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Eye - Anatomy & Physiology (view source)
Revision as of 15:47, 14 August 2009
, 15:47, 14 August 2009no edit summary
| '''Dorsal Rectus'''
| '''Dorsal Rectus'''
| Oculomotor nerve
| Oculomotor nerve
([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN III]])
([[Cranial Nerves - Anatomy & Physiology|CN III]])
| Elevates the eyeball
| Elevates the eyeball
|-
|-
| '''Ventral Rectus'''
| '''Ventral Rectus'''
| Oculomotor nerve
| Oculomotor nerve
([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN III]])
([[Cranial Nerves - Anatomy & Physiology|CN III]])
| Depresses the eyeball
| Depresses the eyeball
|-
|-
| '''Medial Rectus'''
| '''Medial Rectus'''
| Oculomotor nerve
| Oculomotor nerve
([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN III]])
([[Cranial Nerves - Anatomy & Physiology|CN III]])
| Adduction of the eyeball
| Adduction of the eyeball
|-
|-
| '''Ventral Oblique'''
| '''Ventral Oblique'''
| Oculomotor nerve
| Oculomotor nerve
([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN III]])
([[Cranial Nerves - Anatomy & Physiology|CN III]])
| Outward rotation of the eyeball
| Outward rotation of the eyeball
|-
|-
| '''Levator Palpebrae Superioris'''
| '''Levator Palpebrae Superioris'''
| Oculomotor nerve
| Oculomotor nerve
([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN III]])
([[Cranial Nerves - Anatomy & Physiology|CN III]])
| Elevates the upper eyelid
| Elevates the upper eyelid
|-
|-
| '''Lateral Rectus'''
| '''Lateral Rectus'''
| Abducens nerve
| Abducens nerve
([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN VI]])
([[Cranial Nerves - Anatomy & Physiology|CN VI]])
| Abduction of the eyeball
| Abduction of the eyeball
|-
|-
| '''Retractor Bulbi'''
| '''Retractor Bulbi'''
| Abducens nerve
| Abducens nerve
([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN VI]])
([[Cranial Nerves - Anatomy & Physiology|CN VI]])
| Retracts the eyeball
| Retracts the eyeball
|-
|-
| '''Dorsal Oblique'''
| '''Dorsal Oblique'''
| Trochlear nerve
| Trochlear nerve
([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN IV]])
([[Cranial Nerves - Anatomy & Physiology|CN IV]])
| Inward roation of the eyeball
| Inward roation of the eyeball
|-
|-
===Autonomic Innervation of the Eye===
===Autonomic Innervation of the Eye===
Parasympathetic innervation to the eye is supplied by the oculomotor nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN III]]). When parasympathetic innervation is predominant, it acts upon the circular muscles of the iris, causing constriction of the pupil.
Parasympathetic innervation to the eye is supplied by the oculomotor nerve ([[Cranial Nerves - Anatomy & Physiology|CN III]]). When parasympathetic innervation is predominant, it acts upon the circular muscles of the iris, causing constriction of the pupil.
Sympathetic innervation to the eye is via the cranial cervical ganglion. When sympathetic innervation is predominant, it acts upon the radial muscles of the iris, causing dilation of the pupil.
Sympathetic innervation to the eye is via the cranial cervical ganglion. When sympathetic innervation is predominant, it acts upon the radial muscles of the iris, causing dilation of the pupil.
==Central Visual Pathways==
==Central Visual Pathways==
[[Image:Central Visual Pathway.jpg|thumb|right|150px|Central Visual Pathway - Copyright David Bainbridge]]
[[Image:Central Visual Pathway.jpg|thumb|right|150px|Central Visual Pathway - Copyright David Bainbridge]]
The optic nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN II]]) is a paired nerve that carries visual information from the retina to the brain. The ganglion cell axons leave the retina and information passes through the optic nerve to the optic chiasm, where some nerve fibres cross over. The optic tract (the optic nerve fibres) wraps around the cerebral peduncles of the midbrain, where it passes into the lateral geniculate nucleus, which is part of the thalamus. Most of the optic tract axons synapse here, and the remaining fibres branch off and synapse in the pretectal nuclei of the superior colliculi. The integrated visual information is then passed via nerve fibres to the cerebral cortex.
The optic nerve ([[Cranial Nerves - Anatomy & Physiology|CN II]]) is a paired nerve that carries visual information from the retina to the brain. The ganglion cell axons leave the retina and information passes through the optic nerve to the optic chiasm, where some nerve fibres cross over. The optic tract (the optic nerve fibres) wraps around the cerebral peduncles of the midbrain, where it passes into the lateral geniculate nucleus, which is part of the thalamus. Most of the optic tract axons synapse here, and the remaining fibres branch off and synapse in the pretectal nuclei of the superior colliculi. The integrated visual information is then passed via nerve fibres to the cerebral cortex.
===Reflexes with Optic Nerve as the Sensory Arm===
===Reflexes with Optic Nerve as the Sensory Arm===
1. '''Pupillary light reflex''': the constriction of a pupil in response to increased light intensity, and a dilatation of a pupil in response to a decreased light intensity. This reflex also involves parasympathetic fibres of the Oculomotor nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN III]]). The presence of this reflex shows the efficiency of the retina, the optic and oculomotor nerves, and the musculature of the iris.
1. '''Pupillary light reflex''': the constriction of a pupil in response to increased light intensity, and a dilatation of a pupil in response to a decreased light intensity. This reflex also involves parasympathetic fibres of the Oculomotor nerve ([[Cranial Nerves - Anatomy & Physiology|CN III]]). The presence of this reflex shows the efficiency of the retina, the optic and oculomotor nerves, and the musculature of the iris.
2. '''Pupil dilation''': also called mydriasis. It is a sympathetic response.
2. '''Pupil dilation''': also called mydriasis. It is a sympathetic response.
3. '''Menace response''': involves the facial nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN VII]]) in the motor arm of the reflex. The response also requires integration from the cerebral cortex, the cerebellum and the rostral colliculi. However, the menace response is a learned response, so it will not be present in the first few weeks of life.
3. '''Menace response''': involves the facial nerve ([[Cranial Nerves - Anatomy & Physiology|CN VII]]) in the motor arm of the reflex. The response also requires integration from the cerebral cortex, the cerebellum and the rostral colliculi. However, the menace response is a learned response, so it will not be present in the first few weeks of life.
4. '''Fixating response''': involves oculomotor ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN III]]), trochlear ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN IV]]) and abducens ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN VI]]) nerves in the motor arm of the reflex.
4. '''Fixating response''': involves oculomotor ([[Cranial Nerves - Anatomy & Physiology|CN III]]), trochlear ([[Cranial Nerves - Anatomy & Physiology|CN IV]]) and abducens ([[Cranial Nerves - Anatomy & Physiology|CN VI]]) nerves in the motor arm of the reflex.
==Histology==
==Histology==