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Questions and Answers
Which arteries supply intracranial structures with blood?
Which arteries supply intracranial structures with blood?
Where do the vertebral arteries enter the cranium?
Where do the vertebral arteries enter the cranium?
What is the function of the Circle of Willis?
What is the function of the Circle of Willis?
What determines blood flow into each artery at the branch point in the Circle of Willis?
What determines blood flow into each artery at the branch point in the Circle of Willis?
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Which artery supplies the midbrain?
Which artery supplies the midbrain?
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Which vascular territory is associated with difficulty in speech and swallowing?
Which vascular territory is associated with difficulty in speech and swallowing?
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Which artery supplies the pons?
Which artery supplies the pons?
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Which vessel gives rise to the unpaired anterior spinal artery?
Which vessel gives rise to the unpaired anterior spinal artery?
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What is the 2nd most common cause of subarachnoid hemorrhage?
What is the 2nd most common cause of subarachnoid hemorrhage?
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Which artery supplies the cerebellum?
Which artery supplies the cerebellum?
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What does a stroke in the anterior spinal artery territory affect?
What does a stroke in the anterior spinal artery territory affect?
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Where does an extradural hematoma occur?
Where does an extradural hematoma occur?
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What does a stroke in the posterior spinal artery territory affect?
What does a stroke in the posterior spinal artery territory affect?
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What forms radicular arteries supplying the spinal nerve roots?
What forms radicular arteries supplying the spinal nerve roots?
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Where does a subdural hematoma occur?
Where does a subdural hematoma occur?
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What causes a cerebral embolism within the skull?
What causes a cerebral embolism within the skull?
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Which bones form the roof of the orbit?
Which bones form the roof of the orbit?
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What structures are located in the orbit's medial wall?
What structures are located in the orbit's medial wall?
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Which structure covers the sclera and is covered by the cornea?
Which structure covers the sclera and is covered by the cornea?
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What is responsible for the secretion of sebaceous and apocrine glands in the eye region?
What is responsible for the secretion of sebaceous and apocrine glands in the eye region?
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What is the function of the aqueous humor in the eye?
What is the function of the aqueous humor in the eye?
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Which structure allows the drainage of aqueous humor from the eye?
Which structure allows the drainage of aqueous humor from the eye?
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In which type of glaucoma does peripheral vision loss occur initially?
In which type of glaucoma does peripheral vision loss occur initially?
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Which cell layer in the retina absorbs excess light?
Which cell layer in the retina absorbs excess light?
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Why are cones concentrated at the fovea and rods in the periphery of the retina?
Why are cones concentrated at the fovea and rods in the periphery of the retina?
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What is the ratio of photoreceptors to ganglion cells in the periphery of the retina?
What is the ratio of photoreceptors to ganglion cells in the periphery of the retina?
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Which part of the retina has the smallest pixel size?
Which part of the retina has the smallest pixel size?
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What is the main function of the optic disc?
What is the main function of the optic disc?
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Which layer of the eye is responsible for adjusting the thickness of the lens to further refract light?
Which layer of the eye is responsible for adjusting the thickness of the lens to further refract light?
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Which muscles within the iris control the size of the pupil?
Which muscles within the iris control the size of the pupil?
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Which nerve is responsible for innervating the superior oblique muscle?
Which nerve is responsible for innervating the superior oblique muscle?
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Which nerve palsy can result in a 'down and out' eye, droopy eyelid, and large pupil?
Which nerve palsy can result in a 'down and out' eye, droopy eyelid, and large pupil?
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Which layer of the eye includes the structures responsible for controlling pupillary size and accommodation reflex?
Which layer of the eye includes the structures responsible for controlling pupillary size and accommodation reflex?
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Which muscles are responsible for positioning the eye in the orbit and balancing out unwanted movements?
Which muscles are responsible for positioning the eye in the orbit and balancing out unwanted movements?
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Which movement of the eye involves specific muscles responsible for elevation and depression?
Which movement of the eye involves specific muscles responsible for elevation and depression?
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Which nerve is responsible for innervating the lateral rectus muscle?
Which nerve is responsible for innervating the lateral rectus muscle?
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Which structure secretes aqueous humor in the eye?
Which structure secretes aqueous humor in the eye?
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Which reflex allows for adjustments in the shape and convexity of the lens to fine-tune the focus of objects on the retina?
Which reflex allows for adjustments in the shape and convexity of the lens to fine-tune the focus of objects on the retina?
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Which muscles contract with parasympathetic and sympathetic inputs to control pupillary size?
Which muscles contract with parasympathetic and sympathetic inputs to control pupillary size?
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Which structure extends anterior to the lens with a central aperture, the pupil?
Which structure extends anterior to the lens with a central aperture, the pupil?
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Study Notes
Anatomy and Functions of the Eye
- The eye is composed of three layers: fibrous, vascular, and neural tunic (sclera, choroid, and retina).
- The fibrous layer consists of the opaque sclera and the transparent cornea, which covers the anterior 1/6 of the eyeball and bends light to focus it on the fovea.
- The extraocular eye muscles, including the superior rectus, inferior rectus, medial rectus, lateral rectus, superior oblique, and inferior oblique, position the eye in the orbit and balance out unwanted movements.
- Movements of the eye are balanced through elevation and depression, with specific muscles responsible for each movement.
- Clinical testing of extraocular muscles includes abduction and adduction to align the angle of gaze with the pull of specific eye muscles.
- The innervation of the eye muscles involves the oculomotor (III), trochlear (IV), and abducens (VI) nerves, with specific muscles being controlled by different nerves.
- Nerve palsies, such as oculomotor nerve palsy and abducens nerve palsy, can result in specific clinical presentations, including "down and out" eye, droopy eyelid, and large pupil.
- The pigmented (vascular) layer of the eye includes the choroid, ciliary body, iris, and structures responsible for controlling pupillary size and accommodation reflex.
- The iris, a contractile diaphragm, extends anterior to the lens with a central aperture, the pupil, the size of which is controlled by constrictor and dilator pupillae muscles within the iris.
- The ciliary processes secrete aqueous humor and provide attachment for suspensory ligaments of the lens, while the ciliary muscle, within the ciliary body, adjusts the thickness of the lens to further refract light.
- Control of pupillary size involves the constrictor and dilator pupillae muscles, which contract with parasympathetic and sympathetic inputs, respectively.
- The accommodation reflex allows for adjustments in the shape and convexity of the lens to fine-tune the focus of objects on the retina, with the ciliary muscle playing a key role in this process.
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Description
Test your knowledge of the blood supply of the central nervous system with this quiz. Identify the sources of blood supply to intracranial structures and understand the role of the internal carotid arteries.
