Anatomy Flashcards
(123 cards)
1
Q
Insert diagram of surface anatomy
A
Iris is covered by the cornea
While sclera is covered by conjunctiva
Lacrimal lake is the most medial structure
Lacrimal papilla and puncture can be found medially on both eyelids
Pupil is at the centre of the iris
2
Q
What is the name of the corneoscelral junction
A
Limbus
3
Q
Where is the lacrimal gland located?
A
Superolateral to the eye
4
Q
What is the name for the loose arching folds connecting conjunctival membrane to the eyelid?
A
Conjunctival formix
5
Q
What part of the eye has the most refractive power?
A
Cornea
6
Q
Name the six bones that make up the orbit
A
- frontal
- zygomatic
- maxilla
- sphenoid
- lacrimal
- ethmoid
7
Q
Which bones have orbital plates?
A
Frontal, maxilla and ethmoid
8
Q
Name two bones that are thin and fracture easily
A
Maxilla and ethmoid
9
Q
What travels in the optic canal and where does it pass through?
A
Optic nerve and ophthalmic artery through the sphenoid bone
10
Q
Which cranial nerves pass through the superior orbital fissure?
A
CN III, IV, VI
11
Q
What passes through the infraorbital foramen
A
Infraorbital neurovascular bundle
-
12
Q
Describe a blow out fracture
A
Bones surrounding the orbit can withstand high amounts of pressure but this pressure can be transferred to thinner bones - maxilla and ethmoid
13
Q
Name the type of fracture where contents of the orbit pass through the fracture
A
Trap door fracture
14
Q
If the stronger bones do fracture where does it tend to occur?
A
Sutures
15
Q
What muscle makes up the eyelid?
A
Orbicularis oculi
16
Q
Name the two parts of the orbicularis oculi and what they are responsible for
A
- palpebral (gentle closure of the eye)
- orbital (tight closure of the eye)
17
Q
What nerve innervates the orbicularis oculi?
A
CN VII
18
Q
Other than the orbicularis oculi what else is the eyelid made of?
A
Tarsus - fibrous skeleton, thick bands of connective tissue superiorly and inferiorly with a palpebral ligament at either side
19
Q
Name the muscle that elevates the upper eyelid
A
Levator Palpebrae Superioris
20
Q
Where does the LPS attach?
A
To the tarsus and skin
21
Q
Which nerve supplies the LPS?
A
CN III
22
Q
What is the additional slit of smooth muscle attached to the LPS?
A
Mueller’s/superior tarsus
23
Q
What is special about Mueller’s muscle?
A
It has sympathetic supply to aid eye widening
24
Q
What do tarsal glands secrete?
A
Lipids to line the eyelid
25
Name the three layers of the eye
- Fibrous outer layer
- Vascular Layer (Uvea)
- Retina (photosensitive inner layer)
26
What are the two parts of the fibrous outer layer?
Sclera and cornea
27
What makes up the vascular layer?
Iris
Ciliary body
Choroid
28
Where is the anterior segment?
Found in front of the lens and is made of two chambers
- anterior (between cornea and iris)
- posterior (between iris and suspensory ligaments)
29
Where is the posterior segment?
Behind the lens, 2/3rds of the eye and contains vitreous humour
30
What makes people see floaters?
Clumps of collagen
31
Where is aqueous humour secreted from?
Ciliary processes
32
Describe the pathway of aqueous humour
Circulates in posterior chamber then passes through the pupil to the anterior chamber to nourish the cornea
33
Where is aqueous humour reabsorbed?
Scleral venous sinus at the iridocorneal angle
34
Describe the arterial supply to the orbit
1. ICA
2. Carotid canal
3. Ophthalmic Artery (close to optic nerve in canal)
35
Name the branches of the ophthalmic artery
- ciliary arteries
- nasal cavity branches (littles area)
- forehead (scalp branches)
- central artery of the retina
36
Describe the venous drainage of the orbit
Forehead vein, superior ophthalmic vein, inferior ophthalmic vein, central vein mainly drain into the cavernous sinus via the superior orbital fissure
37
What is special about the facial vein?
It is thought to be valveless
38
Where does light focus in the retina?
Posterior area called the fundus
39
What are the different parts of the retina?
Optic Disc, Macula, Fovea
40
What happens at the optic disc?
Entry/exit of blood vessels and CN II axons
41
What is the macula?
Central portion of the retina that has the greatest density of cones
42
What is the fovea?
Centre of the macula, area of most acute vision
43
In which direction do the retinal arteries, veins and ganglion axons lie relative to the retina?
Anterior
44
What is the blind spot?
There are no photoreceptors in the optic disc so light cannot be processed at this area
45
Where is the optic disc in relation to the eye?
Nasal aspect
46
What will interruption of the retinal artery branch result in?
Loss of an area of visual field corresponding to the area of ischaemia
47
What will interruption of the central artery/vein result in?
Monocular blindness
48
What happens to light that hits the nasal retina?
It crosses over at the optic chiasm to the opposite side of the brain
49
What happens to light that hits the temporal retina?
It stays on the same side
50
What eye movements occur in the vertical axis?
Abduction and adduction
51
What eye movements occur in the transverse axis?
Elevation and depression
52
What eye movements occur in the anteroposterior axis?
Intorsion and extorsion
53
Name the seven extra ocular muscles
- Lateral rectus
- Medial rectus
- Superior rectus
- Inferior rectus
- Inferior oblique
- Superior oblique
- LPS
54
Where do the recuts muscle come from and attach onto?
From the annulus to the sclera
55
Where does the superior oblique originate?
Sphenoid
56
Where does the inferior oblique originate?
Orbital plate of the maxilla
57
What is the way to remember the nerve supply to the extra-ocular muscles?
LR6 SO4 AO3
Lateral rectus 6
Superior oblique 4
All others 3
58
What is special about the superior oblique?
It passes through the trochlea
59
Describe the relationship between superior rectus and inferior oblique
Synergistically elevate but are antagonists as rotators
60
Describe the relationship between superior oblique and inferior rectus
Synergistically depress but are antagonists as ab/adductors
61
Where does the LPS originate and insert?
Originates form the lesser ring of sphenoid bone and inserts onto skin and tarsus of superior eyelid
62
Describe the sensory innervation to the face
CN V1 - upper eyelid, cornea, conjunctiva to top of the nose
CN V2 - skin over maxilla and lower eyelid
CN V3 - skin over mandible and TMJ (except angle of mandible)
63
Which nerves originate from CN V1?
Supraorbital and nasal skin branches
64
Which nerve originates from CNV2?
Infraorbital nerve
65
Describe the sensory component of the corneal reflex
APs from the cornea via CNV1 go to the trigeminal ganglion then CN V in the pons
66
Describe the motor component of the corneal reflex
APs from CNVII go to the palpebral part of the orbicularis oculi
67
What is the purpose of the corneal reflex?
Acts as a protective measure to clear the eye and stop anything getting into it
68
What nerves are involved in the vestibule-ocular reflex?
CN VIII, CN III, CN IV and CN VI
69
What is the oculocardiac reflex?
Reflex bradycardia in response to tension on extra ocular muscles/pressure on eye involves connections between CN V1 and CN X
70
What is the sympathetic effect on the eye?
Opens eyes wider to let more light in and focus on further objects
71
What is the parasympathetic effect on the eye?
Less light in to protect the retina, focus on near objects and reflex lacrimation to clean cornea
72
How do eyes open wider?
Muellers muscle has sympathetic innervation and works with LPS
73
Describe the pathway of postsynaptic fibres that supply the Muellers muscle
1. Superior cervical ganglion
2. Internal carotid nerve
3. Internal carotid plexus
4. Axons on ophthalmic artery
5. Branches on orbital structures
74
What muscle is responsible for pupil constriction?
Sphincter pupillae
75
What muscle is responsible for pupil dilation?
Dilator pupillae
76
Name the afferent limb of the pupillary light reflex
Ipsilateral CN II
77
Name the efferent limb of the pupillary light reflex
Bilateral CN III
78
What are the four parts of the neurone chain in the pupillary light reflex?
1. Retinal ganglion
2. Midbrain synapse between CN II and CN III
3. CN III to Ciliary Ganglion
4. Short ciliary nerves to sphincter papillae
79
How does the signal pass from one side to the other?
Ipsilateral signal passed to the ipsilateral pretectal nucleus but then passed to bilateral Ediger Westphal Nuceli
80
What connects the lens to ciliary body?
Suspensory ligaments
81
Describe how the lens changes shape
Ciliary muscles relax and ligaments tighten to flatten the lens
Ciliary muscles contract and ligaments relax to spherical and focus on near objects
82
What is the innervation to stimulate contraction?
Parasympathetic - CN III
83
What are the three rules regarding accommodation reflex?
1. Lens is more optically powerful when spherical
2. Lens naturally wants to relax into spherical shape
3. Ciliary muscle is like a sphincter - small when contracted
84
Name three types of tears
Basal, reflex and emotional
85
Describe basal tears
Clean/nourish/hydrate the avascular cornea, contain lysozyme to hydrolyse the bacterial cell wall
86
Describe reflex tears and the nerve pathway
Extra tears in response to stimuli
Afferent - CN V1
Efferent - CN VII
87
What is the sensory innervation to the cornea?
CN V2
88
Though which ganglion do axons to the lacrimal gland come from?
CN VII at internal acoustic meatus, to pterygopalatine ganglion travel on branches of V2 then V1 to the lacrimal gland
89
Why do you get a runny nose when you cry?
Lacrimal lake connects to the canaliculi which leads to the lacrimal sac which drains into the nasolacrimal duct which connects to the inferior nasal meatus
90
Describe the course of sympathetic nerves
Originate from the autonomic centres and passes down the spinal cord exiting at T1-L2 to the sympathetic chain
91
Where do sympathetic nerves for the head and neck leave the spinal cord and where do they go?
T1, through the sympathetic chain to superior cervical ganglion
92
After sympathetic nerves synapse at the ganglion where do the post-synaptic axons go on the way to the eye?
Enter the internal and external carotid nerves and pass onto the peri-arterial plexus on the surface of the internal carotid artery and then the ophthalmic artery
93
Describe the course of parasympathetic nerves
Leave the CNS via cranial nerves III, VII, IX and X or sacral spinal nerves
94
Name four parasympathetic ganglia in the head and neck
- ciliary
- pterygopalatine
- otic
- submandibular
95
Where is the ciliary ganglion?
Just anterior to optic canal, superior to the orbital tissue with close relation to CNIII
96
What is the only nerve to synapse at the ciliary ganglion?
CN III synapses to the short ciliary nerve
97
Which division of CN III supplies the somatic motor innervation to the extra-ocular muscles?
Superior
98
How does CN III enter the orbit?
Travels from the between the midbrain and pons to the cavernous sinus and then through the superior orbital fissure
99
Describe normal light reflex
Symmetrical and displaced slighty nasally to the centre of the pupils
100
What is the name for the displacement of the light reflex temporally/nasally?
Esotropia - temporally
| Exotropia - nasally
101
What is the name for the displacement of the light reflex inferiorly/superiorly?
Hypertropia - inferiorly
| Hypotropia - superiorly
102
If sclera can be seen superiorly to the iris what does that usually indicate?
Something is pushing the eye forward - proptosis in TED
103
What is the clinical name for a droopy eye?
Ptosis
104
Describe the histology of the cornea
Stroma (collagen based) with epithelium on either side which helps to keep it clear and dry
105
Why is the sclera white?
Different arrangement of collagen compared to the sclera
106
Describe the swinging light test
light is shone into one eye and they both constrict
light is moved quickly to the other and both remain constricted
light is moved back to the first eye again and it will dilate
107
What does the swinging light test indicate?
An afferent problem
108
What conditions cause afferent problems?
Infection, MS, vision threatening
109
Describe the pathway of light from the upper field of vision
Upper visual field hits the inferior retina and travels along the lower retinal neurones which travel round the ventricle in the temporal lobe to the occipital cortex
110
Describe the pathway of light from the lower field of vision
Lower visual field hits the superior retina and travel along the upper retinal neurones which jump over the ventricle and in the parietal lobe to the occipital cortex
111
Name the condition where a patient cannot see anything in the peripheral field of vision
Bitemporal hemianopia - problem at the optic chiasm
112
If a problem presents after the chiasm how will it present and what is it called?
Patient is unable to see things coming from one side
| - contralateral homonymous hemianopia
113
What is the purpose of the meninges?
Protective coverings of the brain and spinal cord
114
Name the three layers of meninges
- dura mater
- arachnoid mater
- pia mater
115
Describe the dura mater, what is its innervation?
Hard, tough covering with sensory supply from CN V made of two layers periosteal and meningeal
116
What happens when the dura mater splits into two layers?
It encloses the dural sinuses which are venous channels that drain deoxygenated blood from the brain
117
Describe the arachnoid mater
Trabeculae extending down towards the pia
118
What is found between the arachnoid mater and the pia mater?
Subarachnoid space
119
What is in the subarachnoid space?
CSF and blood vessels
120
Describe the pia mater
Completely adheres to the brain and nerves/vessels that enter or leave
121
Where does the subarachnoid space end?
S2
122
Where does the spinal cord end?
L2/L3
123
Where is a lumbar puncture performed?
After the spinal cord has ended L3-L5
