Anatomy Lab 4: Pre-Lab
what may lesions to the vagus nerve cause?
-lesions of the vagus nerve can cause a hoarse voice and dysphagia (difficulty swallowing)
types of cranial nerves
-special sensory (3) -voluntary motor (5) -trigeminal -facial -glossopharyngeal -vagus
7. The abducens nerve is cranial nerve _______. Enter the correct Roman numeral.
VI -innervates one extraocular eye muscle which functions to abduct the eye, i.e. look laterally.
23. A patient presents with a hoarse voice. On examination, they demonstrate a sagging palate on the left. Which cranial nerve must you consider? Cranial nerve ______ (#), the _______ nerve, on the _______ side. (3 answers; separate with one space each)
X vagus left **a lesion of the left CN X, vagus nerve, will result in a hoarse voice and dysphagia
3. The accessory nerve is cranial nerve _______. Enter the correct Roman numeral.
XI -the accessory nerve is CN XI -it controls the trapezius and SCM muscles -its lesion interferes with shoulder shrug and turning the head to the contralateral (opposite) side
glossopharyngeal and vagus nerves: similarities and difference
-both carry parasympathetic preganglionic fibres -both carry voluntary motor fibres -both carry general sensory fibres **they differ in their distributions
the facial nerve (CN VII)
-controls muscles of facial expression **these are the muscles that allow us to close our eyes and mouth, smile or show our teeth, and raise our eyebrows -this nerve also receives taste sensation from the anterior 2/3 of the tongue
muscles of facial expression
-distinct from the muscles of mastication, which are controlled by the mandibular division of the trigeminal nerve (V3)
trigeminal nerve (CN V)
-general sensory nerve -trigeminal = triplets (bc this CN consists of 3 major subdivisions) -sensory to the skin of the face
what types of fibres does glossopharyngeal nerve contain?
-its general sensory distribution extends throughout the oropharynx and into the Eustachian (pharyngotympanic) tube -it carries parasympathetic fibres destined to control secretion of the parotid gland
there is a pattern to parasympathetic outflow...
-nerves arising from the CNS deliver parasympathetic preganglionic outflow to their associated ganglia in the PNS **these ganglia contain parasympathetic postganglionic neuronal cell bodies -some parasympathetic ganglia, called terminal ganglia, are located close to the target tissue -other parasympathetic ganglia, called intramural ganglia, are located in the wall of the target tissue
what type of fibres does facial nerve carry?
-the facial nerve also carries parasympathetic preganglionic fibres destined to control secretion of the lacrimal, submandibular and sublingual glands, as well as the mucosa of the nasal and oral cavities -it also carries general sensory fibres from portions of the external ear
how many cranial nerves are there?
12 pairs
parasympathetics carried by cranial nerves
4 cranial nerves contain parasympathetic preganglionic fibres in addition to other functional groups of axons: -the oculomotor (CN III) -facial (CN VII) -glossopharyngeal (CN IX) -vagus (CN X) nerves. **targets of the parasympathetic fibres in cranial nerves IlI, VII, and IX are in the face **targets of the parasympathetic fibres in cranial nerve X are in the thorax and abdomen
4. The olfactory nerve is cranial nerve _______. Enter the correct Roman numeral.
I -transmits sensory information from olfactory receptors to CNS, which are then perceived as smell. -lesion of CN I can result in anosmia
19. You walk into your granny's kitchen and begin to salivate, as she's been baking cookies all day. Which cranial nerve is responsible for the sensory arm of this reflex? Cranial nerve ______ (#), the _____ nerve. (2 answers; separate with one space)
I; olfactory **as you walk into the kitchen, you smell the odor of freshly baked cookie, then you start to salivate. CN I, the olfactory nerve, transmits odorant sensory signal
5. The optic nerve is cranial nerve _______. Enter the correct Roman numeral.
II -it transmits visual info gathered by photoreceptors in the retina
2. The oculomotor nerve is cranial nerve _______. Enter the correct Roman numeral.
III -the oculomotor nerve, CN IlI, controls extraocular eye muscles -lesion to the nerve may result in a misaligned eye (strabismus)
13. Which cranial nerves contain parasympathetic preganglionic fibres? a) trochlear, CN IV b) oculomotor, CN IlI c) glossopharyngeal, CN IX d) abducens, CN VI e) vagus, CN X f) hypoglossal, CN XI g) trigeminal, CN V h) facial, CN VII
III, VII, IX and X
5. The trochlear nerve is cranial nerve _______. Enter the correct Roman numeral.
IV -controls oen extraocular eye muscle which functions to depress the adducted eye
17. Gagging occurs reflexively in response to the application of touch to the back of the pharynx. Which cranial nerve is responsible for the sensory arm of this reflex? Cranial nerve ______ (#), the _______ nerve (2 answers; separate with one space)
IX; glossopharyngeal **responsible for the sensory arm of the gag reflex
21. Which cranial nerve would be associated with a loss of taste on the posterior 1/3 of the right side of the tongue? Cranial nerve ______ (#), the _____ nerve, on the _____ side (3 answers; separate with one space each)
IX; glossopharyngeal; right **CN IX, the glossopharyngeal nerve, is responsible for taste and general sensory innervation of the posterior 1/3 of the ipsilateral tongue -Lost of taste in this region on the right side indicates a lesion to CN IX on the right side
8. The trigeminal nerve is cranial nerve _______. Enter the correct Roman numeral.
V -provides sensory innervation to the skin of face -it contains three subdivisions: ophthalmic (V1), maxillary (V2), mandibular (V3) => the mandibular division also contains motor fibres which control the muscles of mastication
18. The eyes blink reflexively in response to touch. Which cranial nerve is responsible for the sensory arm of this reflex? Cranial nerve ____ (#), the _____ nerve. (2 answers; separate with one space)
V; trigeminal **CN V, the trigeminal nerve, is responsible for general sensory innervation of the face **the ophthalmic division provide sensory innervation to the forehead, upper eyelid, the contents of the orbit and the tip of the nose
1. the facial nerve is cranial nerve ________. Enter the correct Roman numeral.
VII -the facial nerve, cranial nerve VII, controls the muscles of facial expression -this nerve also carries parasympathetic preganglionic and taste fibres
24. The eyes blink reflexively in response to touch. Which cranial nerve is responsible for the motor arm of this reflex? Cranial nerve ______ (#), the _______ nerve (2 answers; separate with one space)
VII facial **CN VII controls the muscles of facial expression -these muscles allow us to close our eyes and mouth, etc.
26. You put your granny's cookie in your mouth, but can't taste it with the anterior 2/3 of your tongue on the left. Which cranial nerve do you suspect is not functioning properly? Cranial nerve ______ (#), the _______ nerve, on the _______ side. (3 answers; separate with one space)
VII facial left **the facial nerve, CN VII, receives taste sensation from the anterior 2/3 of the tongue on the ipsilateral side (in this case, left)
6. The vestibulocochlear nerve is cranial nerve _______. Enter the correct Roman numeral.
VIII -this CN is responsible for our sense of balance and our hearing -it gathers info from receptors in the inner ear
22. A patient presents complaining of imbalance, falling to the right, and difficulty hearing while speaking on the phone with it up against her right ear. Which cranial nerve do you suspect might be involved? Cranial nerve _____ (x), the _______ nerve on the ______ side (3 answers; separate with one space each)
VIII; vestibulocochlear; right **the vestibulocochlear nerve, CN VIII, is involved in the special sensations of hearing and balance **lesion of the nerve will cause ipsilateral deficits, a right side lesion will cause the patient to fall to the right and experience hearing loss in the right ear
9. The vagus nerve is cranial nerve _______. Enter the correct Roman numeral.
X -it is a mixed nerve -it carries parasympathetic fibres that supply the thoracic and most of the abdominal viscera, it is sensory to the external auditory canal, the laryngopharynx and larynx, and motor to muscles of the pharynx (swallow) and larynx (speech)
20. Gagging occurs reflexively in response to the application of touch to the back of the pharynx. Which cranial nerve is responsible for the sensory arm of this reflex? Cranial nerve ______ (#), the _______ nerve (2 answers; separate with one space)
X; vagus nerve **CN X, the vagus nerve, is responsible for the motor arm of the reflex **Vagus nerve is a mixed nerve, it contain motor fibres which control muscles of pharynx and larynx.
16. On protrusion, the patient's tongue points to the left. Which cranial nerve lesion must you consider? Cranial nerve _____ (#), the _______ nerve, on the ________ side (3 answers; separate with one space each)
XII; hypoglossal; left **a lesion of the hypoglossal nerve, CN XII, paralyzes the ipsilateral tongue -because the non-paralyzed side dominates, on protrusion the tongue will point towards the weakened side
what does a lesion in the abducens, trochlear, oculomotor nerve cause?
a lesion of any one of these nerves causes the affected eye to be misaligned (strabismus), and eye movements in certain directions to be limited
what does a lesion in the optic nerve cause?
a visual field deficit
14. Which cranial nerves are exclusively motor to skeletal muscle? a) trochlear, CN IV b) trigeminal, CN V c) accessory, CN XI d) hypoglossal, CN XII e) oculomotor, CN III f) facial, CN VII g) vagus, CN X h) abducens, CN VI
a) trochlear, CN IV c) accessory, CN XI d) hypoglossal, CN XII h) abducens, CN VI **although the oculomotor (CN 111) contains somatic motor fibres, it also contains parasympathetic fibres (so not exclusively motor)
what's the function of the abducens nerve?
abducts the eye
what does a lesion in the olfactory nerve cause?
anosmia (loss of smell)
testing the facial nerve
ask pt to raise their eyebrows and show their teeth **with a lesion of the facial nerve, only one side of their face moves
12. Which cranial nerve convey special senses? a) facial, CN VII b) olfactory, CN I c) trigeminal, CN V d) oculomotor, CN III e) vestibulocochlear, CN VIII f) trochlear, CN IV g) optic, CN II h) vagus, CN X
b) olfactory, CN I e) vestibulocochlear, CN VIII g) optic, CN II **they are cranial nerves that convey smell, vision, balance and hearing respectively
a) ophthalmic (V1) division of trigeminal nerve
branches supply general sensory fibres to the: -forehead -upper eyelid -contents of the orbit and the tip of the nose (including portions of the nasal septum) **green in pic
b) maxillary (V2) division of trigeminal nerve
branches supply sensory fibres to the: -skin of the lower eyelid -side of the nose (both externally and internally) -nasal septum -upper cheek -temple -maxillary teeth -palate -upper lip **orange in pic
c) mandibular (V3) division of trigeminal nerve
branches supply sensory fibres to the: -skin anterior to the ear -over the lower cheek -jaw -mandibular teeth -floor of the mouth -lower lip -chin **this division is also motor to the muscles of mastication **blue in pic
how do the postganglionic axons arising from the terminal ganglia associated with the oculomotor, facial and glossopharyngeal nerves reach their targets?
by joining a branch of the trigeminal nerve
the abducens, trochlear, oculomotor nerve:
control extraocular eye muscles (= the voluntary muscles that position the eye in the orbit)
what's the function of the oculomotor nerve?
controls all over eye movements **also carries parasympathetic preganglionic axons that control smooth muscle in the eye, the sphincter pupillae => parasympathetic input causes pupillary constriction
what's the function of the accessory nerve?
controls the trapezius (shoulder shrug) and sternocleidomastoid (SCM; turning the head to the contralateral side) muscles
cranial nerve II (optic nerve)
conveys information gathered from photoreceptors in the retina, which we perceive as vision
cranial nerve VIII (vestibulocochlear nerve)
conveys information gathered from receptors in the inner ear that monitor i) balance and ii) sound energy which we perceive as hearing
cranial nerve I (olfactory nerve)
conveys information gathered from receptors in the nasal epithelium that respond to odorant molecules in inspired air, which we perceive as smell
what are the 3 special sensory cranial nerves?
cranial nerve I (olfactory nerve) cranial nerve II (optic nerve) cranial nerve VIII (vestibulocochlear nerve)
what are the 5 voluntary motor cranial nerves?
cranial nerve III (oculomotor) cranial nerve IV (trochlear) cranial nerve VI (abducens) cranial nerve XI (accessory nerve) cranial nerve XII (hypoglossal nerve)
25. You walk into your granny's kitchen and begin to salivate, as she's been baking cookies all day. Which cranial nerves are responsible for the motor arm of this reflex? Choose all that apply. cranial nerve V, the trigeminal nerve cranial nerve VII, the facial nerve cranial nerve IX, the glossopharyngeal nerve cranial nerve X, the vagus nerve cranial nerve XII, the hypoglossal nerve.
cranial nerve VII, the facial nerve cranial nerve IX, the glossopharyngeal nerve **secretion from salivary glands, the sublingual, submandibular and parotid glands, are controlled by parasympathetic fibres from CN VII and CN IX.
what other nerves have small areas of general sensory responsibility?
cranial nerves VII, IX, and X **they are largely associated with touch to the external ear and ear canal (VII and X) and portions of the pharynx and larynx (IX and X)
11. Which cranial nerves control the position of the eye in the orbit? a) facial, CN VII b) glossopharyngeal, CN IX c) trigeminal, CN V d) oculomotor, CN III e) abducens, CN VI f) trochlear, CN IV g) optic, CN II h) vagus, CN X
d) oculomotor, CN III e) abducens, CN VI f) trochlear, CN IV **they are all responsible for controlling extraocular eye muscles, muscles which position the eye in the orbit
15. Which one cranial nerve is general sensory to the face AND controls the muscles of mastication? a) vagus, CN X b) trochlear, CN IV c) hypoglossal, CN XII d) trigeminal, CN V e) abducens, CN VI f) oculomotor, CN IlI g) accessory facial, CN VII
d) trigeminal, CN V **the trigeminal nerve (CN V) provides general sensation to the face -one of its three divisions, the mandibular division, contain motor fibres that control muscles of mastication.
what's the function of the trochlear nerve?
depresses the adducted eye
what would a lesion in the facial nerve cause?
if the facial nerve is lesioned, the ipsilateral face is weakened or paralyzed, and these movements cannot be performed
what may lesions in the vestibulocochlear nerve cause?
imbalance and hearing loss
what would a lesion of the accessory nerve cause?
lesion of this nerve weakens or abolishes the movements of the trapezius and SCM muscles
cochlear division of vestibulocochlear nerve
monitors the cochlea, our sense organ of hearing
vestibular division of vestibulocochlear nerve
monitors the vestibular apparatus, which senses our position in, and movement through, space
what's the function of the hypoglossal nerve?
moves the tongue (hypo = inferior; glossus = tongue)
what does a lesion of the oculomotor nerve SPECIFICALLY cause?
mydriasis (= pupil is large) **this makes sense bc the pupil size is normally determined by a balance between parasympathetic input to the constrictor pupillae muscle and sympathetic input to the dilator pupillae muscle **with a lesion of CN III (oculomotor), in the absence of the parasympathetic input to the pupil, sympathetic input is unopposed, and the pupil is dilated
do cranial nerves cross the midline?
no! like spinal nerves, cranial nerves never cross the midline, but always innervate targets ipsilaterally (= on same side)
are these five nerves purely voluntary motor?
not exactly, this is a minor exaggeration **one of these 5 nerves carries parasympathetic (involuntary) outflow as well as voluntary motor output, and so is NOT exclusively voluntary motor
where are the most reliable places to test for sensory deficits of the trigeminal nerve subdivisions?
on the forehead, cheek, and jaw, in a vertical line with the eye
what are the 3 major subdivisions of the trigeminal nerve?
ophthalmic (V1) maxillary (V2) mandibular (V3)
what would a lesion of the hypoglossal nerve cause?
paralysis of the ipsilateral tongue **the tongue is composed of two paired groups of muscles, each innervated by the ipsilateral hypoglossal nerve **lesion of one of the hypoglossal nerves paralyzes the ipsilateral group of muscles -on attempted protrusion of the tongue, the non-paralyzed side dominates and pushed the tongue toward the weakened side
glossopharyngeal nerve (CN IX)
receives taste and general sensory fibres from the posterior 1/3 of the tongue **its name reflects distribution (tongue/glossus and pharynx)
generally, what would a lesion of a subdivision of the trigeminal nerve cause?
sensory deficits in a well-defined pattern **this is illustrated in the pic -in some lesions, the patient might experience a lack of sensation and in others the patient might experience pain -in either case, the distribution of the sensory deficit corresponds to that of a specific trigeminal nerve subdivision or subdivisions, depending on the location of the lesion
cranial nerves vs. spinal nerves
spinal nerves -recall: peripheral nerves that arise from spinal nerves to innervate the body wall and limbs contain specific functional subtypes of axons -these nerves contain: • somatic motor axons that innervate skeletal muscle fibres in the body wall and limbs, • general sensory axons that monitor the body wall and limbs, and • sympathetic postganglionic axons that innervate vascular smooth muscle, arrector pili muscle and glands. **spinal nerves that arise from S2, 3 & 4 contain parasympathetic preganglionic fibres => these fibres do not contribute to the innervation of the body wall and limbs, however, but exclusively to the innervation of abdominal and pelvic viscera cranial nerves -can be purely motor or purely sensory, or mixed -four cranial nerves contain parasympathetic preganglionic axons destined to innervate smooth muscle and glands of the face, thorax and abdomen -some cranial nerves provide sensory input from special sense organs, providing us with vision, smell, hearing and balance senses
what do the voluntary motor cranial nerves innervate?
striated muscle
the parasympathetic ganglia associated with the oculomotor, facial and glossopharyngeal nerves:
terminal ganglia **so they are close to, but not in the target tissue -this means that the postganglionic parasympathetic fibres that arise from these ganglia must travel with another nerve to the target tissue
muscles of mastication:
these muscles move the jaw, allowing us to chew
vagus nerve (CN X)
vagus = wanderer in Latin (vagus nerve wanders through neck, thorax and abdomen) -carries parasympathetic fibres destined to supply thoracic and most of the abdominal viscera -it is general sensory to portions of the external auditory canal, to the laryngopharynx and larynx -it is motor to the muscles of the pharynx (swallowing) and larynx (speech)
what would a lesion of the motor branches of V3 cause?
weakness in the muscles that move the jaw **the jaw on attempted protrusion deviates toward the weakened side