9. anatomy of of the tongue

Question 1

how can the tongue be divided?

Answer 1

anterior 2/3rd (oral part)

posterior 1/3 (pharyngeal part)

Question 2

which nerve carries out general / common sensation of the anterior 2/3rds of the tongue?

Answer 2

general sensation = touch

trigeminal nerve: lingual branch (of V3)

Question 3

which nerve supplies special sensory fibres of taste to the anterior 2/3rds of the tongue?

Answer 3

fibres derived from the chorda tympani branch of the facial nerve (CN VII) hitch-hike with the lingual nerve (V3) to supply taste to anterior 2/3rd

Question 4

aside from special sensory to anterior 2/3rds of tongue, what else do fibres from chorda tympani branch of facial nerve (CN VII) supply?

Answer 4

secretomotor (parasympathetic) fibres to the salivary glands

Question 5

parasympathetic innervation of the parotid gland?

Answer 5

the glossopharyngeal nerve (CN IX) via the otic ganglion

Question 6

parasympathetic innervation to the submandibular and sublingual glands?

Answer 6

parasympathetic input from the facial nerve (CN VII) via the submandibular ganglion

Question 7

what innervates the posterior 1/3rd of the tongue?

Answer 7

glossopharyngeal nerve (CN IX)
(also supplies the parasympathetic - secretory of parotid gland)

Question 8

what does the glossopharyngeal nerve carry? (CN IX)

Answer 8

both general and special taste sensation

Question 9

which portion of the tongue receives sensory AND taste innervation via the vagus nerve?

Answer 9

small portion of the posterior tongue (base) near the epiglottis

Question 10

functions of the extrinsic tongue muscles?

Answer 10

protraction
retraction
side-to-side movement

Question 11

where is the tongue divided? into what?

Answer 11

divided into anterior and posterior parts at sulcus terminalis

Question 12

what is the sulcus terminalis?

Answer 12

a V shaped sulcus behind which is the pharyngeal part of the tongue
(posterior = pharyngeal, anterior = oral tongue)

Question 13

which is the only moveable joint in the skull?

Answer 13

temporomandibular joint

Question 14

how do you test for cranial nerve X (vagus)?

Answer 14

patient asked to open their mouth and say ‘ahhh’

Question 15

why do you ask patients to open their mouth and say ‘ahhh’ when inspecting CN X?

Answer 15

check for deviation of uvula = weakness on contralateral soft palate (opposite) - therefore, lesion of CN X

Question 16

which nerves are you testing for when testing the gag reflex?

Answer 16

CN X (vagus), IX (glossopharyngeal)
CN IX = sensory afferent
CN X = motor efferent

Question 17

how do lesions affecting the hypoglossal nerve on one side of the tongue appear when protruded?

Answer 17

deviate towards the side of the lesion

Question 18

how does hypoglossal nerve and vagal nerve differ in their presentation?

Answer 18

hypoglossal nerve lesion: tongue deviation

vagus nerve lesion: uvula deviation