Transcript Iris - Stephen Tavoni

Figure 13.3a The eye and accessory structures.
Eyebrow
Eyelid
Eyelashes
Site where
conjunctiva
merges with
cornea
Palpebral
fissure
Lateral
commissure
Iris
Eyelid
Pupil
Sclera
(covered by
conjunctiva)
Surface anatomy of the right eye
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Lacrimal
caruncle
Medial
commissure
Figure 13.4 The lacrimal apparatus.
Lacrimal sac
Lacrimal gland
Excretory ducts
of lacrimal glands
Lacrimal punctum
Lacrimal canaliculus
Nasolacrimal duct
Inferior meatus
of nasal cavity
Nostril
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Figure 13.5 Extrinsic eye muscles.
Trochlea
Superior oblique muscle
Superior oblique tendon
Superior rectus muscle
Axis of
rotation
of eye
Lateral rectus muscle
Inferior
rectus muscle
Medial
rectus muscle
Lateral
rectus muscle
Inferior
rectus
muscle
Common
tendinous ring
Inferior
oblique
muscle
Lateral view of the right eye
Superior view of the right eye
Muscle
Lateral rectus
Medial rectus
Superior rectus
Inferior rectus
Inferior oblique
Superior oblique
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Action
Moves eye laterally
Moves eye medially
Elevates eye and turns it medially
Depresses eye and turns it medially
Elevates eye and turns it laterally
Depresses eye and turns it laterally
Controlling cranial nerve
VI (abducens)
III (oculomotor)
III (oculomotor)
III (oculomotor)
III (oculomotor)
IV (trochlear)
Summary of muscle actions and innervating cranial nerves
Figure 13.6a Internal structure of the eye (sagittal section).
Ora serrata
Sclera
Ciliary body
Ciliary zonule
Choroid
(suspensory
Retina
ligament)
Macula lutea
Cornea
Fovea centralis
Iris
Posterior pole
Pupil
Optic nerve
Anterior
pole
Anterior
segment
(contains
aqueous humor)
Lens
Central artery and
Scleral venous sinus
vein of the retina
Optic
disc
Posterior segment
(blind spot)
(contains vitreous humor)
Diagrammatic view. The vitreous humor is illustrated only in the bottom part of the
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Figure 13.13c Focusing for distant and close vision.
View
Ciliary muscle
Lens
Ciliary zonule
(suspensory
ligament)
The ciliary muscle and ciliary zonule are arranged
sphincterlike around the lens. As a result, contraction
loosens the ciliary zonule fibers and relaxation tightens
them.
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Figure 13.7 Pupil constriction and dilation, anterior view.
Sympathetic +
Parasympathetic +
Sphincter pupillae
muscle contracts:
Pupil size decreases.
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Iris (two muscles)
• Sphincter pupillae
• Dilator pupillae
Dilator pupillae
muscle contracts:
Pupil size increases.
Figure 13.8 MicroscopicNeural
anatomy
of the retina.
layer of retina
Pigmented
layer of
retina
Choroid
Sclera
Pathway of
light
Optic disc
Central artery
and vein of retina
Optic
nerve
Posterior aspect of the eyeball
Ganglion
cells
Axons
of
ganglion
cells
Bipolar
cells
Photoreceptors
• Rod
• Cone
Nuclei of
ganglion
cells
Choroid
Outer segments
of rods and cones
Amacrine cell
Horizontal cell
Pathway of signal output
Pathway of light
Pigmented
layer of retina
Cells of the neural layer of the retina
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Inc.
Nuclei of
bipolar
cells
Photomicrograph of
Axons of
ganglion cells
Nuclei of
rods and
cones
retina
Pigmented
layer of retina
Figure 13.11 The electromagnetic spectrum and photoreceptor sensitivities.
10–5
nm
10–3
Gamma
rays
nm
103
1 nm
X rays
UV
nm
106
Infrared
nm
(109 nm =)
1m
Microwaves
103 m
Radio waves
Light absorption (percent of maximum)
Visible light
Blue
cones
(420 nm)
Green Red
Rods
cones cones
(500 nm) (530 nm) (560 nm)
100
50
0
400
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450
500
550
600
Wavelength (nm)
650
700
Figure 13.10 Circulation of aqueous humor.
Cornea
Posterior
segment
(contains
vitreous
humor)
Iris
Lens epithelium
Lens
Cornea
Lens
2
Corneal epithelium
Corneal endothelium
1 Aqueous humor
forms by filtration
from the capillaries
in the ciliary
processes.
2 Aqueous humor
flows from the
posterior chamber
through the pupil into
the anterior chamber.
Some also flows
through the vitreous
humor (not shown).
Aqueous humor
Anterior
segment
(contains
aqueous
humor)
3 Aqueous humor is
reabsorbed into the
venous blood by the
scleral venous sinus.
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Anterior chamber
Ciliary zonule
(suspensory
ligament)
Posterior chamber
Scleral venous
sinus
Corneoscleral
junction
3
1
Ciliary
processes
Ciliary
muscle
Bulbar
conjunctiva
Sclera
Ciliary
body
Figure 13.13 Focusing for distant and close vision.
Sympathetic activation
Nearly parallel rays
from distant object
Lens
Ciliary zonule
Ciliary muscle
Inverted
image
Lens flattens for distant vision. Sympathetic input
relaxes the ciliary muscle, tightening the ciliary zonule,
and flattening the lens.
Divergent rays
from close object
Parasympathetic activation
Inverted
image
Lens bulges for close vision. Parasympathetic input
contracts the ciliary muscle, loosening the ciliary zonule,
allowing the lens to bulge.
View
Ciliary muscle
Lens
Ciliary zonule
(suspensory
ligament)
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The ciliary muscle and ciliary zonule are arranged
sphincterlike around the lens. As a result, contraction
loosens the ciliary zonule fibers and relaxation tightens
them.
Figure 13.18 Visual pathway to the brain and visual fields, inferior view.
Both eyes
Fixation point
Right eye
Suprachiasmatic
nucleus
Pretectal
nucleus
Lateral
geniculate
nucleus of
thalamus
Superior
colliculus
Left eye
Optic nerve
Optic chiasma
Optic tract
Lateral
geniculate
nucleus
Superior
colliculus
(sectioned)
Uncrossed
(ipsilateral) fiber
Crossed
(contralateral) fiber
Optic
radiation
Occipital
lobe
(primary visual
cortex)
The visual fields of the two eyes overlap considerably.
Note that fibers from the lateral portion of each retinal field
do not cross at the optic chiasma.
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Corpus callosum
Photograph of human brain, with the right side
dissected to reveal internal structures.
Figure 13.21a Structure of the ear.
Middle Internal ear
External ear
(labyrinth)
ear
Auricle
(pinna)
Helix
Lobule
External
acoustic
meatus
The three regions of the ear
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Tympanic Pharyngotympanic
membrane (auditory) tube
Figure 13.25a Pathway of sound waves and resonance of the basilar membrane.
Auditory ossicles
MalleusIncus Stapes
Cochlear nerve
Scala vestibuli
Oval
4a
windowHelicotrema
2
3
4b
Scala tympani
Cochlear duct
Basilar
membrane
1
Sounds with
4a
frequencies below
hearing travel through
Round
Tympanic
the
membrane window
helicotrema and do not
Route of sound waves through the ear
Pressure waves excite hair cells.
Auditory
Sound waves
Sounds in the hearing
created
by
the
3
4b
1
2
ossicles vibrate.
vibrate the
stapes pushing on range go through the
cochlear duct, vibrating
Pressure is
tympanic
the oval window
the basilar membrane and
amplified.
membrane.
move through fluid deflecting hairs on inner
in the scala
hair cells.
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vestibuli.
Figure 13.26 Structure of a macula.
Macula of
utricle
Macula of
saccule
Kinocilium
Stereocilia
Vestibular
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Inc.
fibers
Otolith
Otoliths membrane
Hair bundle
Hair cells
Supporting
cells