Orbit and Extraocular Muscle Testing Pt. 1 Flashcards
1
Q
What are the three layers of the eyeball?
A
- ) Outter = Sclera & Cornea
- ) Middle = Choroid, ciliary body, iris
- ) Inner = Retina
2
Q
Tough, white fibrous layer into which the extraocular muscles insert
A
Sclera
3
Q
Transparent anterior portion of the outter layer of the eyeball
A
Cornea
4
Q
The middle layer of the eyeball is composed of the
A
Choroid, ciliary body, and the iris
5
Q
The vascular layer of the eyeball
A
Choroid
6
Q
Made up of the ciliary muscle and the ciliary process
A
Ciliary body
7
Q
Smooth muscle for accommodation of the lense
A
Ciliary Muscle
8
Q
Secretes aqueous humor
A
Ciliary processes
9
Q
The pigmented region that contains smooth muscle that controls the size of the pupil
A
Iris
10
Q
Which two smooth muscles control size of the pupil?
A
Dilator papillae and sphincter papillae
11
Q
Contains the visual receptor cells (rods and cones) and nerve cells of the visual pathway
A
Retina
12
Q
The region of the retina from which all of the nerve fibers emerge to form the optic nerve is the
A
Optic disk
13
Q
There are no receptors in the optic disk, hence it is referred to as the
A
“Blind Spot”
14
Q
The region of the retina with the greatest density of cone (receptor) cells is the
A
Fovea
15
Q
The fovea is located
A
Slightly lateral to the optic disk
16
Q
The fovea is in the center of a pigmented area known as the
A
Macula lutea (yellow spot)
17
Q
When viewing an object, the eye is positioned so that the light from the object is positioned on the
-gives greatest accuity of vision
A
Fovea (central vision)
18
Q
Obtained from light striking on the more peripheral parts of the retina
A
Peripheral vision
19
Q
Recignition of movement is greatest, but acuity and colorof vision is less in
A
Peripheral vision
20
Q
Suspended from the ciliary body by the suspensory ligaments
A
Lens
21
Q
Controls the shape of the lens by controlling the shape of the ciliary body
A
Ciliary muscle (a smooth muscle)
22
Q
What effect on the lens does contraction of the ciliary muscle have?
A
- Decreases radius of ciliary body
- Suspensory ligaments slack
- Lens becomes thicker and more refractive (For focus on near objects)
23
Q
Contracting the ciliary muscle causes the lens to become thicker and more refractive. This is done for focus on
A
Near objects (accommodation reflex)
24
Q
What effect on the lens does relaxation of the ciliary muscle have?
A
-Suspensory ligaments stretch the lens, thus the lens becomes thinner and less refractive
25
Relaxation of the ciliary muscle causes the lense to become thinner and less refractive. This is done for focus on
Distant objects
26
With aging, the lens loses elasticity so that even when the ciliary muscle contracts, the lens is unable to become thicker. This compromises
Near vision (presbyopia)
27
In addition to the change in the shape of the lens, the reflex response for near vision ("near reflex") includes
Constriction of the pupil by the sphincter papillae muscle and convergence of the eyes (by both medial rectus muscles)
28
The region posterior to the lens is the
Vitreous body
29
The region anterior to the lens contains the
Aqueous humor
30
The region anterior to the lens is divided into the
Anterior chamber (between cornea and iris) and posterior chamber (between iris and lens)
31
The anterior and posterior chambers communicate through the
Iris
32
Aqueous humor is secreted into the posterior chamber by the ciliary processes, passes through the pupil, and then enters venous channels in the
Anterior chamber
33
Provides nutrients and oxygen to the avascular cornea and lens
Aqueous humor
34
Excess secretion or inadequate drainage of aqueous humor will result in increased intraocular pressure and may lead to
Glaucoma
35
Occurs when light passes through the cornea, the aqueous humor, the lens, and the vitreous humor
Refraction of light
36
Greatest refraction occurs at the
Cornea
37
Abnormalities in the curvature of the cornea result in refractive errors which cause images to not focus properly on the
Retina
38
This can be corrected with
Glasses or contacts or remodelling of the shape of the cornea (LASIK)
39
The only variable component of the various refractive media and is therefore important for changing focal distances when changing gaze between near and far objects
Lens
40
Has four walls and an apex
Orbit
41
The roof of the orbit is formed mostly by the frontal bone and is related to the
Frontal sinus and the anterior cranial fossa (contains frontal lobe of the brain)
42
The floor of the orbit is formed mostly by the
Maxilla
43
The floor of the orbit is formed mostly by the maxilla and is related to the
Maxillary sinus
44
The medial wall of the orbit is formed mostly by the
Ethmoid and Sphenoid bones
45
The medial wall of the orbit is formed mostly by the ethmoid and sphenoid bones and is related to the
Ethmoid air cells and nasal cavity
46
The lateral wall of the orbit is formed mostly by the
Zygoma and sphenoid bones
47
The lateral wall of the orbit is formed mostly by the zygoma and sphenoid bones and is related to the
Temporal fossa and middle cranial fossa (contians temporal lobe of brain)
48
Contains the temporal lobe of the brain
Middle cranial fossa
49
The posterior openings of the orbit are the
Optic canal, superior orbital fissure, and inferior orbital fissure
50
The optic canal communicates with the middle cranial fossa and conveys the
Optic nerve and opthalmic artery
51
The superior orbital fissure communicates with the middle cranial fossa and conveys the
Superior opthalmic vein and CN III, IV, V1, and VI
52
The superior orbital fissure communicates the superior opthalmic vein to the
Cavernous sinus
53
The inferior orbital fissure communicates with the
Infratemporal fossa (lateral) and pterygopalatine (medial)
54
The inferior orbital fissure communicates with the infratemporal fossa and the pterygopalatine fossa and conveys the
Inferior opthalmic vein, the infraorbital nerve (V2) and the Zygomatic Nerve (V2)
55
The opthalmic veins (emissary veins) communicate with the
Veins of the face, cavernous sinus, and pterygoid venous plexus
56
Emissary veins that can be important pathways for the spread of infection from the face to deeper intracranial or extracranial regions
Opthalmic veins
57
On the anterior surface of the orbit are the
Supraorbital and infraorbital foramen
58
The supraorbital foramen conveys the
Supraorbital nerve, artery, and vein
59
The anterior opening of the infraorbital groove and canal of the floor of the orbit
Infraorbital foramen
60
The infraorbital foramen conveys the
Infraorbital nerve, artery, and vein
61
Exit the front of the orbit but do not have any associated foramina
Supratrochlear nerve (from frontal nerve) and infratrochlear nerve (from nasociliary nerve)
62
Located on the superolateral wall of the orbit and secretes lacrimal fluid through multiple ducts into the conjunctival sac
Lacrimal gland
63
The lacrimal gland secretes lacrimal fluid through multiple ducts into the
Conjunctival sac
64
Lacrimal fluid flows across the lacrimal sac from
Lateral to Medial
65
Lacrimal fluid flows across the lacrimal sac from lateral to medial (with assistance of movement of eyelids) to the medial angle of the eye where it drains into the
Lacrimal canaliculi
66
The lacrimal canaliculi lead into the
Nasolacrimal duct
67
Whatever lacrimal secretion doesn't evaporate from the conjunctival sac is drained through the nasolacrimal duct into the
Nasal cavity
68
From the nasal cavity it can pass into the
Nasopharynx and be swallowed
69
Receives both parasympathetic and sympathetic innervation
Lacrimal gland
70
The parasympathetic pathway of the lacrimal gland includes
Preganglionic fibers from facial nerve and post ganglionic fibers from pterygopalatine ganglion
71
The parasympathetic innervation has a secremotor function, meaning it stimulates
Secretion from the gland
72
The sympathetic pathway of the lacrimal gland includes
Preganglionic fibers that arrise from T1 and postganglionic fibers from superior cervical ganglion
73
The sympathetic function of the lacrimal gland serves the function of
-can modify composition of lacrimal fluid
Vasoconstriction
74
What are the 7 extraocular muscles of the eye?
1. )Levator palpebra superioris
2. ) Superior rectus
3. ) Inferior rectus
4. ) Superior oblique
5. ) Inferior oblique
6. ) Lateral rectus
7. ) Medial rectus
75
Six of the seven extraocular muscles attach tot he eyeball, but only 1 attaches to the eyelid, which one?
Levator palpebrae superioris
76
Which four of the extraocular muscles that are attached to the eyeball originate from a common ring tendon?
Superiot, inferior, lateral, and medial rectus muscles
77
The superior oblique muscle originates from the wall of the orbit near the back
Wall of the orbit near the back
78
The inferior oblique muscle originates from the
Front of the orbit
79
The four rectus muscles insert on the
Front half of the eyeball
80
The two oblique muscles insert on the
Back half of the eyeball
81
The tendon of the superior oblique muscle passes through a fibrocartilage pulley known as the
Trochlea
82
The lateral rectus muscle is innervated by the
Adducens nerve
83
The superior oblique muscle is innervated by the
Trochlear nerve (IV)
84
All other extraocular muscles are innervated by the
Oculomotor nerve (III)
85
What happens when the superior rectus and inferior oblique contract together?
Elevation of the eyeball
86
What happens when the inferior rectus and superior oblique contract together?
Depression of the eyeball
87
The levator palpebrae superioris is composed of two parts, a skeletal muscle part and a smooth muscle part. What is each innervated by?
1. ) Skeletal muscle part = Oculomotor nerve (III)
| 2. ) Smooth muscle part = sympathetic nerves
88
Drooping of the eyelid
Ptosis
89
Ptosis can be caused by either a
CN III lesion or a sympathetic lesion
90
When testing the extraoccular muscles, how can we test the superior and inferior rectus muscle?
Ask the patient to elevate (SR) and depress (IR) the eye from an abducted position
91
When testing the extraocular muscles, how can we test the superior and inferior oblique muscles?
Ask the patient to depress (SO) and elevate (IO) the eyeball from the adducted position
