Eye. Eyelids, eyeball nucleus, accessory organs. Visual analyzer wiring system and centers PDF

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Eye. Eyelids, eyeball nucleus, accessory organs. Visual analyzer wiring system and centers...

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Eye. Eyelids, eyeball nucleus, accessory organs. Visual analyzer wiring system and centers. The eye is an entire complex of organs consisting of the eyeball with the optic nerve, cord, and brain centers, and accessories: the tear machine, eyeball, eyelid, conjunctiva, eyelashes, and eyebrows. Eye covers: • Fibrous covering - cornea, skin. - Odena maintains the shape of an apple. The outer surface is white and smooth, and the inner surface is brown with nerve and blood vessel grooves. - Cornea - Transparent part of the outer shell and acts as a fixed lens, refracting and focusing the rays into the retina. The cornea is more convex than the skin. • The vascular cover forms the middle layer of the eyeball capsule, divided into: - Choroid - A thin, richly veined blood vessel - Croup - An extension of the choroid and anterior to the iris. Associated with lens hanging and its accommodation, produces fluid in the eye. Connects to the iris at the front - Rainbow. It regulates the central opening of the eye, the pupil, and controls the amount of light entering the eye. The pupil diameter can vary from 1 to 8 mm; The iris is located between the cornea and the lens and divides the anterior and posterior chambers of the eye where the fluid of the eye is flushedThe color of the iris depends on the combined effect of the connective tissue and pigment cells to absorb and reflect light energy of different frequencies. The most important factor determining color is the concentration of melanocytes. Iris Muscle: The astringent muscle of the pupil - the smooth muscle ring surrounding the pupil. The parasympathetic nervous system is innervated. The pupil's expanding muscle is the fiber located in a ray. The sympathetic nervous system innervates. • Inner cover. It lays the inside of the eyeball capsule. A distinction is made between the outer and inner layers of the coating. The outer layer of the pigment cells is an adult with a vascular covering. The inner layer is of nerve origin and is called the retina.

In retina: • It is a nervous, perceptible layer of the eyeball • Blind part of the retina

• Visual part of the retina: Contains photoreceptor, photosensitiveSeparate layers of nerve elements: - Rods, flasks, specialized neurons. Flasks (about 6 million) needed to be seen in bright light, sticks (about 120 million) at dusk - There are two layers of bipolar neurons in the middle - Outer - ganglionic layer, from multipolar neurons. Retinal neurons connect themselves to each other at synapses. The nerve fibers from the rods and flasks converge into a single fiber and form the optic nerve. • Central (yellow) spot (2 mm) - vision is best. • Optic nerve disc - blind spot (6 mm)

The nucleus of the eye • Anterior chamber of the eye - between the cornea and the iris • The posterior chamber of the eye - between the iris and the lens. Both chambers are filled with liquid. • Lens - clear, soft, elastic disc, lens axis about 4 mm and diameter in the equator 1 mm. No blood vessels and nerves • vitreous - gel-like, transparent, with a thin fiber network and a proteinaceous fluid. No blood vessels and nerves Accessory organs of the eye • Eyeball bearing • Eyelids - Upper and Lower, Eyelashes, River of Tears, Lake of Tears • The eyelids from the top are limited by the eyebrows • conjunctiva - a thin, transparent film of connective tissue that passes from the eyelids to the eyeball. It covers the entire visible part of the eye except the cornea. • Tear machine: gland (upper lateral corner of the eye socket), drainage ducts, tear pouch, tear duct. • The muscles that move the eyeball (four straight muscles and two oblique muscles).

Visual analyzer wiring system and centers. Wired part of vision • The fibers of the retinal ganglion neurons form the optic nerve (Pair II). • The nerve enters the cranial cavity from the eyelid through the visual canal. The optic nerve crosses in the front of the medial brain. It crosses the inner optic nerve

fibers, and the lateral sides are on the same side of the crossing, starting the visual cord, which ends in the optic vision centers.

Ventral and cortical centers of vision • Submerged centers: lateral (lateral) knee bodies, tuberosity and quadriceps. Neural fibers of the lateral knee and lumbar cushion reach the cortex of the visual sensory system on the inner surface of the occipital lobe. • The top of the quadrilateral are submerged reflex centers of vision. Their fibers reach the motor nerves of the III, IV, VI cranial nerves. and III pair of parasympathetic nuclei, this relationship provides binocular vision, co-ordinated gaze to the object, and helps to accommodate the eye. Also connects with dorsal sm. front horn motor nuclei and lateral intermediate br. This results in reflex contraction of the neck and trunk muscles and reflex expansion of the pupil. Projectional and associative visual cortex • The image of the retina is transmitted through the optic nerve and submucosal centers of vision to the projection field of vision located on the inner surface of the occipital lobe. It evaluates the shape, color, movement and space of an object. The associative visual cortex helps to perceive, to know an object and an object, to evaluate them emotionally. Agnosis, when cognitive processes are impaired, when a person does not recognize them when he or she sees loved ones, familiar objects.

Functional parameters of vision Refraction. Accommodation • The cornea, the eye chamber fluid, the lens, and the vitreous, constitute the optical system of the eye, which passes the light rays before reaching the retina. The lens has the highest breaking power. The power of the optical media of the eye is called refraction. It is measured by dioptres. • Vision is of great importance for vision, i.e. ability to see objects at different distances as the lens convexity changes. • A person can only see well if the subject's image is accurately formed in the retina. This is called normal (emetropic) refraction. If the refractive power is not sufficient, the rays cross the retina, which is far-sighted (hypermetropic) refraction. It has a relatively good view of distant objects and a poor sight at close range.

• If the rays are bent too much, they cross the retina - myopic refraction. In this case, close objects are visible and distant ones are bad.

Visual acuity • It is the degree of brightness of perceived objects. Visual acuity is highest in the central well, where the flasks are dense. The central well flask transmits agitation to only one ganglion cell, switching 1: 1: 1. • The ability of visual centers in the cerebral cortex to differentiate stimuli is important for visual acuity. • Visual acuity is studied by Landolt tables of letters, rings, etc. of various sizes. rows of special characters. The character size for each row varies by 0.1%. Depending on the perceived size of the symbol, visual acuity is determined. Normal visual acuity equates to a unit (V = 1.0) if a person sees the first bottom line from a distance of 5 m.

Abiaxial (binocular) vision • Vision with both eyes as a single organ is the most important prerequisite of spatial vision: it helps to understand the position of objects in space, their relationships, shapes, distance, volume, volume. The human is able to distinguish the depth of space (distance and relief) from 1000 to 2600 meters.

Field of vision or twitch • It is a visible field with fixed gaze and stable head position • The greater the range of stimuli in different parts of the space, the wider the field of vision • The total field of vision consists of the field of view of each eye

Angle of vision • This is the ratio of the distance to the observed object to the size of the object • Due to the accommodation, the eye may change the angle of view when approaching or moving the subject. • If the subject's eyesight is impaired, the subject is locked at different angles and is therefore not accurate

Sensation of light and color

• The light is only felt when the baby is born. His pupils narrow as he turns his eyes to the light source and he blinks. It takes some time for the eyes to get used to getting from dark to light. Eyes adjust to bright light within 4-6 minutes and darker longer. • No newborn color. Colors start at 2-6 months of life and intensify this ability in the second year of life. It starts with red and yellow, then green, and then blue. The sensation of color is fully formed in 8-9 years of life. One can distinguish about 200 shades of black and white luminosity. • Bright contrast contrast is an important feature of vision. Without it, a person would see blurred shapes of objects or mixed stains of light...