The Special Senses

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Slide 1

The Eye and Vision

70% of all sensory receptors are in the eye

Nearly half of the cerebral cortex is involved in processing visual information!

Most of the eye is protected by a cushion of fat and the bony orbit

Slide 2

Accessory Structures of the Eye

Protect the eye and aid eye function

Eyebrows

Eyelids (palpebrae)

Conjunctiva

Lacrimal apparatus

Extrinsic eye muscles

Slide 3

Figure 15.1a

Eyelashes

Sclera

(covered by

conjunctiva)

Site where

conjunctiva

merges with

cornea

Lateral

commissure

Iris

Medial

commissure

Lacrimal

caruncle

Eyelid

Eyelid

Eyebrow

Pupil

Palpebral

fissure

(a) Surface anatomy of the right eye

Slide 4

Eyebrows

Overlie the supraorbital margins

Function in

Shading the eye

Preventing perspiration from reaching the eye

Slide 5

Eyelids

Protect the eye anteriorly

Palpebral fissure—separates eyelids

Lacrimal caruncle—elevation at medial commissure; contains oil and sweat glands

Tarsal plates—internal supporting connective tissue sheet

Levator palpebrae superioris—gives the upper eyelid mobility

Slide 6

Eyelids

Eyelashes

Nerve endings of follicles initiate reflex blinking

Lubricating glands associated with the eyelids

Tarsal (Meibomian) glands

Sebaceous glands associated with follicles

Ciliary glands between the hair follicles

Slide 7

Figure 15.1b

(b) Lateral view; some structures shown in sagittal section

Levator palpebrae

superioris muscle

Orbicularis oculi muscle

Eyebrow

Tarsal plate

Palpebral conjunctiva

Tarsal glands

Cornea

Palpebral fissure

Eyelashes

Bulbar conjunctiva

Conjunctival sac

Orbicularis oculi muscle

Slide 8

Conjunctiva

Transparent membrane

Palpebral conjunctiva lines the eyelids

Bulbar conjunctiva covers the white of the eyes

Produces a lubricating mucous secretion

Slide 9

Lacrimal Apparatus

Lacrimal gland and ducts that connect to nasal cavity

Lacrimal secretion (tears)