this is the last lecture in the series on the visual system and deals with the processing of visual information through the visual cortices and other pathways. visual information is received through 3 types of ganglionic cells- Y type cells receive input from rods and thus detect peripheral movement or light intensity changes. X type cells receive input from cones and as such detect fine detail and color, and W type cells receive peripheral rod input. the center-surround receptive field information then projects to the lateral geniculate nucleus, which then projects information to the primary visual cortex.
within the primary visual cortex there are "ocular dominance columns" that the LGN projects to that are cortical columns that receive input from one eye or another. within these ocular dominance columns there are distinct layers of cells: "simple cells" in the middle layers receive input from ganglionic cells that receive input from receptive fields that are aligned within the same line-- and are thus stimulated by bars of light in the particular orientation of the ganglionic cells. complex cells receive input from several simple cells and therefore detect movement of bars of light. simple cells in layer 4 also receive "monocular input" and complex cells in the upper and lower layers process "binocular" visual information, processing the disparity between retinal information of each eye.
the primary visual cortex then sends information to the neighboring visual cortices, V2 through V5, each cortex processing the visual information in a progressively complex fashion. for example, whereas V1 receives simple light/dark/color input, V2 processes the object/background differences as well as formation of illusory/incomplete boundaries. V2 then projects into two streams: the dorsal stream then goes to V3, then to the middle temporal cortex, and is the "motion processing" or "how and where" of visual processing. the ventral stream goes to V4, then to the inferotemporal cortex, and is the detail oriented "what" pathway of visual processing. (the right side of the inferotemporal cortex is involved in processing complex shapes such as faces, and the left side is involved in language processing).
a few other brain areas involved in visual processing: the superior colliculus is part of the midbrain that receives Y-type visual information, audition, and somatosensory information and is involved in orienting the head and eyes towards visual stimuli via the "extrageniculate" pathway- via the posterior thalamic nuclei and the amygdala. the superior colliculus is also involved in producing the saccadic eye movements (and thus modulates the cranial nerves that innervate the extrinsic eye muscles, CN III, IV, VI), rapid fixations that break up scanning movements and allow the brain to put together bits of visual information in a process analogous to a film movie. the superior colliculus is also involved in the phenomenon of "blindsight", where a lesion in V1 blocks the primary (primitive) visual processing pathway, and visual information flows through the intact "extrastriate" (mammalian) pathway through the superior colliculus.
the suprachiasmic nucleus is a thalamic nuclei that receives receptive field information from ganglionic cells and is involved in mediating the circadian clock. the circadian clock receives information about light/dark cycles and via transcription factor cycles mediates different autonomic regulatory pathways in the body. the factors in the positive transcriptional loop are BMAL1 and PER2; the ones in the negative loop are CRY1,2 and PER1,3. the "central heterodimers" are BMAL1 and CLOCK. the output of these transcriptional loops produces transcription of CLOCK controlled genes which produce proteins that ultimately alter cellular function. the SCN also projects to the liver, adrenals, and pineal, where is mediates melatonin release.
questions
pathways...
1. each side of the visual field projects to the ... side of the brain.
2. what can total blindness in one eye be caused by?
3. what is heteronymous hemianopsia and what can it be caused by?
4. what is homonymous hemianopsia and what is it caused by?
lateral geniculate nucleus...
5. what are the three types of ganglion cells that the lateral geniculate nucleus receives signals from?
6. describe the role of Y type ganglion cells.
7. describe the role of X type ganglion cells.
8. describe the role of W type ganglion cells.
9. lateral geniculate nucleus projects center-surround receptive fields to...
primary visual cortex...
10. what is the primary visual cortex surrounded by?
11. what is the role of simple, complex, and hypercomplex cells in the primary visual cortex?
12. describe how a simple cell in the visual cortex can sense a "bar of light".
13. what do complex cells do?
14. thalamic neurons project contralateral visual field input to...
15. why are ocular dominance columns so named?
16. which layer is monocular input found in the visual cortex?
17. which layer is binocular input found?
18. retinal disparity provides information regarding...
V2-V5...
19. what does the visual association cortex do?
20. describe the dorsal stream from the visual association cortex.
21. describe the ventral stream from the visual association cortex.
22. both streams converge into...
23. what is a difference between the cells of V2 and V1?
24. what is V4 tuned for?
25. what is the inferotemporal cortex tuned for?
wernicke's area, fusiform gyrus, superior colliculus...
26. what is Wernicke's area associated with?
27. how is Wernicke's area connected with Broca's area?
28. inappropriate activity in the fusiform gyrus can lead to...
29. what is synesthesia and how is it related to the fusiform gyrus?
30. describe the superior colliculus: what it is, what it receives, projects to, what function it is involved in.
31. what are saccadic eye movements and how is the superior colliculus involved in producing them?
32. which cranial nerves does the SC modulate?
blindsight, SCN, circadian clock...
33. lesion of primary visual cortex leads to...
34. what is the pathway for visual information in blindsight?
35. what is the suprachiasmatic nucleus and what is it involved in?
36. circadian rhythms depend on...
37. positive transcriptional loops are mediated by...
38. negative transcriptional loops are mediated by...
39. what are the central heterodimers that are activated or inactivated by these transcriptional loops?
40. output from the circadian clock manifests in...
41. where does the SCN project to? which neurotransmitters does it use to do so?
42. what do the hypothalamic nuclei that the SCN projects to involved in?
43. SCN contains neurons that specifically target...
44. what does effect does the SCN have on the pineal gland?
answers
1. contralateral
2. damage to the optic nerve of one eye distal to the optic chiasm.
3. loss of opposite visual fields due to lesions of the optic chiasm.
4. loss of same side visual fields due to a lesions between the optic chiasm and the visual cortex on one side.
5. Y type, X type, W type.
6. receive input from rods in the periphery of the retina and thus are more sensitive to rapid movement or light intensity changes.
7. receive input from cones in the fovea and thus are more sensitive to fine details of objects, and color.
8. also receive input from rods, detecting movement in periphery of visual field.
9. primary visual cortex, V1.
10. secondary, association, and tertiary visual cortices.
11. developing perception of form, color, direction of movement, and binocular vision through hierarchical organization of these cells.
12. it can receive the receptive fields for ganglion cells that are all oriented along the same line and thus the simple cell can be maximally stimulated only when a bar of light hits the retina at the same location and orientation.
13. detect information about movement of bars of light by combining input from several simple cells.
14. ocular dominance columns in the primary visual cortex.
15. because they only receive input from one eye or the other.
16. simple cells in layer 4.
17. the complex cells in the upper and lower layers.
18. the depth of vision.
19. projects visual information into two streams, dorsal and ventral.
20. the dorsal stream is loosely involved with the "how" and "where" of visual processing. the dorsal stream goes from V2 to V3 to the middle temporal cortex to the posterior parietal cortex.
21. the ventral stream is loosely involved with the "what" of visual processing- identifying complex shapes, forms, colors. the stream goes from V2 to V4 and into the inferotemporal cortex, then to the posterior parietal cortex.
22. prefrontal cortex to form working memory.
23. V2 cells are tuned to more complex stimuli, such as the formation of illusory boundaries and distinguishing between object and background.
24. color, simple geometric shapes.
25. recognition of faces and other complex shapes on the right side, perception of language on the left side.
26. understanding symbolic systems.
27. via the arcuate fasciculus.
28. visual hallucinations.
29. the phenonemon in which a subject experiences different sensory modalities simultaneously such as sound and color, possibly related to cross-activation of color and number neurons in fusiform gyrus.
30. a midbrain structure that has an "extrageniculate" visual pathway involved in orienting the head and eyes towards visual stimulus. receives Y type ganglionic signals, audition, somatosensory input, projects to posterior thalamus (pulvinar nuclei) and amygdala.
31. saccadic eye movements are coordinated movements of the eyes which breaks scanning motion into quick
fixations on different points; the superior colliculus mediates these movements along with the frontal eye field in the motor cortex.
32. III, IV, VI.
33. lack of consciousness of visual information.
34. because the primary pathway to the visual cortex is blocked, the extrastriate pathway takes over and compensates.
35. the nucleus that receives light information from the melanopsin ganglion cells and mediates the circadian rhythm.
36. positive and negative transcriptional loops.
37. BMAL1 and PER2
38. CRY1/2 and PER1/3
39. CLOCK and BMAL1.
40. CLOCK-controlled gene expression, which leads to altering of cellular function.
41. to the dorsomedial and paraventricular hypothalamic nuclei, using vasopressin, GABA, and glutamate.
42. autonomic activity, and HPA axis hormone release.
43. liver, pineal, adrenal.
44. mediates release of melatonin which regulates sleep wake cycles, temperature, cortisol release.
Showing posts with label visual system. Show all posts
Showing posts with label visual system. Show all posts
Sunday, April 26, 2009
Tuesday, April 21, 2009
organ systems III: visual system part 2a
this lecture covered the anatomical features of the eye which relate to its refraction and focusing of incoming light; namely, the lens and the muscles that control the convexity of the lens. a bit more of the embryology of the eyes: the eyeballs are derived from the same rostral portion of the neural tube as the cerebrum, and as such have outer layers that are analogous to those in the CNS. the eyes are surrounded by an outer fibrous layer, homologous to the dura mater, followed by a vascular layer composed of anastamosing "choroid" blood vessels which is homologous to the arachnoid and pia mater, followed by a nervous layer which is homologous to the neurons in the CNS.
in order to form focused images the eye must focus beams of light that are diverging from single point sources: in other words, any light source will emit light that diverges and needs to be converged back into a single point in the back of the retina. the lens is a transparent component of the eye (derived from ectoderm) which accomplishes this refraction through its convexity. the convexity of the lens is maintained internally by elastic fibers and externally through the suspensory ligaments, which are attached to the ciliary bodies that surround the lens radially. when these ciliary muscles contract, this relaxes the suspensory ligaments, allowing the internal elastic fibers to create a more convex shape in the lens; and the opposite effect for the relaxation of the ciliary muscles.
the general rule with convexity of lens vs. distance of light source: the further away the light source, the less the beams of light are diverging, and thus less refraction is necessary, and thus less convexity is necessary. the closer the light source, the more divergence is happening, and more refraction is necessary to refocus the light beam at the back of the retina. hyperopia is far sightedness, resulting from an eyeball that is too short- in this case, the light is being focused on a point beyond the retina. myopia is the opposite, resulting from an eyeball that is too long and light being focused in front of the retina. hyperopia is the age related loss of convexity of the lens caused by the loss of elasticity.
a few more anatomical notes: the sclera is the tough white connective tissue that covers the eyeball, from which the extrinsic muscles of the eye insert. the cornea is the translucent, avascular continuation of the sclera that covers the lens and lets light into the eyeball. the vitreous body is the gel like fluid in the eyeball itself which is made largely of water, hyaluronic acid, and type II collagen. the anterior and posterior chambers are deep to the cornea, separated by the iris, and are the site of secretion of the aqueous humor by ciliary processes, which then drains into Schlemm's canal into the vascular system.
questions
embryology...
1. what is the eyeball derived from?
2. what are the neural and pigmented retinal layers derived from?
3. what are the sclera and choroid derived from?
4. what is the lens derived from?
5. optic nerve is surrounded by...
eyeball anatomy...
6. what is the vitreous body and what is it made of?
7. what are "floaters"?
8. what is the hyaloid canal and how is it related to floaters?
9. what are the three outer layers of the eyeball and what CNS structures are they homologous to?
10. what is the sclera?
11. describe the cornea.
12. what does the vascular coat consist of?
refraction and the lens...
13. why are the cornea and lens curved?
14. describe the lens.
15. describe how the lens adjusts the refraction of light according to the distance from the light source.
16. what is hyperopia?
17. what is myopia?
18. what is the resting convexity of the lens maintained by?
19. internal elastic fibers in the lens produce...
20. what is the capsule of the lens made of?
21. describe the production of new lens cells.
22. what is presbyopia and what is it caused by?
23. what is cataracts?
24. describe the suspensory ligaments that attach to the lens.
25. what do suspensory ligaments do?
26. convexity of the lens is altered by...
27. what happens when the ciliary muscles contract?
28. where are the anterior and posterior chambers? what are they partitioned by?
29. where does aqueous humor form and travel to?
30. what does Schlemm's canal do?
31. what is glaucoma caused by?
answers
1. same part of the neural tube that produces the cerebral hemispheres.
2. optic vesicle.
3. embryonic meningeal tissues.
4. ectoderm.
5. dura, arachnoid, pia, subarachnoid space.
6. the gel-like fluid inside the eyeball made of water, hyaluronic acid, type II collagen fibers.
7. tiny clumps of gel in the vitreous body that are too large to be phagocytosed during development.
8. the hyaloid canal is the vestigial remains of the hyaloid artery, remnants of which can turn into floaters.
9. outer fibrous coat homologous to dura mater, vascular coat homologous to arachnoid/pia mater, and nervous coat homologous to CNS layer.
10. dense, white CT, which is the point of insertion for the extrinsic muscles of the eye.
11. the cornea is a transparent, avascular continuation of the sclera in the center of the eyeball which allows light into the eye.
12. a layer of anastamosing blood vessels (choroid) and the ciliary body, which regulates the refraction of light.
13. to refract light from a point source in order to converge back into one point.
14. clear, avascular, and depends on diffusion of nutrients from vitreous humor, like the cornea.
15. for close light sources, the lens becomes more convex and for far away light sources the lens becomes less convex.
16. far-sightedness: eyeball is too short and light converges behind the retina.
17. near-sightedness: eyeball is too long and light converges in front of the retina.
18. internal elastic fibers and suspensory ciliary ligaments.
19. an inherent tendency to bulge.
20. collagen IV and glycoprotein.
21. lens cells are produced from the germinal center on the side of the lens, which then migrate from the germinal zone, lose their nucleus, and become transparent.
22. age-related loss of lens resting convexity caused by loss of elasticity.
23. reduction of vision due to opacity of lens.
24. zonule fibers that extend from ciliary body to the equatorial perimeter of the lens.
25. maintain resting tension and decrease convexity of the lens via outward tension.
26. ciliary muscle.
27. the tension in the suspensory ligaments decreases, which allows the lens to increase its elasticity and convexity.
28. deep to the cornea, partitioned by the iris.
29. formed by the ciliary processes, secreted into the anterior and posterior chambers.
30. absorbs the aqueous humor into veins.
31. a buildup of fluid pressure due to inadequate drainage into Schlemm's canal.
in order to form focused images the eye must focus beams of light that are diverging from single point sources: in other words, any light source will emit light that diverges and needs to be converged back into a single point in the back of the retina. the lens is a transparent component of the eye (derived from ectoderm) which accomplishes this refraction through its convexity. the convexity of the lens is maintained internally by elastic fibers and externally through the suspensory ligaments, which are attached to the ciliary bodies that surround the lens radially. when these ciliary muscles contract, this relaxes the suspensory ligaments, allowing the internal elastic fibers to create a more convex shape in the lens; and the opposite effect for the relaxation of the ciliary muscles.
the general rule with convexity of lens vs. distance of light source: the further away the light source, the less the beams of light are diverging, and thus less refraction is necessary, and thus less convexity is necessary. the closer the light source, the more divergence is happening, and more refraction is necessary to refocus the light beam at the back of the retina. hyperopia is far sightedness, resulting from an eyeball that is too short- in this case, the light is being focused on a point beyond the retina. myopia is the opposite, resulting from an eyeball that is too long and light being focused in front of the retina. hyperopia is the age related loss of convexity of the lens caused by the loss of elasticity.
a few more anatomical notes: the sclera is the tough white connective tissue that covers the eyeball, from which the extrinsic muscles of the eye insert. the cornea is the translucent, avascular continuation of the sclera that covers the lens and lets light into the eyeball. the vitreous body is the gel like fluid in the eyeball itself which is made largely of water, hyaluronic acid, and type II collagen. the anterior and posterior chambers are deep to the cornea, separated by the iris, and are the site of secretion of the aqueous humor by ciliary processes, which then drains into Schlemm's canal into the vascular system.
questions
embryology...
1. what is the eyeball derived from?
2. what are the neural and pigmented retinal layers derived from?
3. what are the sclera and choroid derived from?
4. what is the lens derived from?
5. optic nerve is surrounded by...
eyeball anatomy...
6. what is the vitreous body and what is it made of?
7. what are "floaters"?
8. what is the hyaloid canal and how is it related to floaters?
9. what are the three outer layers of the eyeball and what CNS structures are they homologous to?
10. what is the sclera?
11. describe the cornea.
12. what does the vascular coat consist of?
refraction and the lens...
13. why are the cornea and lens curved?
14. describe the lens.
15. describe how the lens adjusts the refraction of light according to the distance from the light source.
16. what is hyperopia?
17. what is myopia?
18. what is the resting convexity of the lens maintained by?
19. internal elastic fibers in the lens produce...
20. what is the capsule of the lens made of?
21. describe the production of new lens cells.
22. what is presbyopia and what is it caused by?
23. what is cataracts?
24. describe the suspensory ligaments that attach to the lens.
25. what do suspensory ligaments do?
26. convexity of the lens is altered by...
27. what happens when the ciliary muscles contract?
28. where are the anterior and posterior chambers? what are they partitioned by?
29. where does aqueous humor form and travel to?
30. what does Schlemm's canal do?
31. what is glaucoma caused by?
answers
1. same part of the neural tube that produces the cerebral hemispheres.
2. optic vesicle.
3. embryonic meningeal tissues.
4. ectoderm.
5. dura, arachnoid, pia, subarachnoid space.
6. the gel-like fluid inside the eyeball made of water, hyaluronic acid, type II collagen fibers.
7. tiny clumps of gel in the vitreous body that are too large to be phagocytosed during development.
8. the hyaloid canal is the vestigial remains of the hyaloid artery, remnants of which can turn into floaters.
9. outer fibrous coat homologous to dura mater, vascular coat homologous to arachnoid/pia mater, and nervous coat homologous to CNS layer.
10. dense, white CT, which is the point of insertion for the extrinsic muscles of the eye.
11. the cornea is a transparent, avascular continuation of the sclera in the center of the eyeball which allows light into the eye.
12. a layer of anastamosing blood vessels (choroid) and the ciliary body, which regulates the refraction of light.
13. to refract light from a point source in order to converge back into one point.
14. clear, avascular, and depends on diffusion of nutrients from vitreous humor, like the cornea.
15. for close light sources, the lens becomes more convex and for far away light sources the lens becomes less convex.
16. far-sightedness: eyeball is too short and light converges behind the retina.
17. near-sightedness: eyeball is too long and light converges in front of the retina.
18. internal elastic fibers and suspensory ciliary ligaments.
19. an inherent tendency to bulge.
20. collagen IV and glycoprotein.
21. lens cells are produced from the germinal center on the side of the lens, which then migrate from the germinal zone, lose their nucleus, and become transparent.
22. age-related loss of lens resting convexity caused by loss of elasticity.
23. reduction of vision due to opacity of lens.
24. zonule fibers that extend from ciliary body to the equatorial perimeter of the lens.
25. maintain resting tension and decrease convexity of the lens via outward tension.
26. ciliary muscle.
27. the tension in the suspensory ligaments decreases, which allows the lens to increase its elasticity and convexity.
28. deep to the cornea, partitioned by the iris.
29. formed by the ciliary processes, secreted into the anterior and posterior chambers.
30. absorbs the aqueous humor into veins.
31. a buildup of fluid pressure due to inadequate drainage into Schlemm's canal.
Monday, April 20, 2009
organ systems III: visual system part 1
this lecture looked at the basic features of the eye; bones, muscles, and nerves. the orbital cavity is a spherical space that houses the eyeball which is composed of many different bones: frontal, maxilla, zygoma, ethmoid, palatine, sphenoid, lacrimal. the orbital cavity is expressly designed such that the eyes are facing forward and parallel to each other, making the line of sight parallel with the ground. the eye itself only takes up 1/3 of the orbital cavity; the rest of the cavity is filled with muscle, periorbital fat, nerves, and fascia. the fascia that surrounds the eye and suspends it above the floor of the orbital cavity is called the fascia bulbi.
a few more anatomical notes: the corners of the eyes are called the inner and outer canthus. the tarsal plates are dense connective tissue that line the eyelids, and contain tarsal glands which secrete mucus to moisten the eyeballs. the superior and inferior fornices are the space on the insides of the eyelids, which are lined with the conjunctiva, a thin covering which also lines the sclera. the lacrimal apparatus produces tears in the upper lateral edge of the orbital cavity, which migrate across the eye, then drain into through the puncta (skin pores) into the lacrimal canaliculi, which collects into the lacrimal sac, which drains into the nasolacrimal duct, which opens up into the inferior meatus (which is why crying instantaneously produces a runny nose).
eye movements are mediated by 6 muscles. the superior rectus produces a elevation / adduction motion, the inferior rectus produces depression and adduction. the medial rectus adducts and the lateral rectus abducts. the superior oblique, which hooks around the trochlea and approaches the eyeball obliquely, depresses and abducts the eye, while the inferior oblique, which originates from the medial orbital cavity floor, elevates and abducts the eye. the superior, medial, inferior rectus, the levator palpabrae, and inferior oblique are all innervated by the oculomotor nerve (CN III). the superior oblique is innervated by the trochlear nerve (CN IV), and the lateral rectus is innervated by the abducens nerve (CN VI).
questions
anatomical features...
1. what are the bones of the orbital cavity?
2. what are the bones of the orbital cavity designed for?
3. how much of the orbital cavity does the eyeball occupy?
4. what is in the remaining space of the orbital cavity?
5. what is the fascia bulbi?
6. what muscle closes and constricts the eyelids?
7. what is the name for the corners of the eyes?
8. what are the tarsal plates?
9. what are tarsal glands and what do they do?
10. what is the conjunctivum?
11. describe the lacrimal apparatus.
12. where do the tears secreted by the lacrimal glands drain into?
eye movements...
13. what are the muscles that control eye movement?
14. superior oblique hooks around...
15. inferior oblique originates from...
motion of...
16. superior rectus...
17. inferior rectus...
18. medial rectus...
19. lateral rectus...
20. superior oblique...
21. inferior oblique...
nerves...
22. where do the nerves to the eye enter the orbital cavity?
23. what are the motor nerves that innervate the eye muscles?
24. what is the sensory nerve that innervates the eyeball and orbital cavity?
answers
1. frontal, maxilla, zygoma, ethmoid, palatine, sphenoid, lacrimal.
2. to orient the eyes in a forward position (so that vision is parallel to the ground)
3. 1/3
4. muscles, fascia, nerves, periorbital fat.
5. the CT sheath that surrounds the eyeball and suspends it off of the orbital floor.
6. orbicularis oculi.
7. the inner and outer canthus.
8. dense CT that support the eyelids.
9. glands within the tarsal plates that secrete mucus to moisten the eyes.
10. the lining of the superior and inferior fornices and covering of the sclera.
11. lacrimal glands in the upper lateral recesses of the eye secretes tears into the superior fornix.
12. puncta (skin pores), canaliculi and lacrimal sac, nasolacrimal duct, inferior meatus.
13. the four rectuses (superior, inferior, lateral, medial), superior and inferior oblique, and levator palpabrae superioris.
14. trochlea
15. medial orbital floor.
16. elevation and adduction
17. depression and adduction
18. adduction
19. abduction
20. depression and abduction
21. elevation and abduction
22. the superior orbital fissure.
23. oculomotor (CN III) innervates the superior, inferior, medial rectus, inferior oblique, levator palpebrae superioris. trochlear (CN IV) innervates the superior oblique. abducens (CN VI) innervates the lateral rectus.
24. trigeminal (V1)
a few more anatomical notes: the corners of the eyes are called the inner and outer canthus. the tarsal plates are dense connective tissue that line the eyelids, and contain tarsal glands which secrete mucus to moisten the eyeballs. the superior and inferior fornices are the space on the insides of the eyelids, which are lined with the conjunctiva, a thin covering which also lines the sclera. the lacrimal apparatus produces tears in the upper lateral edge of the orbital cavity, which migrate across the eye, then drain into through the puncta (skin pores) into the lacrimal canaliculi, which collects into the lacrimal sac, which drains into the nasolacrimal duct, which opens up into the inferior meatus (which is why crying instantaneously produces a runny nose).
eye movements are mediated by 6 muscles. the superior rectus produces a elevation / adduction motion, the inferior rectus produces depression and adduction. the medial rectus adducts and the lateral rectus abducts. the superior oblique, which hooks around the trochlea and approaches the eyeball obliquely, depresses and abducts the eye, while the inferior oblique, which originates from the medial orbital cavity floor, elevates and abducts the eye. the superior, medial, inferior rectus, the levator palpabrae, and inferior oblique are all innervated by the oculomotor nerve (CN III). the superior oblique is innervated by the trochlear nerve (CN IV), and the lateral rectus is innervated by the abducens nerve (CN VI).
questions
anatomical features...
1. what are the bones of the orbital cavity?
2. what are the bones of the orbital cavity designed for?
3. how much of the orbital cavity does the eyeball occupy?
4. what is in the remaining space of the orbital cavity?
5. what is the fascia bulbi?
6. what muscle closes and constricts the eyelids?
7. what is the name for the corners of the eyes?
8. what are the tarsal plates?
9. what are tarsal glands and what do they do?
10. what is the conjunctivum?
11. describe the lacrimal apparatus.
12. where do the tears secreted by the lacrimal glands drain into?
eye movements...
13. what are the muscles that control eye movement?
14. superior oblique hooks around...
15. inferior oblique originates from...
motion of...
16. superior rectus...
17. inferior rectus...
18. medial rectus...
19. lateral rectus...
20. superior oblique...
21. inferior oblique...
nerves...
22. where do the nerves to the eye enter the orbital cavity?
23. what are the motor nerves that innervate the eye muscles?
24. what is the sensory nerve that innervates the eyeball and orbital cavity?
answers
1. frontal, maxilla, zygoma, ethmoid, palatine, sphenoid, lacrimal.
2. to orient the eyes in a forward position (so that vision is parallel to the ground)
3. 1/3
4. muscles, fascia, nerves, periorbital fat.
5. the CT sheath that surrounds the eyeball and suspends it off of the orbital floor.
6. orbicularis oculi.
7. the inner and outer canthus.
8. dense CT that support the eyelids.
9. glands within the tarsal plates that secrete mucus to moisten the eyes.
10. the lining of the superior and inferior fornices and covering of the sclera.
11. lacrimal glands in the upper lateral recesses of the eye secretes tears into the superior fornix.
12. puncta (skin pores), canaliculi and lacrimal sac, nasolacrimal duct, inferior meatus.
13. the four rectuses (superior, inferior, lateral, medial), superior and inferior oblique, and levator palpabrae superioris.
14. trochlea
15. medial orbital floor.
16. elevation and adduction
17. depression and adduction
18. adduction
19. abduction
20. depression and abduction
21. elevation and abduction
22. the superior orbital fissure.
23. oculomotor (CN III) innervates the superior, inferior, medial rectus, inferior oblique, levator palpebrae superioris. trochlear (CN IV) innervates the superior oblique. abducens (CN VI) innervates the lateral rectus.
24. trigeminal (V1)
Subscribe to:
Posts (Atom)