Orbit 解剖學科鄭授德 本教材之圖片取自於 1. Gray s Anatomy for Students, 3rd ed., 2015, by Drake, Vogl, and Mitchell 2. Clinically Oriented Anatomy, 7th ed., 2014, by Moore, Dalley, and Agur 3. Anatomy, an Essential Textbook, 2013, by Giloroy, Voll, and Wesker 4. Clemente Anatomy, A Regional Atlas of the Human Body, 1997, 4th ed 5. Gray s Anatomy, the Anatomical Basis of Clinical Practice, 2008, 40th ed.
Bony orbit Sup. frontal bone Med. frontal process of maxilla Inf. zygomatic process of maxilla zygomatic bone Lat. frontal processes of zygomatic bone zygomatic processes of frontal bone
Roof Frontal and sphenoid bones (lesser wing); anterior cranial fossa is above the roof Anteromedially frontal sinus, trochlear fovea Anterolaterally lacrimal fossa
Medial wall By maxilla, lacrimal, ethmoid, and sphenoid bones Ethmoid air cells, frontoethmoidal suture, anterior and posterior ethmoidal foramina (for ant. and post. ethmoidal nn. and vessels) Lacrimal bone Lacrimal groove (with posterior lacrimal crest of lacrimal bone, and anterior lacrimal crest of maxilla) Optic canal on the sphenoid bone
Floor also the roof of maxillary sinus, contains maxilla, zygomatic, and palatine bones Inferior orbital fissure separates the inferior wall from lateral wall. Lateral wall zygomatic bone and greater wing of sphenoid bone
Eyelids Palpebral fissure between upper and lower eyelids 1. Skin and subcutaneous tissue ST may accumulate blood under injury 2. Orbicularis oculi 3. Orbital septum Extension of periosteum in upper and lower eyelids Attaches to the tendon of levator palpebrae superioris m. and tarsus of lower eyelid 4. Tarsus and levator palpebrae superioris 5. Conjunctiva reflects onto sclera as superior and inferior conjunctival fornices. Conjunctival sac is formed when eyelids close.
Orbicularis oculi innervated by CN VII 1. Palpebral part: in eyelids Medial palpebral ligament to ant. lacrimal crest Lateral palpebral ligament to zygomaitc bone 2. Orbital part: around orbit 3. Lacrimal part: medial end, attaches to post. lacrimal crest drains tears
Tarsus Superior tarsus and inferior tarsus attach through medial palpebral ligament to anterior lacrimal crest of maxilla attach through lateral palpebral ligament to zygomatic bone Tarsal glands embed in the tarsal plates, and open to the free margin of eyelids
Levator palpebrae superioris Levator palpebrae superioris muscle O: post. part of the roof of orbit, sup. to optic foramen I: ant. surface of superior tarsus F: raises upper eyelid N: CN III Superior tarsal muscle O: inferior surface of levator palpebrae superioris I: upper edge of superior tarsus F: assists to maintain upper eyelid elevation N: sympathetic fibers from superior cervical ganglion Loss function of either of these two muscles causes drooping of upper eyelid (ptosis)
Glands Sebaceous glands and sweat glands associated with eyelash blockage and inflammation cause stye ( 麥粒腫 針眼 ) on the edge of eyelids Tarsal glands opening on the edge of eyelids blockage and inflammation cause chalazion ( 霰ㄒㄧㄢˋ 粒腫 ) on the inner surface of eyelids
Vessels 1. Ophthalmic a. Supratrochlear a. Supra-orbital a. Lacrimal a. Dorsal nasal a. 2. Facial a. Angular a. 3. Superficial temporal a. Transverse facial a. 4. Brr. of superficial temporal a. Ext. venous drainage with associated aa. Int. venous drainage to ophthalmic vv. Lymph drainage to parotid primarily, and (medial corner of orbit to) submandibular nodes
Innervation Sensory: Supra-orbital, supratrochlear, infratrochlear, lacrimal brr. of CN V 1 Infra-orbital br. of CN V 2 Motor: CN VII palpebral part of orbicularis oculi (unable to close eyelid tightly) CN III levator palpebrae superioris (complete ptosis) Sympathetic ff. superior tarsal m. (partial ptosis) Horner s syndrome Lesion on sympathetic trunk in neck pupillary constriction( 縮瞳 ) partial ptosis( 垂瞼 ) absence of sweating( 乾 ) vasodilation( 結膜紅 ) endophthalmos( 眼球下陷 )
Lacrimal apparatus Lacrimal glands and ducts: Orbital part: in lacrimal fossa of frontal bone Palpebral part: inferior to levator palpebrae superioris Lacrimal lake medial end of conjunctival sac Lacrimal punctum opening of lacrimal canaliculus Lacrimal canaliculi drain to lacrimal sac Lacrimal sac between medial palpebral ligament and lacrimal part of orbicularis oculi m. Nasolacrimal duct drain to inferior meatus of nasal cavity
Innervation 1. Sensory innervation Lacrimal br. of CN V1 2. Secretomotor (parasympathetic) innervation Preganglionic parasympathetic ff. in CN VII > Greater petrosal n. > N. of pterygoid canal > Pterygopalatine gang. (synapse) > Postganglionic ff. > Maxillary n. > Zygomatic n. > Zygomaticotemporal n. > Lacrimal n. > Lacrimal gland
Innervation 3. Sympathetic innervation Superior cervical gang. > Postgang. sympathetic ff. > Plexus surrounding int. carotid a. > Deep petrosal n. > N. of pterygoid canal > Pass through pterygopalatine ganglion > same as postganglionic parasympathetic ff. > > > Lacrimal gland
Fissures and foramina Optic canal Between body and lesser wing of sphenoid bone passed by optic n. (CN II) and ophthalmic a. Superior orbital fissure Between roof and lateral wall of orbit passed by CN III (superior and inferior brr.), CN IV, CN VI, and CN V 1 (lacrimal, frontal, and nasociliary brr. of ophthalmic n.)
Fissures and foramina Inferior orbital fissure Between lateral wall and floor Connects orbit with pterygopalatine fossa passed by maxillary n. and zygomatic br., and vv. to pterygoid venous plexus Connects orbit with infratemporal fossa Connects orbit with temporal fossa Infra-orbital foramen Infra-orbital groove on the floor connects to infra-orbital canal anteriorly, and opens on the face at infra-orbital f. Passed by infra-orbital n. (br. of CN V 2 )
Other openings on medial wall Anterior and posterior ethmoidal foramina passed by ant. and post. ethmoidal nn. and vessels, to ethmoid bone Nasoacrimal canal passed by nasolacrimal duct, leads to inferior nasal meatus Lacrimal gland Optic canal Ethmoidal foramina Nasolacrimal duct
Periosteum lining the orbit; extends as orbital septa Thickening in posterior end around optic canal as common tendinous ring (origin of four rectus mm.) Periorbita
Fascial sheath of the eyeball Enclose eyeball, attaches to: sclera at the point of optic nerve entering eyeball, sclera near the edge of cornea, fascial sheath of muscles The lower part of fascial sheath is suspensory ligament.
Check ligaments of the medial and lateral rectus muscles Thickening of investing sheath covering med. and lat. recti Medial check ligament attaches to the point immediately posterior to posterior lacrimal crest. Lateral check ligament attaches to the orbital tubercle of zygomatic bone.
Extrinsic muscles Extra-ocular mm. for moving eyeball or raising upper eyelid Elevation moving pupil superiorly Depression moving pupil inferiorly Abduction moving pupil laterally Adduction moving pupil medially Internal rotation rotating upper part of pupil medially External rotation rotating upper part of pupil laterally
Levator palpebrae superioris Function: raises upper eyelid; innervation: CN III Superior tarsal muscle (smooth muscle) by sympathetic ff. Origin: inferior surface of levator palpebrae superioris Function: assists to maintain upper eyelid elevation
Rectus muscles Superior and inferior rectus muscles Function: Sup. rectus elevates, adducts, and internal rotates Inf. rectus depresses, adducts, and external rotates Innervation: Sup. rectus sup. br. of CN III Inf. rectus inf. br. of CN III Medial and lateral rectus muscles Function: Med. rectus adducts Lat. rectus abducts Innervation: Med. rectus inf. br. of CN III Lat. rectus CN VI
Oblique muscles Superior oblique Origin: body of sphenoid bone It runs along medial border of roof of orbit, passes through fibrocartilaginous pully (trochlea). The muscle runs deep to superior rectus muscle Inserts to outer posterior quadrant of eyeball Function: turn pupil down and out Innervation: CN IV
Oblique muscles Inferior oblique Origin: medial side of floor of orbit, posterior to orbital rim Insertion: outer posterior quadrant of eyeball Function: turn pupil up and out Innervation: inferior br. of CN III
SR IO IR SO
Internal carotid a. gives off ophthalmic a. Arteries through optic canal into orbit gives off: Lacrimal a. lateral side of obit, to supply lacrimal gland, anterior ciliary br. to eyeball, lateral eyelid Central retinal a. enters the center of optic n. to retina; its branches can be seen with a ophthalmoscope; occlusion leads to blindness Long and short posterior ciliary aa. pierce sclera to supply inside of eyeball Muscular aa. supply extrinsic mm. Supra-orbital a. passes through supra-orbital f., to supply forehead and scalp to vertex
Posterior ethmoidal a. through posterior ethmoidal f. to supply ethmoidal air cells and nasal cavity Anterior ethmoidal a. through anterior ethmoidal f.; gives off anterior meningeal br.; enters nasal cavity to supply septum and lateral wall; ends as dorsal nasal a. (ext. nasal a.) Medial palpebral aa. supply medial area of upper and lower eyelids Dorsal nasal a. supply upper surface of nose Supratrochlear a. supplies forehead
Veins 1. Supra-orbital v. and angular v. > Superior ophthalmic v. > through superior orbital fissure > Cavernous sinus 2. Inferior ophthalmic v. > joining with superior ophthalmic v. through superior orbital fissure > Cavernous sinus (infection can be spread from outside to cranial cavity) through inferior orbital fissure > Pterygoid plexus of veins 1
1. Optic nerve [II] 2. Oculomotor nerve [III] 3. Trochlear nerve [IV] 4. Abducent nerve [VI] 5. Postganglionic sympathetic fibers 6. Ophthalmic nerve [V1] 6-1. Lacrimal nerve 6-2. Frontal nerve 6-3. Nasociliary nerve 7. Ciliary ganglion 7-1. Parasympathetic root 7-2. Sensory root 7-3. Sympathetic root Innervation
Optic nerve [II] Extension of brain; surrounded by meninges and subarachnoid space High intracranial pressure increases the pressure in subarachnoid space, and causes edema of optic disc (papilledema). Through optic canal with ophthalmic a.
Oculomotor nerve [III] Anterior surface of brainstem, between midbrain and pons > in the lateral wall of cavernous sinus > divides into sup. and inf. brr. > enter orbit through superior orbital fissure >
Oculomotor nerve [III] Sup. br. > 1. superior rectus m. 2. levator palpebrae superioris m. Inf. br. > 1. medial rectus 2. inferior rectus 3. inferior oblique 4. br. to ciliary ganglion (with pregang. parasym. ff.)
Trochlear nerve [IV] From posterior surface of midbrain > enters the edge of tentorium cerebelli > in the lateral wall of cavernous sinus (below CN III) > through sup. orbital fissure (above common tendinous ring) > upper border of superior oblique
Abducent nerve [VI] Anterior surface of brain stem between pons and medulla > through cavernous sinus (lateral to int. carotid a.) > through superior orbital fissure > through common tendinous ring > lateral rectus m.
Moore, 7th ed., Fig. I-45, p.60
Sympathetic fibers T1 (upper thoracic segments) > Preganglionic ff. > Spinal nn. > White rami > thru T1 sym. gang. > Sym. trunk > Superior cervical ganglion (synapse) >
Sympathetic fibers Superior cervical ganglion (synapse) > Postganglionic ff. > along internal carotid a. and brr. > Ophthalmic a. > Orbit > Pass through ciliary ganglion (without synapse) > Short ciliary nn. > Eyeball > Dilator pupillae m. Long ciliary nn. > Eyeball > Dilator pupillae m.
Ophthalmic nerve [V1] Pure sensory n. from orbit, face, scalp Trigeminal ganglion > in the lateral wall of cavernous sinus (inferior to CN IV & III) > divides into 3 brr.: 1. Lacrimal n. > above common tendinous ring > through superior orbital fissure 2. Frontal n. > above common tendinous ring > through superior orbital fissure 3. Nasociliary n. > through common tendinous ring > through superior orbital fissure
Lacrimal n. Along upper border of lat. rectus > receives a br. from zygomaticotemporal n. (carries postgang. parasym. & sym. ff.) > Lacrimal gland (by CN VII) Conjunctiva Lateral upper eyelid
Frontal n. Between levator palpebrae superioris and periorbita > divides into 2 brr.: 1. Supratrochlear n. > above trochlea > Conjunctiva Skin on upper eyelid Lower medial forehead 2. Supra-orbital n. > through supra-orbital notch > Upper eyelid Conjunctiva Forehead to midscalp
Nasociliary n. Deep in orbit > between sup. and inf. brr. of CN III > gives off communicating br. with ciliary gang. (sensory root) > medial wall of orbit > gives off brr.: 1. Long ciliary nn. > eyeball (with sensory and sym. ff.) 2. Posterior ethmoidal n. > through posterior ethmoidal foramen > posterior ethmoidal air cells sphenoid sinus 3. Infratrochlear n. > medial part of upper and lower eyelids lacrimal sac skin of the upper nose 4. Anterior ethmoidal n. > through anterior ethmoidal foramen > anterior cranial fossa nasal cavity skin of the lower nose
Ciliary ganglion Parasympathetic ganglion of CN III; associated with nasociliary n. of CN V1; located at the lateral side of optic n. Synapse for pre- and postgang. parasym. ff.; traversed by postgang. sym. ff. It receives three roots: 1. Parasympathetic root 2. Sensory root 3. Sympathetic root 2 1 3
Parasympathetic root CN III > gives off parasym. root (carries pregang. parasym. ff.) > synapse in ciliary ganglion > gives off postgang. parasym. ff. > short ciliary nn. > eyeball > Sphincter pupillae m. (constrict pupil) Ciliary m. (accommodation of lens) Sensory root Trigeminal gang. > CN V 1 > Nasociliary n. > sensory root pass through ganglion > short ciliary nn. > Sensory innervation of eyeball Sympathetic root Superior cervical ganglion > gives off postgang. sym. ff. > along plexus on int. carotid a. > though common tendinous ring > gives off a br. to join ophthalmic n. > from nasociliary n. gives off a sym. root > traverse ciliary gang. > short ciliary nn. > eyeball > Dilator pupillae m.
Eyeball Globe-shaped, bulges anteriorly as transparent cornea (1/6 surface area) Light passes from ant. to post.: 1. Cornea > 2. Anterior chamber > 3. Iris, pupil > 4. Posterior chamber, lens > 5. Vitreous chamber > 6. Retina
Anterior and posterior chambers Anterior chamber between cornea and iris Pupil central opening of iris Posterior chamber between iris and lens Aqueous humor fills the posterior chambers, and flows through pupil into anterior chamber, and is absorbed into scleral venous sinus. Glaucoma amount of intraocular fluid increases, and consequently the intra-ocular pressure.
Lens and vitreous humor Biconvex transparent disc cataract is caused by the opacity of lens Vitreous body (vitreous humor) gelatinous substance in posterior segment (postrenal chamber)
Walls of the eyeball 1. Outer fibrous layer: cornea and sclera 2. Middle vascular layer: choroid, ciliary body and iris 3. Inner layer: retina, and internal covering of iris and ciliary body
Arterial supply 1. Short posterior ciliary aa. from ophthalmic a to pierce sclera and enter choroid layer 2. Long posterior ciliary aa. lateral and medial to optic n., run in choroids and anastomose with anterior ciliary aa. 3. Anterior ciliary aa. from muscular brr.; anastomose with long posterior ciliary aa. in choroid layer 4. Central retinal a. traverse the optic n. and enters eyeball at optic disc Venous drainage Four large veins (vorticose veins) enter superior and inferior ophthalmic vv. Central retinal v. runs with a.
1-1. Sclera 1. Fibrous layer of the eyeball Dense connective tissue; pierced by optic n. and attached by mm.; covering lateral and posterior of 5/6 eyeball surface Fascial sheath covering outer surface of sclera from entrance of optic n. to corneoscleral junction Inner surface of sclera loosely attaches to choroid vascular layer. 1-2. Cornea Transparent; anterior 1/6 of eyeball surface
2. Vascular layer of the eyeball 2-1. Choroid Thin, highly vascular pigmented layer firmly attaches to retina loosely attaches to sclera 2-2. Ciliary body between choroid and iris Ciliary m. smooth muscle ff., arranged longitudinally, circularly, and radially; innervated by CN III Contraction of the ciliary m. shrinks the ciliary body ring. Ciliary processes projections toward lens Zonular fibers extending from ciliary processes, attach to lens. Collectively form suspensory ligament of lens 2-3. Iris Circular structure with central opening, pupil; smooth mm. including: Sphincter pupillae m. innervated by parasym. ff., constricts the pupil Dilator pupillae m. innervated by sym. ff., dilates the pupil
Retina 3. Inner layer of the eyeball 3-1. Nonvisual part covers internal surface of ciliary body and iris Junction irregular ora serrata 3-2. Optic part sensitive to light 3-2-1. Pigmented layer outer layer, attaches to choroids 3-2-2. Neural layer attaches to pigmented layer around optic n. and at ora serrata
Optic disc optic n. leaves the eyeball there; the central a. enters eyeball there; without light receptor there (blind spot) Macula lutea with central depression, fovea centralis, thinner retina, and higher sensitivity with more cones (sensitive to color) and fewer rods (functioning in dim light)