Chapter 17: Special Senses from Human Anatomy Sixth Edition

These flashcards cover key vocabulary and concepts related to the special senses as outlined in Chapter 17 of the Human Anatomy textbook.

General Senses (Somatosensory) 

Refers to the senses that perceive general stimuli from the body, including pain, temperature, touch, and pressure.

somatosensory

system responsible for processing sensory information from the skin and musculoskeletal system, such as touch, temperature, and pain.

Free nerve endings

• warm receptors

• cold receptors

• Nociceptor (pain)

Tactile discs 

light touch and pressure 

Hair root plexus (peritrichial endings) 

mvmt of hairs

Tactile corpuscles

• Oval mass in dermal papillae

  • sense light touch, texture perception 

End bulbs

similar to tactile corpuscles but located in mucous membranes

• bulbous corpuscles 

• lamellar corpuscles 

• muscles spindles 

• tendon ligament 

Bulbous corpuscles

• Flat shape

• Sense pressure, skin stretch, and joint movement

Lamellar corpuscles

• onion like 

• Sense deep pressure, stretch, tickle, and vibration

Muscle spindles

• fusiform

• sense skeletal muscle stretch

Tendon organs

• leaflike

• sense tendon stretch caused by muscle activity 

Gustation

the sense of taste, detecting flavors through taste buds on the tongue.

Taste buds

• tongue has the most 

• some in soft palate, pharynx, epiglottis, cheeks and testes 

Lingual papillae

• surface projection on tongue 

• Types

  • Filiform

  • folate

  • fungiform

  • Vallate

Filiform 

• most numerous

• tiny spikes 

• 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, surrounded by trenches and containing many taste buds.

Taste buds contain taste celss: 

• Banana-shaped

• Taste hairs

  • Receptor for taste

• Synapse with sensory nerve

Taste Pore

• Hole on epithelial surface of tongue

Olfaction

The sense of smell, involving olfactory neurons and olfactory receptors.

• olfactory mucosa 

• Olfactory neurons 

• olfactory bulbs  

Olfactory mucosa

• Roof of nasal cavity

• Contains 10 to 20 million olfactory neurons

Olfactory neurons

have olfactory hairs (cilia) with binding sites for odor molecules

• olfactory cell axons make olfactory nerve (CN I)

Olfactory bulbs

swollen tips of olfactory tracts at base of frontal lobes

Auditory ossicles

Three small bones in the middle ear, comprised of the malleus, incus, and stapes, that transmit sound vibrations.

Outer ear included

• Auricle (Pinna)

  • w/ helix and lobule

• Auditory canal

  • w/ guard hairs, cerumen

Middle Ear

• Tympanic membrane (eardrum)

•  Tympanic cavity of temporal bone

•  Auditory (eustachian) tube

•  Auditory ossicles: malleus, incus, stapes

•  Oval window on Cochlea (inner ear)

•  Muscles: stapedius, tensor tympani

Inner Ear

•  Bony labyrinth – maze

in temporal bone

• Membranous labyrinth – tube within maze

• Endolymph – fluid in membranous labyrinth

• Perilymph – fluid between membranous labyrinth and bone

• Bony labyrinth – maze

in temporal bone

• Vestibule

• Utricle and saccule

• Three semicircular canals

• Cochlea – snail shaped

Anatomy of the Membranous Labyrinth 

The membranous labyrinth is a complex system of interconnected tubes and sacs filled with endolymph, located within the bony labyrinth of the inner ear. It includes structures such as the cochlea, vestibule, and semicircular canals, essential for hearing and balance.

Cochlear duct (inner ear) 

• is an organ of hearing in the inner ear 

  • Contains spiral organ w/ hair cells: inner hair cells and outer hair cells 

  • Stereocilia of hair cells project into tectorial membrane 

  • contain endolymph 

  • Hair cells connect w/ sensory neurons that form the cochlear division of CN VIII

Equilibrium

• coordinations, balance, orientation 

  • Three semicircular canals

  • Utricle and saccule 

Scala vestibuli (inner ear) 

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 and Utricle

• Saccule is vertical, utricle is horizontal

• Each hair cell of a macula has a kinocilium embedded

in the otolithic membrane (Otoliths = Calcium stones)

The semicircular ducts

• Three semicircular ducts: anterior, posterior, and lateral

•  Each duct has an ampulla with a crista ampullaris

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

Accessory Structures of the orbit 

• keep foreign substances out of the eye

  • eyebrows

  • eyelids

  • conjunctiva

eyelids (palpebrae) include 

• Palpebral fissure

•   Medial/lateral commissures (canthi)

•   Tarsal gland

•   Eyelashes

Lacrimal Apparatus includes:

• Lacrimal gland

  •  Tears travel across conjunctiva and cornea

• Lacrimal punctum

  •  Small pore in eyelid

• Lacrimal canal

• Lacrimal sac

• Nasolacrimal duct

  • Drains to nasal cavity

Extrinsic Eye muscle 

Superior rectus

• Moves gaze up

Inferior rectus

• Moves gaze down

Medial rectus

• Moves gaze medially

Lateral rectus

• Moves gaze laterally

Superior oblique

• Tendon through trochlea

Inferior oblique

Anatomy of the eyeball (Fibrous tunic)

• Sclera – white fibrous tissue

• Cornea – transparent, anterior

Anatomy of the eyeball (Vascular tunic) 

• 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

Anatomy of the eyeball (Tunica interna) 

• Retina – lines posterior two-thirds of eye contains the neural layer

Optical Chambers and Humors 

• Aqueous humor 

• Lens 

• Vitreous body

Aqueous humor

Posterior chamber – from lens to iris
Anterior chamber – from iris to cornea
Scleral venous sinus – drains aqueous humor back to blood

lens

Ciliary body- aqueous humor

Neural components of the eye

• Retina 

• optic nerve

• Macula lutea

Retina

Ora serrata – anterior

Optic nerve

exits at optic disc

• Is the “blind spot” without receptors

Macula lutea

• Central patch for detailed vision

• Fovea centralis – pit within macula

Vitreous body (vitreous humor)

Vitreous chamber – behind lens

Retina

The neural layer of the eye responsible for receiving light and containing photoreceptors (rods and cones).

Rods

• Photoreceptors in the retina that are responsible for night (scotopic) vision and monochromatic

• Rhodopsin- pigment 

Cones

• Day (photopic) vision, trichromatic

• Photospins- three different pigments

  • red, blue, green 

Bipolar cells

• interneurons 

  • receive input from rods and cones  

Ganglion cells

• Receive input from bipolar cells

• Axons form optic nerve

Cochlea

The spiral-shaped structure in the inner ear that plays a critical role in hearing by converting sound vibrations into nerve impulses.

Tactile discs

Nerve endings located in the stratum basale of the epidermis that sense light touch and pressure.

Lacrimal apparatus

The structure involved in tear production and drainage, including the lacrimal gland and lacrimal sac.

Ciliary body

A ring of smooth muscle in the eye that controls the shape of the lens and produces aqueous humor.

Vitreous body

The clear gel-like substance that fills the space between the lens and the retina in the eyeball.

Macula lutea

The central region of the retina that is responsible for high acuity vision, containing a high density of photoreceptors.

Otoliths

Calcium stones in the otolithic membrane; they play a crucial role in the sense of balance by responding to gravitational changes.

Semicircular canals

Three canals in the inner ear that help maintain balance by detecting rotational movements of the head.

Eustachian tube

The tube that connects the middle ear to the nasopharynx and helps equalize pressure on both sides of the tympanic membrane.

Sclera

The white outer layer of the eyeball that provides structure and protection.

Pupil

The opening in the center of the iris that regulates the amount of light entering the eye.

Tectorial membrane

The membrane in the cochlea that interacts with hair cells and is crucial for the process of hearing.

Fovea centralis

A small pit in the retina that contains a high concentration of cones and provides the sharpest vision.