (CNIV)
What is the somatic motor function of CNIV?
Trochlear nerve
Somatic motor function: superior oblique muscle which passes through the trochela (pulley)
What are the branches, somatic motor function and sensory function of CNV
TRIGEMINAL NERVE–mixed nerve
Branches: opthalmic, maxillary, mandibular (innervates the muscles of mastication)
Somatic motor function: mastication
Somatic sensory: facial sensation like pain, temp, touch, pressure.
What is the somatic motor function of CNVI?
Abducens Nerve
Somatic motor function: innervate the lateral rectus (ABDUCTS THE EYEBALL) muscle LR6
What is the somatic motor function, special sensory function, and parasympathetic innervation of CNVII?
FACIAL NERVE–mixed nerve
Somatic motor: facial muscles used for eating, communication.
Sensory function: taste on the anterior 2/3 of tongue
Parasympathetic innervation: sublingual, submandibular lacrimal gland.
What is the sensory function of CNVIII?
Vestibulocochlear nerve
Sensory function: vestibular branch-special somatic sensory, equilibrium
cochlear branch-special somatic sensory, hearing
What is the somatic motor and somatic sensory function of CNIX
Glossopharyngeal nerve
Somatic Motor: helps with swallowing. innervates the pharyngeal constrictor muscles and the bit of tongue muscles that help with swallowing
Somatic sensory: posterior 1/3 of tongue that dips into the pharynx. taste information.
Which cranial nerve has axons that leave the head or neck?
Vagus CNX
What is the somatic motor function and somatic sensory of CNX?
Vagus
Somatic Motor: swallowing and vocalization
Somatic sensory: taste on the epiglottis
What is the pathway and somatic motor function of CNXI?
Accessory nerve
Pathway: starts from the rootlets in the cervical region of the spine and they gather together and they come up alongside the medulla oblongata and they pass the foramen magnum and then they make a u-turn and come right back out the jugular foramen with CNX.
Somatic motor: gives head and neck movement—> innervates sternocleidomastoid and the upper fibers of the traps.
What is the somatic motor function of CNXII?
Hypoglossal nerve
Somatic motor: innervate the intrinsic and extrinsic muscles of the tongue. aid tongue movements during feeding, swallowing, and speech.
What are the neumonics for CN functions?
I Some II Say III Marry IV Money V But VI My VII Brother VIII Says IX Big X Brains XI Matter XII More
How many PAIR of spinal nerves are there?
31, 62 total
What kind of information do spinal nerves contain?
Both efferent and afferent information
Each spinal nerve is attached by what?
Dorsal and ventral root
How do the ventral and dorsal roots form?
Form from a series of rootlets which span the length of the spinal cord segment
What type of information travels in the dorsal and ventral roots?
Dorsal = sensory ventral = motor
What type of information traves in the dorsal and ventral rami?
both
What is a nerve plexus?
a network of axons
Which spinal nerves do not form nerve plexuses?
Dorsal rami and ventral rami T2-T12
Why is it important that plexuses exist?
Because of plexuses, if a single spinal nerve is damaged, it does not completely paralyze any limb muscles.
Dorsal rami supply the back of the trunk in what way?
In a segmented fashion
The T2-12 ventral rami supply the remainder of the thorax in what way?
in a segmented fashion
Describe the cervical plexus and the most important nerve coming from this plexus
- highest plexus in the body
- C1-C4
- located deep in the neck under the sternocleidomastoid muscle
- Phrenic Nerve: courses down the thoracic cavity and innervate your diaphragm (skeletal muscle). Provides both efferent and afferent innervation to the diaphram
Why is the phrenic nerve so important?
Because without it, there is no information coming from the diaphragm or information going towards the diaphragm and we need this thing to expand in order to breath… so it’s important.
Why are high level spinal cord injuries so lethal?
Because I am likely to damage spinal nerves contributing to the phrenic nerve which helps us breath
What are hiccups?
Hyperstimulation of the phrenic nerve. Eating spicy foods can irritate it because it passes through the esophagus
Describe the brachial plexus
C4-T1
- all of these axons and nerve structures are going to pass underneath the clavicle and come down into the axillary region.
- these axons are going to go all over the anterior and posterior brachial and antebrachial compartments.
What are the major nerves coming from the brachial plexus?
Posterior brachial and antebrachial: axilliary nerve and radial nerve.
Anterior: musculocutaneuos nerve (brachial)
median and radial nerve (antebrachial–lower arm)
Describe the lumbar plexus
L1-L4
-start at the psoas muscle, wrapping around it.
What are the major nerves of the lumbar plexus?
Obturator and femoral nerve
What is the femoral nerve responsbile for?
innervating the skin and muscles of the anterior thigh(quads)
What does the obturator nerve innervate?
the medial thigh compartment —adductors and the skin over the adductors
What is the smallest plexus?
sacral
describe the sacral plexus
L4-S4
Describe the Sciatic nerve
- largest nerve in the body because it is two nerves encased together–>tibial nerve and the common fibular (superficial and deep (peroneal) nerve) nerve before they separate after the knee.
- in the sacral plexus
- passes through the greater sciatic notch
- resposible for motor and sensory information of the entire lower limb except for the anterior thigh compartment and the medial thigh compartment.
What is a dermatome?
An area of the skin that provides sensory input to the CNS via one pair of spinal nerves
Maps of dermatomes are useful for what?
- for surgeons trying to block pain from certain areas.
- diagnose issues with certain areas if patients presents problems with feeling in certain areas.