The Orbit & its contents by Dr. Rabia I. Gandapore.pptx

Eye Anatomy

1. The Orbital Region (Bony Orbit, Ocular Muscles, Lacrimal & Ciliary Gland And Eyeball) Dr. Rabia Inam Gandapore Assistant Professor Head of Department Anatomy (Dentistry-BKCD) B.D.S (SBDC), M.Phil. Anatomy (KMU), Dip. Implant (Sharjah, Bangkok, ACHERS) , CHPE (KMU),CHR (KMU), Dip. Arts (Florence, Italy )

2. Teaching Methodology LGF (Long Group Format) SGF (Short Group Format) LGD (Long Group Discussion, Interactive discussion with the use of models or diagrams) SGD (Short Group) SDL (Self-Directed Learning) DSL (Directed-Self Learning) PBL (Problem- Based Learning) Online Teaching Method Role Play Demonstrations Laboratory Museum Library (Computed Assisted L earning or E-Learning) Assignments Video tutorial method

3. Goal/Aim (main objective) To help/facilitate/augment the students about the: Describe walls and openings in the orbital cavity . Enumerate foramen and fissures in bony orbit and structures passing through it . Explain origin, insertion, nerve supply and action of extra-ocular muscles Discuss lacrimal and ciliary glands . Describe features & relevant clinical anatomy of: • Outer Coat • Cornea • Middle Coat • Inner Coat • Aqueous Humour • Vitreous Body

4. Specific Learning Objectives (cognitive ) At the end of the lecture the student will able to: Recognize the gross anatomical features of the Describe walls and openings in the orbital cavity . Enumerate foramen and fissures in bony orbit and structures passing through it. Explain origin, insertion, nerve supply and action of extra-ocular muscles Discuss lacrimal and ciliary glands . Describe features & relevant clinical anatomy of: • Outer Coat • Cornea • Middle Coat • Inner Coat • Aqueous Humour • Vitreous Body Sketch labeled diagram of the Eyeball & tabulated extra-ocular muscles

5. Psychomotor Objective: (Guided response ) A student to draw labelled diagram of Eyeball & tabulated extra-ocular muscles

6. Affective domain To be able to display a good code of conduct and moral values in the class. To cooperate with the teacher and in groups with the colleagues. To demonstrate a responsible behavior in the class and be punctual, regular, attentive and on time in the class. To be able to perform well in the class under the guidance and supervision of the teacher. Study the topic before entering the class. Discuss among colleagues the topic under discussion in SGDs. Participate in group activities and museum classes and follow the rules. Volunteer to participate in psychomotor activities. Listen to the teacher's instructions carefully and follow the guidelines. Ask questions in the class by raising hand and avoid creating a disturbance. To be able to submit all assignments on time and get your sketch logbooks checked.

7. Lesson contents Clinical chair side question: Students will be asked if they know what is the function of Eyeball Outline: Activity 1 The facilitator will explain the student's to Recognize the G ross anatomical features and openings in the orbital cavity . Enumerate foramen and fissures in bony orbit and structures passing through it. Explain origin, insertion, nerve supply and action of extra-ocular muscles Discuss lacrimal and ciliary glands . Describe features & relevant clinical anatomy of: • Outer Coat • Cornea • Middle Coat • Inner Coat • Aqueous Humour • Vitreous Body Activity 2 The facilitator will ask the students to make a labeled diagram of the Sketch labeled diagram of the Eyeball & tabulated extra-ocular muscles Activity 3 The facilitator will ask the students a few Multiple Choice Questions related to it with flashcards .

8. Recommendations Students assessment: MCQs, Flashcards, Diagrams labeling. Learning resources: Langman’s T.W. Sadler, Laiq Hussain Siddiqui, Snell Clinical Anatomy , Netter’s Atlas , BD Chaurasia’s Human anatomy, Internet sources links.

9. Orbital Region Eyelids Movements of Eyelids

10. Orbital Region O rbits are a pair of bony cavities that contain: Eyeballs A ssociated muscles, nerves, vessels F ats L acrimal apparatus . Eyelids: Orbital opening is guarded by 2 thin, movable folds. protect eye from injury & excessive light by their closure

11. Eyelids Upper eyelid: is larger & more mobile. E ye closed: it completely covers cornea of eye. E ye open : looking straight ahead it covers upper margin of cornea . Lower eyelid: smaller & less mobile. When eye open : lies just below cornea When eye closed: rises only slightly. Upper & Lower eyelids: meet at medial & lateral angles . P alpebral fissure: elliptical opening between eyelids & is the entrance into conjunctival sac .

12. S uperficial surface of eyelids: covered by skin D eep surface: covered by mucous membrane called C onjunctiva . Eyelashes: short , curved hairs on free edges of eyelids, arranged in double or triple rows at mucocutaneous junction . S ebaceous glands (glands of Zeis ): open directly into eyelash follicles . C iliary glands (glands of Moll ): modified sweat glands , open separately between adjacent lashes. Tarsal glands: long , modified sebaceous glands that pour their oily secretion onto margin of lid; their openings lie behind eyelashes. This oily material prevents overflow of tears & helps make the closed eyelids airtight.

13. Lacus lacrimalis : small space which separates more rounded medial angle from eyeball Caruncula lacrimalis : small , reddish yellow elevation in center of Lacus lacrimalis Plica semilunaris : reddish semilunar fold , lies on lateral side of caruncle . Papilla lacrimalis : Near medial angle of eye a small elevation . It projects into lacus Punctum lacrimale : On summit of papilla is a small hole which leads into canaliculus lacrimalis . Punctum & Canaliculus carry tears down into the nose

14. Conjunctiva : thin mucous membrane that lines eyelids & is reflected at superior & inferior fornices onto anterior surface of eyeball. Its epithelium is continuous with that of cornea. U pper lateral part of superior fornix: pierced by ducts of lacrimal gland. Conjunctival sac: Conjunctiva forms potential space, it opens at palpebral fissure. Subtarsal sulcus: Beneath eyelid groove, it runs close to & parallel with margin of lid. It tends to trap small foreign particles introduced into conjunctival sac & clinically important

15. F ramework of eyelids: formed by fibrous sheet, orbital septum . Its attached to periosteum at orbital margins. Tarsal Plates: is thickened at margins of lids to form; superior & inferior tarsal plates . Lateral palpebral ligament: lateral ends of plates are attached by a band to a bony tubercle just within orbital margin. Medial palpebral ligament: medial ends of plates are attached by a band to crest of lacrimal bone. Tarsal glands: are embedded in posterior surface of tarsal plates. Orbicularis oculi muscle: superficial surface of tarsal plates & orbital septum are covered by its palpebral fibers . aponeurosis of insertion of L evator palpebrae superioris muscle pierces the orbital septum to reach anterior surface of superior tarsal plate & skin.

16. Movements of the Eyelids P osition of eyelids at rest depends on tone of: Orbicularis oculi muscles L evator palpebrae superioris muscles P osition of eyeball. E yelids are closed by: C ontraction of: orbicularis oculi muscles R elaxation of: levator palpebrae superioris muscles . Eye is opened by: Levator palpebrae superioris raising upper lid. On looking upward : levator palpebrae superioris contracts upper lid moves with eyeball. On looking downward : Both lids move Upper lid continues to cover upper part of cornea Lower lid is pulled downward by conjunctiva, its attached to sclera & lower lid.

17. Muscles of Eyeball & Eyelids Origin Insertion Action Nerve Supply

18. Extrinsic Muscles 6 voluntary muscles that run from posterior wall of orbital cavity to eyeball: 1. Superior rectus: to raise cornea upward , inferior oblique muscle must assist 2. Inferior rectus: inferior rectus to depress cornea downward , superior oblique muscle must assist. Superior & inferior recti are inserted on medial side of vertical axis of eyeball, they not only raise & depress cornea, respectively, but also rotate it medially . 3. Medial rectus 4. Lateral rectus 5. Superior oblique muscles 6. Inferior oblique muscles .

19. Movements of Eyeball C enter of cornea or pupil: is used as anatomic “anterior pole” of eye Elevation: rotation of eye upward Depression : rotation of eye downward Abduction : rotation of eye laterally Adduction: rotation of eye medially Rotatory movements: use upper rim of cornea (or pupil) as marker. Eye rotates: Medially L aterally .

20. S. No. Muscles Origin Insertion Nerve Supply Action Extrinsic Muscles of Eyeball (Striated Skeletal Muscle) 1. Superior Rectus Tendinous ring on posterior wall of orbital cavity Superior surface of eyeball just posterior to corneoscleral junction Oculomotor nerve (3rd cranial nerve) Raises cornea upward and medially 2. Inferior Rectus Inferior surface of eyeball just posterior to corneoscleral junction Depresses cornea downward and medially 3. Medial Rectus Medial surface of eyeball just posterior to corneoscleral junction Rotates eyeball so that cornea looks medially 4. Lateral Rectus Lateral surface of eyeball just posterior to corneoscleral junction Abducent nerve (6th cranial nerve) Rotates eyeball so that cornea looks laterally 5. Superior Oblique Posterior wall of orbital cavity Passes through pulley and is attached to superior surface of eyeball beneath superior rectus Trochlear nerve (4th cranial nerve) Rotates eyeball so that cornea looks downward and laterally 6. Inferior Oblique Floor of orbital cavity Lateral surface of eyeball deep to lateral rectus Oculomotor nerve (3rd cranial nerve) Rotates eyeball so that cornea looks upward and laterally

21. Intrinsic Muscles I nvoluntary ciliary muscle C onstrictor & D ilator pupillae of iris: take no part in movement of eyeball

22. S. No. Muscles Origin Insertion Nerve Supply Action Intrinsic Muscles of Eyeball (Smooth Muscle) 1. Sphincter pupillae of iris Parasympathetic via oculomotor nerve Constricts pupil 2. Dilator pupillae of iris Sympathetic Dilates pupil 3. Ciliary muscle Parasympathetic via oculomotor nerve Controls shape of lens; in accommodation, makes lens more globular Muscles of Eyelids 1. Orbicularis Oculi 2. Levator palpabrae superioris Back of orbital cavity Anterior surface and upper margin of superior tarsal plate Striated muscle oculomotor nerve, smooth muscle sympathetic Raises upper lid

23. Fascial Sheath of Eyeball S urrounds eyeball from optic nerve to corneoscleral junction . It separates eyeball from orbital fat & provides it with a socket for free movement. It is perforated by tendons of orbital muscles & is reflected onto each of them as a tubular sheath . S heaths for tendons of medial & lateral recti are attached to medial & lateral walls of orbit by triangular ligaments called medial & lateral check ligaments . Lower part of fascial sheath , which passes beneath the eyeball & connects the check l igaments , is thickened & serves to suspend eyeball; its called suspensory ligament of eye & is suspended from medial & lateral walls of orbit, as if in a hammock.

24. Lacrimal Appratus Lacrimal glands Lacrimal ducts

25. Lacrimal Apparatus Lacrimal Gland consists of: O rbital part: large P alpebral part: small which are continuous with each other around lateral edge of aponeurosis of levator palpebrae superioris . It is situated above eyeball in anterior & upper part of orbit, posterior to orbital septum. It opens into lateral part of superior fornix of conjunctiva by 12 ducts .

26. Parasympathetic secretomotor nerve: supply is derived from lacrimal nucleus of facial nerve. Preganglionic fibers : reaches pterygopalatine ganglion ( sphenopalatine ganglion) via nervus intermedius & its great petrosal branch and via nerve of pterygoid canal. Postganglionic fibers : leave ganglion & joins maxillary nerve. It then pass into its zygomatic branch a& zygomaticotemporal nerve. They reach lacrimal gland within lacrimal nerve. Sympathetic postganglionic nerve supply is from internal carotid plexus & travels in deep petrosal nerve,nerve of pterygoid canal, maxillary nerve, zygomatic nerve, zygomaticotemporal nerve & lacrimal nerve.

27. Lacrimal Ducts Tears circulate across cornea & accumulate in lacus lacrimalis . tears enter canaliculi lacrimales through puncta lacrimalis . canaliculi lacrimales pass medially & open into lacrimal sac , which lies in the lacrimal groove behind medial palpebral ligament & is the upper blind end of the nasolacrimal duct . Nasolacrimal duct: 0.5 in. (1.3 cm) long & emerges from lower end of lacrimal sac . D uct descends downward, backward & laterally in a bony canal & opens into inferior meatus of nose . opening is guarded by a fold of mucous membrane known as lacrimal fold . This prevents air from being forced up the duct into lacrimal sac on blowing nose

28. The Orbit Openings into the orbital cavity Orbital fascia

29. The Orbit P yramidal cavity: Base: Anterior Apex: P osterior. O rbital margin above : frontal bone L ateral margin : processes of frontal & zygomatic bones Inferior margin : zygomatic bone & maxilla M edial margin : processes of maxilla & frontal bone. Roof: orbital plate of frontal bone (separates orbital cavity from anterior cranial fossa & frontal lobe of cerebral hemisphere) Lateral wall: zygomatic bone & greater wing of sphenoid Floor : orbital plate of maxilla ( separates orbital cavity from maxillary sinus) Medial wall: before backward by frontal process of maxilla, lacrimal bone, orbital plate of ethmoid (which separates orbital cavity from ethmoid sinuses ) & body of sphenoid

30. Openings into the Orbital Cavity Orbital opening: Lies anteriorly. About one sixth of eye is exposed; the remainder is protected by walls of orbit . The openings into orbital cavity are: Supraorbital notch (Foramen ): situated on superior orbital margin. It transmits supraorbital nerve & blood vessels Infraorbital groove & canal : Situated on floor of orbit in orbital plate of maxilla; they transmit infraorbital nerve (a continuation of maxillary nerve) & blood vessels. Nasolacrimal canal: Located anteriorly on medial wall; it communicates with inferior meatus of nose . It transmits nasolacrimal duct . Inferior orbital fissure: Located posteriorly between maxilla & greater wing of sphenoid; it communicates with pterygopalatine fossa. It transmits maxillary nerve & its zygomatic branch , inferior ophthalmic vein & sympathetic nerves . Superior orbital fissure: Located posteriorly between greater & lesser wings of sphenoid; it communicates with the middle cranial fossa. It transmits the lacrimal nerve , frontal nerve , trochlear nerve , oculomotor nerve (upper & lower divisions), abducent nerve , nasociliary nerve & superior ophthalmic vein . Optic canal: Located posteriorly in lesser wing of sphenoid; it communicates with middle cranial fossa. It transmits optic nerve & ophthalmic artery.

31. Orbital Fascia Is periosteum of bones that form walls of orbit. It is loosely attached to bones & is continuous through foramina & fissures with the periosteum covering outer surfaces of bones . M uscle of Müller, or orbitalis muscle : thin layer of smooth muscle that bridges inferior orbital fissure. Its supplied by sympathetic nerves & its function is unknown .

32. The Eyeball Movements of eyeball Facial Sheath of EYEBall Structure and Coats of the eyeball Fibrous coat Vascular pigmented coat Nervous coat Contents of the eyeball

33. Structure of Eye E mbedded in orbital fat but is separated from it by fascial sheath of eyeball . E yeball consists of 3 coats : F ibrous coat V ascular pigmented coat N ervous coat.

34. Coats of Eyeball Fibrous Coat: made up of a a . P osterior opaque part : Sclera b. Anterior transparent part: C ornea.

35. a. The Sclera O paque sclera is composed of dense fibrous tissue & is white . Posteriorly , its pierced by optic nerve & is fused with dural sheath of that nerve. L amina cribrosa is area of sclera that is pierced by nerve fibers of optic nerve . Its also pierced by ciliary arteries & nerves & associated veins; venae vorticosae . Its directly continuous in front with cornea at corneoscleral junction, or limbus .

36. b. Cornea T ransparent cornea is largely responsible for refraction of light entering eye. Its in contact posteriorly with aqueous humor . Blood Supply: avascular & devoid of lymphatic drainage. Its nourished by diffusion from aqueous humor & from capillaries at its edge. Nerve Supply: Long ciliary nerves from ophthalmic division of trigeminal nerve Function of Cornea: refractive medium of eye . This refractive power occurs on the anterior surface of cornea, where refractive index of cornea (1.38) differs greatly from that of air . The importance of tear film in maintaining normal environment for corneal epithelial cells should be stressed.

37. 2. Vascular Pigmented Coat C onsists , from behind forward , of: a. Choroid: composed of an: Outer: pigmented layer Inner: highly vascular layer b. Ciliary body c. Iris

38. b. Ciliary Body : continuous: P osteriorly with choroid A nteriorly it lies behind peripheral margin of iris . Its composed of: 1. Ciliary ring: posterior part of body & its surface has shallow grooves; ciliary striae . 2. Ciliary processes: are radially arranged folds, or ridges, to posterior surfaces of which are connected the suspensory ligaments of l ens 3. Ciliary muscle: composed of meridianal & circular fibers of smooth muscle. Meridianal fibers : run backward from region of corneoscleral junction to ciliary processes. C ircular fibers : are fewer in number & lie internal to meridianal fibers .

39. Nerve supply: ciliary muscle is supplied by parasympathetic fibers from oculomotor nerve . After synapsing in ciliary ganglion , postganglionic fibers pass forward to eyeball in short ciliary nerves . Action: Contraction of ciliary muscle, especially meridianal fibers , pulls ciliary body forward. This relieves tension in suspensory ligament, & elastic lens becomes more convex . This increases refractive power of lens

40. c. Iris & Pupil Iris: contractile , pigmented diaphragm Pupil: central aperture Its suspended in aqueous humor between cornea & lens . P eriphery of iris is attached to anterior surface of ciliary body . It divides the space between lens & cornea into an Anterior Chamber P osterior Chamber M uscle fibers of iris are involuntary & consist of circular & radiating fibers . a. Circular fibers : form sphincter pupillae & are arranged around margin of pupil . b. Radial fibers : form dilator pupillae & consist of thin sheet of radial fibers that lie close to posterior surface .

41. Nerve supply: a. Sphincter pupillae : is supplied by parasympathetic fibers from oculomotor nerve . After synapsing in ciliary ganglion, postganglionic fibers pass forward to eyeball in short ciliary nerves . b. Dilator pupillae : is supplied by sympathetic fibers , which pass forward to eyeball in long ciliary nerves . Action : a. Sphincter pupillae : constricts pupil in presence of bright light & during accommodation . b. Dilator pupillae : dilates pupil in presence of light of low intensity or in presence of excessive sympatheti c activity such as occurs in fright .

42. 3. Nervous Coat: The Retina R etina consists of an: a. Outer pigmented layer: contact with choroid b. Inner nervous layer : contact with the vitreous body P osterior 3 quarters of retina is receptor organ . Its anterior edge forms a wavy ring; ora serrata , & nervous tissues end here. A nterior part of retina is nonreceptive & consists of pigment cells , with a deeper layer of columnar epithelium. It covers ciliary processes & back of iris .

43. At the center of posterior part of retina is an oval, yellowish area ; macula lutea , which is area of retina for the most distinct vision . It has a central depression; fovea centralis . O ptic nerve leaves retina about 3 mm to medial side of macula lutea by optic disc . O ptic disc is slightly depressed at its center , where its pierced by central artery of retina . At optic disc is a complete absence of rods & cones so that it is insensitive to light & is referred to as the “ blind spot .” Ophthalmoscopic examination: optic disc is seen to be pale pink in color , much paler than surrounding retina.

44. Contents of Eyeball consist of: R efractive media A queous humor V itreous body L ens.

45. a. Aqueous Humor C lear fluid that fills anterior & posterior chambers of eyeball . It’s a secretion from ciliary processes , via it enters posterior chamber . It flows into anterior chamber through pupil & is drained away through spaces at the iridocorneal angle into canal of Schlemm Obstruction: to draining of aqueous humor results in a rise in intraocular pressure called glaucoma . This can produce degenerative changes in retina i.e. blindness .

46. Function Of Aqueous Humor T o support wall of eyeball by exerting internal pressure maintaining its optical shape . It also nourishes cornea & lens removes products of metabolism ; Note: cornea & lens do not possess a blood supply .

47. b. Vitreous Body fills eyeball behind the lens & is a transparent gel . H yaloid canal is a narrow channel that runs through the vitreous body from the optic disc to posterior surface of lens; in fetus , it is filled by the hyaloid artery , which disappears before birth.

48. Function of vitreous body C ontribute slightly to magnifying power of eye . S upports posterior surface of lens A ssists in holding neural part of retina against pigmented part of retina .

49. C. The Lens transparent , biconvex structure enclosed in a transparent capsule. Its situated behind iris & in front of vitreous body & is encircled by ciliary processes . L ens consists of an elastic capsule , which envelops the structure; a cuboidal epithelium , which is confined to anterior surface of lens ; & lens fibers , which are formed from cuboidal epithelium at equator of lens . L ens fibers make up bulk of lens . E lastic lens capsule is under tension, causing lens constantly to endeavor to assume a globular rather than a disc shape. Lens is attached to ciliary processes of ciliary body by suspensory ligament . The pull of radiating fibers of suspensory ligament tends to keep the elastic lens flattened so that eye can be focused on distant objects..

50. Accommodation of the Eye To accommodate eye for close objects , ciliary muscle contracts & pulls ciliary body forward & inward so that radiating fibers of suspensory ligament are relaxed. This allows elastic lens to assume a more globular shape . With advancing age : lens becomes denser & less elastic ,& ability to accommodate is lessened (presbyopia ). This disability can be overcome by use of an additional lens in form of glasses to assist the eye in focusing on nearby objects.

51. Constriction of Pupil during Accommodation of Eye To ensure that light rays pass through central part of lens so spherical aberration is diminished during accommodation for near objects , the sphincter pupillae muscle contracts so pupil becomes smaller . Convergence of Eyes during Accommodation of Lens In humans, retinae of both eyes focus on only one set of objects (single binocular vision). When an object moves from a distance toward an individual , the eyes converge so that a single object , not two, is seen. Convergence of eyes results from coordinated contraction of medial rectus muscles .

52. Clinical Correlations

53. Clinical Testing for Actions of Superior & Inferior Recti AND Superior & Inferior Oblique Muscles Physician tests eye movements: Patient is asked to look vertically upward or downward. Example: Origins of superior & inferior recti are situated about 23° medial to their insertions so when the patient is asked to turn cornea laterally, these muscles raise (superior rectus) or lower (inferior rectus ) cornea. Test for Superior Oblique: ask patient to look medially & downward at tip of his or her nose . Test for inferior Oblique: asking patient to look medially & upward. Because lateral & medial recti are simply placed relative to eyeball , asking patient to turn cornea directly laterally tests lateral rectus & turning cornea directly medially tests medial rectus .

54. Eye Trauma Eyeball: well protected by bony orbit but provides no protection from small objects i.e. golf balls & cause severe damage on lateral side. Blowout fractures of orbital floor involving maxillary sinus occur due to blunt force to face . If the force is applied to eye , the orbital fat explodes inferiorly into maxillary sinus, fracturing orbital floor. Not only can blowout fractures cause displacement of eyeball , but cause double vision (diplopia), injure infraorbital nerve , producing loss of sensation of skin of cheek & gum on that side. Entrapment of inferior rectus mus cle in fracture may limit upward gaze.

55. Strabismus Many cases of strabismus are non-paralytic caused by an imbalance in action of opposing muscles . This type of strabismus is known as concomitant strabismus common in infancy .

56. Pupillary Reflexes R eaction of pupils to light & accommodation: depend on integrity of nervous pathways. 1. Direct light reflex : N ormal pupil reflex contracts when a light is shone into patient’s eye. N ervous impulses pass from retina along optic nerve to optic chiasma & optic tract Before reaching lateral geniculate body , fibers leave the tract & pass to oculomotor nuclei on both sides via pretectal nuclei . From parasympathetic part of nucleus , efferent fibers leaves midbrain in the oculomotor nerve & reach the ciliary ganglion via nerve to inferior oblique. Postganglionic fibers pass to constrictor pupillae muscles via short ciliary nerves .

57. 2. Consensual light reflex T ested by shining light in one eye & noting contraction of pupil in opposite eye . This reflex is possible because the afferent pathway just described travels to parasympathetic nuclei of both oculomotor nerves .

58. 3. Accommodation reflex is contraction of pupil that occurs when a person suddenly focuses on a near object after having focused on a distant object . N ervous impulses pass from retina via optic nerve , optic chiasma , optic tract, lateral geniculate body, optic radiation & cerebral cortex of occipital lobe of brain . V isual cortex is connected to eye field of frontal cortex . From here, efferent pathways pass to parasympathetic nucleus of oculomotor nerve . From there, efferent impulses reach constrictor pupillae via oculomotor nerve , ciliary ganglion & short ciliary nerves .

59. Horner’s Syndrome

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