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26 Cards in this Set
- Front
- Back
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) What are the ocular muscles derived from embryologically? What type of nerve fibers innervate these muscles?
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Ocular muscles are somite derived skeletal muscle and thus are innervated by GSE fibers.
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What type of ganglion is the ciliary ganglion? What nerve is it attached to? What is the function of this ganglion?
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Ciliary Ganglion:
- Presynaptic autonomic fibers from inferior division of Oculomotor n. (CN III) - Postsynaptic parasympathetic fibers carried by short ciliary nerves to supply ciliary muscle (accommodation of lens) and sphincter pupillae (constriction of pupil) - Postsynaptic sympathetic fibers carried by long ciliary nerves to dilator pupillae - located between optic n. (CN II) and lateral rectus, close to apex of orbit |
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Why are the anastomoses between the facial vein and ophthalmic veins of such great clinical importance?
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The facial vein is important clinically because it has a direct connection to the ophthalmic vein and then to a deep venous sinus within the cranial cavity, the cavernous sinus. Bacteria can enter the facial vein and gain access to internal cranial structures resulting in infection there. This is probably the reason our mothers always said not to squeeze our pimples.
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What larger vessel is the ophthalmic artery a branch off of? Why is occlusion of the central artery of the retina of great clinical concern?
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Opthalmic a. is a branch of the Internal Carotid A.
Central Retinal Artery: terminal branches are end arteries; obstruction by emboli results in instant blindness. Extent of blindness determined by area normally supplied by blockage. |
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What is the anatomical name for the eyeball?
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bulbus oculi
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What structures comprise the external (fibrous) coat of the eyeball? The middle coat? The internal coat?
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External Coat
Sclera: opaque part of the fibrous coat covering the posterior 5/6 of the eyeball; anterior part of sclera visible through transparent bulbar conjunctiva as “white of the eye” Cornea: transparent part of the fibrous coat covering the anterior 1/6 of the eyeball Middle (Vascular) Coat Choroid: dark brown membrane between the sclera and the retina; forms largest part of vascular layer and lines most of the sclera Ciliary body: muscular as well as vascular; connects choroid with circumference of the iris; folds on internal surface (ciliary processes) secrete aqueous humor Iris: lies on anterior surface of lens; thin contractile diaphragm with a central aperture (pupil) for transmitting light; Internal (Retinal) Coat – compose optic retina Outer layer (pigmented cells) Inner layer (nervous cells) |
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What are the four refractive media of the eye?
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Cornea:
- circular area of the anterior part of the outer fibrous coat of the eyeball - largely responsible for refraction of light that enters eye; transparent, avascular and sensitive to touch - supplied by opthalmic nerve (CN V1) - nourished by aqueous humor, lacrimal fluid, oxygen absorbed from air, peripheral capillaries Aqueous humor: - produced by ciliary processes - watery solution that provides nutrients for avascular cornea and lens - drains into scleral venous sinus after passing through posterior chamber to anterior chamber Lens: - posterior to iris and anterior to vitreous humor - transparent biconvex structure enclosed in a capsule - changes shape due to contraction of ciliary muscle to accommodate near and far vision Vitreous body: - transparent jelly-like substance filling interior of eyeball - holds retina in place and supports lens |
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What is the "nerve" of vision? Why is this nerve really a brain tract?
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Optic Nerve (CN II) → Nerve of Vision
- The optic nerve is the second of twelve paired cranial nerves but is considered to be part of the central nervous system as it is derived from an outpouching of the diencephalon during embryonic development. Consequently, the fibers are covered with myelin produced by oligodendrocytes rather than the Schwann cells of the peripheral nervous system. This is an important issue, as fiber tracks of the mammalian central nervous system (as opposed to the peripheral nervous system) are incapable of regeneration and hence optic nerve damage produces irreversible blindness. The fibers from the retina run along the optic nerve to nine primary visual nuclei in the brain, from whence a major relay inputs into the primary visual cortex. |
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Which structure gives the eye its globular shape?
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External coat
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What is the function of the lens?
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The convexity of the lens (particularly the anterior surface) varies with contraction of the ciliary muscle in order to change the focal point such that the entering light is focused on the retina to accommodate both near and far vision.
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To which structure of the eyeball do the ocular muscles insert?
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Sclera
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The cornea is continuous with which structure?
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Sclera
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What artery does the central artery of the retina arise from? Why is it often considered an "end" artery?
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Central Retinal Artery: branch of Opthalmic a.; terminal branches are end arteries; only blood supply to most of retina; obstruction by emboli results in instant blindness. Extent of blindness determined by area normally supplied by blockage.
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To where does the central vein of the retina usually drain?
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Central retinal vein usually drains to cavernous sinus directly but it may join one opthalmic vein.
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What is meant by the terms "binocular" vision and "stereoscopic" vision? Which animals possess one or both of these? Why do you think these abilities may have evolved?
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Binocular vision is vision in which both eyes are used together. The word binocular comes from two Latin roots, bin for two, and oculus for eye. Having two eyes confers at least four advantages over having one. First, it gives a creature a spare eye in case one is damaged. Second, it gives a wider field of view. For example, a human has a horizontal field of view with one eye of about 150 degrees and with two eyes of about 180 degrees. Third, it gives binocular summation in which the ability to detect faint objects is enhanced. Fourth it can give stereopsis in which parallax provided by the two eye's different positions on the head give precise depth perception. Such binocular vision is usually accompanied by singleness of vision or binocular fusion, in which a single image is seen despite each eye's having its own image of any object.
FOUND IN CARNIVOROUS HUNTERS Stereopsis is the process in visual perception leading to perception of the depth or distance of objects. It comes from two Greek roots, stereo meaning solidity, and opsis meaning vision or sight. That means it could refer to any sort of visual depth perception, but since about the 1960s it has come to refer to depth perception from binocular vision, requiring two eyes. Prior to then, it was often referred to as "binocular stereopsis". INCREASED DEPTH PERCEPTION ESPECIALLY AT NEAR DISTANCES FOR USE WITH TOOLS. FOUND ONLY IN HIGHER PRIMATES/HUMANS |
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What muscles form the boundaries of the posterior triangle of the neck?
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Anterior: Sternocleidomastoid muscle (posterior border)
Posterior: Trapezius muscle (anterior border) Inferiorly: Clavicle (middle third) |
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What does the external jugular vein drain into? What are its main tributaries?
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**reason for valves in head and neck veins: because we spend 1/3 of our lives lying down and don’t want blood rushing to our brain.
**Anterior Jugular Vein has NO VALVES because it does not pass near brain. Formed by: retromandibular v. posterior auricular v. large communicating branch of IJV Tributaries: transverse cervical v., suprascapular v., anterior jugular v. |
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What does the external jugular vein drain into? What are its main tributaries?
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**reason for valves in head and neck veins: because we spend 1/3 of our lives lying down and don’t want blood rushing to our brain.
**Anterior Jugular Vein has NO VALVES because it does not pass near brain. Formed by: retromandibular v. posterior auricular v. large communicating branch of IJV Tributaries: transverse cervical v., suprascapular v., anterior jugular v. Drains into: Subclavian v. |
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Are the nerves of the superficial posterior triangle region of branchial arch origin? If so, which ones?
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• Spinal Accessory N. (CN XI) – spinal root {5th/6th Arch Derived}
• Ventral Rami C5-T1 pass through as three trunks of brachial plexus • Ventral Rami C1-C4 present as Cervical plexus and associated nerves |
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What are the root values of the greater occipital, lesser occipital, greater auricular, transverse cervical and supraclavicular nerves? Which of these nerves are from ventral rami? Which of these nerves are from the dorsal rami?
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Greater Occipital n.: C2 Dorsal Ramus
Lesser Occipital n.: C2 Ventral Ramus Greater Auricular n.: C2-C3 Ventral Rami Transverse Cervical n.: C2-C3 Ventral Rami Supraclavicular n.: C3-C4 Ventral Rami |
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What do the greater occipital, lesser occipital, greater auricular, transverse cervical and supraclavicular nerves nerves do? What type(s) of fibers do they carry?
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Greater Occipital n. (GSA): sensory to skin of posterior neck and covering occipital bone
Lesser Occipital n. – (GSA): sensory to skin of neck and scalp posterosuperior to auricle Greater Auricular n. – (GSA): sensory to skin covering parotid gland, posterior aspect of auricle, and area extending from angle of mandible to mastoid process Transverse Cervical n. – (GSA): sensory to skin covering anterior triangle Supraclavicular n. – (GSA): sensory to skin of neck and shoulder |
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Where is the "interscalene triangle"? What structures emerge from it?
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Triangle formed. . .
Anteriorly Anterior scalene Posterior: Middle Scalene Inferior: First Rib (to which both muscles attach) Structures: Three trunks of brachial plexus Axillary Artery (but NOT vein) |
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What is meant by the term "entrapment neuropathy"? How would this relate to the interscalene triangle region?
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entrapment neuropathy: any of a group of neuropathies in which a peripheral nerve is injured by compression in its course through a fibrous or osseofibrous tunnel or at a point where it abruptly changes its course through deep fascia over a fibrous or muscular band. Examples include carpal tunnel syndrome, cubital tunnel syndrome, meralgia paresthetica, Morton's neuralgia, musculospiral paralysis, pronator syndrome, and tarsal tunnel syndrome. Called also nerve compression syndrome, compression n., and pressure n.
Relevant in case of interscalene region because anatomical variations (i.e. additional muscle slips, accessory cervical rib, or exostosis (bony spur or outgrowth) on the first rib could narrow the passage through this area resulting in an entrapment neuropathy involving the brachial plexus. Could also cause ischemia due to compression of Axillary artery. |
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What is the function of the omohyoid muscle?
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Omohyoid muscle: depresses, retracts, and steadies hyoid bone
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What are the boundaries of the anterior triangle of the neck?
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Anterior – median line of neck
Posterior – anterior border of Sternocleidomastoid muscle Superior – inferior border of mandible Apex – jugular notch in manubrium of sternum Roof – subcutaneous tissue containing platysma muscle Floor – pharynx, larynx, and thyroid gland covered by pretracheal layer of deep cervical fascia |
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How many branches arise from the internal carotid artery in the neck? How many branches arise from the external carotid artery in the neck?
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Internal Carotid A. (0) – NO BRANCHES IN THE NECK
External Carotid A. (8) – superior thyroid a., ascending pharyngeal a., lingual a., facial a., occipital a., posterior auricular a., maxillary a., superficial temporal a. “Some anatomists like fucking; others prefer S & M.” |
