4,503
edits
Changes
Equine Special Senses - Horse Anatomy (view source)
Revision as of 16:07, 22 November 2012
, 16:07, 22 November 2012→Lens
The mature lens is transparent and biconvex. The centers of the lens surface are referred to as the anterior and posterior '''poles'''. The circumference of the lens is known as the '''equator'''. The center of the lens itself is referred to as the '''nucleus''', which is surrounded by the lens '''cortex'''. Attached to the lens equator are '''zonular ligaments'''; the zonules attach the lens to the ciliary body and mediate accommodation. Contraction of the ciliary body muscles relieves tension on the zonules, which in turn, allows the elastic capsule to retract; this causes the lens to become more convex. This change in the shape of the lens changes the focal length of the lens.
The mature lens is transparent and biconvex. The centers of the lens surface are referred to as the anterior and posterior '''poles'''. The circumference of the lens is known as the '''equator'''. The center of the lens itself is referred to as the '''nucleus''', which is surrounded by the lens '''cortex'''. Attached to the lens equator are '''zonular ligaments'''; the zonules attach the lens to the ciliary body and mediate accommodation. Contraction of the ciliary body muscles relieves tension on the zonules, which in turn, allows the elastic capsule to retract; this causes the lens to become more convex. This change in the shape of the lens changes the focal length of the lens.
The lens metabolizes mostly through anaerobic glycolysis; metabolism is limited by the avascular state of the lens and low oxygen supply. The lens is completely dependent on the aqueous humor for nutrients. Pathological changes within the lens result in deposition of lens protein, disruption of lens fibres and hence loss of lens transparency known as a '''[[Cataracts - Donkey|cataract]]]'''.
The lens metabolizes mostly through anaerobic glycolysis; metabolism is limited by the avascular state of the lens and low oxygen supply. The lens is completely dependent on the aqueous humor for nutrients. Pathological changes within the lens result in deposition of lens protein, disruption of lens fibres and hence loss of lens transparency known as a '''[[Cataracts - Donkey|cataract]]'''.
==Ear==
==Ear==