Anatomy Flashcards
Eyelids
What’s the skin like. Malignancy.
skin thin fat free.
Susceptible to radiation and malignancy are 4 times more common on the lower lid than the upper lid. Malignant drag you down. Benign equal distribution on both lids.
Skin is thicker at lid margins with follicles, short hairs and small sebaceous glands. (more things make it thicker)
Eyelids whats the skin like and malignancy
skin thin fat free.
Susceptible to radiation and malignancy are 4 times more common on the lower lid than the upper lid. Malignant drag you down. Benign equal distribution on both lids.
Skin is thicker at lid margins with follicles, short hairs and small sebaceous glands. (more things make it thicker)
Musculature -
What are the 3 muscles and what are they innervated by and what do they do
Lastly what is the tarsal plate and describe eyelashes
-orbicularis oculi- ⅓ of the thickness and its a striated muscles. Sphincter action muscle, holds the lids tightly against the eye, innervated by cranial nerve 7. (Sphincter= 7) close the eyes
-levator palpebrae superioris- only in the upper lid and raises the upper lid, striated tendinitis as enters lid. Controlled by cranial nerve 3 any damage to this nerve=ptosis. Droopy eyelids. LPS=3.
-tarsal muscle- aka inferior muller, smooth muscle and sympathetically innervated. Aids levator muscle in pulling back eyelids hence when situation of fear sympathetic system is stimulated and you are wide eyed. (TarSSSal= scared. Smooth muscle symp.
-tarsal plate- sits behind these layers, fibrous layer more developed in upper lid . Plate fibre protein.
(eyelashes 2-3 irregular rows of cilia and they are replaced 2-3 times a year)
Eyelid glands
Meibomian
Zeiss
Glands of moll
Lacrimal
Goblet cells what did they do.
Palpebral conjunctival vessels
Meibomian/tarsal glands- produce oil, single row of openings along lid margins behind the lashes. 30-40 among upper lid (bigger) 20-30 lower lid. Mainly driven by parasympathetic innervation. MeiPomian glands (parasymp) if these get blocked it can lead to inflammation-> internal hordeolum infection, Chalazion (internal style) from chronic inflammation. Lipid tear film oil layer.
- Zeiss sebaceous glands- Meibomian is lipid tear film oil layer and Zeiss is oil but lubrication of eyelashes and surrounding skin. In pairs opening into lash follicles
(You have nice Zeiss lashes, if you dont have Zeiss glands not Zeiss lashes)
-glands of moll- watery substance= cleanliness of eyelashes. Primitive sweat gland opening directly onto skin surface. (Molly is sweaty, dirty needs to be cleaned) tear film watery layer rather than oil.
goblet cells- conjunctival mucin producers. (Produce mucin onto conjunctiva) Mucins help to protect and lubricate the ocular surface, tear film stability tears spread evenly across ocular surface, helps to trap and clear away debris pathogens and foreign particles from ocular surface. (Inadequate mucin= dry eye sxs ocular discomfort irritation due to tear film etc)
-palpebral accessory lacrimal glands and glands of wolfring- in peripheral tarsal plate. Palpebral=ppp peripheral park. (Peripheral far away in park outside= wolf) similar structure or function to lacrimal gland= tear production, tear distribution, lubrication of ocular surface= moist. Helps with serous secretion. Henle= lower eyelid. Heine lower.
Wolfs are up high.
palpebral conjunctival vessels nourish cornea when lids are closed. =sleeping
Defence mechanisms-
mechanisms- reflex lacrimation to irrigate ocular surface
Conjunctival surface contains mucous secreting goblet cells
Intraocular fluids counting antioxidants
Wet surface removes waste products
Reflex blink is 200 ms
Eye lashes protect, orbit
Closed eyelids. And lacrimal lake with lysozymes, lactoferrin and antibodies
Lens design stabilisation
Must provide stable axis location of cyl independent of rx
Maximise physiological performance
Toric designs rely on interaction of upper lid with lens stabiliation features
Upper lids squeezes thicker areas of lens= balancing rotational forcew
Conjunctiva what does it do, what are the most active tissues and what does mucus production do
3 layers of the conjunctiva and pls describe mucous membrane again mucous important overall why can we put cls on conj
Joins eyelid to the eyeball. Stops cls going behind eye. Protective of debris of foreign objects entering.
Most active tissues are immune cells
mucus production to wet corneal and conjunctival surfaces, stabilise the tear film as it retains moisture and trap pathogens.
Palpebral- thick and vascular (palpebral is eyelid which is thick and vacular)
Bulbar- thin and translucent (bulbar covers the conjunctiva so we know its thin and translucent)
Forniceal- vascularised and adherence to underlying orbital fat and areolar tissue
PBF
Mucous membranes are loose vascular tissue =MLOOSEcous membranes
Contains capillaries radial and closed. 2 layers epithelium and stroma.
Limited sensory innervation so can place cls on
Conjunctivitis reasons and what we would see
Reactions to infection or allergy or inflammation
Mechanical trauma- staining
Degeneration uv or dry- pingeuculum or pterygium
Immune response- papillary conjunctivitis, oedema or hyperaemia
Liver disease- billiburin accumulation yellow
Subconj haemorrhage- trauma or high bp
Reacs
Discharge- exudates from dilated vasculature so mucous from vernal conj or dry eye, mucopurulent from chlamidyial or bacterial and watery from allergic and viral.
Follicles- hyperplastic tissue, encircled by blood vessels, clear fluid filled pockets of lymp and macrophages eg viral/ chlamidyia
Papillae- hyperplastic conjunctival tissue full of inflammatory cells blood vessels in centre- allergy bacteria cl etc
cornea
78 percent water 15 percent collagen
Squamous cells wing cells columnar or basal cells
Avascular transparent regular smooth. Microvilli on surface. Thicker peripherally
Mitosis in basal cells replenishes epithelium. Cell apoptosis washed away via tears. Cell life cycle is 3-4 days. 14 days to regen
Damage increases mitosis by 53 percent
Langerhan cells from limbus stem cells bone marrow
different layers of the cornea
Bowman’s layer=- cell free. 16 micrometers thick thins towards limbus. Random mesh of collagen fibrils. Tough but if damaged it scars. Bowman is tough but words scar. (Bowman is a random mesSh) he takes collagen.
Stroma- 0.5mm thick thickest main corneal strength. Regular lattice structure lack of BVs. Lamellea turnover time is 12 months.
Contains 2-3 percent keratocytes responsible for spacing of fibrils or stromal communication wound healing
Descemets membrane- 3-20 micrometers thick. Structureless slightly elastic secreted by endothelium. Thickens throughout life 1.3 micrometers per decade. Irregular anteriorly. Localised central thickening -guitar. Fuchs= affects endo
Endo= single layer hexagonal cells. Cells/mm squared decreases with age.
18-20 micrometre diameter, 5 micrometers thick. Full of organelles glucose in and lactate out. Cells held by tight junctions. Active bicarbonate pump. No mitosis. Irregularity of cells= polymegathism.
Corneal innervation
What are sensory meres and PNS
Highest sensitivity is central and around lid margins
Sensitivity decreases w age iris colour depth, skin pigment . Same in 2 eyes no diff w gender except menstrual
Daytime variation low in morning and slight loss incision
Affec by some diseases. Affec by low dk wear less than 7.7 percent. Worse w hema ew pmma
Loss of innervation= oxygen deprivation and mechanical assault
Sensory meres- come from trigeminal nerve
Neurophysiology and sensation- PNS functional types of ocular sensory neurons. Change response
Why is the cornea transparent
Stroma transmits around 90 percent of incident light without any deviation or scattering
Diffraction theory- orderly arranged stromal fibrils behave as diffraction gratings= destructive interference
Corneal transparency
Epithelium has a high aerobic metabolism
Lactate and metabolite accumulation increases osmotic gradient in stroma
Hydrophillic it’s of gags also natural tendency to draw in water
Epi and endo= barrier
Endo pumps several ions from endo to aqueous by carbonic anhydrase. Na enters in return
Endo cell pumps own volume in around 5 mins
Diabetes and cls
Corneas have abnormal healing and epi adhesion- from alterations in basement membrane
No difference in corneal sensitivity
Corneal oxygen uptake reduced atpase unaffected
Shape foe don cells and central corneal thickness similar
Glucose seeing cls in works
Limbus what is it and what is found there and why does neovacularaotn occur
Depth 1mm. 1.5 horizontally 2 vertically. Longer vertically. Limbertically
Site of aqueous drainage system
Terminal arteries and recurrent arteries supply perilimbal conjunctiva
Stem cells- daughter cells transient amplifying cells. Palisades of Vogt fine radial white lines leading into cornea. Provides cells.
Neovascularisaiton- cross of new bvs from cornea to limbus.
Hypoxia lactic acid, stromal softening
Mechanical- irritation
What does the cornea need and what must it eliminate
Cornea needs- 02, glucose, amino acids, vitamins, minerals
Cornea must eliminate- co2, lactic acid, necrotic cells and water
