L16 Spectial Pathways

Question 1

• Cranial Nerves of taste:

Answer 1

( سبعهتسعهعشره)
• Anterior 2/3 tongue: chorda tympani→ Facial nerve
• Posterior 1/3 tongue: Glossopharyngeal nerve
• Most posterior part of the tongue: Vagus nerve

Question 2

first order neuron of taste ?

Answer 2

-geniculate ganglion of the facial nerve
-inferior ganglia of the glossopharyngeal and vagus nerves

Question 3

second order neuron of taste ?

Answer 3

nucleus solitarius

Question 4

The third order neuron of taste is the?

Answer 4

posteromedial ventral nucleus of the thalamus.

Question 5

In taste pathway, axons of the cells pass through the sensory radiation to the gustatory area in the ?

Answer 5

superior wall of the posterior ramus of the lateral sulcus

Question 6

Olfactory pathways

Answer 6

Olfactory Receptors ( mucosa ) ( above superior cocha) > Olfactory nerve fiber pass through cribriform plate
> olfactory bulb > olfactory tract > lateral , medial stria>
olfactory cortex ( direct ) without relaying in the thalamus

Question 7

carries the axons to the olfactory area of the
cerebral cortex؟

Answer 7

lateral olfactory stria

Question 8

carries the fibers that cross the median plane in the anterior commissure to pass to the olfactory bulb of the opposite side?

Answer 8

medial olfactory stria

Question 9

Primary olfactory cortex in?

Answer 9

uncus, limen insulae (apical region of the insula) and corticomedial part of the amygdaloid body.

Question 10

Secondary olfactory cortex is?

Answer 10

the entorhinal area (anterior part of the parahipocampal gyrus that lies behind the uncus

Question 11

The connection between the two olfactory systems of both sides???

Answer 11

anterior commissure

Question 12

Visual Pathway (Visual component of visual pathway) ?

Answer 12

Axons of ganglion cells of the retina → optic nerve → optic chiasm (partial decussation) → optic tract → lateral geniculate nucleus (thalamic relay nucleus for vision) → corona radiata (optic radiation) → primary visual cortex 17

Question 13

the first order neuron in visual pathway?

Answer 13

Bipolar cells

Question 14

second order neuron in visual pathway?

Answer 14

ganglion cells

Question 15

Rt optic tract composed of?

Answer 15

Nasal fibers of LT eye
Temporal fibres of RT eye

Question 16

Pupillary Light Reflex?

Answer 16

Light directed into one eye cause both pupils to constrict.

Impulse from the retina→ Optic tract axons (afferent limb) → lateral root of the optic tract → lateral geniculate body→ superior brachium→ pretectal nucleus→ Edinger-Westphal nucleus (bilaterally) → inferior division of the oculomotor nerve (as preganglionic parasympathetic fibres) → Ciliary ganglion→ postganglionic parasympathetic fibres (short ciliary nerves) → Sphincter pupillae muscle

Question 17

Both pupils constrict in the consensual light reflex because the?

Answer 17

pretectal nucleus sends fibers to the parasympathetic nuclei on both sides of the midbrain

Question 18

The response of the pupil of the illuminated eye is called?

Answer 18

the direct pupillary light reflex.

Question 19

• That of the other eye is called ?

Answer 19

the consensual pupillary light reflex.

Question 20

When visual attention is directed to a nearby object 3 things happen in a reflex manner:

Answer 20

1- convergence of eyes
2- contraction of ciliary muscle ( thickening of lens )
3- pupillary constriction (reducing aberration, increasing its depth)

Question 21

accommodation reflex?

Answer 21

Normal visual pathway → primary visual cortex → visual association cortex –> superior colliculus and/or pretectal area or (visual eye field in the medial side of the frontal lobe through the superior longitudinal bundle) → Corticobulbar fibers → Edinger-Westphal nucleus → ciliary ganglion → short ciliary nerves → sphincter pupillae muscle and ciliary muscle (contraction of the ciliary muscle increase the thickness of the lens) with convergance of both eyes by the contraction of medial rectus in both side

Question 22

convergance of both eyes by the contraction of?

Answer 22

medial rectus in both side

Question 23

Auditory pathway?

Answer 23

Spiral ganglion of cochlea → Cochlear nuclei → Superior Olivary nucleus → Lateral Lemniscus → Inferior Colliculus → Medial Geniculate body → Auditory Cortex 41,42

Question 24

decussating fibers of cochlear nuclei ?

Answer 24

trapizoid body

Question 25

Why there is no complete loss of hearing whin the fibers of auditory pathway damaged in the level of pons?

Answer 25

Some fibers doesn’t decussate

Question 26

Types of fibers in lateral leminscus ?

Answer 26

Auditory fibers

Question 27

Receptors of Vestibular Pathways?

Answer 27

Cristae ampularis in the ampulla of the semicircular ducts on each side

Question 28

1st order neuron in vestibular pathway?

Answer 28

vestibular (Scarpa’s) ganglion

Question 29

2nd order neuron in vestibular pathway?

Answer 29

vestibular nuclei

Question 30

3rd order neuron in vestibular pathway?

Answer 30

posteromedial ventral nucleus of the thalamus is the 3rd order neuron

((which then pass to through the optic radiations to reach the vestibular area opposite the sensory area of the face))