Eyebrows Anatomy and Function PDF

Eyebrows Monday, September 25, 2023 5:12 PM SCALP acronym: to remember layers - S - skin Eyebrows:...

Eyebrows Monday, September 25, 2023 5:12 PM SCALP acronym: to remember layers - S - skin Eyebrows: - C - connective tissue (dense) - Located between superior nuchal line and superior orbital rim - A - aponeurosis (muscle) - L - loose connective tissue - P - periosteum 3 layers of the skin: 2. Dermis 1. Epidermis: 3. Hypodermis - Outer layer of the skin Composition: - Composed of 4 cells: 1. Connective tissue Subcutaneous tissue a. Fibroblasts - Composed of adipose and Epidermal Function Produce Extra - Cells that produce collagen and elastin loose connective tissue Cell Name b. Collagenous fibers - Collagen: provides structure and tensile strength Keratinocytes Provide structure and Fibrous protein 90% of c. Elastic fibers water-resistant properties keratin cells in - Elastin: provides elasticity and enables movement epider d. Adhesive proteins mis e. Ground substance Melanocytes Helps prevent UV damage Produce - All other CT embedded in it by filtering UV light pigment - Substances travel through it (melanin) - Transparent get composed of: Langerhans White blood cell NA □ Water cells Role in immune response □ Glycosaminoglycans □ Proteoglycans Merkel cells Attach to nerve endings NA 2. WBC's to form "light touch" ○ Immune response receptors 3. Adnexal structures ○ Hair follicles, hair, sebaceous glands, sweat glands - Avascular ○ Relies on dermis for blood supply - Attached to basement membrane ○ Connect epithelial cells to underlying dermis ○ Serves as partial barrier allows water and small molecules to pass into dermis Keratinocytes: composed of 4 layers 1. Stratum basale (inner) ○ Cells undergo mitosis and then migrate through outer layers 2. Stratum spinosum 3. Stratum granulosum - Cells lose nucleus and become flattened 4. Stratum corneum (outer) ○ Dead, flattened cells filled with keratin ○ Cells are shed through desquamation desquamation creation Ways to remember: Basement : lowest floor of the house Stairs: go up the stairs to get to the … Ground floor: on the ground floor there is a Ceiling: top part of the house Muscles that innervate the eyebrow: (ALL INNERVATED BY CNVII) Muscle Location/fiber type Function Image Frontalis Vertical fibers Elevates the eyebrow (surprised Originate: high on scalp expression) Insert: near supraorbital Dense Connective tissue: margin - Connect skin to underlying muscle - Supplies eyebrows through arteries, veins and nerves - Composition: ○ Fibroblasts ○ Collagenous fibers ○ Elastic fibers ○ Adhesive proteins ○ Ground substance Corrugator Oblique fibers Depress the medial (confused Originate: supraciliary brow expression) arch Insert: medial forehead Loose Connective Tissue: - Connects top 2 layers to underlying periosteum - Considered the danger zone ○ Pus & blood spread easily in this layer and infections can pass into cranial cavity through veins Periosteum: - Covering of a bone Procerus Vertical fibers Depress the medial - Composed of: (angry Originate: nasal bone brow ○ Dense irregular connective tissue expression) Insert: medial forehead § Fibroblasts § Collagenous fibers § Ground substance ○ Osteogenic cells § Stem cells that divide and differentiate into osteoblasts ○ Osteoblasts § Form bone matrix Orbicularis Oblique fibers Depress the brows; oculi Originate: medial orbital protracts (closes) the rum (maxillary and eyelid lacrimal bones) Insert: lateral palpebral ligament Eyebrows Quiz: Wednesday, September 27, 2023 6:58 AM 1. What do the keratinocytes produce and where are they located? 2. In which layer of the epidermis are keratinocytes produced? In which layer does desquamation occur? 3. The ground substance of the dermis contains? What is its function? 4. Describe the vasculature of the epidermis 5. Purpose of the dense connective tissue? 6. What is the function of the frontalis muscle? 7. Where does the corrugator muscle insert and originate? 8. Which muscle is mainly responsible for this expression? 9. Label these muscles 10. What is the periosteum and what does it contain? Answer key: 1. Protein keratin and located in the epidermis 2. Produced - stratum basale Desquamation - stratum corneum 3. Water, GAG's, proteoglycans also for transport and structure of CT in dermis 4. Avascular 5. Connect skin to muscle 6. Elevate the eyebrow 7. Originate: supraciliary arch Insert: medial forehead 8. Frontalis a. frontalis b. Orbicularis oculi c. Corrugator d. procerus 10. Outer lining of the bone composed of dense irregular CT, osteogenic cells and osteoblasts  Opt 114 - Orbital Blood Supply Tuesday, September 5, 2023 10:26 AM Aneurysms in the ICA can lead to… - VF defects - because of the proximity to the optic chiasm - Ptosis- because of proximity to CN 3 which innervates the Levator muscle - Vision Loss - because the ophthalmic artery supplies the globe/retina Aorta - Largest artery in the body - Carries oxygen-rich blood from heart -> parts of body Branching of the Aorta: Branching of the ophthalmic artery: OPTHALMIC ARTERY - 1st major branch of the cerebral portion of the ICA - COURSE: anteriorly to enter orbit through orbit through the optic canal within the dural sheath of the Optic Nerve - Gives off 9 branches along its course - Most Notable Bracnches: ○ Lacrimal artery ○ Medial palpebral arteries (2, superior and inferior) Lacrimal Artery Course: 1. Branches from the ophthalmic artery after it enters the orbit 2. Then courses up the lateral rectus 3. Supplies the lacrimal gland 4. Pierces the orbital septum to enter the UL and LL as the lateral palpebral arteries (2, superior and inferior) 5. Links with the medial palpebral arteries to form the palpebral arcades □ Supply the eyelids and palpebral and forniceal conjunctiva Medial Palpebral Arteries (2, superier & inferior) Lateral rectus Course: Opthalmic artery --------------------------------------------- 1. Branch from the ophthalmic artery after it enters the orbit 2. Pierce the orbital septum to enter the UL and LL 3. Connects with the lateral palpebral arteries to form the palpebral arcades (marginal and peripheral) Arcades (unfortunately not the ones with games) Arcade- Medial and Lateral arteries are joined; redundancy of blood supply Marginal palpebral arcade: **"Margin" bc it's closer to the eyelid margin □ Anterior to tarsal plate □ Supplies the UL and LL near the eyelid margin □ Supplies the cornea when the eyelids are protracted (eye closed) Peripheral palpebral arcade □ Anterior to tarsal (Müller's) muscle □ Supplies the UL and LL near the peripheral edge of the tarsal plate □ Supplies the forniceal conjunctiva □ Supplies the cornea when the eyelids are protracted (eye closed) Lateral Palpebral Arteries: (superior and inferior) - Comes from the lacrimal artery - After the lacrimal artery pierces through the orbital septum it enters the eyelids - Anastomose with medial palpebral arteries to form the arcades - Supplies eyelids and palpebral and forniceal conjunctiva (conjunctiva in fornix) ***expect occasional Anki/ Quizlet accessory materials ~ weekly and at end of major topics such as eyelids, eyebrows, orbit, etc! Opt 114 - Arteries Quiz Thursday, September 21, 2023 12:40 PM 1. The ophthalmic artery branches off of which artery? 2. The facial artery and the maxillary artery both branch from which artery? 3. Which of these is not a zone of the internal carotid artery? a. Cervical b. Anterior c. Petrous d. Cavernous 4. The maxillary artery supplies what? 5. Label these structures: 6. What arteries anastomose to make the palpebral arcades? 7. What do the inferior and superior lateral palpebral arteries supply? 8. What is the location of the peripheral palpebral arcade in relation to the marginal palpebral arcade? Answer key: 1. Internal carotid artery 2. External carotid artery 3. Anterior 4. LL and nasolacrimal apparatus 5. Label a. Medial palpebral artery b. Lateral palpebral artery c. Lacrimal artery d. Ophthalmic artery e. Internal carotid artery 6. Medial and lateral palpebral arteries 7. Eyelids and palpebral and forniceal conjunctiva 8. Further away from the margin of the eyelid Eyelid Innervation Wednesday, September 27, 2023 2:35 PM Sensory innervation of the eyelid: (how information enters out eyelid) Frontal Nerve Lacrimal Nerve Ophthalmic nerve (V1) Supraorbital and Supratrochlear Nerve Nasociliary Nerve Trigeminal Nerve (CN5) Maxillary branch (V2) Infraorbital nerve (runs through infraorbital foramen) Mandibular branch (V3) Motor innervation of the eyelid: (how information exits our eyelid) Muscle Nerve Image Orbicularis Oculi CN VII (Facial Nerve) - Temporal branch - Zygomatic branch Levator Muscle CN III (Oculomotor nerve) - Superior division Superior and inferior tarsal muscle Sympathetic Fibers: - Smooth muscle -> Involuntary -> Automatic NS -> Sympathetic NS Eyelid Innervation Quiz Wednesday, September 27, 2023 3:18 PM Label the nerves that provide sensory innervation to the eyelid: Fill in the blanks: Answers: A. Lacrimal Nerve B. Frontal Nerve C. Ophthalmic Nerve D. Trigeminal nerve (CN5) E. Maxillary nerve F. Mandibular Nerve G. Infraorbital Nerve H. Nasociliary Nerve I. Supraorbital/supratrochlear nerve 1. Ophthalmic nerve 2. Mandibular Nerve 3. Lacrimal Nerve 4. Infraorbital Nerve (LL) 5. Infratrochlear nerve (LL, UL) 6. Supraorbital Nerve (UL) Eyelid Structures Tuesday, September 26, 2023 8:51 AM General Lid Structure - Upper eyelids (RUL and LUL) ○ extend from the conjunctival fornix to the superior orbital rim (superior orbital margin) - Lower eyelids (RLL and LLL) ○ extend from the conjunctival fornix to the nasojugal and palpebromalar sulci - Upper and lower eyelids meet at the canthus ○ Lateral canthus Layers of the eyelid: § 5-7 mm medial to the lateral orbital rim Anterior Lamella Skin § directly on the globe Orbicularis Oculi Muscle ○ Medial canthus Middle Lamella Orbital Septum Retractor Muscle § at the medial orbital rim Posterior Lamella Tarsal Plate § separated from the globe by the lacrimal lake Palpebral conjunctiva - palpebral fissure: Opening between the upper and lower eyelids ○ Horizontally: ~30 mm ○ Vertically: ~10 mm § Vertical palpebral fissure = MRD-1 + MRD-2 § Marginal Reflex Distance-1 (MRD-1) - the distance between the corneal reflex and the UL margin □ 4-4.5 mm is normal § Marginal Reflex Distance-2 (MRD-2) - the distance between the corneal reflex and the LL margin □ >5 mm is normal - Structures of the Eyelids Structures Function Attachments Notable Features Contains: Images Skin Barrier to the outside n/a Thinnest skin in the body (see eyebrow section for environment ( LL) rigidity and lateral palpebral About 30 millimeters (see lacrimal section for more ligament (canthal tendons) horizontal information) Upper edge of the superior Superior / Inferior tarsus to the levator palpebral sulcus (crease) aponeurosis and superior Location of my Meibomian tarsal muscle glands Lower edge the inferior UL>LL tarsus to the Open onto eyelid capsulopalpebral fascia and margin the inferior tarsal muscle Sebaceous glands Orbital Septum Anterior barrier of the orbit UL becomes a thickening of Arcus Marginalis NA Separates the eyelids and the Periosteum at the lacrimal sac from the orbit superior rim to Prevent infection from Distal fibers merged entering the orbit with the levator Keeps orbital fat in place aponeurosis LL becomes a thickening of the periosteum at the inferior orbital rim Distal fibers merge with the capsulopalpebral fascia Orbicularis Oculi Skeletal muscle that acts as Oblique fibers Innervated by CN 7 Specialized muscle fibers: Muscle protractor of UL and LL Originate: medial orbital Riolan's muscle Contraction closes the rum (maxillary and ○ Maintains the lid eyelid lacrimal bones) margin close to Divided into 2 regions Insert: after circling eye, the globe Orbital region insert into lateral ○ Gray line: ○ Closes eye palpebral ligament (separates tightly and Orbital region/ Concentric anterior and depresses the fibers posterior lamella) brow Extend from orbital rim surgical landmark Palpebral region to forehead, temple, and for anterior ○ Contraction cheek border of muscle closes eye Palpebral region / semilunar Horner's muscle gently fibers ○ Aids in lacrimal ○ Preseptal Extend from lateral pump mechanism § In front of palpebral ligament § Think: orbital across the eyelid to the Horner's in septum medial palpebral the corner ○ Pretarsal ligament § In front of tarsal plate Levator Palpebrae Skeletal muscle that acts as Originate: lesser wing of the Note linkage to superior N/A Muscle the main retractor of the UL sphenoid rectus muscle Courses forward above the (as eye looks up/ lid superior rectus muscle retracts) sheath blends with the Antagonist = Orbicularis SR Oculi When eye looks up = Levator Aponeurosis: eyelid retracts Superior= orbital Inserts: becomes superior septum transverse ligament and ends Medial=medial at the levator aponeurosis palpebral ligament Superior transverse Lateral= lateral ligament condenses palpebral ligament near Whitnall's Anterior= anterior ligament surface of tarsal plate ○ Superior palpebral sulcus Tarsal Muscle Smooth muscle that UL Only muscle that is moving N/A (Mueller's muscle) functions as the accessory Originates: from the lower lid & inferior tarsal retractor of the UL and LL levator muscle ~10 mm In upper lid, helps muscle Contraction opens the above tarsus supplement movement of lid Inserts: superior levator muscle border of tarsus or 2-5 mm below LL Originates: capsulopalpebral fascia Inserts: lower border of tarsus Capsulopalpebral Connective tissue that is the Fibers arise from Lockwood's Inferior palpebral sulcus NA Fascia main retractor of LL ligament and the sheaths of Fold/grove beneath the Inferior rectus and LL inferior oblique Divides eyelid into Inferiorly: attaches to orbital pretarsal and septum preseptal regions Superiorly: attaches to lower border of tarsus, muscle fibers of orbicularis oculi muscle, and skin Palpebral Conjunctiva Mucous membrane that Extends from eyelid margin NA Goblet cells: secrete mucin, lines the underside of the to the fornix component of tear film (see lids lacrimal section for more information) Accessory lacrimal glands of Krause and Wolfring: secrete aqueous portion of tear film (see lacrimal section for more information) Levator Aponeurosis Fan shaped tendon of the Superiorly: fuses with orbital Anterior attachment NA levator muscle septum creates superior palpebral Divides lacrimal gland into Medially: attaches with sulcus orbital and palpebral lobes medial palpebral ligament Fold 8-12 mm above Antagonists of orbicularis (canthal tendon) UL margin oculi muscle Laterally: attaches to lateral Divides eyelid into palpebral ligament (canthal tarsal and septal tendon) regions Anteriorly: attaches to Can be absent if anterior surface of tarsal levator aponeurosis plate, muscle fibers of attaches to skin orbicularis oculi, and eyelid inferiorly skin Eyelid Margin Eyelashes in ciliary portion NA NA Eyelashes of eyelid margin Lacrimal papilla/ puncta Each lash replaces Mucocutaneous junction every 5 months and (MCJ) takes 10 weeks to Ciliary and lacrimal grow portion of eyelid Function to protect margin the eye: very sensitive Transition between to touch! palpebral conjunctiva and skin Lid wiper region Ciliary and lacrimal portion of eyelid margin Elevated strip of palpebral conjunctiva posterior to MCJ Comes into contact with globe with blinking Meibomian gland orifices Ciliary portion of eyelid margin Row along eyelid Secretes oils (lipids) onto skin in front of MCJ  OPT 114 - Lacrimal System Friday, September 22, 2023 10:21 AM - tear film covers ocular surface (cornea & conjunctiva) Average tear break up time = 10 seconds - Blind spontaneously = basal tears - Anterior to tear film 3 kinds of tears: - 3 layers of tear film (old theory) ○ Lipid layer Basal Tears Secreted to coat ocular surface Activates parasympathetic system ○ Aqueous layer In response to stimulation of CNV with CN7 ○ Mucin layer - Normal blinking - 2 layers of tear film (newer theory) - Meibum released upon blinking ○ Lipid layer Reflex tears Secreted in response to irritant Activation of parasympathetic system ○ Mucoaqueous layer (mucin and aqueous layer are more integrated than once - Mucin and aqueous secreted in response believed) to CNV Emotional Secreted in response to limbic system Activation of parasympathetic system tears - Emotions Glands/Cells that produce components of tear film: 2. Goblet Cells 3. Accessory lacrimal glands 4. Lacrimal gland 1. Meibomian glands - Divided into 2 lobes by levator aponeurosis: - Type of epithelial cell that secrets gel-forming mucins - Types: a. Meibum of the lipid bilayer ○ Orbital lobe - Layer of tear film: ○ Krause: ○ Mucoaqueous layer § Forniceal conjunctival stroma § In lacrimal fossa of the frontal bone temporally - More in UL than LL ○ Palpebral lobe - Location: ○ Wolfing: - Glands open onto lid margin onto the skin § Located in superior temporal eyelid ○ interspersed within conjunctival epithelial cells § Located in palpebral ○ Posterior to grey line - Cells in lacrimal gland: ○ Concentrated in nasal and inferior nasal regions conjunctival stroma along ○ Anterior to mucocutaneous junction ○ Acinar cells ○ Absent around limbus posterior border of tarsal - Ciliary part of eyelid margin § Secrete aqueous by merocrine methods ○ Concentrated at the ocular surface plate § Decreases as you move to the superficial layer - Secretion: ○ Ductal cells Meibum (what meibomian glands secrete) - Produces: ○ Aqueous portion of tear film by ○ Myoepithelial cells Production/Secretion: ○ Gel-forming Mucin (glycoproteins): merocrine methods § Muscle cells that allow acinar cells to release - Acini of sebaceous glands secrete meibum § MUC5AC (most prominent) - Layer of tear film: products by holocrine method into a central duct § Glycoprotein (protein + carbohydrate) ○ Mucoaqueous - Composition of the aqueous - Holocrine method § MUC 1,4,16 ○ Water ○ The entirety of the cell is release □ Transmembrane proteins - hold tear § 98-99% Regulation: film to the ocular surface ○ Electrolytes - Meibum production regulated by hormones ○ Rich in serine, threonine, and cysteine § Na+, K+, Mg2+, Ca+2, Cl-, HCO3-, PO4-3 (androgen and estrogen) § Serine and threonine (OH functional groups) = § Function 1: Maintain fluid balance ○ Stimulate hormone receptors sights of O-glycosylation (sugar bonded to □ Measured through osmolarity § Leads to increase in gene oxygen) ® Normal = ~300 mOsm/L transcription for enzymes □ Heavy glycosylation = negative charge □ Hyperosmolarity = dry eye associated with fatty acid and to glycoprotein ® Aqueous deficient (autoimmune): cholesterol synthetic pathways □ Able to mix with aqueous layer of tear ◊ Lacrimal gland isn't producing ○ Androgen film (hydrophobic) enough aqueous portion of the § Think: testosterone § Cysteine-rich forms disulfide bonds tear film so poor production Composition: □ Mucoadhesive properties ◊ Less water, more electrolytes - Amphipathic lipids (phospholipids & fatty - Regulation: ® Oil glands (caused by medications) acids) ○ Stimulation of sensory nerves (CN5 trigeminal ◊ Abnormal tear evaporation or low ○ In contact with mucoaqueous layer nerve) in the cornea/conjunctiva contribute to tear volume ○ Provide structural stability to tear film secretion § Function 2: Acts as buffer (bicarbonate) - Non-polar lipids (waxes, cholesterol, ○ Motor innervation is unknown □ pH = 6.8-8.2 triglyceride) - Secretion: ○ Soluble proteins ○ In contact with air ○ Use both merocrine and apocrine methods § Immune response ○ Creates hydrophobic barrier □ Lysozymes, lactoferrin, lipocalin, Storage: immunoglobulins, cytokines carbohydrate § Wound healing - Meibum is stored in central duct and is secreted upon blinking due to mechanical □ Growth factors, matrix metalloproteinases pressure (Corneal healing) Layer of tear film: ○ Glucose - Lipid layer § Energy metabolism for the cornea Serine/threonine ○ Lactate § Energy metabolism protein ○ Urea § Waste product - Secretion of aqueous ○ Regulated by neural control ○ Stimulation of sensory nerves in the cornea/conjunctiva MUC 1,4,16 (transmembrane protein) (CN5) ○ Motor innervation is through parasympathetic system Glycocalyx: helps stick aqueous layer of tear film to the eye Acini Central duct Hordeolum - Meibum stuck in the gland - Concern for bacteria bypassing the orbital septum - Can progress to preseptal cellulitis BIG PICTURE! All of the components in tears: Secreted by goblet cells - Electrolytes, glucose, proteins, water, etc concentration is higher closer to ocular surface MUC 1,4 16 (goblet cells are a type of epithelial cell) Ocular surface Krause and Wolfring (accessory lacrimal glands) Acinar cells of lacrimal gland Goblet Cells Meibomian glands Goblet Cells lacrimal system - drainage Tuesday, September 26, 2023 10:26 AM Eyelid drainage: Occurs during eyelid closure Why can we not reuse tears? Tears are drained by: Image old tears as 'old bath water' Capillary action: Helps remove cellular debris, toxins and waste ○ Movement of water without external force Some also evaporate off of the eye so we need to Horner's muscle: replenish Components of nasolacrimal apparatus 1. Puncta 2. Lacrimal canaliculus 3. Lacrimal sac 4. Nasolacrimal duct Hole in lacrimal portion of eyelid margin Tubes that join puncta with lacrimal sac Middle of lacrimal papilla Sac of tear collection Lined with Epithelia cells (reabsorption of tears) Opens into lacrimal Lined with Epithelial cells Surrounded by: Lined by epithelial cells canaliculus (reabsorption of tears) ○ Elastic tissue 2 portions: Superior and inferior Surrounded by: ▪ Permits dilation ○ Intraosseous ○ Elastic tissue ○ Horner's muscle In nasolacrimal canal ▪ Permits dilation ▪ Aids in pumping within maxillary bone ○ Horner's muscle 3 portions: ○ Membranous/meatal ▪ Aids in pumping ○ Vertical § Within nasal mucosa Location: ▪ Connected to puncta § Opens into inferior ○ Lacrimal fossa ▪ 2mm long meatus of nasal cavity ▪ Lacrimal and ▪ Dilates to form ampulla § Covered by mucosal fold maxillary bone ○ Horizontal called valve of Hasner ○ Medial palpebral ligament ▪ Runs along lid margin (8mm) □ Prevents reflux of ▪ Holds sac against ○ Common canaliculus tears anterior and ▪ Superior and inferior horizontal portions join □ Can be obstructed posterior lacrimal ▪ Connects to the lacrimal sac by maxillary sinus crests ▪ Valve of Rosenmuller Created by the angle of the common canaliculus entry into lacrimal sac Helps prevent reflux of tears back into eye Evaporation of tears: - Normal time for tears on eyelid = 10 seconds - Poor lipid layer (think meibum/meibomian glands) = faster evaporation - During evaporation: ○ Lipids diffuse towards Mucoaqueous layer -> ○ Mucin at ocular surface is now contaminated with lipids (lose of hydrophilicity) -> ○ Tear film ruptures  Lacrimal System - extras Tuesday, September 26, 2023 11:04 AM Mucoaqueous layer Lipid layer Maintain health of corneal and conjunctival epithelial cells Prevents evaporation by increasing stability of tear film Provide nutrients to underlying avascular corneal tissue Creates a barrier at lid margin Flush away debris and toxins Prevents spillover of tears at lid margin First line of defense in microbial infections Prevents migration of lipids produced by facial skin onto ocular surface Provides smooth refractive surface Forms a water tight seal when the eyelids are closed Protect against mechanical shock Aids in lubrication of the eyelids during blinking Aids in lubrication for eyelids during blinking Aging complication Result Keratinization of MG ducts and MG dropout Decline meibum Decrease in sex hormones Decline in meibum Lacrimal gland duct fibrosis Decline in volume of tears Decrease number of goblet cells Decline in mucins # of corneal nerves decreases with age Less reflux tearing Eversion of lower puncta Poor drainage Innervation Blood supply Lacrimal gland: Nasociliary apparatus: Sensory innervation Motor innervation - Angular, infraorbital and dorsonasal artery of lacrimal gland by Lacrimal Gland: of lacrimal gland CN V (ophthalmic by - Lacrimal artery nerve/lacrimal parasympathetic nerve) fibers Horner's muscle: Innervation by temporal and zygomatic branches of orbicularis oculi muscle Orbital Bones Monday, September 25, 2023 9:27 PM - Bones (Cranium, Facial, and Orbital) - Foramen, fissure, fossa Cranium Bones Bones of the Face Pneumonic: My Mouth’s Palate Never Liked Fried Zucchini In Vinegar Bones of the Orbit Orbital Contents (general) Tuesday, September 26, 2023 1:08 PM - Globe divisions - Connective tissues - Blood vessels - Orbital Fat - Muscles Sheets of Dense Connective Tissue found in the Orbit: Structure Location Function Tenon’s Capsule Covers the sclera -Strong Barrier Covers EOM’s as they insert into sclera -separates globe from orbit Merges with sclera/conj at the limbus (anterior) Continuous with Dural sheath of ON (posterior) Orbital Septum Courses the entire rim of the orbit to the tarsal plate Separates eyelids and lacrimal sac from the orbit (Palpebral Fascia) continuous with periosteum at orbital rim Keeps orbital fat in place Periorbita Covers the bone of the orbit attachment site for muscle, ligaments, & tendons Anteriorly continuous with periosteum vascular use support structure Posteriorly continuous with rural sheath of ON Transverse Dense Connective Tissue Ligaments Ligament Course/ Location Function Whitnall’s superior orbit Support (Superior transverse From lateral orbital wall to medial orbital wall Maintains space b/w structures ligament) Where levator muscle ends and levator aponeurosis begins Lockwood’s inferior orbit Support (Suspensory Ligament) From lateral orbital wall to medial orbital wall Maintains space b/w structures contributes to capsulopalperbral fascia formation Medial Check expansion of the medial rectus sheath Prevents over-action of medial attaches to lacrimal bone rectus Lateral Check expansion of lateral rectus sheath Prevents over-action of the lateral attaches to zygomatic bone rectus Orbital Septal System- web of interconnecting connective tissue septa - Organize, anchor, and support structures of the globe Orbital Nerves § Optic Nerve (CN 2)- sense of sight § Oculomotor nerve (CN 3)-innervates levator muscle and 4 EOM’s (MR, SR, IO, IR) § Trochlear (CN 4)-Innervates Superior Oblique EOM § Ophthalmic (CN 5-V.1) § Maxillary (CN 5- V.2) § Abducens (CN 6)- innervates Lateral Rectus EOM Blood Vessels Ophthalmic Artery (and branches) Superior/ Inferior Ophthalmic Veins Muscles 4 Recti Muscles 1. Medial Rectus (MR) 2. Lateral Rectus (LR) 3. Superior Rectus (SR) 4. Inferior Rectus (IR) 2 Oblique Muscles 1. Superior Oblique (SO) 2. Inferior Oblique (IO) Eyelid Retractors- control movement of eyelids 1. Levator Palpebrae 2. Superior (Muller’s)/Inferior Tarsal muscles 3. Capsulopalpebral Fascia (not an actual muscle) Orbital Fat Space not occupied= filled w/ adipose tissue Predominant @ Orbital Apex Surrounds Optic Nerve Held in place by the orbital septum 2 fat pads anterior to levator aponeurosis Nasal, central 3 fats pads posterior to the orbital septum Nasal, central, temporal Overview Monday, September 25, 2023 5:13 PM The eye = globe - Located in the orbit - Organ responsible for sight 3 Coats of the Eye 1. Outer fibrous layer 2. Vascular layer (uvea) 3. Inner neural layer - Sclera (85%) - Iris - Retina ○ When looking at eye, opaque white ○ Anterior layer ○ Neural tissue portion ○ Gives eye color ○ Converts light energy to and ○ Functions: ○ Pupil (hole) located in the center electrical signal & sends it to the § Provide structure and shape ○ 2 muscles (that require blood brain ○ Divided further into 3 parts supply = vascular layer) § Signal exits/enters via Optic § Episcleral § Iris dilator - dilates pupil Nerve § Sclera § Iris sphincter - constricts □ Most anterior ON: optic § Lamina fusca pupil disc/ optic nerve head ○ Covered by tenon's capsule and - Ciliary body - Macula conjunctiva ○ Middle layer ○ Small, central retina responsible for - Cornea (15%) ○ Continuous with iris central vision ○ Transparent because we need light ○ Contains: ○ Fovea to enter § Ciliary muscle § Center of macula ○ Main refractive system of the eye (accommodation) § Highest VA's due to curvature □ Zonules - attach body § High concentration of cones - Limbus: where cornea transitions to to lens sclera/tenon's capsule/conjunctiva § Ciliary process (aqueous humor secretion) - Choroid ○ Poster layer ○ Continuous w/ ciliary body ○ Provide nutrition to 1/3 of retina thru network of blood vessels Macula Optic Nerve 3 Fluid-Filled Chambers General Eye Structures and Functions 1. Anterior Chamber a. Cavity between the cornea and the iris/lens Blood vessels 2. Posterior chamber ○ provide nourishment and oxygen a. Cavity between the ciliary body and the lens Nerves ○ provide sensory and motor innervation - Continuous with one another through the pupil Extraocular muscles (EOM's) - Contain aqueous humor ○ move the eyes and the eyelids ○ Produced by the ciliary process Connective tissue ○ Clear fluid that provides nourishment for surrounding structures ○ provide structural support 3. Vitreous chamber ○ anchor soft tissue to bone a. Largest chamber ○ compartmentalizes areas b. Between the lens and retina Fat c. Contains the vitreous humor ○ provides cushion and insulation i. Clear gel like substance that maintains the shape of the eye Bone ○ provides protection Accommodation system in the eye: Zonules relaxed Looking at near target: Lens accommodating - "adding more plus to the system" Ciliary muscle contracts Looking at distant target: Tension created in the zonules Lens not accommodating: "less plus in the system" Ciliary body relaxed Computer-animated model of accommodation - Supplementary video: 25983 Great YouTube video is you need more of an explanation! Overview quiz Monday, September 25, 2023 5:16 PM 1. What structure supplies nourishment to the retina? 2. What structure is the main refractive system of the eye? 3. Why is the iris considered part of the vascular layer of the eye? 4. The retina converts light energy to ______ ______? 5. When the ciliary muscle contracts, what happens to the zonules and the crystalline lens? 6. What humor is present in the posterior chamber? What is it produced by? 7. Purpose of the fat in the orbit? 8. Which receptor is the highest in the macula/fovea? Answer key: 1. Choroid 2. Cornea 3. Contains 2 muscles that control the size of the pupil that have vascular components 4. Electrical signals 5. Zonules relax/have less tension and crystalline lens accommodates adding more plus to the op 6. Aqueous humor produced by the ciliary process 7. Provides cushion and insulation 8. Cones - which are responsible for our color vision