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Flashcards in Intro to Cranial Nerves Deck (221):
1

What are the functional modalities of cranial neurons?

general somatic afferent (GSA), general somatic efferent (GSE), general visceral afferent (GVA), general visceral efferent (parasympathetics, GVE),special sense (SVE) such as olfaction, taste, hearing, and balance

2

What is derived from pharyngeal arches?

branchiomeric mm.

3

What is associated with pharyngeal arch 1?

Cranial nerve 5, trigeminal nerve
branchiomeric muscles- mm. mastication, tensor tympani, tensor veli palantini, mylohyoid, ant. belly digastric
skeletal derivatives- malleus, incus, sphenomandibular lig.

4

What is associated with pharyngeal arch 2?

Cranial nerve VII, facial nerve
branchiomeric mm.- mm. facial expression, stapedius, stylohyiod, posterior belly digastric
skeletal derivatives- stapes, styloid process, stylohyiod ligament, lesser horn and superior body of hyoid

5

What is associated with pharyngeal arch 3?

Cranial nerve IX, glossopharyngeal n.
branchiomeric mm- stylopharyngeus
skeletal derivatives- greater horn and inferior body of hyoid

6

What is associated with pharyngeal arch 4 and 6?

Cranial nerve X, vagus nerve
branchiomeric mm.- most palatal mm., most pharyngeal mm., all laryngeal mm.
skeletal derivatives- laryngeal cartilages

7

CN I

olfactory nerve

8

CN II

optic nerve

9

CN III

Oculomotor nerve

10

CN IV

trochlear nerve

11

CN V

trigeminal
V1- ophthalmic
V2- maxillary
V3- mandibular

12

CN VI

Abducens n.

13

CN VII

facial nerve

14

CN VIII

Vestibulocochlear nerve

15

CN IX

glossopharyngeal nerve

16

CN X

vagus nerve

17

CN XI

accessory nerve

18

CN XII

hypoglossal nerve

19

What is the function of CN 1?

olfactory does special sense of smell (olfaction)

20

What is the function of CN II?

optic- special cense vision

21

What is the function of CN III?

Oculomotor- motor of extraocular
parasympathetic- ciliary muscle and sphincter pupillae

22

What is the function of CN IV?

trochlear- motor of superior oblique (extraocular m.)

23

What is the function of CN VI?

Abducens- motor of lateral rectus

24

What is the function of CN V1?

general sensory- forehead, surface of eye, bridge of nose

25

What is the function of CN V2?

general sensory- cheek, upper lip, side of eye

26

What is the function of CN V3?

general sensory- chin, lower lip, towards temple
motor- muscles derived from pharyngeal arch number 1, mm. of mastication

27

What is the function of CN VII?

motor- muscles derived from pharyngeal arch number 2
parasympathetics- lacrimal gland, submandibular gland, sublingual gland
general sensory-external ear
special sense- taste and anterior 2/3 of the tongue

28

What is the function of CN VIII?

Vestibulocochlear n.
special sense- hearing and balance

29

What is the function of CN IX?

glossopharyngeal n.
motor- muscles derived from pharyngeal arch 3
parasympathetics- parotid gland
general sensory- pharynx, middle ear, carotid body, carotid sinus
special sense- taste to posterior tongue

30

What is the function of CN X?

motor- muscles derived from pharyngeal arches 4 and 6
parasympathetic- below the neck with parasympathetic etics
general sensory- external ear, larynx
special sense- taste at the epiglottis

31

What is the function of CN XI?

accessory n.
motor- SCM and traps

32

What is the function of CN XII?

hypoglossal n.
motor- tongue muscles

33

What is stern's rule for the word "tensor"?

CN V3= innervation

34

What is stern's rule for the word "palate"?

CN X= innervation

35

What is stern's rule for tongue/"glosso"?

CN XII= innervation

36

What nerves innervate the skeletal muscles of the orbit of the eye?

CN III, IV, VI

37

What is responsible for pupillary constriction?

Oculomotor n. CN III- parasympathetics

38

What causes lacrimation to the eye?

Facial n. (CN VII parasympathetics)

39

What causes blinking?

Ophthalmic n. (CN V1) - sensation to surface of the eye
Facial n. (CN VII)- orbicularis oculi m.
Oculomotor n. (CN III) - levator palpebrae superioris m.
Sympathetics to tarsal muscle

40

What is nerves are responsible for taste?

facial n. does ant. 2/3 of tongue
glossopharyngeal n. does post. 1/3 of tongue
vagus n. does epiglottis

41

What is the motor component of the glossopharyngeal nerve?

stylopharyngeus- elevates pharynx and larynx during swallowing and speaking

42

What do parasympathetics run with to innervate the ciliary m and constrictor pupillae m ?

Oculomotor n.
CN III

43

What do parasympathetics run with to innervate the lacrimal gland, submandibular gland, and sublingual gland?

facial nerve CN VII

44

What do parasympathetics run with to innervate the parotid gland?

glossopharyngeal nerve
CN IX

45

What do parasympathetics run with to innervate postcranial?

vagus n.
CN X

46

Which nerve is responsible for lacrimation?

facial nerve

47

Which nerve is responsible for blinking?

ophthalmic n.- sensation to the surface of the eye

48

What nerve is responsible for the levator palpebrae superioris m?

Oculomotor n.

49

What innervates the tarsal m?

sympathetics

50

What nerve is responsible for audition?

inner ear (cochlear n.)

51

What nerve and muscle is responsible for middle ear function?

mandibular n. and tensor tympani m.

52

What nerve innervates the stapedius?

facial nerve

53

What nerve innervates the tensor veli palatini m. or auditory tube function?

mandibular n.

54

What nerve is responsible for balance (inner ear)?

vestibular nerve coming off of vestibular cochlear

55

What nerve is responsible for production of nasal mucosa?

facial and trigeminal

56

What nerve is responsible for laryngeal function?

vagus n.

57

What are the muscles of mastication?

temporalis, masseter, medial and lateral pterygoids

58

What is responsible for the tongue movements?

hypoglossal n.

59

What innervates the palatoglossal m.

vagus n.

60

What is responsible for taste of the anterior 2/3 of the tongue?

facial nerve --> more specifically the chorda tympani nerve

61

What is responsible for taste of the epiglottis?

vagus nerve

62

What is responsible for salivation/salivary glands?

facial- submandibular n. and sublingual n.

63

What are the primary nerves involved in swallowing?

CN IX, CN X, CN XII

64

What is considered the true dura in the brain?

the meningeal layer- it is the layer that is continuous down the entire spinal column

65

Through what nerve is the dura pain sensitive?

intracranial sensory innervation via trigeminal n. and vagus n.

66

What is the superior sagittal sinus?

a sinus filled with venous blood where the periosteum pulled away from the meningeal layer or true dura

67

In which space is the CSF?

the subarachnoid space

68

What is a dural fold?

2 meningeal layers of true dura fused together

69

What is the purpose of the falx cerebri?

to separate the right and left hemispheres

70

What is he tentorial incisure

the triangular opening in the tentorium cerebelli through which the brainstem extends from the posterior into the middle cranial fossa

71

What is the purpose of the cerebellum tentorium?

it separates the cerebral hemispheres from the cerebellum

72

What are the dural venous sinuses in the brain?

superior sagittal sinus, inferior sagittal sinus, transvers sinus, occipital sinus, straight sinus, sigmoid sinus, superior and inferior petrosal sinuses cavernous sinus

73

Where do all of the sinuses of the brain meet?

confluence of the sinus

74

Where is the cavernous sinus in the brain and what are its contents?

Location: lateral to body of sphenoid bone (and sella turcica)
Contents:
Venous blood
Internal carotid a.
Nerves:
Oculomotor n (CN III)
Trochlear n (CN IV)
Ophthalmic n (CN V1)
Maxillary n (CN V2)
Abducens n (CV VI)

75

What are the purposes of the sinuses?

cerebral veins dump their contents into the dural venous sinuses... they penetrate the arachnoid and pass through subdural space to enter sinuses

76

subdural hematoma

commonly due to rupture of superior cerebral veins... there is an accumulation of venous blood between arachnoid and meningeal layer of the dura

77

What are the meningeal arteries embedded within?

the endocranium

78

epidural or extradural hematoma

most commonly due to rupture of the middle meningeal artery... extravasated blood accumulates between calvarium and cranial dura (periosteal layer)... fatal unless treated promptly

79

What is the intraventricular flow of CSF?

lateral ventricles --> interventricular foramina --> third ventricle --> cerebral aqueduct --> fourth ventricle --> central canal of spinal cord

80

How does the CSF exit the ventricular system?

median aperature (foramen of Magendie) --> cisterna magna
lateral aperatures --> pontine cistern

81

How does cerebral spinal fluid absorb back into the dural venous system?

via the arachnoid villi

82

hydrocephalus

aqueductal stenosis- CSF obstruction at cerebral aqueduct... lateral and 3rd ventricles dilate

83

What is the non neural basis of visual acuity?

ability to discriminate between adjacent points in an image; non neural is based on the size of image projected on the retina; focus of image by refractive media to the retina

84

What is the neural basis on visual acuity?

density of photoreceptors in the fovea versus peripheral retina

85

What are the functions of the eye?

detect light, focus images clearly, compress information

86

How does the eye detect light?

the central retina (fovea) does details and color... the peripheral retina emphasizes motion and contrast

87

How does the eye focus on images clearly on the retina?

most of the refraction occurs at the air-cornea interface, there is also an adjustable lens (accommodation) for near objects

88

sclera

sclera is the fibrous layer of the eye... it is continuous with the dura mater (also considered the white of the eye)

89

conjunctiva

epithelium lining of inner surface of eyelids and anterior surface of sclera (not part of the fibrous layer)

90

Iris

dilator pupillae m.
sphincter pupillae m.

91

ciliary body

ciliary m.; zonule fibers (suspensory ligaments); ciliary processes which form the aqueous humor

92

choroid

choroidal vessels

93

What makes up the uveal tract which is the second layer of the eye?

iris, ciliary body, choroid

94

What makes up the innermost layer of the eye?

retina- part of the eye that is light responsive

95

What makes up the posterior segment of the eye?

vitreous humor, retina, optic nerve, choroid

96

What divides the anterior and posterior segment of the eye?

anterior border of the vitreous humor

97

What part of the eye is affected by light?

peripheral retina and vision, the fovea and central vision

98

What is the part of the retina that in not neural?

retinal pigment epithelium (RPE)

99

What is the neural signal path for phototransduction?

through the ganglion cells - Optic nerve

100

What are the purpose of the photoreceptors in the retina?

they are mostly made up of rods and transform light stimulus into a electrical signal

101

How do the RPE support photoreceptor function?

by reducing light scatter

102

How does the peripheral retina deal with motion and contrast?

there are many photoreceptors converging to fewer ganglion cells

103

What is the purpose of the fovea?

it has the highest density of cone photoreceptors and the least distortion of light

104

foveation

movements of eye brings light to focus on the fovea

105

How does the fovea offer maximum discrimination, highest visual acuity, and detail?

there is one photoreceptor for 1 bipolar for 1 ganglion

106

What artery supplies most of the neural retina (except the photoreceptors)?

the central retinal artery which is a branch of the ophthalmic artery... this arterial supply is absent at the fovea

107

What artery supplies outer 1/3 of retina ie the RPE and photoreceptors?

choroid

108

What is the visual consequence of macular degeneration?

central vision will be knocked out... commonly due to cholesterol deposits between the RPE and choroid

109

What occurs with a retinal detachment?

flashes of light, specks floating, curtain dropping... this typically occurs between the neural photoreceptors and the RPE

110

Optic disc

axons of ganglion cells (optic n.) and retinal vessels... these lack photoreceptors and the optic disc is considered the blind spot

111

What kind of information does the optic nerve carry?

information about the entire visual field of that eye

112

What would happen with a right optic nerve lesion?

complete right eye blindness = right monocular vision loss

113

What is the image that is displayed on your retina?

inverted (vertically)
revered (horizontally)

114

Where does the temporal retina receive visual information from?

the medial part of the eyes visual field (nasal hemifield)

115

Where does the nasal retina receive visual information from?

the lateral part of our eyes visual field (temporal hemifield)

116

Where do axons from the temporal retina project?

the ipsilateral optic tract

117

Where do axons from the nasal retina project?

they cross at the optic chiasm and project to the contralateral optic tract

118

What kind of information does the optic tract carry?

information about the contralateral visual field

119

right optic tract lesion

left homonymous hemianopia- left visual field of eyes is out

120

hemianopia

half visual field

121

homonymous

same side

122

optic chiasm lesion

Bitemporal hemianopia... lateral fields of both eyes is out... tunnel vision

123

saccades

right and left eye work in a coordinated fashion... a simultaneous movement of both eyes

124

What are the functions of the superior rectus?

elevates and intorts

125

What are the functions of the inferior rectus?

depression and extorsion

126

What are the functions of the superior oblique?

depressed and intorts

127

What are the functions of the inferior oblique?

elevation and extorsion

128

What are the muscles that intort the eye?

superior oblique and superior rectus

129

What are the muscles that extort the eye?

inferior oblique and inferior rectus

130

What two muscles must you pair together if you just want to look up or down?

and intort muscle and an extort muscle to balance eachother out

131

pursuit

allows eye to closely follow a moving object

132

trochlear nerve

innervates the superior oblique muscle which depresses and intorts

133

abducens nerve

innervates the lateral rectus muscle which acts to abduct the eye

134

Oculomotor nerve

superior rectus, inferior rectus, medial rectus, inferior oblique, levator palpebrae superioris
also parasympathetics to the sphincter pupillae m. and ciliary muscle

135

orbicularis oculi m.

depresses the eyelid and is innervated by the facial nerve

136

levator palpebrae superioris

elevates the eyelid and is innervated by the Oculomotor

137

tarsal m.

assists in elevating the upper lid... innervated by sympathetics

138

what is the purpose of blinking?

to spread tears across the surface of the eye, cornea and conjunctiva

139

lacrimal gland

secretes into the eye because of innervation done by the facial nerve

140

what is the excretory process of the lacrimal apparatus?

lacrimal puncta --> lacrimal canaliculi --> lacrimal sac --> nasolacrimal duct --> middle meatus of the nasal cavity

141

How do the parasympathetics innervate the lacrimal gland?

preganglionic via the facial nerve --> synapse at the pterygopalatine ganglion --> postganglionic they travel on the trigeminal nerve

142

What is the sensory limb of the coronary blink reflex?

there is irritant to the cornea/ conjunctiva which sends nerve signals via the nascociliary n. a branch from ophthalmic n.

143

What is the motor limb of the sensory light reflex?

the nerve signals are sent to the eye via the facial nerve to the orbicularis oculi m.

144

strabismus

misaligned visual axes (due to a neural/motor imbalance usually

145

diplopia

double vision

146

if a patient is unable to abduct the right eye what kind of lesion is it?

abducens lesion on the right side

147

What are the consequences of a unilateral lesion of R. abducens N?

the lateral rectus muscle is paralyzed
diplopia occurs due to unopposed medial rectus m.
face also turns to side of lesion to restore binocular vision

148

upper lid ptosis

inability to retract the upper eyelid (eyelid is depressed)

149

What are the characteristics of a unilateral lesion of a R. Oculomotor n. lesion?

eyelid is depressed and the eye is turned laterally and slightly down... there may also be mydriasis which is a dilated eye

150

Oculomotor palsy

upper lid ptosis
extropic globe (down and out)
strabismus and diplopia
mydriasis (dilated pupil)
lack of accommodation

151

Trochlear nerve palsy

extorted eye and impaired depression because there is paralysis of the superior oblique

152

unilateral lesion of the r. trochlear n.?

extorted right eye results in diplopia
head tilt to unaffected side (point chin to lesion)
intort L. eye to restore binocular vision

153

horner's syndrome

interruption of sympathetic outflow: upper lid ptosis (tarsal m. paralysis)
miosis (constricted pupil)
facial flushing (vaso dilation)
Anhidrosis (sweat gland denervation)

154

focusing on a near object triad

. Convergence of optic axes (somatic motor)
Oculomotor nucleus signals both medial rectus mm. to contract (disconjugate eye movements) to eliminate diplopia
2. Lens Accommodation (parasympathetic)
Oculomotor efferent axons from Edinger-Westphal nucleus signal ciliary m. to contract to eliminate blur
Reduce tension of suspensory ligaments of lens
Curvature of lens increases (higher refractive index)
3. Pupillary constriction (parasympathetic)
Oculomotor efferent axons from Edinger-Westphal nucleus signal sphincter pupillae m. to contract
Small pupil sharpens image on retina and reduces light intensity

155

What is the muscle that lies in the superficial cervical fascia?

platysma m.

156

What are the muscles that lie in the deep cervical fascia the investing layer?

SCM m. and the trapezius m.

157

What are the anterior and posterior triangles of the neck subdivided by?

suprahyoid and infrahyoid m.

158

What is included in the vertebral compartment?

includes CVs and mm. for neck movement and stability... is also surrounded by vertebral fascia

159

What are the cutaneous nerves for the cervical plexus?

transverse cervical n.
supraclavicular n.
greater occipital nerve
lesser occipital nerve

160

what is the motor innervations from the cervical plexus?

mm. of neck, infrahyoid muscle, and diaphragm

161

What is in the vascular compartment of the deep cervical fascia?

carotid aa., internal jugular v, vagus nerve... which are all surrounded by the carotid sheath

162

What are the layers within the visceral compartment of the deep cervical fascia?

endocrine layer- thyroid gland, parathyroid gland
respiratory layer- larynx, and trachea
alimentary layer- pharynx: nasopharynx, oropharynx, laryngopharynx and the esophagus

163

What does the deep neck spaces consist of?

buccopharyngeal fascia, alar fascia, prevertebral fascia

164

retropharyngeal space

between the buccopharyngeal fascia and the alar fascia... at the base of the skull to superior mediastinum

165

danger space of the neck

between the alar fascia and the prevertebral fascia... base of skill to diaphragm

166

What encloses and protects the middle and internal ear?

temporal bone

167

where does conductive hearing loss happen?

middle and external ear

168

Where does sensorineural hearing loss happen?

inner ear

169

What innervates the superior external acoustic meatus?

auriculotemporal nerve from the mandibular division of trigeminal

170

What innervated the inferior external acoustic meatus?

vagus nerve

171

What innervates most of the outer ear?

greater auricular n. (C2-C3)

172

What is the innervation of the auricle?

auriculotemporal n.
vagus n.
facial n.
two cervical nerves: greater auricular n. and the lesser occipital n.

173

What is the innervation of the tympanic membrane in the lateral surface?

superiorly it is innervated by the auriculotemporal n.
inferiorly it is innervated by the vagus

174

What makes up the inner ear?

tympanic cavity
ear ossicles: malleus, incus, stapes (lateral to medial)

175

What are the muscles in the middle ear?

tensor tympani innervated by mandibular nerve
stapedius innervated by facial nerve

176

What are the walls of the middle ear?

laterally it is the tympanic membrane; medially there is the promontory and oval and round windows

177

What is the roof of the middle ear?

tegman tympani

178

What is the flood of the middle ear?

jugular bulb

179

What is the posterior wall of the middle ear?

mastoid air cells

180

what is the anterior wall of the middle ear?

pharyngotympanic, Eustachian and auditory tube

181

What is the function of the Eustachian tube?

ventilations and pressure regulation; by the tensor veli palatini m.

182

In cleft palate patients where would there be a dysfunction?

in the tensor veli palatini muscle

183

What is the function of the tensor veli palatini?

it actively widens the lumen

184

What is the protection function of the Eustachian tube?

dampens loud sounds from the nasopharynx; active against reflux of nasopharyngeal secretions

185

What is the drainage and clearance function of the Eustachian tube?

mucociliary transport system

186

What is the function of the glossopharyngeal n. in the ear?

sensory via the tympanic nerve plexus... tympanic cavity, tympanic membrane, mastoid air cells and the auditory tube

187

Where does the chorda tympani nerve pass through?

pas between the malleus and incus

188

conductive hearing loss?

external ear... cerumen impaction
middle ear is otitis media

189

what is the primary cause of otitis media?

dysfunction of the Eustachian tube

190

What makes up the inner ear?

semicircular canal, vestibule, cochlea

191

What is the membranous labyrinth of the inner ear?

cochlear duct in cochlea, utricle and saccule in the vestibule, semicircular duct in the semicircular canal

192

What makes up the neurosensory epithelium?

organ od corti on basilar membrane in the cochlea, macule in the vestibule, the crista ampullaris in the semicircular canal

193

How does the transmission and transduction of sound work?

air pressure waves and transduced to mechanical energy that is transduced to fluid movement in the inner ear

194

basilar membrane

determines the frequency of the sound that we hear

195

What is the first sign of compression of the Oculomotor nerve?

slowness of the pupillary response to light

196

What stimulates the organ of Corti?

the basilar membrane

197

Where does the ability to hear high frequencies occur?

at the base of the basilar membrane

198

Where does the ability to hear low frequencies occur?

the apex of the basilar membrane

199

impedence mismatch

When there is low air impedence and high fluid impedence you lose 99.9% of sound energy

200

How are incisions to release pus from a middle ear abscess made?

postero-inferiorly because the superior half is much more vasculature

201

What are the solutions to impedence mismatch?

external ear amplification
middle ear amplification- because of large surface area of the tympanic membrane going to the footplate of the stapes

202

What overlays the oval window?

the stapes

203

What is the solution to localization of sound?

binaural comparisons

204

What helps to solve the problem of loud noises?

there is middle ear dampening- done by the tensor tympani muscle innervated by mandibular nerve also the stapedius muscle which is innervated by the nerve to the stapedius off of the facial nerve

205

What is the acoustic (Stapedial reflex)?

the afferent limb in done by the cochlear n. (bilaterally) and the efferent limb is done by the facial n. (direct and consensual)

206

What do we do to fix the issue of complexity of sounds?

the left ear hears music and goes to the right hemisphere... the right ear hears spoken communication and goes to the left hemisphere

207

What helps us control our balance?

vestibular apparatus- made up of the vestibule and semicircular canals and the saccule and utricle and semicircular ducts

208

What is the purpose of the saccule and utricle?

they sense gravity and linear movement or acceleration

209

what is the purpose of the semicircular ducts?

rotational movement (angular acceleration)

210

What comprises the lateral nasal wall?

inferior middle and superior turbinates

211

What gives sensory innervation to the nasal cavity?

trigeminal nerve ophthalmic and maxillary nerves off of the trigeminal

212

Where do autonomics travel to access the nasal mucosa?

sympathetics and parasympathetics travel on the trigeminal nn.

213

What is the airflow resistance between the two nasal cavities controlled by?

sympathetics... the engorgement by blood of the anterior ends of the inferior nasal turbinates

214

Where do all of the arteries of the nasal septum converge?

kiesselbach area- branch of Sphenopalantine artery and posterior and anterior ethmoidal arteries... this causes anastomosis between the ECA and the ICA

215

What are the paranasal sinuses?

frontal sinus, ethmoid sinus, nasal cavity, maxillary sinus

216

where does the sphenoidal sinus drain?

sphenoidal recess

217

What drains into the superior meatus?

posterior ethmoidal cells

218

What all drains into the middle meatus?

anterior and middle ethmoidal cells through the ethmoidal bulla and the frontal and maxillary sinus through the semilunar hiatus

219

What drains into the inferior meatus?

nasolacrimal duct

220

Which paranasal sinus has the most difficulty draining?

maxillary sinus

221

Why does the maxillary sinus drain poorly?

because its ostium is located superiorly... dental pain may be indicative of maxillary sinus