EYE

Label

Label

7 BONES OF ORBIT

The anatomy of the medial aspect of the palpebral fissure

Label parts of lacrimal system

Major parts of Lacrimal Drainage System

Arterial blood supply of the orbit and its contents

Arterial blood supply of the orbit and its contents

Contents • Extraocular muscles • Arteries • Veins • Fat • Globe • Extraocular muscles • Arteries o ophthalmic artery and its branches (ocular and orbital) o infra-orbital artery • Veins o superior ophthalmic vein o inferior ophthalmic vein o infra-orbital vein • Fat • Lacrimal gland

o branches of the maxillary division of the trigeminal nerve (CN Vb)  zygomatic nerve  zygomaticotemporal nerve  zygomaticofacial nerve  infra-orbital nerve o abducens nerve (CN VI) • autonomic nerves and ganglia o ciliary ganglion o sympathetic root to the ciliary ganglion (parasympathetic root travels in the oculomotor nerve)

CONTENTS OF ORBIT The chief contents of the orbit. A, superior orbital fissure and optic canal, anterior aspect. The optic canal and adjacent part of the fissure are surrounded by the common tendinous ring, from which the four recti arise. The lacrimal, frontal, and trochlear nerves enter the orbit above the ring. The superior and inferior ophthalmic veins leave the orbit usually above and below the ring, respectively. The optic canalcontains the optic nerve and the ophthalmic artery. The optic nerve is surrounded by its dural sheath (and by the subarachnoid space ) B, a superposable view showing the muscular cone anterior to the common tendinous ring. All the structures that pass through the ring lie at first within the muscular cone. The ophthalmic artery crosses (usually above) the optic nerve and is accompanied by the nasociliary nerve. The nerves to the extraocular muscles are shown in green, the sensory nerves in yellow, and the ciliary ganglion in mauve. The short ciliary nerves arise from the ganglion.

Apex of orbit : Label 1-14

COMMUNICATIONS OF ORBIT The orbit communicates posteriorly with the intracranial cavity via the optic canal, through which the optic nerve and ophthalmic artery is transmitted. Immediately inferolateral to the optic canal is the superior orbital fissure, through which most neurovascular structures pass. The infratemporal fossa is accessed via the inferior orbital fissure, which is in direct continuation with the infraorbital foramen, through which the infraorbital nerve exits to supply the skin below the eye (and where it is often damaged by a blow-out fracture). Medially, small communications with the paranasal sinuses are via the anterior ethmoidal foramen and posterior ethmoidal foramen. Anteriorly, the supraorbital notch is closed inferiorly by the orbital septum forming a fibrous supraorbital foramen. The nasolacrimal duct drains the nasolacrimal sac via the nasolacrimal foramen. The orbit communicates with the middle cranial fossa (via the optic canal and superior orbital fissure), the infratemporal and pterygopalatine fossae ( via the inferior orbital fissure), the inferior meatus of the nose (via the nasolacrimal canal), the nasal cavity (via the anterior ethmoidal foramen), and the face ( via supraorbital and infraorbital foramina).

RELATIONS OF ORBIT The orbit is related on its superior side to the anterior cranial fossa and usually to the frontal sinus, laterally to the temporal fossa in (anterior) and to the middle cranial fossa (posterior), on its inferior side to the maxillary sinus, and medially to the ethmoidal and the anterior extent of the sphenoidal sinuses.

MARGINS OF ORBIT The margin of the orbit, readily palpable, is formed by the frontal, zygomatic, and maxillary bones . It may be considered in four parts: superior, lateral, inferior, and medial. The superior margin, formed by the frontal bone, presents near its medial end either a supraorbital notch or a supraorbital foramen, which transmits the nerve and vessels of the same name. The lateral margin is formed by the zygomatic process of the frontal bone and the frontal process of the zygomatic bone. The inferior margin is formed by the zygomatic and maxillary bones. The infraorbital foramen, for the nerve and artery of the same name, is less than 1 cm inferior to the inferior margin. The medial margin, formed by the maxilla as well as by the lacrimal and frontal bones, is expanded as the fossa for the lacrimal sac. The fossa passes inferiorly through the floor of the orbit as the nasolacrimal canal, which transmits the nasolacrimal duct from the lacrimal sac to the inferior meatus of the nose

WALLS OF THE ORBIT The roof (frontal and sphenoid bones) presents the fossa for the lacrimal gland anterolaterally and the trochlear pit for the cartilaginous or bony pulley of the superior oblique muscle anteromedially. The optic canal lies in the posterior part of the roof, between the roots of the lesser wing of the sphenoid bone. It transmits the optic nerve and ophthalmic artery from the middle cranial fossa. The posterior aspect of the lateral wall (zygomatic and sphenoid bones) is demarcated by the superior and inferior orbital fissures. The superior orbital fissure lies between the greater and lesser wings of the sphenoid bone. It communicates with the middle cranial fossa and transmits cranial nerves III, IV, and VI, the three branches of the ophthalmic nerve, and the ophthalmic veins (fig. 45-5). The inferior orbital fissure communicates with the infratemporal and pterygopalatine fossae and transmits the zygomatic nerve. The lateral walls of the two orbits are set at approximately a right angle from one another, whereas the medial walls are nearly parallel to each other (fig. 45-3). The floor (maxilla, zygomatic, and palatine bones) presents the infraorbital groove and canal for the nerve and artery of the same name. The inferior oblique muscle arises anteromedially, immediately lateral to the nasolacrimal canal. The medial wall (ethmoid, lacrimal, and frontal bones) is very thin. Its main component (the orbital plate of the ethmoid) is papyraceous (paper-thin). At the junction of the medial wall with the roof, the anterior and posterior ethmoidal foramina transmit the nerves and arteries of the same name.

EYELIDS -THE WINDOWS TO THE SOUL Eyelid is made up of many structures, including skin and subcutaneous tissue, the orbicularis oculi muscle, the submuscular areolar tissue, the fibrous layer, the lid retractors, fat pads, and the conjunctiva.

Label

EYELIDS COMPOSED OF Skin: At less than 1 mm thick, the skin on your eyelids is the thinnest on your entire body. Subcutaneous fat, or fat under the skin, is fairly sparse in the skin around the eye, and all subcutaneous fat tissue is completely absent from the medial and lateral palpebral ligaments, which connect to a comparatively thick area of dense connective tissue known as the tarsal plate. The orbicularis oculi muscle is considered a superficial muscle associated with facial expressions. Specifically, this muscle is used for blinking, voluntary winking, and forcibly closing your eye.

The fibrous layer is made up of five main structures: The submuscular areolar tissue is made up of fairly loose connective tissue below the orbicularis oculi muscle. The fibrous layer is made up of five main structures: 1. The tarsal plates, which are comprised of a dense fibrous tissue, are in charge of the structural integrity of each lid. Each plate also includes around 25 sebaceous glands. 2. The medial palpebral ligament holds the inner aspect of the tarsal plate in place, and is related to the orbicularis oculi muscle and the tear ducts. 3. The lateral palpebral ligament originates at the tarsal plate and helps keeps other structures, including the lateral canthus, stable. 4. The orbital septum is a band of connective tissue that attaches to the outer aspect of the orbital bone, joins the lid retactors at the lid margins, and works somewhat like a diaphragm. 5. The orbicularis retaining ligament attaches the orbicularis oculi muscle to the lower rim of the orbit, or eye socket.

Eyelid retractors are exactly what they sound like: a group of muscles responsible for opening and closing your eyes. The upper eyelid retractors, also called the levator palpebrae muscles, keep the upper eyelid elevated. The lower eyelid retractors are smoother, and form the inferior tarsal muscles, giving some shape and mobility to the lower eyelids. Fat pads:Your upper eyelids have two fat pads, one located centrally that is relatively broad and made up of yellow coloured fat, and one located more towards your nose (or medial) and is made up of a paler yellow or white fat.The lower eyelids share the same pads as the upper, with one addition. The lower eyelids also have a third, smaller fat pad that lies in front of the inferior oblique muscle, which elevates the eye. Conjunctivais a smooth, clear mucous membrane that covers your eye, and lines the inside of your eyelids.

GLANDS OF EYELID 1. Meibomian gland lipid content (sebum) spills out of the acini at the mucocutaneous lid junction to coat the ocular surface. The lipid then becomes the smooth film meibum on the surface. Meibomian glands are a type of sebaceous gland locatedin the tarsal plate of the upper and lower eyelids. Blockage of this gland leads to “chalazion” formation. 2. Glands of Moll, also known as ciliary glands, are modified apocrinesweat glands that are found on the margin of the eyelid. They are next to the base of the eyelashes, and anterior to the Meibomian glands within the distal eyelid margin. 3. Glands of Zeis are unilobar sebaceous glands located on the margin of the eyelid. The glands of Zeis service the eyelash. These glands produce an oily substance that is issued through the excretory ducts of the sebaceous lobule into the middle portion of the hair follicle. Infection of any gland leads to formation of stye or hordelum ” on the margins of eyelid.

Label

Label the parts of tear film & cornea

Label layers of retina

Label pathway light reflex

Label the parts of lens

INDIVIDUAL EYE MUSCLE MOVMENTS