Special Sense

humors of the eye

• vitrous humor

• aqueous humor

vitrous humor

forms in utero

aqueous humour

• formed by ciliary body

• flows from posterior chamber to anterior chamber through the pupil

• reabsorbed in blood stream

cones

color vision (most in fovea centralis)

rods

noncolor

visual pathway

1. photoreceptors of retina stimulate CN II

2. enters through the optic canal and decussate

3. optic tracts travel to the thalamus

4. optic radiations project to visual cortex

damage to optic tract→

damage to both eyes

damage to optic nerve→

damage to one eye

which cranial nerve associates with superior rectus m.?

CN III

which cranial nerve associates with inferior rectus m.?

CN III

which cranial nerve associates with lateral rectus m.?

CN VI

which cranial nerve associates with medial rectus m.?

CN III

which cranial nerve associates with superior oblique m.?

CN IV

which cranial nerve associates with inferior oblique m.?

CN III

SO_LR_AO_

4, 6, 3

olfaction (smell)

primitive sense that utilizes chemoreceptors; CN I; odorants must be volatile

olfaction pathway

1. olfactory epithelim

2. olfactory sensory neurons

   1. olfactory cilia (dendrites)

   2. nonmyelinated axons

3. project through cribiform plate to form olfactory bulb

4. SYNAPSE

5. olfactory tract to the olfactory cortex

5 basic tastes

• sweet

• salty

• sour

• umami

• bitter

taste pathway

1. taste buds (papillae)

2. CN VII, IX, or X

3. enter through respective foramina

4. solitary nucleus

5. thalamus

6. gustatory cortex

3 parts of ear anatomy

1. external ear

2. middle ear

3. internal ear

middle ear

• tympanic membrane→oval window

• ossicles

  • incus

  • malleus

  • stapes

• tensory tympani m.

• stapedius m. 

• pharyngotympanic tube

internal ear

• semicircular canals

• utricle and saccule

• cochlea

• CN VIII

• round and oval windows

auditory pathway

1. sound waves vibrate the tympanic membrane

2. auditory ossicles vibrate; pressure is amplified

3. pressure waves created by stapes pushing on oval window move through fluid in the scala vestibuli

4. sounds with frequencies below the hearing range travel through and dont excite hair cells; those within range go through the choclear duct, deflecting hair cells

vestibular organs

• contain two englargements→ utricle and saccule

• saccule macula detects vertical movement

• utricle macula detects horizontal movement

vestibular organs 2

• three semicircular canals are filled with endolymph

• each canal has an ampulla

• detect rotational changes

semicircular canals

• anterior

• posterior

• lateral