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Special Senses

Semicircular canals

What is 2?

Cochlea

What is 3?

Eustachian tube

What is 5?

Lobule of auricle

What is 7?

Tympanic membrane

What is 8?

External acoustic meatus

What is 9?

Helix

What is 13?

Malleus

What is 1?

Incus

What is 2?

Stapes

What is 3?

Oval window (covered by stapes footplate)

What is 4?

Cochlear duct

What is 6?

Round window

What is 8?

Tympanic membrane

What is 10?

External acoustic meatus

What is 11?

Sclera

What is 3?

Choroid

What is 4?

Retina

What is 6?

Optic disc

What is 10?

Vitreous body

What is 11?

Ciliary body

What is 14?

Lens

What is 16?

Anterior chamber

What is 17?

Pupil

What is 18?

Iris

What is 19?

Cornea

What is 20?

Conjunctive

What is 22?

Tarsal gland

What is 23?

Lacrimal gland

What is 1?

Lacrimal gland

What is a?

superior lacrimal canal

What is c?

lacrimal sac

What is d?

inferior lacrimal punctum

What is e?

inferior lacrimal canal

What is f?

nasolacrimal canal

What is g?

Layers of the ey

Arrowhead: retina; Arrow: choroid, Curved arrow: sclera

Cornea

1: epithelium; 2: stroma; 3: endothelium

Retina

A: ganglion cell layer; B: nerve fibre layer; Arrow: inner limiting membrane

Fovea Centralis

Arrowhead: reduced number of nuclei; Arrow: outer nuclear layer

vestibule

is responsible for the sense of static equilibrium (gravitational) and linear acceleration equilibrium.

scala vestibuli

cochlear duct

(scala media)

vestibular membrane

roof of membrane; extremely thin

basilar membrane

floor of membrane; hair cells found here

tectorial membrane

middle membrane

hair cells

organ of Corti

(spiral organ) hair cells here

scala tympani

auricle

(pinna)

external auditory canal

external auditory meatus, external acoustic meatus)

tympanic membrane

ear drum)

tympanic cavity

oval window

...

auditory tube

pharyngotympanic or Eustachian tube

cochlear duct

vestibular membrane

basilar membrane

organ of Corti

spiral organ)

scala tympani

(tympanic duct)

cochlear nerve

saccule

lump closest to snail

semicircular canals

responsible for the sense of dynamic equilibrium

ampullae

widening of the canals

vestibular nerve

vestibulocochlear nerve

round window

tiny opening on bottom of cochlea

The innermost layer of the eye is the internal tunic, or retina. The stratified nature of the retina can be seen in the diagram of slide 1 and also in the photographic representation in slide 2. Note the "stacking" arrangement of the layers in both slides. The upper right corner of slide 2 shows a dark, thick line, the pigment layer of the retina, which lies tightly adhered to the choroid. The layer adjacent to the pigmented layer consists of columnar receptors for sensing light: the layer of rods and the cones. The layers below the rods and cones consist of two other principal nerve cell types: the bipolar cells, which transfer the nerve signals to the ganglion cell layer, and ganglion neurons themselves, which summarize all the inputs from bipolar calls and translate them into coded nerve impulses. The ganglion neurons contain axons that leave the eye and comprise the nerve fibers of the optic nerves, optic chiasma, and optic tracts. Not shown in the diagram in slide 1 are the amacrine and horizontal cells which conduct nerve signals laterally in the retina and help sharpen the edges of images that we see.

The innermost layer of the eye is the internal tunic, or retina. The stratified nature of the retina can be seen in the diagram of slide 1 and also in the photographic representation in slide 2. Note the "stacking" arrangement of the layers in both slides. The upper right corner of slide 2 shows a dark, thick line, the pigment layer of the retina, which lies tightly adhered to the choroid. The layer adjacent to the pigmented layer consists of columnar receptors for sensing light: the layer of rods and the cones. The layers below the rods and cones consist of two other principal nerve cell types: the bipolar cells, which transfer the nerve signals to the ganglion cell layer, and ganglion neurons themselves, which summarize all the inputs from bipolar calls and translate them into coded nerve impulses. The ganglion neurons contain axons that leave the eye and comprise the nerve fibers of the optic nerves, optic chiasma, and optic tracts. Not shown in the diagram in slide 1 are the amacrine and horizontal cells which conduct nerve signals laterally in the retina and help sharpen the edges of images that we see.

Select slide 3 to see a special area of the retina, the area of greatest visual acuity called the fovea. Here the layer of ganglion cells has been pushed to the side as well as the bipolar cells. Light can then fall directly upon the rod and cone layer, which only contains cones so that maximum clarity can be obtained. Identify the following features: "a" lies within a concavity at the posterior pole of the eye, the important fovea centralis. Only cones, densely arrayed, are found at "b", providing for very high visual acuity.

Select slide 4 to see the overall retina structure: "a" lies within the choroid coat, with the pigmented layer of the retina running vertically just to the right. "b" lies among a portion of the rods and cones called the outer segment. "c" lies among the cell bodies of the rods and cones. "d" lies among the synaptic connections between the rod and cones and the bipolar cells. "e" lies among the cell bodies of the bipolar, horizontal and amacrine cells. "f" lies among the axons of the bipolar cells and dendrites of the ganglion cells. "g" lies among cell bodies of ganglion cells. Compare with the drawing in slide 1.

Most taste buds are located on the surface and the papillae of the tongue, but some are found in the oral cavity and pharynx. Pictured in slide 1 is a typical taste bud. Note the resemblance to a "rose bud" with the petal-like neuroepithelial cells "NE" arranged circularly within the bud. Slide 2 shows a low-powered section of a papilla of the tongue, showing several taste buds (one of which is indicated by the arrow) aligned in a row.

Select slide 3 to see a high-powered close-up of a taste bud. The arrow points to a taste pore which allows fluids in the mouth to contact the receptor cells within the taste bud. Sites on the receptor cell membrane form loose combinations with molecules in food and drink, depolarizing the receptor cell and generating an impulse to the brain that is interpreted as sweet, salty, bitter, sour, or some other combination thereof. The molecules must be dissolved in water to gain access to the receptor membranes. A perfectly dry tongue will not taste.

3 parts of the ear

1. External ear (green)
2. Middle Ear
3. Inner ear

Components of the External Ear

- Auricle pinna (green)
(funnel that collects sound waves)
-external auditory meatus ~2.5 cm
(in temporal bone- s-shaped tube (yellow dot)

Location of middle ear

Located in tympanic cavity of temporal bone. 2-3mm width between outer and inner

Tympanic cavity follows the membrane

air filled space in temporal bone

Auditory ossicles

They increase the force of sound wave but decrease amplitude
(ossilate sound)

Components of auditory ossicle

MIS
Malleus
Incus
Stapes

Malleus

-attached to eardrum
-head is attached to tympanic cavity by ligament
-short process attaches to tympanic membrane - and articulates with next process moving inward

Incus

-triangular shape-2 processes
-Articulates its short process with malleus
-head attached to tympanic cavity by ligament
-long process articulates with next ossicle- stapes

Stapes

-Arch and footplate
(looks like stirrup)
- Footplate held by ligament over oval window (ring like)

Oval window

Where the inner ear begins

Muscles of inner ear

Stapedius muscles
Tensor tympani

Stapedius muscle

From posterior wall of tympanic cavity and inserts into the stapes.

Tensor tympani

Arises from the wall of the auditory tube-inserts to malleus

Auditory tube

(eustachian tube)
-connects middle ear to throat
-equalizes pressure between middle and atm
this is why infection in throat can get to ear.

Osseus labyrinth composition

-Fluid filled chambers
-Fleshy tubes
=Membraneous Labyrinth

Between osseous and membranous labaryinth there is .....

Another fluid similar to CEREBRAL SPINAL FLUID!
Perilymph (blue)

In order from oval window

1.Vestibule (two organs of balance)
2.Semicircular canals (derive from 1)
3.Cochlea (derives from 1)

Semicircular Canals

-contain semicircular ducts
(detect cephalic rotation)
-bony that contain fleshy loops

Cochlea

Derives from vestibule
-snail like shape
-contains the organ of hearing

Cochlea components

-Modiolus -bony outer part / core of cochlea!
(arrows in green box)

Cochlea compartments

T-Scala Vestibuli (up the ladder)
M-Cochlear ducts
L-Scala tympani (down the ladder 1)

Hair cells of organ of corti attach to...

Tectorial membrane - which is below the vestibular membrane.

The movement of hair cells convey as neural impulses ...

perceived as sound

Innervation for sound by hair cells

CN 8

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