UNIT 5: Tongue + Hypoglossal Nerve Flashcards

1
Q

what is considered a muscular hydrostat

A

tongue

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2
Q

what is a muscular hydrostat

A

a fluid filled incompressible epithelial bag - the muscles serve as the fluid

a constant volume sys

any reduction in volume in one part is associated w an equivalent inc in another part

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3
Q

what are the two anatomical divisions of the tongue

A

oral tongue

pharyngeal tongue

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4
Q

oral tongue includes

A

anterior 2/3 w/i oral cavity (tongue dorsum aka superior surface)
tip, blade, front, back

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5
Q

pharyngeal tongue includes

A

posterior 1/3 aka tongue base
w/i oropharynx

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6
Q

what are the general features of the anterior 2/3 of the tongue? midline depression?

A

thick rough, epithelial covering

midline depression = longitudinal sulcus

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7
Q

4 types of papillae on ant 2/3 of tongue

A

fungiform
filiform
folliate (simple)
vallate

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8
Q

papillae

A

microscopic projections

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9
Q

fungiform papillae are …. and contain …

A

mushroom shaped paillae
contain taste buds

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10
Q

where do you find fungiform papillae

A

scattered over tongue dorsum and sides

predominant on tip of tongue

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11
Q

fungiform papillae are innervated by

A

chorda tympani of CN VII

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12
Q

which type of papillae is most numerous

A

filiform papillae

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13
Q

describe filiform papillae, do they have taste buds? purpose?

A

very small, sharp pointed projections on tongue dorsum

no taste buds, used to grip food

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14
Q

what type of paillae is highly dev in cats?

A

filiform

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15
Q

which papillae accounts for the rough texture of the tongue dorsum?

A

filiform

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16
Q

how are filiform papillae arranged?

A

in parallel rows

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17
Q

describe foliate papillae

A

variable in humans

mucosal folds present on the lateral aspects of the tongue, anterior to the palatoglossal arch

aka simple papillae

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18
Q

what are foliate papillae covered by

A

epithelium containing taste receptors

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19
Q

which are the largest papillae

A

vallate

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20
Q

how are vallate paillae arranged? what shape are they?

A

7-12 arranged in posteriorly pointing arrowhead

cylinder-shape surrounded by a moat w taste buds on the cylinder and in the wall of the moat

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21
Q

what division do the vallate papillae form?

A

division bw anterior 2/3 and posterior 1/3 of tongue

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22
Q

vallate papillae are innervated by

A

CN XI (glosso)

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23
Q

describe the surface of the pharyngeal tongue (post 1/3)

A

smooth, thin, nodular covering due to presence of lingual tonsils in underlying submucosa

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24
Q

terminal sulcus is

A

a groove on the pharyngeal tongue that is just posterior to circumvallate papillae

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25
Q

foramen cecum is a

A

small pit w/i the terminal sulcus on the pharyngeal tongue - marks the embryological origin of the thyroid gland

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26
Q

median and lateral glossoepiglottic folds on the pharyngeal tongue form the

A

valleculae at junction w epi

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27
Q

describe the ventral and inferolateral tongue

A

thin, smooth mucous membrane

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28
Q

lingual frenulum is

A

a fold of mucosa that attaches underside of tongue to floor of mouth

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29
Q

on either side of the lingual frenulum you will see

A

lingual veins seen thru thin mucosa

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30
Q

sublingual papilla is

A

opening of duct of submandibular salivary gland (L and R on either side of mouth)

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31
Q

sublingual folds of mucosa overlie the ______, with openings along the

A

sublingual salivary glands, w openings along the sublingual fold

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32
Q

5 basic taste sensations

A

salty
sweet
sour
bitter
umami

33
Q

current hypothesis of how taste is mapped is

A

each papilla contains receptors for each taste sensation

34
Q

which areas that send taste signals are innervated by CN IX?

A

posterior 1/3
tastes from soft palate and lingual surface of epi

35
Q

what CN innervated anterior 2/3 of the tongue?

A

chorda tympani of CN VII

36
Q

Taste from laryngeal surface of epi and larynx is supplied by

A

CN X

37
Q

the gustatory nucleus is in

A

the NTS of the medulla

38
Q

the gustatory cortex is in the

A

lateral cortex, insula

39
Q

complex tastes also involve participation of the

A

olfactory nerve CN I

40
Q

so what 4 CNs are involved in taste?

A

CN IX, CN X, CN VII, CN I

41
Q

all muscles of the tongue are ____, with the two sides partially separated by the _____

A

bilateral
median septum

42
Q

median septum is

A

a fibrous partition that runs from tongue tip to hyoid bone (doesn’t reach surface of the tongue)

43
Q

intrinsic muscles of the tongue are …… and are responsible for

A

contained in the hydrostat, arranged at right angles

responsible for shape

44
Q

extrinsic muscles of the tongue are …. and are responsible for ….

A

originate outside the tongue, pass into the tongue thru root

responsible for position and shape

45
Q

the 4 intrinsic muscles of the tongue are

A

superior longitudinal
inferior longitudinal
transverse
vertical

46
Q

superior longitudinal: O, I, A, Inn

A

O = fibrous tissue near epi and hyoid, and the median septum
I = lateral regions of tongue and apex
A= shortens tongue; acts on tongue tip - elevating, retracting, turning tip unilaterally
Inn = hypoglossal (CN XII)

47
Q

superior longitudinal forms

A

broad band beneath the dorsal epithelium

48
Q

inferior longitudinal: O, I, A, Inn

A

O = tongue root and hyoid bone
I = tongue tip
A= shortens tongue; turns tip down, deviates
Inn = CN XII

49
Q

inferior longitudinal occupies…

A

lower sides of tongue

50
Q

transverse is arranged at

A

right-angle to the longitudinal fibres

51
Q

transverse: O, I, A, Inn

A

O = median septum
I = fibrous tissues at lateral margins
A = narrows and elongates tongue
Inn = CN XII

52
Q

vertical is perpendicular to

A

transverse and longitudinal

53
Q

vertical: O, I, A, Inn

A

O = inferior and lateral margins of tongue
I = dorsal membranous cover
A = flattens and widens
Inn = CN XII

54
Q

what are the 4 extrinsic muscles of the tongue

A

genioglossus
hyoglossus
styloglossus
palatoglossus

55
Q

genioglossus: O, I, A, Inn

A

O = mental spine of mandible
I = mucous membrane of tongue dorsum from base to tip; inferior fibres insert into hyoid bone
A = protrudes tongue, depresses central portion
Inn = CN XII

56
Q

genioglossus is a

A

large muscle making up bulk of the tongue

57
Q

hyoglossus is a

A

quadrilateral sheet on side of tongue, lateral to genioglossus

58
Q

hyoglossus: O, I, A, Inn

A

O = greater cornu and body of hyoid bone
I = mucous membrane on lateral margins of tongue
A = pulls down sides of tongue
Inn = CN XII

59
Q

styloglossus is a

A

slender muscle, runs inferiorly/anteriorly, passing below superior constrictor of pharynx

60
Q

styloglossus: O, I, A, Inn

A

O = styloid process of temporal bone, stylomandibular ligament
I = posterolateral portion of tongue, interdigitates w hyoglossus
A = lifts sides of tongue, pulls tongue backward
Inn = CN XII

61
Q

palatoglossus forms the

A

anterior faucial pillars; marks junction bw oral cavity and pharynx

62
Q

palatoglossus: O, I, A, Inn

A

O = inferior surface of palatal aponeurosis (palatine bone)
I = posterolateral portion of tongue
A = elevates and retracts tongue base; depresses soft palate (narrows the oropharyngeal isthmus)
Inn = pharyngeal branch of CN X

63
Q

hypoglossal CN XII has how many fibre types

A

one, GSE

64
Q

how does the hypoglossal nerve dev?

A

does not dev from a branchial arch, therefore somatic vs visceral

i.e. Developing along the neural tube, remember it comes from somites (give rise to skin and muscles of limbs and muscles of the tongue)

65
Q

the hypoglossal nerve supplies ____ extrinsic muscles of the tongue and ____ intrinsic muscles of the tongue

A

3/4
all

66
Q

describe the intracranial course of the hypoglossal nerve

A

cell bodies of LMNs are contained in the hypoglossal nucleus in the medulla

hypoglossal nerve exits cranium via hypoglossal foramen in the posterior cranial fossa (near foramen magnum)

67
Q

there is _____ innervation of all tongue muscles except _____

A

bilateral
genioglossus (contralateral)

68
Q

hypoglossal nerve extracranial course:

A

courses medial to CN IX, X, XI

runs bw arteries and veins

passes lateral to hyoglossus and genioglossus, and then supplies target muscles

69
Q

cortical neurons that drive the genioglossus muscle project only to the ______ hypoglossal nuclei, therefore to test CN XII you can…

A

contralateral

test the action of the genioglossus - if the muscle contracts bilaterally it will protrude the tongue, if innervation is impaired it will deviate laterally on protrusion to the side of weakness

70
Q

the right and left hypoglossal nuclei are located close to the midline of the _____, a nuclear lesion tends to affect ______ nuclei causing ….

A

medulla

both nuclei causing loss of innervation to the tongue

71
Q

6 ways to test CN XII functions

A

symmtery of tongue at rest
symmetry on protrusion
range of motion on lateralization
range of motion on elevation
range of motion on retraction
accuracy and speech of diadochokinesis

72
Q

during dev, where does the anterior 2/3 of the tongue arise from

A

the mounds of tissue at the fusion line bw the mandibular processes of the 1st arch

tuberculum impar and lateral lingual swellings

73
Q

during dev, where does the posterior 1/3 of the tongue arise from

A

a swelling, hypobranchial eminence, at the midline bw the 3rd and 4th arches

74
Q

anterior half of hypobranchial eminence grows forward to

A

fuse w the anterior tongue at sulcus terminalis

75
Q

posterior half of the hypobranchial eminence becomes the

A

epiglottis

76
Q

where do the muscles of the tongue arise from

A

somites - blocks of tissue in the occipital region

cells migrate and infiltrate the epithelial covering of the dev tongue formed by the 1st, 3rd, 4th arches

nerve associated w somites = CN XII

77
Q

how does the epiglottis form

A

anterior half of hypobranchial eminence migrates to tongue base

transverse depression devs bw anterior and posterior halves of hypobranchial eminence

depression deepends w backward migration of posterior half = glossoepiglottic fossa then divided into calleculae by the median glossoepiglottic fold

78
Q

they hypoglossal nerve is purely

A

a motor nerve