Hyaloid artery
Encyclopedia
The hyaloid artery is a branch of the ophthalmic artery
, which is itself a branch of the internal carotid artery
. It is contained within the optic stalk
of the eye
and extends from the optic disc
through the vitreous humor to the lens
. Usually fully regressed before birth
, its purpose is to supply nutrients to the developing lens in the growing fetus
.
During the tenth week of development in humans (time varies depending on species), the lens grows independent of a blood supply and the hyaloid artery usually regresses. Its proximal portion remains as the central artery of the retina
. Regression of the hyaloid artery leaves a clear central zone through the vitreous humor, called the hyaloid canal
or Cloquet's canal. Cloquet's canal is named after the French physician Jules Germain Cloquet
(1790–1883) who first described it.
Occasionally the artery may not fully regress, resulting in the condition persistent hyaloid artery. More commonly, small remnants of the artery may remain. Free remnants can sometimes be seen as "floater
s". An anterior remnant of the hyaloid artery can be seen in some people as Mittendorf's dot, a small pinpoint-like scar on the posterior surface of the lens. A posterior remnant may be seen where the artery left the optic disc, and is known as Bergmeister's papilla
.
Ophthalmic artery
The ophthalmic artery is the first branch of the internal carotid artery distal to the cavernous sinus. Branches of the OA supply all the structures in the orbit as well as some structures in the nose, face and meninges...
, which is itself a branch of the internal carotid artery
Internal carotid artery
In human anatomy, the internal carotid arteries are two major arteries, one on each side of the head and neck. They arise from the common carotid arteries where these bifurcate into the internal and external carotid artery, and they supply the brain....
. It is contained within the optic stalk
Optic stalk
The optic vesicles project toward the sides of the head, and the peripheral part of each expands to form a hollow bulb, while the proximal part remains narrow and constitutes the optic stalk....
of the eye
Human eye
The human eye is an organ which reacts to light for several purposes. As a conscious sense organ, the eye allows vision. Rod and cone cells in the retina allow conscious light perception and vision including color differentiation and the perception of depth...
and extends from the optic disc
Optic disc
The optic disc or optic nerve head is the location where ganglion cell axons exit the eye to form the optic nerve. There are no light sensitive rods or cones to respond to a light stimulus at this point. This causes a break in the visual field called "the blind spot" or the "physiological blind spot"...
through the vitreous humor to the lens
Lens (anatomy)
The crystalline lens is a transparent, biconvex structure in the eye that, along with the cornea, helps to refract light to be focused on the retina. The lens, by changing shape, functions to change the focal distance of the eye so that it can focus on objects at various distances, thus allowing a...
. Usually fully regressed before birth
Childbirth
Childbirth is the culmination of a human pregnancy or gestation period with the birth of one or more newborn infants from a woman's uterus...
, its purpose is to supply nutrients to the developing lens in the growing fetus
Fetus
A fetus is a developing mammal or other viviparous vertebrate after the embryonic stage and before birth.In humans, the fetal stage of prenatal development starts at the beginning of the 11th week in gestational age, which is the 9th week after fertilization.-Etymology and spelling variations:The...
.
During the tenth week of development in humans (time varies depending on species), the lens grows independent of a blood supply and the hyaloid artery usually regresses. Its proximal portion remains as the central artery of the retina
Retina
The vertebrate retina is a light-sensitive tissue lining the inner surface of the eye. The optics of the eye create an image of the visual world on the retina, which serves much the same function as the film in a camera. Light striking the retina initiates a cascade of chemical and electrical...
. Regression of the hyaloid artery leaves a clear central zone through the vitreous humor, called the hyaloid canal
Hyaloid canal
Hyaloid canal is a small transparent canal running through the vitreous body from the optical nerve disc to the lens; in the fetus it contains a prolongation of the central artery of the retina, the hyaloid artery...
or Cloquet's canal. Cloquet's canal is named after the French physician Jules Germain Cloquet
Jules Germain Cloquet
Jules Germain Cloquet was a French physician and surgeon who was born and practiced medicine in Paris. His older brother, Hippolyte Cloquet , was also a physician...
(1790–1883) who first described it.
Occasionally the artery may not fully regress, resulting in the condition persistent hyaloid artery. More commonly, small remnants of the artery may remain. Free remnants can sometimes be seen as "floater
Floater
Floaters are deposits of various size, shape, consistency, refractive index, and motility within the eye's vitreous humour, which is normally transparent. At young age the vitreous is perfectly transparent, but during life imperfections gradually develop. The common type of floater, which is...
s". An anterior remnant of the hyaloid artery can be seen in some people as Mittendorf's dot, a small pinpoint-like scar on the posterior surface of the lens. A posterior remnant may be seen where the artery left the optic disc, and is known as Bergmeister's papilla
Bergmeister's papilla
Bergmeister’s papilla arises from the centre of the optic disc, consists of a small tuft of fibrous tissue and represents a remnant of the hyaloid artery....
.
External links
- The Vitreous Humor at TedMontgomery.com
- "What are those threads that float in your field of vision?" at Straight DopeCecil AdamsCecil Adams is a name, possibly a pseudonym, designating the American author of The Straight Dope, a popular question and answer column published in The Chicago Reader since 1973. Ed Zotti is Adams' current editor....