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Equine Special Senses - Horse Anatomy (view source)
Revision as of 16:29, 22 November 2012
, 16:29, 22 November 2012→Eye
The vitreous humour is a transparent hydrogel that occupies almost 3/4 of the volume of the eye in the '''posterior segment''' of the globe; it is composed of 99% water with collagen fibrils as a skeleton for hylaronic acid. The vitreous body is attached to peripheral structures only at the edge of the optic nerve, near the ora serrata and at the posterior lens capsule. It acts as a clear medium for transmission of light between the lens and retina and provides mechanical support for the internal structures of the eye.
The vitreous humour is a transparent hydrogel that occupies almost 3/4 of the volume of the eye in the '''posterior segment''' of the globe; it is composed of 99% water with collagen fibrils as a skeleton for hylaronic acid. The vitreous body is attached to peripheral structures only at the edge of the optic nerve, near the ora serrata and at the posterior lens capsule. It acts as a clear medium for transmission of light between the lens and retina and provides mechanical support for the internal structures of the eye.
===The Wall (retina, uvea and sclera)===
===The Wall (retina, uvea and sclera)===
The retina is the inner layer of the eyeball, it develops from the '''optic vesicle''', which is an outgrowth of the diencephalon. It remains connected to the diencephalon via the '''{Equine Cranial Nerves - Horse Anatomy#Optic Nerve (II)|optic nerve]]'''. It can be divided into the non-visual retina (lines the back of the ciliary body) and the optic part of the retina.
The retina is the inner layer of the eyeball, it develops from the '''optic vesicle''', which is an outgrowth of the diencephalon. It remains connected to the diencephalon via the '''{Equine Cranial Nerves - Horse Anatomy#Optic Nerve (II)|optic nerve]]'''. It can be divided into the non-visual retina (lines the back of the ciliary body) and the optic part of the retina.
====Sclera====
====Sclera====
The sclera is continuous with the cornea at the point of the '''limbus'''. It is similar to the cornea, except that it is vascular, and has dense, irregular, fibrous connective tissue.
The sclera is continuous with the cornea at the point of the '''limbus'''. It is similar to the cornea, except that it is vascular, and has dense, irregular, fibrous connective tissue.
===Around the Eye (Adnexa)===
====Extraocular Muscles====
[[Image:Extraocular Muscles.jpg|thumb|right|200px|Extraocular Muscles - Copyright David Bainbridge]]
{| style="width:75%; height:200px" border="1"
!'''Muscle'''
!'''Innervation'''
!'''Function'''
|-
| '''Dorsal Rectus'''
| Oculomotor nerve
([[Cranial Nerves - Anatomy & Physiology|CN III]])
| Elevates the eyeball
|-
| '''Ventral Rectus'''
| Oculomotor nerve
([[Cranial Nerves - Anatomy & Physiology|CN III]])
| Depresses the eyeball
|-
| '''Medial Rectus'''
| Oculomotor nerve
([[Cranial Nerves - Anatomy & Physiology|CN III]])
| Adduction of the eyeball
|-
| '''Ventral Oblique'''
| Oculomotor nerve
([[Cranial Nerves - Anatomy & Physiology|CN III]])
| Outward rotation of the eyeball
|-
| '''Levator Palpebrae Superioris'''
| Oculomotor nerve
([[Cranial Nerves - Anatomy & Physiology|CN III]])
| Elevates the upper eyelid
|-
| '''Lateral Rectus'''
| Abducens nerve
([[Cranial Nerves - Anatomy & Physiology|CN VI]])
| Abduction of the eyeball
|-
| '''Retractor Bulbi'''
| Abducens nerve
([[Cranial Nerves - Anatomy & Physiology|CN VI]])
| Retracts the eyeball
|-
| '''Dorsal Oblique'''
| Trochlear nerve
([[Cranial Nerves - Anatomy & Physiology|CN IV]])
| Inward roation of the eyeball
|-
|}
[[Image: eye gross structure.JPG |thumb|right|200px|Dissected canine eye- Copyright C. Clarkson and T.F. Fletcher, University of Minnesota]]
All of the extraocular muscles originate at the equator of the eyeball.
====Adnexa====
[[Image:Adnexa.jpg|thumb|right|200px|Adnexa - Copyright David Bainbridge]]
The adnexa refers to the accessory structures of the eye, including the eyelids and the lacrimal apparatus. It contains three layers of the tear film:
1. Deep mucous: from conjunctival goblet cells, adheres tears to the conjunctiva
2. Middle aqueous: from main and third eyelid lacrimal glands; it cleanses, oxygenates and fills optimal defects; it contains [[IgA]] (immunoglobulin A)
3. Superficial oily layer: from tarsal glands (modified sebaceous glands); prevents evaporation
==Ear==
==Ear==