Anatomy Flashcards
(154 cards)
1
Q
What are the features of the bony orbit?
A
Apex=optic canal, roof, medial wall, lateral wall, floor
2
Q
What is the base?
A
Clinically known as orbital rim. Combined orbital margins
3
Q
What protects the eyes from a direct blow?
A
Orbital margins
4
Q
What is an orbital blowout fracture?
A
A traumatic deformity of the orbital floor or medial wall, typically resulting from impact of a blunt object larger than the orbital aperture, or eye socket
5
Q
What aspect of the medial wall and orbital floor put them at risk of an orbital blowout fracture?
A
They are extremely thin
6
Q
In an orbital blowout fracture what can happen to the orbital contents?
A
It can become trapped
7
Q
In an orbital blowout fracture what can happen to the infraorbital NVB?
A
It can be damaged
8
Q
What is the external layer of the eyelid?
A
Orbicularis oculi- orbital and palpebral part (superior and inferior)
9
Q
What is the orbital septum made up of?
A
Sheet of fascia
10
Q
Where are the tarsal glands found?
A
Embedded in the tarsi
11
Q
What do the tarsal glands secrete?
A
Lipids
12
Q
What is the iris covered by?
A
Cornea
13
Q
What is the punctum?
A
Opening for tears
14
Q
What does the conjunctiva do in terms of foreign bodies?
A
Forms a defensive barrier to FBs penetrating deep into the orbit
15
Q
What does the lacrimal gland produce?
A
Lacrimal fluid
16
Q
Where is the lacrimal gland located?
A
In the lacrimal fossa of the orbit-superolateral to the eye
17
Q
What is the innervation of the lacrimal gland?
A
CNVII parasympathetic
18
Q
Where are tears collected?
A
Lacrimal sac
19
Q
What happens to lacrimal fluid when it’s produced?
A
Washes over eye, pushed towards medial angle, draims through lacrimal puncta, eventually reaches inferior meatus
20
Q
Through what duct do tears drain through?
A
Nasolacrimal duct
21
Q
What are the 3 layers of the eye?
A
Fibrous, uvea, retina
22
Q
What is the outer layer of the eye?
A
Fibrous
23
Q
What are the 2 parts of the fibrous layer?
A
Sclera-muscle attachment, cornea-2/3 refractive power
24
Q
What is the middle layer of the eye?
A
Uvea (vascular layer)
25
What are the 3 parts of the uvea?
Iris-pupil diameter, ciliary body-controls iris, shape of lens and secretion of aqueous humour, choroid-nutrition and gas exchange
26
What is the inner layer of the eye?
Retina (photosensitive)
27
What are the segments of the eye?
Anterior and posterior
28
What makes up the anterior segment?
Anterior chamber and posterior chamber
29
What is the anterior chamber?
Chamber of eye beween cornea and iris, contains aqueous humour
30
What is the posterior chamber?
Chamber of eye between iris and suspensory ligaments, contains aqueous humour
31
What is the posterior segment?
Segment of eye behind lens. Contains vitreous body
32
What is contained with the vitreous body?
Vitreous humour (holds choroid and retina against sclera)- common location for 'floaters'
33
What is a cataract?
Clouding of the lens
34
What is the circulation pathway of aqueous humour?
Ciliary body> aqueous circulates within posterior chamber> aqueous then passes through pupil into anterior chamber> aqueous reabsorbed into scleral venous sinus at iridocorneal angle
35
What does the ciliary body do?
The ciliary processes secrete aqueous
36
What can raised Intra-ocular pressure cause?
Ischaemia of the retina
37
What is the fundus?
Posterior area where light is focused
38
What is within the fundus?
Optic disc, macula, fovea
39
What is significant about the optic disc?
Point of CNII formation, only point of entry/exit for blood vessels and CNII axons, blind spot to light
40
What is significant about the macula?
It has the greatest density of cones in the eye
41
Where is the fovea located?
Centre of the macula
42
What is the fovea?
Depression of 1.5mm diameter- the area of most acute vision
43
What does complete interruption of flow in a retinal artery branch/retinal vein cause?
Loss of an area of visual field corresponding to the area of ischaemia
44
What does complete interruption of the central (end) artery or vein cause?
Monocular blindness
45
What are the 3 layers of the retina and their position?
The photoreceptors, ganglion cells lie anterior to the photoreceptor cells , axons of ganglion cells lie anterior to the ganglion cells and photoreceptor cells
46
Where do the retinal veins and arteries lie in relation to the retina?
Anteriorly
47
What part of your brain will light from the right visual field be processed?
Left primary visual cortex
48
Where is light from objects in the lower visual field processed by?
Upper part of the primary visual cortex
49
What is the visual pathway?
R/L visual field>lens>retina> optic nerve> optic chiasm> lateral geniculate nucleus (LGN), primary visual cortex
50
Light from objects passing through which retina will cross over at the optic chiasm?
Nasal retina
51
Where is the central (end) artery of the retina?
Within the optic nerve
52
What is the significance of the central vein of the retina?
It is the only vein draining the retina (and is located within optic nerve)
53
What is the danger triangle?
Danger area for bacterial infection/squeezing spots etc. From upper lip/external nose to between eyebrows
54
Where does the inferior ophthalmic vein drain into?
Mainly into superior ophthalmic vein
55
Where does the orbit also drain into?
Anteriorly into the facial vein
56
How many extraocular muscles do we have?
7
57
What are the 4 rectus muscles?
Superior rectus, inferior rectus, medial rectus, lateral rectus
58
Where do all the rectus muscles originate and insert?
All originate from common tendinous ring, all insert onto sclera
59
What are the 2 oblique muscles?
Superior oblique and inferior oblique
60
Where do the oblique muscles insert?
Sclera
61
What does the leator palpebrae superioris do?
Lifts the upper eyelid
62
How can you remember the somatic motor innervation of EO muscles?
LR6 SO4 AO3 - Lateral rectus: CNVI, Superior Oblique: CNIV, All Others: CNIII
63
What movements can the eyeball make on the vertical axis?
Abduction/adduction-direction of gaze
64
What movements can the eyeball make on the transverse axis?
Elevation/depression-direction of gaze
65
What movements can the eyeball make on the anteroposterior axis?
Intorsion (medially)/extorsion (laterally)-superior pole of eyeball
66
What is the direction of your optical axis?
Straight forward (different to orbital axis)
67
Why do muscles of the eye usually have multiple movements?
Due to angle of attachment based on orbital canal position
68
True or false: The orbital septum lies just anterior to the orbicularis oculi muscle.
False
69
The tear film has antibacterial properties due to...?
Action of lysozyme
70
At what rate is the tear film produced by the lacrimal gland?
A constant rate
71
What is the pH of tears?
7.6
72
What is the conjunctiva composed of?
Palpebral and bulbar parts
73
What part of the conjunctiva is more vascular?
Bulbar
74
Where is the cornea thinnest?
In the middle(check)
75
How thick is the cornea?
540 microns thick
76
What does the stroma of the cornea contain?
Regularly spaced collagen fibres
77
How does the endothelium maintain transparency of the cornea?
By pumping fluid into the stroma
78
What is the lens attached to the ciliary body by?
Zonules
79
What does a decrease in tension of zonular fibres allow for?
Near focussing
80
Do the lens fibres have good or bad lens regeneration properties?
Bad
81
What is the outermost part of the lens known as?
The cortex
82
What is the uvea composed of?
Iris, ciilary body and choroid
83
What is the uvea's role in absorbing reflected light in the eye?
It has none
84
What is the suspensory ligament?
A thick fascial sling that holds the eye just above the floor or the orbit
85
Where does the suspensory ligament attach to?
Zygoma laterally
86
What may result in the eye lowered towards the orbital floor?
Fractured zygoma. Diplopia may occur
87
What can damage to the infraorbital NVB?
Fractured zygoma
88
What can damage to the infraorbital NVB result in?
A general sensory deficit of facial skin
89
Where will a fractured zygoma tend to rotate?
Rotate medially towards floor of the orbit
90
What does CNV1 supply (general sensory)?
Upper eyelid, cornea, conjuctiva, forehead, skin of root/bridge/tip of nose
91
What does CNV2 supply (general sensory)?
Skin of lower eyelid, skin over maxilla, skin of ala of nose, skin mucosa of upper lip
92
What is the general sensory supply of the angle of the mandible?
Greater auricular nerve-branch of C2/3 spinal nerves
93
When a blink (corneal) reflex occurs how are APs conducted centrally?
Centrally via CNV1 to trigeminal ganglion then in CNV5 to pons
94
When a blink reflex occurs how are APs conducted peripherally?
Peripherally in CNVII to the eyelid part of orbicularis oculi
95
How can a blink be elicited?
Sterile point of cotton wool, gently touch the cornea
96
What is the space inbetween the pre-tracheal and prevertebral fascia?
Retropharyngeal space
97
What ganglion of the sympathetic cervical chain is associated with supply to the orbit?
Superior
98
What often fuses to form the stellate ganglion?
Inferior cervical and 1st thoracic ganglia
99
What cranial nerves contain parasympathetic axons?
CNIII,VII,IX,X
100
What ganglion does the CNIII parasympathetic axons synapse with and then supply ?
Ciliary ganglion in the orbit, and then to the eye
101
Where does CNIII connect with the CNS?
Near the midline at the junction between the midbrain and pons
102
Where does CNIII leave the cranial cavity?
Superior orbital fissure
103
What branches of CNIII come through the superior orbital fissure?
Superior and inferior
104
What does the superior branch of CNIII supply?
SR and LPS
105
What does the inferior branch of CNIII supply?
MR, IR, IO and ciliary ganglion (parasympathetic supply)
106
What plexus supplies the orbit?
Internal carotid plexus
107
What nerve do sympathetic axons travel in post optic canal and ciliary ganglion(do not synapse here)?
Long and short ciliary nerve
108
What nerve do parasympathetic axons travel post ciliary ganglion?
Short ciliary nerve
109
What do autonomic axons from the ciliary nerves do?
Control the diameter of the iris (and pupil) & the refractive shape of the lens
110
What do the long ciliary nerves form the first part of?
The afferent limb of the blink reflex
111
What are the autonomic reflexes of the eye?
Wide eye opening of fight or flight, light reflex, accomodation reflex, reflex tear production, vestibulo-ocular reflex, oculocardiac reflex
112
What CNS connections occur in the vestibulo-ocular reflex?
CNVIII & CNs III,IV, VI
113
What is the oculocardiac reflex?
Reflex bradycardia in response to tension on the extraocular muscles or pressure on the eye
114
What CNS connections occur in the oculocardiac reflex?
CNV1 and CNX
115
What are the sympathetic eye functions?
Open wider, get more light into eye, focus on far objects, emotional lacrimation
116
What are the parasympathetic eye functions?
Allow orbicularis oculi to work, get less light into eyes, focus on near objects, reflex lacrimation
117
What kind of muscle is levator palpebrae superioris?
Skeletal and smooth
118
What muscle dilates the pupil?
Dilatory pupillae fibres
119
What is the insertion of the dilator pupillae fibres?
All around the internal circumference of iris (mobile)
120
What is the origin of the dilator pupillae fibres?
All around the external circumference of iris (fixed_
121
What is the reflex in the stimulated eye?
The direct light reflex
122
What is the reflex in the non-stimulated eye?
The consensual light reflex
123
What is the special sensory limb of the light reflex?
The ipsilateral CNII
124
What is the motor limb of the light reflex?
Bilateral via CNs III
125
How many neurone chains in the light reflex?
4
126
What is the 1st neurone chain in the light reflex ?
Retinal ganglion cells pass via ipsilateral optic nerve to decussate in optic chiasm, then synpase in the pretectal nucleus of midbrain
127
What is the 2nd neurone chain (Bilateral) in the light reflex ?
Located entirely within midbrain and connect the pretectal nucleus to the next synapse in the Edinger Westphal nucleus (location of cell bodies of parasympathetic axons of CNIII)
128
What is the 3rd neurone chain (Bilateral) in the light reflex ?
Pass from EW nucleus, via CNII then its inferior division, to synpase in the ciliary ganglion
129
What is the 4th neurone chain (Bilateral) in the light reflex ?
Course in the short ciliary nerves to the sphincter pupillae muscles
130
How is the refractive shape of the lens controlled in far vision?
Ciliary muscle relaxes in far vision, ligament tightens and lens flattens to focus on object in distance
131
How is the refractive shape of the lens controlled in near vision?
Ciliary muscle contracts in near vision, ligament relaxes and lens becomes spherical to focus on object nearby
132
What components of the accomodation reflex (response to near) are assessed?
Bilateral pupillary constriction (CNs III), bilateral convergence -medial rotation of both eyes (CNs III), bilateral relaxation of lens-lens becomes spherical due to contraction of ciliary muscles (CNsIII)
133
What are the 3 types of tears?
Basal, reflex, emotional
134
What do basal tears do and contain?
Clean/nourish and hydrate avascular cornea. Contains lysozyme (hydrolyse bacterial cell walls)
135
What are reflex tears?
Extra tears in response to mechanical or chemical stimulatioon
136
What do postsynaptic sympathetic fibres reach levator palpebrae superioris via?
Superior cervical sympathetic ganglion, internal carotid nerve and plexus, axons are carried on ophthalmic artery and on its branches to orbital structures
137
Do sympathetics dilate or constrict the pupil?
Dilate
138
What is a non-physiologically enlarged pupil?
Mydriatic pupil
139
What do mydriatic drugs do?
Induce dilation of the pupil
140
Do parasympathetics constrict or dilate the pupil?
Constrict
141
What is a non-physiologically constricteed pupil?
Miotic pupil
142
What is a fixed dilated (blown) pupil a sign of?
Pathological injury-CNIII pathology (inhibting the pupillary constriction action of parasympathetic axons in ciliary nerves)
143
Where is the encircling arrangement of sphincter pupillae fibres?
All around the internal circumference of iris
144
What are the afferent and efferent limbs of lacrimation of reflex tears?
Afferent is CNV1 from cornea/conjunctiva. Efferent is parasympathetic axons originating from CNVII
145
The presynaptic parasympathetic axons for what are contained with the chorda tympani?
Submandibular and sublingual glands
146
Is the intracranial volume constant or varied?
Constant
147
What 3 membranes make up the meninges?
Dura, arachnoid, pia
148
What is the space between arachnoid and pia?
Sub-arachnoid space
149
What are the meninges?
Protective coverings of brain and spinal cord
150
Describe the dura mater
'Hard mother', tough, sensory supply from CNV, encloses dural venous sinuses
151
Describe the arachnoid mater
'Spidery mother', arachnoid granulations
152
What is within the subarachnoid space?
Circulating CSF and blood vessels
153
Describe the pia
'Faithful mother', adheres to brain (and vessels and nerves entering/leaving)
154
Where is CSF reabsorbed into?
Into the dural venous sinuses, via arachnoid granulations
