Overview of Special Senses and the Eye

The eyeball is composed of two main parts: a wall and internal components.

The eyeball wall consists of three layers: outer fibrous, middle vascular, and inner retinal layers.

The outer fibrous layer includes the sclera, which maintains eyeball shape, and the transparent cornea, which refracts light.

The middle vascular layer comprises the choroid, ciliary body, and iris.

The ciliary body suspends the lens, accommodates it for focusing, and produces aqueous humor.

The sclera is the white part of the eye; it maintains the shape of the eyeball.

The cornea is the transparent front part of the eye; it refracts light entering the eye.

The iris is the colored part of the eye. It controls the size of the pupil, regulating the amount of light entering the eye.

The iris controls pupil size using circular and radial muscles.

The retina has a visual and non-visual part.

The area where the optic nerve exits the retina, creating a blind spot.

A fluid that fills the anterior and posterior chambers of the eye, providing nutrients and maintaining pressure.

Increased intra-ocular pressure due to abnormal aqueous humor drainage.

A transparent structure in the eye that focuses light onto the retina.

Opacity of the lens, causing gradual vision blurring.

Fluid pressure inside the eye; important for maintaining eye shape and function.

A transparent, gelatinous substance that fills the posterior chamber of the eye, helping maintain its round shape.

Muscles that control the movement of the eyeball, allowing us to look in various directions.

A muscle that elevates the upper eyelid, allowing us to open our eyes.

Drooping of the upper eyelid caused by paralysis of the levator palpebrae superioris muscle.

A muscle that elevates, adducts, and internally rotates the eyeball.

A muscle that depresses, adducts, and externally rotates the eyeball.

A muscle that adducts the eyeball, moving it towards the nose.

A muscle that abducts the eyeball, moving it away from the nose.

A thin, oval-shaped membrane separating the external ear canal from the middle ear, also known as the eardrum. It's about 1 cm in diameter and angled at 55 degrees.

The thin and flexible part of the tympanic membrane.

The thick and taut part of the tympanic membrane.

The tympanic membrane has two surfaces: external (concave) and internal (convex). The internal surface features the umbo and malleolar folds.

A bright reflection visible on the lower anterior part of the tympanic membrane when using an otoscope.

The middle ear is divided into two parts: the tympanic cavity (adjacent to the eardrum) and the epitympanic recess (above the eardrum).

The middle ear has six walls: roof, floor, posterior, anterior, lateral, and medial.

The medial wall of the middle ear has five features: oval window, round window, promontory, stapedial artery opening, and facial nerve canal.

The main artery supplying the eye, branching from the internal carotid artery. It has numerous branches, a vital one being the central retinal artery.

A branch of the ophthalmic artery that directly supplies the retina, vital for vision. Blockage of this artery (CRAO) leads to blindness.

Veins responsible for draining blood from the eye. They connect with the cavernous sinus, allowing potential spread of infections from the face to the brain.

A triangular area on the face, where facial infections can spread to the cavernous sinus via the ophthalmic veins, potentially leading to serious complications.

Cranial Nerve II, responsible for transmitting visual information from the eye to the brain, making sight possible.

Cranial Nerve III, responsible for controlling most eye movements by innervating several extraocular muscles.

Cranial Nerve IV, responsible for controlling the superior oblique muscle, a specific eye muscle that helps rotate the eye downward and outward.

Cranial Nerve VI, responsible for controlling the lateral rectus muscle, allowing the eye to move outwards.

A tube connecting the middle ear to the pharynx, equalizing pressure and draining mucus.

Three tiny bones in the middle ear: malleus, incus, and stapes. They transmit sound vibrations.

A muscle in the middle ear that tenses the eardrum to reduce loud noise.

A muscle in the middle ear that dampens vibrations of the stapes to protect from loud sounds.

The bony outer shell of the inner ear, containing the membranous labyrinth.

A fluid-filled membrane inside the bony labyrinth, containing sensory organs for hearing and balance.

Three curved tubes in the bony labyrinth that detect head movement and rotation.

A spiral-shaped part of the inner ear that converts sound vibrations into neural signals.