CH. 17 | Special Senses

Free Nerve Ending

- Warm receptors

- Cold receptors

- Nociceptors (pain)

Tactile discs

- Light Touch and Pressure

Hair root plexus

- Also called peritrichial endings

- Movement of hair is picked up by these receptors

Tactile corpuscles

- Oval mass in dermal papillae

- Sense light touch, texture perception

(Find in the dermis)

End Bulbs

- Similar to tactile corpuscles but located in mucous membranes

Bulbous corpuscles

- Flat

- Sense pressure, skin stretch, and joint movement

Lamellar corpuscles

- Onion-life

- Sense deep pressure, stretch, tickle, and vibration

Muscle spindles

- Fusiorm

- Sense skeletal muscle stretch

Tendon organs

- Leaflike

- Sense tendon stretch caused by muscle activity

What's another name for general senses?

Somatosensory

Gustation

Taste

Taste buds

Tongue has the most, but some are in the soft palate, pharynx, epiglottis, cheeks and testes.

- Contain taste cells

Taste hairs

Receptor for taste

Taste pore

Hole on epithelial surface of tongue

Lingual papillae

Surface projections on tongue

Filiform

most numerous, tinyspikes, no buds

Folate

ridges on tongue sides, buds in children

Fungiform

mushroom shaped-bumps, have buds

Vallate

large bumps in a row at the back of the tongue, have buds

Olfaction

Smell

Olfactory mucosa

- Roof of nasal cavity

- Contains 10 to 20 million olfactory neurons

Olfactory neurons

Have olfactory hairs (cilia), which are binding sites for odor molecules

- Olfactory cell axons make olfactory nerve (CN1)

Olfactory bulbs

Swollen tips of olfactory tracts at base of frontal lobes

Parts of the ear

outer ear, middle ear, inner ear

Outer Ear

- Auricle (pina) with helix and lobule

- Auditory canal with guard hairs + cerumen

(Cerumen is earwax)

Middle Ear

- Tympanic membrane

- Tympanic cavity of temporal bone

Auditory (eustachian) tube

- Auditory ossicles

- Oval window on Choclea

- Muscles (stapedius, tensor, tympani)

What is the eardrum?

Tympanic membrane

What are the 3 ossicles? From lateral to medial?

Malleus, incus, stapes

(Lateral to medial)

What are the ear muscles?

Stapedius and tensor tympani

Inner Ear

- Bony labyrinth

- Membranous labyrinth (Endolymph and perilymph)

- Vestibule (Uritcle and saccule)

- Three semicircular canals

- Cochlea

Bony Labyrinth

Maze in temporal bone

Membranous labyrinth

Tube within maze

Endolymph

Fluid in membranous labyrinth

Perylymph

Fluid between membranous labyrinth and bone

Cochlea

Snail shaped thing

What parts are in the vestibule?

Utricle and saccule

Describe the Cochlear duct

- Organ of hearing

- Contains spiral organ, which contain inner and outer hair cells

- Contains Endolymph

- Hair cells connect with sensory neurons that form the cochlear division of CN VIII

What projects into the tectorial membrane?

Stereocilia

Scala vestibuli

Chamber above vestibular membrane

- Begins near oval window

- Contains perilymph

Scala tympani

Chamber below basilar membrane

- Ends at round window that is covered by secondary tympanic membrane

- Contains perilymph

Vestibular Apparatus

Equilibrium (Coordination, balance, orientation)

- Three semicircular canals

- Utricle and saccule

Saccule

Vertical

Utricle

Horizontal

Kinocilium

A hair cell of macula, which are embedded in the otolithic membrane

(Otoliths = calcium stones)

Semicircular Ducts

- Anterior, posterior, lateral

- Each duct has ampulla at the base, which have Crista ampullaris in each ampulla

- Hair cells project into gelatinous cupula and bend with fluid movement

Orbit Structures

- Keep foreign substances out of the eye/support

- Eyebrows, eyelids (palpebrae)

- Conjuctiva

Eyelids (palpebrae)

- Palpebral fissure

- Medial/lateral commissaries (canthi)

- Tarsal gland

- Eyelashes

Conjunctiva

Transparent mucous membrane

In what order do tears flow in the Lacrimal Apparatus?

- Lacrimal gland

- Lacrimal punctum

- Lacrimal canal

- Lacrimal sac

- Nasolacrimal duct

Lacrimal gland

Tears travel across conjuctiva and cornea

Lacarimal punctum

Small pore in eyelid

Nasolacrimal duct

Drains to nasal cavity

What are the extrinsic eye muscles?

- Superior, inferior, medial, and lateral rectus

- Superior and inferior oblique

Superior rectus

Moves gaze up

Inferior rectus

Moves gaze down

Medial rectus

Moves gaze medically

Lateral rectus

Moves gaze laterally

Superior oblique

Tendon through trochlea

What are the eyeball layers? Superficial to deep.

1. Fibrous tunic

2. Vascular tunic (uvea)

3. Tunica interna

Fibrous Tunic

Made of sclera and cornea

Sclera

White fibrous tissue

Cornea

Transparent, anterior portion

Vascular tunic (uvea)

- Choroid

- Ciliary body

- Suspensory ligaments

- Iris

Choroid

Pigmented layer behind retina

Ciliary body

Ring of smooth muscle around lens

Suspensory ligaments

Holds lens in place and stretch/loosen when ciliary body contracts/relaxes

Iris

Pigmented diaphragm controlling pupil diameter

(Goes bigger or smaller to decide how much light goes through; in a dark room, eyes get used to the dark room. When we turn on the light, the iris constricts and makes our pupil smaller. The opposite goes for when we are in a dark room)

Tunica interna

Makes the retina

Retina

- Lines posterior 2/3 of eye

- Contains the neural layer

Posterior chamber

Lens to iris

Anterior chamber

Iris to cornea

Scleral venous sinus

drains aqueous humor back to blood

Ciliary Body

Produces aqueous humor

Vitreous body/humor

Contains the vitreous chamber (behind the lens)

(Looks like a blob of jelly if you dissect it)

Ora serrata

The anterior margin of the retina

The optic disc

- Where the optic nerve exits.

- "Blind spot" without receptors

Macula Lutea

- Central patch of detailed vision

- Contains the fovea centralis (pit within macula)

What drains our tears?

The lacrimal punctum

Rods

- Night (scotopic) vision or monochromatic vision

- Rhodopsin pigment

Cones

- Day (photo pic) vision or trichromatic vision

- Photopsins (have three pigments: red, blue, green)

Bipolar cells

Inter neurons, which receive input from rods and cones

Ganglion Cells

- Receive input from bipolar cells

- Axons from optic nerve