Lecture Quiz 4 Flashcards
Define nerve
cordlike organ of the PNS consisting of peripheral axons enclosed by connective tissue
Define endoneurium
loose connective tissue that surrounds axons
Define perineurium
coarse connective tissue that bundles fibers into fascicles
Define epineurium
tough fibrous sheath around a nerve
What is the sensory division in the PNS?
afferent
carry impulses to the CNS
What is the motor division in the PNS?
efferent
carry impulses from the CNS
What is the mixed division of the PNS?
sensory and motor fibers carry impulses to and from CNS
this is the most common type of nerve
What are the four types of peripheral nerves?
all mixed nerves somatic afferent somatic efferent visceral afferent visceral effernt
What are the four cranial nerves that carry parasympathetic fibers?
Oculomotor (III)
Facial (VII)
Glossopharyngeal (IX)
Vagus (X)
Describe nerve I
Oflactory
arises from the olfactory epithelium
passes through the cribriform plate of the ethmoid bone
fibers run through the olfactory bulb and terminate in the primary olfactory cortex
What type of nerve is nerve I?
somatic afferent
solely carries afferent impulses for the sense of smell
Describe nerve II
optic
arises from retina of the eye
optic nerves pass through the optic canals and converge to the optic chiasm
optic radiation fibers run to the visual cortex
What type of nerve is nerve II?
somatic afferent
functions solely by carrying afferent impulses for vision
Describe nerve III
oculomotor
fibers extend from the ventral midbrain, pass through the superior orbital fissure, and go to the extrinsic eye muscles
What type of nerve is nerve III?
somatic efferent visceral efferent (size of pupil) functions in raising the eyelid, directing the eyeball, constricting the iris, and controlling the lens shape
Where are the parasympathetic cell bodies found in nerve III
cell bodies are found in the ciliary ganglia
Describe nerve IV
trochlear
fibers emerge from the dorsal midbrain and enter the orbits ia the superior orbital fissures
innervate the superior oblique muscle
What type of nerve is nerve IV?
somatic efferent
primarily a motor nerve that directs the eyeball
Describe nerve V
trigeminal
fibers run from the face to the pons via the superior orbital fissure, the foramen rotundum, and the foramen ovale
What are the divisions of the trigeminal nerve?
ophthalmic (V1) - superior orbital fissure
maxillary (V2) - foramen rotundun
mandibular (V3) - foramen ovale
What type of nerve is nerve V?
somatic afferent
somatic efferent
conveys sensory impulses from various areas of the face and supplies motor fibers for mastication
Describe nerve VI
Abducens
fibers leave the inferior pons and enter the orbit via the superior orbital fissure
What type of nerve is nerve VI?
somatic efferent
primarily a motor nerve innervating the lateral rectus muscle
Describe nerve VII
facial
fibers leave the pons, travel through the internal acoustic meatus, and emerge through the stylomastoid foramen to the lateral aspect of the face
What type of nerve is nerve VII?
somatic efferent
visceral afferent
visceral efferent
motor functions include facial expression and the transmittal of autonomic impulses to lacrimal and salivary glands
sensory function is taste from the anterior two-thirds of the tongue
Describe nerve VIII
vestibulocochlear
fibers arise from the hearing and equilibrium apparatus of the inner ear, pass through the internal acoustic meatus, and enter the brainstem at the pons-medulla border
What are the two divisions of the vestibulocochlear nerve?
cochlear (hearing)
vestibulo (balance)
What type of nerve is nerve VIII?
somatic afferent
functions are solely sensory
equilibrium and hearing
Describe nerve IX
glossopharyngeal
fibers emerge from the medulla, leave the skull via the jugular foramen, and run to the throat
What type of nerve is nerve IX?
somatic efferent
visceral afferent
visceral efferent
What does nerve IX innervate?
motor - part of the tongue and pharynx, and provides motor fibers to the parotid salivary gland
sensory - fibers conduct taste and general sensory impulses from the tongue and pharynx
Describe nerve X
Vagus
the only cranial nerve that extends beyond the head and neck
fibers emerge from the medulla via the jugular foramen
What type of nerve is nerve X?
visceral afferent visceral efferent mixed nerve most motor fibers are parasympathetic fibers to the heart, lungs, and visceral organs sensory function is in taste
Describe nerve XI
accessory
formed from a cranial root emerging from the medulla and a spinal root arising from the superior region of the spinal cord
spinal root passes upward into the cranium via foramen magnum
leaves the cranium via the jugular foramen
What type of nerve is nerve XI?
somatic efferent
primarily a motor nerve
supplies fibers to the larynx, pharynx, and soft palate
innervates the trapezius and sternocleidomastoid, which move the head and neck
Describe nerve XII
Hypoglossal
fibers arise from the medulla and exit the skull via the hypoglossal canal
What type of nerve is nerve XII
somatic efferent
innervates both extrinsic and intrincis muscles of the tongue, which contribute to swallowing and speech
What cranial nerves are involved in eye movement?
III
IV
VI
What cranial nerves are part of the PNS (visceral efferent)?
III
VII
IX
X
What cranial nerves are purely for motor fxn?
III IV VI XI XII
What cranial nerves are purely sensory functions?
I
II
VIII
What cranial nerves are both sensory and motor?
V VII VIII IX X
What is a reflex?
a rapid, predictable motor response to a stimulus
What are three characteristics of a reflex?
it may be:
intrinsic or learned
involve only peripheral nerves and the spinal cord
involve higher brain centers as well
What are the five components of a reflex arc?
receptor sensory neuron integration center motor neuron effector
What is the receptor in the reflex arc?
the site of the stimulus