Eyelid Anatomy Lecture 3 PDF
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This document details the learning objectives for a lecture on eye anatomy, focusing on facial muscles and eyelid functions. It also covers the components of the tear film and different glands within the eyelid.
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Learning Objectives hat are the facial muscles that contribute to eye-opening and eyebrow movements? Be able to W describe the actions of each muscle Innervated by CN VII ○ Frontalis: raises eyebrows (surprised) ○ Corrugator: moves brows medially and...
Learning Objectives hat are the facial muscles that contribute to eye-opening and eyebrow movements? Be able to W describe the actions of each muscle Innervated by CN VII ○ Frontalis: raises eyebrows (surprised) ○ Corrugator: moves brows medially and down (concentration) ○ Procerus: moves brows down and medially (aggression) ○ Orbicularis oculi: lowers eyebrows Explain the functions of the eyelids Protects the eye Pushes tear film into medial canthus (moves tears down) Spreads tear film with blinks Produces components of tear film Describe the muscles of the eyelid that are responsible for opening and closing the eye Identify which cranial nerves innervate each muscle Identify voluntary and involuntary actions of each muscle (smooth vs. striated) Identify and describe the actions of any additional muscles that arise from the main muscles in the eyelid Describe the cause of eyelid conditions that arise when each muscle is affected 1. Orbicularis oculi a. LOWERS eyelid/closes eye b. CN VII c. Palpebral = light, gentle eye closure (reflex blink) i. Muscle of Riolan → (meibomian glands) maintains lids close to the globe, may help secrete meibum ii. Muscle of Horner → (lacrimal canaliculi) moves tears through drainage system d. Orbital = forceful eye closure (forceful blink) e. CN 7 palsy = unable to move any of the facial muscles controlled by CN (frontalis, corrugator, procerus, orbicularis) i. Eye unable to drain tear film (dry eye) 2. Superior palpebral levator a. OPENS eyelids b. CN III superior division (upper lid only) c. Whitnall ligament → levator to move superior/inferior, supports upper lid d. Lockwood ligament → supports lower globe, houses several EOMs e. CN 3 palsy = ptosis with EOM involvement (eye turned down and out) 3. Superior tarsal plate of Muller a. Smooth muscle (involuntary movements) b. Additional lid elevation c. Ptosis 4. Inferior tarsal plate of Muller a. Smooth muscle (involuntary movements) b. Additional lid opening c. Ptosis Identify and describe the location and function of the various glands in the eyelids Exocrine glands ○ Holocrine → secretes COMPLETE cells Meibomian glands Glands of Zeis ○ Apocrine → secretes PART of cytoplasm Glands of Moll ○ Merocrine → ACELLULAR, secretory secreition Lacrimal glands Meibomian glands ○ Lipid layer ○ Secrete meibum (lipid layer of tear film) ○ Within the tarsal plate Glands of Zeis ○ ADJACENT to hair follicle ○ Releases sebum into follicle support and lubrication Glands of Moll ○ Located NEAR hair follicle ○ May provide immune defense and lash lubrication ○ Center lined with cuboidal cells Accessory lacrimal glands ○ Produce aqueous layer of tear film ○ Gland of Krause = near fornix ○ Gland of Wolfring = near tarsal plate Describe the conjunctiva How does the tissue transition from the skin of the eyelid to the palpebral conjunctiva Palpebral vs bulbar conjunctiva tissue structure and function ○ Palpebral conj = lines the eyelid 2 layers: non-keratinized stratified epithelium & stromal layer Goblet cells = secrete mucin layer of tear film Vit A deficiency with loss of goblet cells Stimulated by parasympathetic NS → nerves) Crypts of Henle = invaginations, lined with goblet cells ○ Bulbar conj = lines the white portion of the eye/lines the globe Describe the orbital septum and the structures that are anterior to the orbital septum Orbital septum ○ Protects the orbit from infection ○ Eyelid encompasses the structures anterior to the orbital septum Tenon capsule ○ Dense CT, inner to conj ○ Protects globe, reduces friction Canthus ○ Where upper and lower lids meet ○ Lateral (temporal) ○ Medial (nasal) Plica semilunaris → fold of conj,allows eye movement Caruncle → mass of modified skin Lacrimal lake → reservoir of tear collection Lid margin ○ Papilla → contains punctum ○ Punctum → opening for tear drainage ○ Meibomian gland poes ○ Cilia → eyelashes *epicanthal folds = vertical folds that hide medial canthus
