Chapter 22 Special Senses

Name the multiple white structure?

Auditory ossicles

Cilliary processes

Black. Folds secrete aqueous humor (watery).

Choroid

Brownish layer deep to the sclera. Absorbs light.

Inner ear

Consists of the boney labrynth and the membranous labyrnth.

Organ of Corti

Contained in the cochlear duct. Rests on the basilar membrane. Composed of hair cells and the tectorial membrane.

Vestibularcochlear Nerve

Cranial Nerve VIII - White structure leading away from the cochlea. Carries impulses for hearing to the brain.

Nasolacrimal duct

Drains under INFERIOR CONCHAE in nasal cavity

Vitreous humor

Gel-like substance. Represented by a large plastic ball on the model. Located between the lens and the retina.

Primary visual cortex

In the occipital lobe of the cerebrum

External ear

Leads from the outside of the ear to the tympanic membrane.

Round window

Located below the oval window, covered by a small membrane. Dampens vibration. Represented by a blue dot painted on the model.

Conjuctiva

Membrane lines inside of palpebae and covers front of eye, except cornea. (Pink eye)

Vascular tunic

Middle layer

The cranial nerves associated with extrinsic eye muscles:

Oculomotor Nerve III Trochlear Nerve IV Abducens VI

Photorecptor layer

Rods- dim light, black and white Cones- bright light, color

Cochlea

Snail shaped boney structure. Fluid filled chambers for hearing.

Lacrimal glands

Superior and lateral to eye. Produces tears. Bacterial enzyme LYSOZYME

Gusatory pathway

Taste buds→Cranial nerve VII, IX, X→limbic system and/or thalamus→parietal lobe

Gustatory Sensation

Taste. Taste buds located in papillae on tounge.

Semi Circular Canals

The boney covering around the semicircular ducts. Filled with perilymph.

Pinna

Top of the ear. Collects sound waves. Outer flap of elastic cartilidge covered by skin.

Lacrimal ducts

Tube from gland to conjuctiva of upper lid

Ampulla

Expanded portion at the end of the semicircular ducts. Near the vestibule. Filled with endolymph.

The olfactory nerve is made up of two parts:

Olfactory bulb and the olfactory tract. Which is the white bulge above the roof of the nasal cavity where nerve fibers from olfactory receptors synapse with neurons which then travel to the brain.

Iris

Part of the Vascular tunic (middle layer). Colored disc shaped structure containing pigmented epithelium. Composed of two layers of muscle.

Lacrimal canal

medial corner of the eye

Olfactory Adaptation

Decreased sensitivity is rapid.

Oval window

Entrance to inner ear (scala vestibuli) Stapes rests on oval window. It is covered by stapes. Looks like a staple on the model.

Vestibule

Expanded area of the boney labrynth to which the semi circular canals and cochlea are attached. Contains the utricle and saccule. Used mostly for static equilibrium

Perilymph

Filled with anything boney

Extrinsic Eye Muscles

6 per eye and help move eye. Red/brown muscles on exterior of eyeball, used to move eye.

Tectorial membrane

A stiff membrane that rests on top of the hair cells. (yellow with a white outline)

Middle ear

Air filled cavity in the temporal bone. Between the tympanic membrane and the oval window.

Anterior Cavity

Anterior of the to the lens. Contains Aqueous humor

Cilliary muscle

Attached to lens by suspensory ligaments, used to change the shape of the lens for focusing. Red structure on the side of ciliary processes.

Lens

Avascular (Does not have its own blood supply). Focuses light. Transparent plastic structure, looks like a magnifying glass. Suspensory ligaments suspend the lens.

Cornea

Avascular - does not have its own blood supply. Covers the front of the eye. Transparent layer on anterior surface of the eyeball. (Clear pastic dome)

Optic disc

Blind spot. Where optic nerve exits the eye. No photoreceptors here.

Fovea centralis

Central portion of the macula lutea where most cones are located. Highest concentration of cones most visual resolution. No rods. Mascular degeneration. The center of the yellow circle located on the retina.

Olfactory sensation

Cranial nerve I - Sense of smell. Located in superior nasal cavity, cribriform plate and nasal septum

Optic Nerve

Cranial nerve II contains neurons leading from the rods and cones in the retina to the brain.

How do the structures travel from the cranial cavity?

Cribriform plate of the ethmoid bone

Tympanic membrane

Eardrum. End of the external ear. Vibrates when sound waves hit it. Transparent piece of plastic on the model.

Eustachian Tube (auditory)

Enters from the nasopharynx. Auditory connects to the throat. Red with blue outline on the model.

The cranial nerves associated with the gustatory sensation:

Facial nerve VII Glossopharyngeal nerve IX Vagus nerve X

Endolymph

Filled with anything membranous

Basilar membrane

Forms the floor of the cochealear duct. The organ of Corti rests on this.

Vestibular Membrane

Forms the top of the cochlear duct.

Name the center of the yellow circle located on the retina

Fovea centralis

Malleus

Hammer - first of the three ossicles. Fits against the tympanic membrane.

Incus

Hershey kiss - second of the three ossicles, has a flat side and triangular in shape.

Nervous Tunic (retina)

Inner layer of the eye. The retina contains photo receptors: rods and cones. Seen as ORANGE or grayish purple on some models.

Scala tympani

Lower chamber inside cochlea. Ends at round window. Connected to the scala bestibulie at the "tip of the snail shell" Filled with perilymph.

What is the name of the bacterocydal enzyme produced by the laccramal gland?

Lysozyme

Stapes

MIS Speedway- third of the three ossicles, rests on the oval.

Name the entire yellow circle located on the retina

Macula lutea

The three auditory ossicles (ear bones)

Malleus, incus, stapes. Located in the middle ear forming a pathway for vibration from the tympanic membrane to the oval window. Connected by the synovial joints.

Cochlear Duct

Middle duct. Membranous portion of the cochlea. Contains endolymph. (middle orange)

Olfactory pathway

Olfactory receptors' axons olfactory nerves/CN1 (olfactory bulb olfactory tract) impulse eventually to cerebral cortex

Pupil

Opening in the iris which allows light to enter the eye. Dilates in dim light, constricts in bright light due to the action of circular and radial muscles.

Cribriform plate of the ethmoid bone

Openings in the ethmoid bone through which nerve fibers pass from receptros to the olfactory bulb. Holes allow contact from cranial.

Sclera

Optic Nerve II - White outer portion of the eyeball. White tough tissue.

Fibrous tunic

Outer layer

External auditory canal (EAC)

Passes into to temporal bone.

What is the scala tympani filled with?

Perilymph

Auditory pathway:

Pinna - collects sound waves External Auditory Canal - transmits sound waves Tympanic Membrane - vibrates when hit by sound waves Malleus - vibrates Incus - vibrates Stapes - vibrates membrane covering oval window Oval Window - start of scala vestibuli, which is filled with periplymph Perilymph in Cochlea (scala vestibuli first, then scala tympani second) vibrates Endolymph in Cochlear Duct - vibrates Hair cells, microvilli/stereocilia, tectorial membrane = Organ of Corti - bend and generate electric impulse Vestibulocochlear Nerve (CN VIII) - sends impulse to brain

Ceruminous glands

Produces cerumen (wax).

Name the boney structure that surrounds the semicircular ducts?

Semicircular canal

Membranous Labrynth

Set of membranous tubes containing sensory receptors for hearing & equilibrium and all filled with endolymph utricle, saccule, ampullae, 3 semicircular ducts, cochlear duct.

Boney Labrynth

Set of tubelike cavities in temporal bone. 3 semicircular canals (equilibrium), vestibule (equilibrium) & cochlea (hearing) lined with periosteum & all filled with perilymph. Surrounds & protects Membranous Labyrinth

Macula lutea

Specific area of retina straight back from the pupil. Contains the FOVEA CENTRALIS. Represented by a yellow spot on the retina.

Lacrimal Apparatus

Tears.

Two different areas that the smell impulse travels to from the olfactory pathway:

Temporal lobe - conscious awareness of smell Frontal lobe - identification of the odor

Posterior Cavity

The cavity posterior to the lens, contains vitreous humor.

Vestibulococlear Nerve VIII

The cranial nerve that sends signals to the cochlear and superior olivary nuclei within the medulla oblongata. Contains two parts.

Hair cells

They have long microvilli on the surface and look like very small paint brushes. (Peachy pink)

Semi Circular Ducts

Three membranous semicircular ducts exposed on the model. Contains endolymph. Function in dynamic equillibrium.

Utricle and Saccule

Two small membranous sacs located inside the boney vestibule. Contain macula Used primarily for static equilibrium- head position as well as linear acceleration and deceleration. Not seen on the models.

Scala vestibuli

Upper boney chamber inside the cochlea. Begins at oval window. Filled with perilymph.

Circular muscle (pupillary constrictor muscle fibers)

Used to constrict the pupil. Parasympathetic Nervous System stimulates pupillary constriction allowing less light into the eye. Located on the back of the iris, yellow HOROZONTAL lines

Radial Muscle (pupillary dilator muscle fibers)

Used to dilate pupils. Sympathetic Nervous system stimulates pupillary dilation allowing more light into the eye. Located on the back of the iris, yellow VERTICAL lines.

The two membranous structures found inside of the vestibule?

Utricle and saccule

Aqueous humor

Watery liquid. Located in the space between the lens and the cornea.

Olfactory Receptor Cells

White nerve fibers on the nasal septum and roof of nasal cavity. These are contained in a layer called olfactory epithelium. Their axons pass through the cribriform plate to synapse with neurons in the olfactory bulb.

Palpebra (Eyelids)

protection, lubrication, etc.