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Anatomy of the eyelids
The document provides an anatomy overview of the eyelids. It discusses the key structures of the eyelids including the orbicularis oculi muscle, levator palpebrae superioris muscle, tarsal plates, septum orbitale, canthi, caruncle, plica semilunaris, and eyelid margins. The document also describes the layers of the eyelid from skin to conjunctiva and the position and function of the eyelids.
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Anatomy of the eyelids
- 1. Anatomy Of TheEyelids Dr. Sameeksha Agrawal
- 2. Introduction • Eyelids arethe mobile curtains placed in front of the eyeballs • Protect the eyes from injuries & excessive light • Help in spreading of the tear film over the eyeball & its drainage • Important contribution to the facial features of an individual • Gives an idea about the state of wakefulness & attention
- 3. Extent • The uppereyelid extends from the eyebrow downward to end in a free margin, which forms the superior boundary of palpebral fissure • The lower eyelids below merge into the skin of the cheek
- 4. Lid Folds 1) SuperiorLid Fold: Lies 4 mm above the edge of the eyelid Formed by the fibrous slips arising from the LPS tendon which pass forwards between the muscle bundles of orbicularis muscle to insert into the skin (it is less developed in Mongols) 2) Inferior Lid Fold: Less distinct Formed by the slips arising from the fascia surrounding the inferior rectus muscle & are inserted into the skin
- 5. Lid Folds 3) NasojugalFold (medially) 4) Malar Fold (laterally) Note: These folds limit the spread of blood or fluid downwards from the eyelids into cheek
- 6. Position Of TheEyelids • In primary position of gaze, the upper eyelid covers about 1/6th of the cornea & the lower eyelid just touches the cornea
- 7. Canthi • The twoeyelids meet at lateral & medial end to form the Lateral & the Medial Canthi • Lateral canthus lies in contact with the eyeball & it is 5-7 mm away from the lateral orbital margin • Medial canthus is rounded,and is separated from the globe by tear lake (lacus lacrimalis). In this area, there is caruncle & plica semilunaris
- 8. Canthi • Normally thelateral & the medial canthi lie at the same horizontal level. Sometimes the lateral canthus is slightly elevated (about 2mm) than the medial one. • Greater elevation of the lateral canthus results in a mongoloid slant to the fissure, and the opposite results into an antimongoloid slant
- 9. • Mongoloid slantin trisomy 21 • Anti mongoloid slant in treacher collin syndrome
- 10. Caruncle and Plica-semilunaris •Caruncle is a small, fleshy, ovoid structure attached to the inferomedial side of plica semilunaris. It is a modified skin, and it contains sebaceous glands and fine, colorless hairs • Plica semilunaris is a narrow, highly vascular, crescent-shaped fold of the conjunctiva located lateral to & partly under the caruncle Its lateral border is free & separated from the bulbar conjunctiva, which it resembles histologically It is a vestigial structure analogous to the nictitating membrane (3rd eyelid) seen in other animals
- 11. Palpebral Fissure • Itis the exposed zone between the upper & lower eyelids • Elliptical in shape • In adults, it is about 27-30mm long & 8-11 mm wide • The upper eyelid is more mobile than the lower, and can be raised 15 mm by the action of the LPS muscle alone. If frontalis is also used, then an additional 2 mm elevation can be achieved
- 12. Eyelid Margins • Nearlyflat, 2mm wide • Each lid margin is divided into two parts (lacrimal & ciliary) by the lacrimal papilla, which is a small elevation present on the medial side, containing an opening, the lacrimal punctum in its centre • Lacrimal portion (medial part) is rounded & devoid of lashes or glands • Ciliary portion (lateral part) consists of a round anterior border & a sharp posterior border. The capillarity induced by this sharp angle of contact is important for proper moistening of the surface of eye
- 13. Eyelid Margins • Thepart lying in between the two borders is known as the Inter-marginal strip • Along the entire length of the free margin of the eyelid is the delicate Grey Line (or the Inter-marginal Sulcus), corresponding histologically to the most superficial portion of the orbicularis muscle, the muscle of Riolan, & to the avascular plane of the lid. Anterior to this line, the eyelashes (cilia) arise, & behind it are the openings of the tarsal (meibomian) glands just anterior to the mucocutaneous junction.
- 14. Eyelashes • Are arrangedin 2 or 3 irregular rows along the anterior part of the inter- marginal strip • They are usually longer & more numerous on the upper eyelid than on the lower one • They are darker than the scalp hair & tend to remain so throughout the life • Each cilium has a life-span of 3-4 months • The margins contain the glands of Zeis, which are modified sebaceous glands associated with the cilia, & the glands of Moll, apocrine sweat glands of skin
- 15. Layers of eyelid •From superficial to deep, each eyelid consists of the following structures: a) Skin b) Layer of subcutaneous areolar tissue c) Layer of striated muscles d) Submuscular areolar tissue e) Fibrous layer f) Layer of non-striated muscle fibres g) Conjunctiva
- 16. Skin • The skincovering the eyelids is elastic, having a fine texture, is thinnest in the body & folds easily thereby, contributing to the ease & speed of mobility of the upper eyelid. • Nasal part of the skin is smooth, shining & greasy in comparison to the temporal part. Fine hair are seen on the temporal part of the skin.
- 17. Skin • Microscopic structure:The epidermis is stratified squamous epithelium & composed of 6-7 layers of cells. The basal layer of epidermis shows unicellular sebaceous glands & numerous typical eccrine sweat glands. • The dermis or corium is composed of a thin layer of dense connective tissue, with rich network of elastic fibers, blood vessels, lymphatics & nerves. A variable number of melanocytes are also present, which may increase their pigment production in response to chronic oedema or inflammation.
- 18. Subcutaneous Areolar Tissue •It lies beneath the skin. • It is loose & fat less. It is thus readily distended by blood & oedema. • The overlying skin may be easily mobilized during plastic surgery. • This layer is non-existent near the ciliary margin, at the lid folds, & at medial & lateral angles where the skin is attached to the underlying ligaments.
- 19. Layer Of StriatedMuscles • This layer consists of two muscles: 1) Orbicularis oculi 2) Levator palpebrae superioris
- 20. The Orbicularis oculiMuscle • It is arranged in several concentric bands around the palpebral fissure. Of all the facial muscles, the orbicularis has fibres with the smallest diameter. • It can be divided into two parts: a) Orbital part b) Palpebral part • The Orbital part forms the most peripheral fibres of the orbicularis, which arise from the anterior part of the medial palpebral ligament & the adjacent bones. The fibres run covering the orbital margin in the form of a large ellipse & meet at the lateral palpebral raphe.
- 21. The Orbicularis oculiMuscle
- 22. The Orbicularis oculiMuscle • Superiorly, deep to the eyebrow the orbicularis fibres intermingle with those of the frontalis & thereby gain insertion into the skin of eyebrow • The upper medial fibres of the orbital part which pass to the skin of the medial part of the eyebrow are termed as “musculus superciliaris”. • Inferiorly, the medial & lateral peripheral fibres of the orbital part which are attached to the skin of cheek are called “musculus malaris”.
- 23. The Orbicularis oculiMuscle • The orbital part acts like a sphincter & functions solely as a voluntary muscle. It helps in forced closure of the eyelids & thus pull the eyebrows downward. • The Palpebral Part of orbicularis is subdivided into preseptal & pretarsal portions.
- 24. The Orbicularis oculiMuscle • The preseptal fibres arise from the lacrimal fascia, posterior lacrimal crest (deep head) & the anterior part of the medial palpebral ligament (superficial head). • The fibres pass superiorly & inferiorly in front of the orbital septum & unite at the lateral palpebral raphe.
- 25. The Orbicularis oculiMuscle • The pretarsal fibres also arise by a deep head (from the lacrimal fascia & posterior lacrimal crest) & a superficial head (from the medial palpebral ligament). • The fibres pass laterally above & below, overlying the upper tarsus & lower tarsus, respectively; & join laterally to form a lateral canthal tendon which is inserted over the lateral orbital tubercle of Whitnall.
- 26. The Orbicularis oculiMuscle The fibres of pretarsal portion which arise from the lacrimal fascia & upper part of posterior lacrimal crest help in the drainage of tears by lacrimal sac & are known as Pars lacrimalis (Horner’s Muscle). The fibres of the pretarsal portion which run along the lid margin behind the ciliary follicles form the Pars ciliaris (muscle of Riolan); these fibres keep the lids in close apposition to the globe.
- 27. The Orbicularis oculiMuscle • Disinsertion of the lower eyelid retractors from the tarsus may result in lower lid laxity, followed by spastic entropion, an inward turning of the eyelid margin. • In general, the palpebral part of the orbicularis helps in gentle closing of the eyelids during blinking, sleep & soft voluntary closure. • The entire orbicularis is supplied by the branches of Facial nerve.
- 28. The Levator palpebraesuperioris Muscle • Origin: it takes origin at the apex of the orbit from the undersurface of lesser wing of sphenoid above the annulus of Zinn, by a short tendon which is blended with the underlying origin of superior rectus muscle. • Course & Attachments: LPS has a flat ribbon like belly. It overlies the superior rectus as it travels anteriorly towards the eyelid.
- 29. The Levator palpebraesuperioris Muscle • The Whitnall ligament (also known as the Check ligament of LPS) results from a condensation of tissue surrounding the superior rectus & levator muscle. Actually it is a thickened band of orbital fascia which extends from the trochlear pulley to the capsule of the orbital lobe of lacrimal gland • “Recognition of this ligament during ptosis surgery is important, as severing of Whitnall’s ligament can lead to failure of LPS function.”
- 30. The Levator palpebraesuperioris Muscle • Near the WL, the LPS changes direction from horizontal to more vertical, and it divides anteriorly into the aponeurosis and posteriorly into the Superior Tarsal muscle (also known as Muller’s muscle) • The aponeurosis inserts into the anterior surface of the tarsus & passes by the medial & lateral horns into the canthal tendons
- 31. The Levator palpebraesuperioris Muscle • The fibrous elements of the aponeurosis pass through the orbicularis muscle & insert subcutaneously to produce the superior eyelid fold • The aponeurosis also inserts into the trochlea of the superior oblique muscle & into the fibrous tissue bridging the supraorbital notch. Attacments also exist with the conjunctiva of the upper fornix & with the orbital septum.
- 32. The Levator palpebraesuperioris Muscle • Fleshy / horizontal part of LPS is 40mm long, while tendinous / vertical part is 15mm long & 30mm wide. • Nerve supply & action: LPS is supplied by a branch of superior division of the oculomotor nerve and it acts as an elevator of the upper eyelid. Its action is antagonised by the palpebral portion of the orbicularis muscle.
- 33. Submuscular Areolar Tissue •It consists of a layer of loose connective tissue present between the orbicularis muscle & fibrous layer. • The nerves & vessels of the lids lie in this layer, & so to anaesthetize the lid, injection is made in this plane. • This layer also splits the eyelid into two -the anterior lamina & posterior lamina – which are easily approached through the gray line.
- 34. Submuscular Areolar Tissue •In the upper eyelid, superiorly this layer communicates with the subaponeurotic stratum of the scalp. Hence, the pus or blood can make its way into the upper eyelid from the dangerous area of the scalp. • In the lower eyelid, the submuscular tissue lies in a single space behind the orbicularis. In the upper eyelid, this space is traversed by the LPS muscle, which divides it into two – the pretarsal space & the preseptal space.
- 35. Submuscular Areolar Tissue •The Pretarsal Space is small area which appears fusiform in a vertical section. The peripheral arterial arcade is present in this space. Its anterior boundary is levator aponeurosis and posterior boundary is tarsal plates. • The Preseptal Space appears triangular in vertical section. It is bounded in front by the orbicularis, behind by the septum orbitale, and above by the preseptal cushion of fat.
- 36. Submuscular Areolar Tissue •Preseptal cushion of fat is a crescent-shaped pad of fat which lies in front of the septum and behind the orbicularis muscle to which it is firmly adherent. Its upper border lies along the superior orbital margin, to which it may overlap at times, & its lower border corresponds to the upper palpebral furrow.
- 37. Fibrous Layer • Itis the framework of the lid & consists of: 1) Tarsal plates (thick central part) 2) Septum orbitale (thin peripheral part) 3) Medial palpebral ligament 4) Lateral palpebral liigament
- 38. Tarsal Plates • Tarsiare firm plates of dense fibrous tissue that forms the skeleton of the eyelids, giving them shape & firmness. They are attached to the orbital margin by the medial & the lateral palpebral ligaments. • The tarsi are about 29mm long & 1mm thick. The upper tarsus is about 10-11mm in height & lower tarsus is 4-5mm in height.
- 39. Tarsal Plates • Septumorbitale & Muller’s muscle are attached at the superior border of the upper tarsus. • The orbital septum, capsulopalpebral fascia & inferior palpebral muscle are attached to the inferior border of the lower tarsus
- 40. Tarsal Plates • Anteriorsurface of each tarsus is convex and seperated from the orbicularis muscle by loose areolar tissue, so that muscle moves freely on the tarsus. • Posterior surface of the tarsal plates is concave coinciding with the curvature of globe, and is lined by conjunctiva which is firmly adherent to the tarsal plates. • Tarsal / meibomian glands are embedded in the substance of the tarsal plates.
- 41. Septum orbitale /Palpebral Fascia • It is a thin floating membrane, that takes part in all the movements of eyelids. • It is comparatively thick & strong on the lateral side than the medial side, & in the upper eyelid than the lower eyelid. • It encircles the orbit as an extension of the periosteum of the roof & floor of the orbit.
- 42. Septum orbitale /Palpebral Fascia • Posterior to the orbital septum lies the orbital fat. In both upper & lower eyelids, the orbital septum attaches to the aponeurosis. Thus it acts as a barrier to anterior & posterior extravasation of blood or the spread of inflammation. It also delimits the lateral spread of edema, inflammation, & blood as it is tightly adherent to the orbital margins.
- 43. Septum orbitale /Palpebral Fascia • Structures piercing through the septum orbitale: 1) Lacrimal vessels & nerves 2) Supraorbital vessels & nerves 3) Supratrochlear artery & nerve 4) Infratrochlear nerve 5) Anastomosing vein between the angular & ophthalmic vein 6) Superior & inferior palpebral arteries 7) Aponeurosis of LPS in the upper eyelid 8) Expansion of the inferior rectus in the lowerlid
- 44. Layer Of Non-striatedMuscle Fibres • Muller’s Muscle: It is a smooth (non-striated), sympathetically innervated muscle that originates from the undersurface of the LPS in the upper eyelid. • A similar smooth muscle arises from the capsulopalpebral head of inferior rectus in the lower eyelid.
- 45. Layer Of Non-striatedMuscle Fibres • The Muller muscle attaches to the upper border of the upper tarsus & to the conjunctiva of the upper fornix. • The capsulopalpebral muscle, which is a much weaker muscle than the Muller muscle, attaches to the lower border of the lower tarsus.
- 46. Layer Of Non-striatedMuscle Fibres • They are supplied by the sympathetic nerve fibres. Thus, sympathetic irritation leads to the retraction of the lids & paralysis leads to Horner’s Syndrome.
- 47. Conjunctiva • It isthe posterior most layer of eyelid. • It extends from the mucocutaneous junction at the lid margin to the conjunctival fornix. • It is firmly adherent to the poosterior surface of tarsal plates & Muller’s muscle.
- 48. Conjunctiva • Palpebral conjunctivacan be subdivided into three parts: 1) Marginal conjunctiva 2) Tarsal conjunctiva 3) Orbital conjunctiva
- 49. Conjunctiva • Marginal conjunctiva:it extends from the lid margin to about 2 mm on the back of the lid up to a shallow groove – the sulcus subtarsalis. • It is actually a transition zone b/w the skin & the conjunctiva proper. • At the sulcus subtarsalis, the perforating vessels pass through the tarsus to supply the conjunctiva. • This sulcus is a common site for lodgement of a conjunctival foreign body.
- 50. Conjunctiva • Tarsal Conjunctiva:is thin, transparent, & highly vascular. • It is firmly adherent to the whole tarsal plate in the upper eyelid. In the lower eyelid, it is adherent only to half width of the tarsus. • The tarsal glands are seen through it as yellow streaks. • Tarsal conjunctiva is a common site for follicular & papillary reactions.
- 51. Conjunctiva • Orbital conjunctiva:it lies loose b/w the tarsal plate & fornix. • Orbital conjunctiva of the upper eyelid is loose & lies over the Muller’s muscle.
- 52. Glands Of TheEyelids • These include: 1) Tarsal / Meibomian glands 2) Glands of Zeis 3) Glands of Moll 4) Accessory lacrimal glands of Wolfring
- 53. Tarsal / MeibomianGlands • These are modified holocrine sebaceous glands that are arranged vertically in parallel rows through the tarsus. • Their distribution & number within the eyelid can be observed by infra-red transillumination of the eyelid. • A single row of 30-40 meibomian orifices is present in the upper eyelid (b/w the gray line & the posterior border of the lid), but there are only 20-30 orifices in the lower eyelid.
- 54. Tarsal / MeibomianGlands • Secretions from the tarsal glands are oily in nature & perform the following functions: 1) The oily marginal tear strip prevents the overflow of tears across the lid margin. 2) The oily layer prevents evaporation of tears & allows smooth movements of the eyelids over the globe. 3) It ensures air-tight closure of the eyelids.
- 55. Glands Of Zeis •These are also modified sebaceous glands, attached directly to the eyelash follicle. • Usually, two glands are associated with each cilium. • Secretions from these glands prevent the eyelashes from becoming dry & brittle. • It also contributes to the oily layer of the tear film.
- 56. Glands Of Moll •These are modified apocrine sweat glands, which lie b/w the cilia. • These are more numerous in the lower eyelid than the upper.
- 57. Accessory Larimal GlandsOf Wolfring • These are microscopic accessory lacrimal glands present along the upper border of superior tarsus & along the lower border of the inferior tarsus. • These are about 2-5 in the upper lid & 2-3 in the lower lid.
- 58. Arterial Supply • Theeyelids are mainly supplied by the medial & lateral palpebral arteries, which are branches of the dorsal nasal & lacrimal arteries. • The superior & inferior arteries enter the upper & lower eyelids, by piercing through the septum orbitale above & below the medial palpebral ligament, respectively.
- 59. Arterial Supply • Eachmedial palpebral artery then anastomoses with the corresponding lateral palpebral artery to form marginal arterial arcades which lie in the sub-muscular plane in front of the tarsal plate some 2-3mm away from the lid margin, in each eyelid. • In the upper eyelid another arcade (superior or peripheral arterial arcade) is formed from the superior branches of medial palpebral artery, which lies near the upper border of the tarsal plate.
- 60. Arterial Supply • Thetarsal arcades of the eyelids also receive anastomosing twigs from the superficial temporal artery, transverse facial artery & infraorbital artery. • Branches from the arterial arcades go forward to supply orbicularis & skin, & backward to supply the tarsal glands & conjunctiva.
- 61.
- 62. Venous Drainage • Veinsare larger & more numerous than the arteries of eyelids. These are arranged in two sets of venous plexuses in each eyelid: 1) Pre-tarsal Venous Plexus: It drains structures superficial to the tarsus, mainly into the angular vein on the medial side, which ultimately drains into the internal jugular vein; & superficial temporal & lacrimal veins on the lateral side, which ultimately drain into the external jugular vein.
- 63. Venous Drainage 2) Post-tarsalVenous Plexus: it drains structures posterior to the tarsal plates into the ophthalmic veins.
- 64. Lymphatic Drainage • Lymphaticplexuses are two in each eyelid: 1) Superficial or Pre-tarsal plexus drains lymph from the skin & the orbicularis muscle. 2) Deep or Post-tarsal plexus drains lymph from the tarsal plate region & conjunctiva.
- 65. Lymphatic Drainage • Lymphvessels are arranged in 2 groups: 1) Medial Group: The two superficial medial channels drain the medial half of the lower lid, medial quarter of the upper lid & medial commissure into the superficial submandibular lymph nodes. The two deep medial channels drain the conjunctiva of the medial 2/3rds of the lower lid & caruncle into the deep submandibular lymph nodes.
- 66. Lymphatic Drainage 2) LateralGroup: The superficial lateral trunk drains the superficial structures of the lateral 3/4th of the upper lid & of the lateral part of the lower lid, into the superficial parotid lymph nodes & preauricular lymph nodes. The deep lateral trunk drains the entire conjunctiva of the upper lid & the conjunctiva of the lateral 1/3rd of the lower lid into deep parotid lymph node.
- 67. Nerve Supply Motornerves: 1) Facial nerve (orbicularis) 2) Oculomotor nerve (LPS) Sensory nerves are derived from branches of the 2nd & 1st division of Trigeminal nerve Sympathetic nerves supply the non-striated muscles , the vessels & the glands of the skin. Most of the nerves lie in the submuscular plane b/w the orbicularis & the tarsal plate. Therefore to anaesthetize the lid, injection should be made in this compartment.
- 68.