Cranial Nerves Flashcards
CN 1
Olfactory
CN 2
Optic
CN 3
Oculomotor
CN 4
Trochlear
CN 5
Trigeminal
CN 6
Abducens
CN 7
Facial
CN 8
Vestibulocochlear
CN 9
Glossopharyngeal
CN 10
Vagus
CN 11
Accessory
CN 12
Hypoglossal
The graphic used for CN is on slide 2
memorize it
Cranial nerves are functionally either ____ (afferent) neurons only, or ___ (some combination of afferent (sensory) and efferent (motor) neurons)
sensory
mixed
Only ENTIRELY SENSORY cranial nerves?
Olfactory (CN1)
Optic (CN2)
One cranial nerve is so predominantly sensory that its motor function is frequently overlooked?
Cranial nerve VIII (vestibulocochlear)
Cranial nerves ___, ___, and ___ are thus called sensory nerves (even though CN VIII is not exclusively sensory)
I, II, and VIII
There are no cranial nerves that are exclusively ___ throughout their entire length
motor
Cranial nerves __, __, __, __, and __ are commonly called motor nerves because their function is predominantly motor
They are often said to be “mixed, mainly motor” or “mixed, primarily motor” (as in the following slides)
III, IV, VI, XI, and XII
It is a general principle that the sensory function of such nerves is ____ of the muscles over which they exert motor control (the following slides assume that fact, and do not necessarily repeat proprioceptive functions)
proprioception
Cranial nerves __, __, __, and __ are termed mixed nerves because they have substantial motor and sensory functions, and contain axons of both sensory and motor neurons
V, VII, IX, and X
Most cranial nerves that have a motor function innervate more than one muscle, but the sole mission of two cranial nerves is to innervate a single muscle each.
Which cranial nerves?
Trochlear (IV) innervates the superior oblique
Abducens (VI) innervates the lateral rectus
Both muscles are extrinsic muscles of the eye
All ___ cranial nerves have neurons that innervate somatic (skeletal) muscles
motor
Some motor cranial nerves also have autonomic motor axons, which are?
III (oculomotor)
VII (facial)
IX (glossopharyngeal)
X (vagus)
The autonomic axons are part of the ___ division, and innervate glands, smooth muscle, and cardiac muscle
parasympathetic
Entirely sensory
Contains axons that conduct nerve impulses for the sense of smell (olfaction)
Short function: smell
I – Olfactory
Olfactory bulb and olfactory tract are not CN I
I – Olfactory
Entirely sensory
Contains axons that conduct nerve impulses for the sense of smell (olfaction)
Short function: smell
Olfactory receptors are ___ neurons
bipolar
Bundles of axons of the receptors extend through the ____ of the ethmoid
cribiform plate
The olfactory receptors are bundles of axons that extend through cribiform plate (of ethmoid). These bundles, taken together, make up the ___
CN 1 – olfactory
Loss of the sense of smell is called ____
anosmia
Entirely sensory
Contains myelinated axons that conduct nerve impulses for vision
Optic nerve versus optic tract; optic chiasma
Short function: vision
II – Optic
II – Optic
Entirely sensory
Contains myelinated axons that conduct nerve impulses for vision
Optic nerve versus optic tract; optic chiasma
Short function: vision
Rods and cones in the retina are light sensitive cells that relay signals to ____, which convey the impulses to ganglion cells, also in the retina.
Axons of the ganglion cells form the optic nerve, and those same axons continue on to form the ___
bipolar cells
optic tract
After the ____, is when the optic nerve becomes the optic tract
optic chiasm
Mainly motor
Controls extrinsic eye muscles not innervated by IV and VI
Innervates intrinsic eye muscles: ciliary muscle (on lens) sphincter pupillae (iris)
Short function: eye movement
III – Oculomotor
III – Oculomotor
Mainly motor
Controls extrinsic eye muscles not innervated by IV and VI
Innervates intrinsic eye muscles: ciliary muscle (on lens) sphincter pupillae (iris)
Short function: eye movement
Innervates most extrinsic eye muscles
Parasympathetic innervation to intrinsic eye muscles
Innervates levator palpebrae superioris (muscle of the upper eyelid)
III – Oculomotor
III – Oculomotor
Innervates most extrinsic eye muscles
Parasympathetic innervation to intrinsic eye muscles
Innervates levator palpebrae superioris (muscle of the upper eyelid)
Innervates intrinsic eye muscles: ciliary muscle (on lens) sphincter pupillae (iris)
III – Oculomotor
Controls extrinsic eye muscles not innervated by IV and VI
III – Oculomotor
Parasympathetic innervation to intrinsic eye muscles
III – Oculomotor
Innervates levator palpebrae superioris (muscle of the upper eyelid)
III – Oculomotor
III – Oculomotor
pupillary light response test
Both pupils should constrict when light is shined in only one eye
Mainly motor
Innervates superior oblique muscle of the eye
Only cranial nerve to arise from the posterior aspect of the brain stem
Short function: eye movement
IV – Trochlear
Innervates superior oblique muscle of the eye
IV – Trochlear
Only cranial nerve to arise from the posterior aspect of the brain stem
IV – Trochlear
The trochlea (trochle = pulley) is a pulleylike loop through which the tendon of the ___ muscle passes
superior oblique
The superior oblique moves the eyeball ____
inferiorly and laterally
Mixed
Largest of the cranial nerves
Emerges from pons isolated from other cranial nerves
Provides sensory neurons to face, head, and anterior 2/3 tongue
Motor neurons control chewing movements
Short function: mastication, facial sensation
V – Trigeminal
Provides sensory neurons to face, head, and anterior 2/3 tongue
NO TASTE, just sensation
V – Trigeminal
Motor neurons control chewing movements
V – Trigeminal
Short function: mastication, facial sensation
V – Trigeminal
Dermatome for most of the skin of face and scalp?
V – Trigeminal
Emerges from pons isolated from other cranial nerves
V – Trigeminal
The trigeminal has two roots:
smaller motor root supplying the muscles of mastication
Larger sensory root, which has three branches, which consists of:
Ophthalmic nerve
Maxillary nerve
Mandibular nerve
Small root of trigeminal supplies what?
muscles of mastication
Three branches of larger sensory root of trigeminal
Ophthalmic nerve
Maxillary nerve
Mandibular nerve
Mainly motor
Innervates lateral rectus muscle of the eye
Nerve is also called the abducent
Short function: eye movement
VI – Abducens
Innervates lateral rectus muscle of the eye
VI – Abducens
The lateral rectus muscle moves the eye laterally
VI – Abducens
___ causes abduction of the eye (movement away from the midline of the body), hence the name of the nerve that supplies it
abducens
Mixed
Somatic motor axons innervate muscles of facial expression, and stylohyoid, posterior belly of digastric, and stapedius muscles
Parasympathetic axons extend to lacrimal glands, nasal glands, and saliva-producing sublingual and submandibular glands
VII – Facial
Somatic motor axons innervate muscles of facial expression, and stylohyoid, posterior belly of digastric, and stapedius muscles
VII – Facial
CN VII (Facial) affects what muscles?
muscles of facial expression
stylohyoid
digastric (posterior portion)
stapedius
Parasympathetic axons extend to lacrimal glands, nasal glands, and saliva-producing sublingual and submandibular glands
VII – Facial
CN VIII (Facial) extends to what glands?
lacrimal
nasal
sublingual
submandibular
Short function: facial expression, taste, salivation, lacrimation
VII – Facial
Sensory axons extend from taste buds in the anterior two-thirds of the tongue (the mobile tongue)
VII – Facial
“Short” function of cranial nerve seven? (facial)
facial expression
taste
salivation
lacrimation
Mainly sensory
Formerly known as the acoustic, or auditory nerve
Vestibular branch carries impulses for equilibrium
Cochlear branch carries impulses for hearing
Short function: balance, hearing
VIII – Vestibulocochlear
Vestibular branch carries impulses for equilibrium
VIII – Vestibulocochlear
Cochlear branch carries impulses for hearing
VIII – Vestibulocochlear
Motor function of CN VIII?
“setting the tone” for the actual receptors
Mixed
Sensory axons to: posterior 1/3 of tongue for taste from taste buds, and for tactile sensation; baroreceptors in carotid sinus and chemoreceptors in carotid bodies
Motor fibers to: parotid gland
Short function: taste, salivation, innervation of pharynx
IX – Glossopharyngeal
Sensory axons to: POSTERIOR 1/3 of tongue for taste from taste buds, and for tactile SENSATION
!!!
IX – Glossopharyngeal
baroreceptors in carotid sinus and chemoreceptors in carotid bodies
IX – Glossopharyngeal
monitors changes in BP, CO2, etc.
Motor fibers to: parotid gland
IX – Glossopharyngeal
Short function: taste, salivation, innervation of pharynx
IX – Glossopharyngeal
Mixed
The longest cranial nerve
Short function: swallowing, talking, cardiac, GI tract, respiration, taste
X – Vagus
Short function: swallowing, talking, cardiac, GI tract, respiration, taste
X – Vagus
The ___ is widely distributed in the head, neck, thorax, and abdomen
vagus nerve
Sensory function in taste, touch, pain, temperature, and proprioception from the epiglottis and pharynx;
vagus nerve
monitoring of blood pressure, oxygen, and carbon dioxide
vagus nerve
Somatic motor function in swallowing, coughing, and voice production
vagus nerve
Autonomic motor function (parasympathetic) in smooth muscle contraction and relaxation of GI tract, slowing of the heart rate, and secretion of digestive fluids
vagus nerve
____ of the vagus nerves causes hypersecretion of acidic gastric fluids, which results in ulceration of the stomach wall
Hyperactivity
Mixed
Originates from both the brain stem and the spinal cord, so it is sometimes called the spinal accessory (only cranial nerve to have a spinal cord component)
Impulses to voluntary muscles used in swallowing, and to trapezius and sternocleidomastoid
Short function: pharynx & larynx muscles, neck & shoulder movement
XI – Accessory
Originates from both the brain stem and the spinal cord, so it is sometimes called the spinal accessory (only cranial nerve to have a spinal cord component)
XI – Accessory
Impulses to voluntary muscles used in swallowing, and to trapezius and sternocleidomastoid
XI – Accessory
Short function: pharynx & larynx muscles, neck & shoulder movement
XI – Accessory
CN XI sends impulses to what muscles?
Muscles used in swallowing
Trapezius
Sternocleidomastoid
Mixed
Innervates all intrinsic muscles of the tongue as well as all extrinsic tongue muscles except the palatoglossus, for movements in speech and swallowing
Short function: tongue movement
XII – Hypoglossal
Hypoglossal innervates all intrinsic and extrinsic muscles of the tongue, except for ___, for movements of speech/swallowing
palatoglossus
Palatoglossus is supplied by ___
CN X (vagus)
