Eye Anatomy Lecture 1 PDF

1 Eye Anatomy  GROSS ANATOMY OF THE ORBITAL BONES & ORBITAL SOFT TISSUE.  OCULAR ADNEXA, LACRIMAL SYSTEM AND CONJUNCTIVA Yousef Awlad Mohammad B.S. Optometry. M.S. Health Informatics Gross Anatomy ( medical terminology...

1 Eye Anatomy  GROSS ANATOMY OF THE ORBITAL BONES & ORBITAL SOFT TISSUE.  OCULAR ADNEXA, LACRIMAL SYSTEM AND CONJUNCTIVA Yousef Awlad Mohammad B.S. Optometry. M.S. Health Informatics Gross Anatomy ( medical terminology ) 2 Directional and regional terms:  Anterior, or ventral: toward the front  Posterior, or dorsal: toward the back  Superior, or cranial: toward the head  Inferior, or caudal: away from the head  Medial: toward the midline  Lateral: away from the midline  Proximal: near the point of origin  Distal: away from the point of origin Body Planes and Sections 3  Body is 3D.  Can be split into three planes:- Sagittal. Coronal/frontal. Transverse. Sagittal Plane  Definition : The sagittal plane divides the body into left and right sections. It runs vertically from front to back.  Types: Midsagittal Plane: Divides the body into equal left and right halves. Parasagittal Plane: Divides the body into unequal left and right parts.  Significance: Anatomical Reference: Used to describe locations and movements, such as flexion and extension. Medical Imaging: Essential for MRI and CT scans to visualize internal structures. Applications: Important in fields like anatomy, medicine, and physical therapy for understanding body alignment and movement. 4 Coronal or frontal Plane Definition: The coronal plane divides the body into anterior (front) and posterior (back) sections. It runs vertically from side to side. Significance: Anatomical Reference: Helps describe the location of structures in relation to the front and back of the body. Movement Analysis: Essential for understanding movements like abduction and adduction. Applications: Widely used in medical imaging (e.g., MRI, CT scans) and anatomical studies to visualize body structures in relation to one another. 5 Transverse plane 6  Definition: The transverse plane, also known as the horizontal plane, divides the body into superior (upper) and inferior (lower) sections. It runs horizontally, perpendicular to the sagittal and coronal planes.  Significance:  Anatomical Reference: Used to describe the location of structures in relation to their position above or below other structures.  Movement Analysis: Important for understanding rotational movements and actions like twisting  Applications: Commonly utilized in medical imaging techniques (e.g., CT scans and MRIs) to provide cross-sectional views of the body, allowing for detailed examination of internal organs and structures. Anatomy of the eye 7  The eyeball is a spherical structure divided into three main layers:  1. Fibrous Layer:  Sclera: The white, outer layer providing protection and shape.  Cornea : The transparent front part that refracts light.  2. Vascular Layer (Uvea) :  Iris: The colored portion that regulates light entry through the pupil.  Ciliary Body: Adjusts the lens for focusing and produces aqueous humor.  Choroid: A vascular layer supplying nutrients to the retina.  3.Inner Layer:  Retina: Contains photoreceptors (rods and cones) that convert light into neural signa  Optic Nerve: Transmits visual information to the brain. Spaces within the Eye 8  The human eye contains several key spaces that are essential for its function: Anterior Chamber: Located between the cornea and the iris. Filled with aqueous humor, which helps maintain intraocular pressure and provides nutrients to the cornea and lens. Posterior Chamber: Found behind the iris and in front of the lens. Also filled with aqueous humor, connecting to the anterior chamber through the pupil. Vitreous Chamber: The largest space, located behind the lens and filling the main part of the eyeball. Contains vitreous humor, a gel-like substance that maintains the eye's shape and supports the retina. The Orbit 9  The orbit, or eye socket, is a bony cavity that houses and protects the eyeball and its associated structures.  Structure: Composed of seven bones (frontal, zygomatic, maxilla, nasal, lacrimal, ethmoid, and sphenoid) that form a protective enclosure.  Function :  Protection: Shields the eye from trauma and environmental factors.  Support: Provides attachment points for extraocular muscles, enabling eye movement.  Passageways: Contains openings for nerves and blood vessels that supply the eye.  In addition to the eyeball, the orbit houses fat, connective tissue, and structures like the lacrimal gland, which is essential for tear production.  10 The orbit Ocular appendages 11  Ocular appendages support and protect the eye.  Key components include: Eyelids: Movable folds of skin that cover and protect the eye; they help spread tears and block debris. Conjunctiva: A transparent mucous membrane lining the eyelids and covering the white part of the eye (sclera), providing lubrication and protection. Lacrimal Glands: Located above the outer corner of each eye, these glands produce tears to keep the eye moist and help remove debris. Extraocular Muscles: Six muscles attached to the eyeball that control its movements, allowing for a wide range of motion and coordination.  12 Eyelids  Functions :  Protects the eye from injury and light  Distribution of tears.  Drainage of tear.  The upper Eyelid is larger and more mobile than the lower.  They meet at the medial and lateral angles ( canthi).  13 Eyelids  Upper Lid: Supraorbital Nerve (Ophthalmic Division of CN V).notiavrenni yrosneS : Supratrochlear Nerve (Ophthalmic Division of CN V) dna daeherof laideM :.notiasnes dil reppu Lacrimal Nerve (Ophthalmic Division of CN V).notiubirtnoc yrosneS :  Lower Lid: Infratrochlear Nerve (Ophthalmic Division of CN V).notiavrenni yrosneS : Infraorbital Nerve (Maxillary Division of CN V).notiasneS :  Eyebrow 14  Lie at the junction of the forehead and the upper lid  The medial end of each lie just inferior to the orbital margin while the lateral just above the orbital margin Movement of the eyebrow ▪ Up by the frontalis muscle ▪ Down by orbital part of orbicularis oculi ▪ Medially by corrugator supercilia ▪ All supplied by the 7th cranial nerve ( nerve of facial expression) 15  16 Eyebrow  Blood Supply and Drainage of the Eyebrow  Blood Supply: Supraorbital Artery: Main artery supplying the eyebrow and forehead. Frontal Artery: Contributes to vascularization in the area.  Venous Drainage: Supraorbital Vein: Drains blood from the eyebrow region. Frontal Vein: Channels blood into the facial vein or cavernous sinus.  Lymphatic Drainage: Lymphatic vessels drain into preauricular lymph nodes and submandibular lymph nodes, aiding in waste removal and immune response.  17 Eyebrow  Eyebrows play key roles in protection and expression. Protection: Keep sweat and debris out of the eyes. Expression: Convey emotions like surprise and anger. Structure: Composed of coarse hair that enhances facial symmetry. Cultural Significance: Influence beauty standards and grooming practices.  Eyebrows are essential for both eye health and non-verbal communication.  18 The eye lashes  Longer and more numerous on the upper eyelid and curved upward and downward in the lower eyelid, 150 in the upper lid, 75 in the lower.  Arranged in double or triple rows.  Very thin  Do not become gray with age, replaced every 100-150 days  They contain sebaceous gland of zeis and modified sweat glands of Moll.  Become continuous with the conjunctiva just in front of the Meibomian glands.  The Tarsal glands 19 (Meibomian glands)  20-25 in each lid, Single row.  Seen as yellowish lines on the inner surface of everted eyelids  The orifices of the tarsal glands mark the site of junction btn skin and conjunctiva.  Function: 1. Their oily consistency prevents tear overflow 2. Helps to make closed eyelids airtight 3. Forms external layer of tear film and prevents rapid evaporation of tear  20 The structure of the eyelid  From superficial to deep:  Skin  Subcutaneous tissue  Orbicularis oculi  Orbital septum and tarsal plates  Smooth muscle  Conjunctiva  The upper lid receives the insertion of the levator muscle.  Palpebral fissure 21 The palpebral fissure is the opening between the upper and lower eyelids. The upper and lower eyelids meet at the corners of the palpebral fissure in the lateral and medial canthi. The palpebral fissure typically has an almond-like shape The width and height can vary among individuals; average dimensions range from 25 to 30 mm in width and 10 to 12 mm in height, depending on factors like age and ethnicity. Palpebral fissure 22  Normal position of the eyelids  Upper: covering 1-2 mm of the upper cornea.  Lower : just below the lower margin of the cornea.  The margin of each lid is:  2 mm thick.  30 mm long.  At the medial end of each lid:  Lacrimal papillae.  Lacrimal puncta 0.4-0.8 mm  23 Muscle Control of the Palpebral Fissure  Muscle Control: The fissure's size is influenced by the orbicularis oculi muscle (which closes the eyelid) and the levator palpebrae superioris muscle (which raises the upper eyelid).  Orbicularis Oculi:  Function: Closes the eyelids; essential for blinking and tear distribution.  Parts:  Palpebral Portion: Gentle closure during blinking.  Orbital Portion: Stronger closure for protection against bright light or irritants.  Levator Palpebrae Superioris:  Function: Elevates the upper eyelid, widening the palpebral fissure.  Innervation: Controlled by the oculomotor nerve (CN III). 24  25 Conjunctiva  The conjunctiva is a thin, transparent membrane that covers the white part of the eye (sclera) and lines the inner surface of the eyelids.  It plays a critical role in protecting the eye and keeping it moist.  Divided into three parts:  Bulbar conjunctiva: covers the sclera.  Palpebral conjunctiva: lines the inner surface of the eyelids.  Fornix (conjunctival fornix): the junction between the bulbar and palpebral conjunctiva. 26  27 Conjunctiva  Bulbar Conjunctiva  Covers the anterior part of the sclera.  Merges with the corneal epithelium at the limbus (corneoscleral junction).  Allows smooth movement of the eyeball.  Palpebral Conjunctiva  Lines the inner eyelids.  Contains numerous goblet cells that secrete mucus, helping to maintain tear film and prevent dryness.  Protects the eye from foreign particles.  28  Conjunctival Fornix  The junction between the bulbar and palpebral conjunctiva.  Forms a flexible fold, allowing movement of the eye and eyelids.  Contains accessory lacrimal glands (Krause and Wolfring) which contribute to tear production.  29 Conjunctival Layers  Epithelium: Stratified squamous or columnar cells, depending on the region.  Contains goblet cells.  Substantia propria (Stroma): Connective tissue layer with lymphoid tissue.  Rich in blood vessels and lymphatics. 30  31 Conjunctival Blood Supply& Nerve Supply  Blood supply  The conjunctiva is supplied by branches of the ophthalmic artery.  Blood vessels are more prominent in the bulbar region.  Nerve supply  Sensory innervation is provided by branches of the trigeminal nerve (ophthalmic division).  Highly sensitive to irritants, resulting in reflexive blinking or tearing.  32 Function of the Conjunctiva  Protects the eye by trapping debris and preventing infections.  Maintains moisture through tear production and secretion of mucus from goblet cells.  Aids in immune defense with lymphoid tissue and antibodies. 33  34 Clinical Importance Common conditions involving the conjunctiva Conjunctivitis Pterygium Lacrimal apparatus 35  The lacrimal apparatus is the system responsible for the production, distribution, and drainage of tears, playing a crucial role in maintaining the health of the eye.  Key components include: Lacrimal Glands: Produce tears that lubricate and protect the eye. Tears: Composed of water and proteins, they help flush away debris. Lacrimal Ducts: Transport tears to the eye's surface during blinking. Nasolacrimal Duct: Drains excess tears into the nasal cavity.  This system ensures eye comfort and maintains overall ocular health.  36 Lacrimal gland & tear Location Function Tear composition Situated in the Produces tears to Water, electrolytes, superolateral aspect of maintain a moist surface proteins (such as the orbit. on the eye. lysozyme), and lipids Divided into two parts: Orbital and Palpebral portions.  37 Lacrimal gland & tear Blood supply Nerve supply  Lacrimal Artery: A branch of the  Lacrimal Nerve: A branch of the ophthalmic division of the trigeminal nerve (CN V1). The ophthalmic artery (itself a branch of the lacrimal nerve carries sensory innervation and internal carotid artery). The lacrimal conveys autonomic fibers. artery travels with the lacrimal nerve to  Autonomic Innervation of the Lacrimal Gland supply the gland. Parasympathetic Fibers: Stimulate tear production via the facial nerve and the  Additional Contributions: Smaller Vidian nerve. branches from the anterior and posterior Sympathetic Fibers: Regulate blood flow ciliary arteries and the facial artery may but do not affect tear production. also contribute to the gland’s blood supply.  38 Lacrimal & nasolacrimal duct Lacrimal duct Nasolacrimal duct  Comprised of the puncta (openings on  a continuation of the lacrimal duct the eyelids), canaliculi (small channels), system that drains tears into the nasal and the lacrimal sac. cavity , Extends from the lacrimal sac down through the nasolacrimal canal to  Collects tears produced by the lacrimal the inferior nasal meatus. gland and facilitates their movement toward the nasolacrimal duct. 39  40 Clinical Significance Common Conditions Dacryostenosis: Narrowing or blockage of the nasolacrimal duct, often seen in infants, leading to excessive tearing and discharge. Dacryocystitis: Infection of the lacrimal sac due to obstruction, causing pain, swelling, and redness. Obstruction: Can result from trauma, infection, or inflammation, necessitating interventions like probing or surgical drainage  41 Thank you