The Bony Orbit PDF

The Bony Orbit by: Jason M. Ortiz, OD, RN  The Bony Orbit v Bony orbit; orbital cavity - Space of compartment of head which is bound by the internal surface of the wall of orbit. - Contains the eye, anterior portion of the optic nerve, ocular muscles and ocular adnexa - They...

The Bony Orbit by: Jason M. Ortiz, OD, RN  The Bony Orbit v Bony orbit; orbital cavity - Space of compartment of head which is bound by the internal surface of the wall of orbit. - Contains the eye, anterior portion of the optic nerve, ocular muscles and ocular adnexa - They are placed on the either side of the midsagittal plane of the skull between the cranium and the skeleton of the face - Shaped like a four sides pyramid: Base: at the anterior orbital margin Apex: at the posterior margin ( at the optic foramen)  The Bony Orbit v Bony orbit; orbital cavity Ø Measurements of the Orbit: Depth of the orbit -------------------------------------- 40mm Height of the Orbital Opening ------------------------- 35mm Width of the Orbital Opening -------------------------- 40mm Interorbital distance ----------------------------------- 25mm Volume ------------------------------------------------- 30mm Volume ratio of the orbit to the eye ------------------ 5.5:1  The Bony Orbit v Bony orbit; orbital cavity Ø Function: 1) Designed to support and provide protection to the orbital soft tissues 2) Socket for the eyeball, containing the muscles, orbital fats, nerves, vessels proper to it 3) It also transmits certain vessels and nerves to supply the areas of the orbital aperture.  The Bony Orbit v Bony orbit; orbital cavity Ø Function: 1) Designed to support and provide protection to the orbital soft tissues 2) Socket for the eyeball, containing the muscles, orbital fats, nerves, vessels proper to it 3) It also transmits certain vessels and nerves to supply the areas of the orbital aperture.  The Bony Orbit v Bony orbit; orbital cavity Ø Contetns of Orbit: 1. Eyeball 2. Orbital Fats & Fascia 3. Blood vessels of the eye 4. Long and Short Ciliary Nerves 5. Lacrimal Glands 6. Optic Nerve 7. EOM 8. Levator Palpebrae Superioris (LPS) 9. Plain Orbital Muscles  The Bony Orbit v Bony orbit; orbital cavity Ø Contetns of Orbit: 1. Eyeball - Spheroidal structure containing sense receptors for vision - Houses the retina- an extremely active layer of nerve tissue made up of millions of light receptors (photoreceptors)  The Bony Orbit v Bony orbit; orbital cavity Ø Contetns of Orbit: 2. Orbital Fats and Fascia - Lies posterior to the orbital septum and anterior to the levatoraponeurosis (upper lid) or the capsulopalpebral fascia (lower lid). 3. Levator Palpebrae Superioris - muscle in the orbit that elevates the superior (upper) eyelid  The Bony Orbit v Bony orbit; orbital cavity Ø Contetns of Orbit: 4. Blood Vessels of the eye - consist of ophthalmic artery and a central retinal artery (an artery that branches off of the ophthalmic artery) provide blood to each eye. - ophthalmic veins (vortex veins) and a central retinal vein drain blood from the eye. - These blood vessels enter and leave through the back of the eye.  The Bony Orbit v Bony orbit; orbital cavity Ø Contetns of Orbit: 5. Long and short ciliary nerves - provide sensory innervation to the eyeball, including the cornea. 6. Lacrimal Glands - are paired, almond-shaped exocrine glands, one for each eye, that secrete the aqueous layer of the tear film  The Bony Orbit v Bony orbit; orbital cavity Ø Contetns of Orbit: 7. Optic Nerve - also known as the second cranial nerve(CN II) - a paired cranial nerve that transmits visual information from the retina to the brain. 8. Extra Ocular Muscle (EOM) - Responsible for controlling the movements of the eyeball and upper eyelid. - Also known as the “Extrinsic eye muscles”  The Bony Orbit v Bony orbit; orbital cavity Ø Contetns of Orbit: 9. Plain Orbital Muscle - muscles in the orbit that covers and protects the whole eye from injury and trauma. - It also acts as caution to protect the orbital bone from fractures.  The Bony Orbit ORBITAL MARGIN Is the most commonly quadrilateral with round corners. Ø Made up of three bones: Frontal Zygomatic Maxillary Ø All these three bones are usually thick at the orbital margin and the sutures along which they join are extensive. Ø These are the strongest part of the orbital margin.  The Bony Orbit ORBITAL MARGIN Ø Superior Orbital margin Formed by the frontal bone An easily palpable prominence, sharp in its lateral two thirds located 25mm from the midline and more rounded medially. it is concave downwards, convex forwards  The Bony Orbit ORBITAL MARGIN Ø Superior Orbital margin Structure found: 1. Supra orbital notch/ foramen –transmits the supraorbital artery and nerve 2. Supraorbital grooves – - found 10mm medial to the supraorbital notch. - Transmits the supratrochlear nerves and arteries. 3. Supreciliary - it is small opening near the supraorbital notch - it transmits the nutrient artery and a branch of the supraorbital nerve to the frontal air sinus.  The Bony Orbit ORBITAL MARGIN Ø Lateral Orbital Margin - Formed by: Zygomatic bone Lateral angular process (zygomatic process) of the frontal bone - The thickest among the margins but it is also the most exposed to injury.  The Bony Orbit ORBITAL MARGIN Ø Inferior Orbital Margin Formed by the zygomatic bone and the maxilliary bone This margin is raised slightly above the floor or the orbit. Ø Medial Orbital Margin Formed by: Anterior lacrimal crest on the frontal process of the maxilla Posterior lacrimal crest on the lacrimal  The Bony Orbit Clinical Note: Relatively heavy construction of the orbital margin makes it quit resistant blunt trauma, but it can relatively be broken. Breakage of one of the bones forming the orbital margin is called “Communication fracture”. But trauma to the facial aspect of the maxillary, frontal, or zygomatic bones often produces in part of the bone away from the site of the impact. In partial the orbital plates may rupture. This situation is called “Blowout fracture”  The Bony Orbit v Bones of the Orbit Ø Paired bones: a. Lacimal bone b. Palatine bone c. Maxillary bone d. Zygomatic bone Ø Unpaired bones: a. Frontal bone b. Ethmoid bone c. Sphenoid Bone  The Bony Orbit PAIRED BONES OF THE ORBIT  The Bony Orbit A. Lacimal bone - Makes up the most anterior part of the medial wall of the orbit - Size and shape of a fingernail (the smallest bone of the skull and the most fragile bone of theface) - Comes from the latin word “Lacrima” for “tear”  The Bony Orbit A. Lacimal bone Function of the lacrimal bone: 1) Support parts of the lacrimal apparatus (lacrimal sac and lacrimal canaculi) -2) Helps form the medial wall of the orbit  The Bony Orbit A. Lacimal bone Ø 2 Surfaces of Lacrimal Bone: I. Lateral surface II. Medial surface  The Bony Orbit A. Lacimal bone Ø 2 Surfaces of Lacrimal Bone: I. Lateral surface - faces towards the contents of the orbit (orbital surface) - notable feature of the lateral surface is a vertical ridge called ”Posterior lacrimal crest”  The Bony Orbit A. Lacimal bone Ø 2 Surfaces of Lacrimal Bone: I. Lateral surface Posterior lacrimal crest divides the lateral surface of the bone into 2portions: 1. Anterior portion 2. Posterior portion  The Bony Orbit A. Lacimal bone Ø 2 Surfaces of Lacrimal Bone: I. Lateral surface 1. Anterior portion - related to the lacrimal sac and lacrimal canaliculi - Anterior to the posterior lacrimal crest- is a longitudinally positioned groove called the lacrimal groove (or lacrimal sulc us).  The Bony Orbit A. Lacimal bone Ø 2 Surfaces of Lacrimal Bone: I. Lateral surface 1. Anterior portion - Inner margin of this lacrimal sulcus- unites with the frontal process of the maxilla and in this wayforms the lacrimal fossa.  The Bony Orbit A. Lacimal bone Ø 2 Surfaces of Lacrimal Bone: I. Lateral surface 1. Anterior portion Superior part of the lacrimal fossa- houses the lacrimal sac Inferior part of the lacrimal fossa- contains the nasolacrimal duct The Bony Orbit  The Bony Orbit A. Lacimal bone Ø 2 Surfaces of Lacrimal Bone: I. Lateral surface 2. Posterior - Posterior to the posterior lacrimal crest- is a smooth surface that participates in forming themedial wall of the orbit which is also the place of origin of the orbicularis oculi muscle.  The Bony Orbit A. Lacimal bone Ø 2 Surfaces of Lacrimal Bone: I. Lateral surface Relations: Lateral surface also extends in the shape of a hook called the lacrimal hamulus and it articulates with the lacrimal tubercle of the maxilla. In this way, the lacrimal bone and the maxilla enclose the lacrimal canaliculus.  The Bony Orbit A. Lacimal bone Ø 2 Surfaces of Lacrimal Bone: II. Medial surface - faces the nasal cavity, which is why it is also called the ”nasal surface” - There is notable longitudinal furrow on this surface, which corresponds to the posterior lacrimal crest of the orbital surface.  The Bony Orbit A. Lacimal bone Ø 2 Surfaces of Lacrimal Bone: II. Medial surface Anterior to the furrow is a portion of the bone that forms part of the middle nasal meatus Posteriorly to the furrow articulates with the ethmoid bone, and in this way encloses some ethmoidal air cells  The Bony Orbit A. Lacimal bone Ø 4 Borders of Lacrimal Bone 1. Anterior border of the lacrimal bone - articulates(joints) with the frontal process of the maxilla 2. Posterior border articulates with the orbital lamina of the ethmoid bone 3. Superior border articulates with the frontal bone 4. Inferior border- divided into two parts by the inferior edge of the posterior lacrimal crest.  The Bony Orbit A. Lacimal bone Ø 4 Borders of Lacrimal Bone 4. Inferior border- divided into two parts by the inferior edge of the posterior lacrimal crest. a. Inferior border (placed posteriorly to the posterior lacrimal crest) - articulates with the orbital plate of the maxilla  The Bony Orbit A. Lacimal bone Ø 4 Borders of Lacrimal Bone 4. Inferior border- divided into two parts by the inferior edge of the posterior lacrimal crest. b. Anteriorly & extends downward - This extension is called the ”Descending process” - Articulates with the lacrimal process of the inferior nasal concha - Participates in enclosing the bony canal for the nasolacrimal duct.  The Bony Orbit B. Palatine Bone - A paired bone located between the maxillae and the pterygoid process ofthe sphenoid bone.  The Bony Orbit B. Palatine Bone Ø Function of the Palatine Bone: 1. Helps in building the three cavities within the skull: a. Oral cavity b. Nasal cavity c. Orbits 2. Articulating (joints) with five bones: a. Maxilla b. Sphenoid c. Ethmoid d. Inferior nasal concha e. Vomer  The Bony Orbit B. Palatine Bone Ø Function of the Palatine Bone: 3. Contributes to the skeletal framework of the: a. Inferior orbital fissure b. Pterygopalatine c. Pterygoid fossae  The Bony Orbit B. Palatine Bone Ø The palatine bone is composed of two plates 1. Horizontal plates 2. Perpendicular plates Relations: These two plates are connected together and form a characteristic “L-shape bone”  The Bony Orbit B. Palatine Bone I. Horizontal Plate Ø Location: Transverse plane Ø Comprises of: 1) Bony core of the posterior quarter of the hard palate 2) Floor of the nasal cavity Ø Shape: Quadrangular (4 borders)  The Bony Orbit B. Palatine Bone I. Horizontal Plate Ø 4 Borders of the Horizontal Plate: 1. Medial border 2. Lateral border 3. Anterior border 4. Posterior border  The Bony Orbit B. Palatine Bone I. Horizontal Plate Ø 4 Borders of the Horizontal Plate: 1. Medial border - Articulates with the horizontal plate of the contralateral palatine bone - Forms the posterior part of the nasal crest  The Bony Orbit B. Palatine Bone I. Horizontal Plate Ø 4 Borders of the Horizontal Plate: 2. Lateral border - Continuous with the perpendicular plate - Features the greater palatine foramen through which the greater palatine nerve and vessels pass.  The Bony Orbit B. Palatine Bone I. Horizontal Plate Ø 4 Borders of the Horizontal Plate: 3. Anterior Border - Articulates with the palatine process of maxilla - Together, the horizontal plate of palatine bone and the maxilla comprise the hard palate.  The Bony Orbit B. Palatine Bone I. Horizontal Plate Ø 4 Borders of the Horizontal Plate: 4. Posterior Border - faces the posterior wall of the pharynx - The medial ends of the posterior surfaces of both horizontal plates together form a bony projection in the midline, called the median posterior nasal spine.  The Bony Orbit B. Palatine Bone I. Horizontal Plate Ø 4 Borders of the Horizontal Plate: 4. Posterior Border Ø Median posterior nasal spine - Relation: This spine serves as an attachment site for the uvular muscle  The Bony Orbit B. Palatine Bone II. Perpendicular plate - Continues from the lateral margin of the horizontal plate - It bears this name as it forms a 90° angle with the horizontal plate (giving the noticeable L-shape to the palatine bone)  The Bony Orbit B. Palatine Bone II. Perpendicular plate Ø Two surfaces of the perpendicular plate 1. Nasal Surface 2. Maxillary surface  The Bony Orbit B. Palatine Bone II. Perpendicular plate Ø Two surfaces of the perpendicular plate 1. Nasal Surface - Faces the nasal cavity, forming a part of its lateral wall - Contributes to the inferior nasal meatus  The Bony Orbit B. Palatine Bone II. Perpendicular plate Ø Two surfaces of the perpendicular plate 1. Nasal Surface - Faces the nasal cavity, forming a part of its lateral wall - Contributes to the inferior nasal meatus  The Bony Orbit B. Palatine Bone II. Perpendicular plate Ø Two surfaces of the perpendicular plate 1. Nasal Surface - Has 2 Crest: a) Conchal crest - Located in the superior portion of the nasal surface - Articulates with the inferior nasal concha  The Bony Orbit B. Palatine Bone II. Perpendicular plate Ø Two surfaces of the perpendicular plate 1. Nasal Surface - Has 2 Crest: b) Ethmoidal crest - Located in the superior portion of the conchal crest - The middle nasal concha attaches.  The Bony Orbit B. Palatine Bone II. Perpendicular plate Ø Two surfaces of the perpendicular plate 2. Maxillary surface - Has 2 walls a) Medial wall of the pterygopalatine fossa - the posterosuperior smooth area b) Medial wall of the maxillary sinus - the anterior smooth area  The Bony Orbit B. Palatine Bone II. Perpendicular plate Ø Two surfaces of the perpendicular plate 2. Maxillary surface Note: The maxillary surface is also marked by an oblique groove called the “Greater palatine groove” Greater palatine grove - transmits the structures which pass through the greater palatine foramen  The Bony Orbit B. Palatine Bone II. Perpendicular plate Ø Two surfaces of the perpendicular plate 2. Maxillary surface Note: The adjacent surface of the maxilla closes this groove, converting it into the Greater palatine canal. Ø Greater palatine canal - Transmits the greater palatine nerve, artery and vein  The Bony Orbit B. Palatine Bone II. Perpendicular plate Ø 4 borders of the perpendicular plate - The borders of the perpendicular plate serve for the articulations with the neighboring bones 1. Anterior border 2. Posterior border 3. Superior border 4. Inferior border  The Bony Orbit B. Palatine Bone II. Perpendicular plate Ø 4 borders of the perpendicular plate 1. Anterior border - Shows a laminar projection at the level of the conchal crest. - Articulates with the inferior nasal concha. - Forms a part of the medial wall of the maxillary sinus  The Bony Orbit B. Palatine Bone II. Perpendicular plate Ø 4 borders of the perpendicular plate 2. Posterior border - articulates with the medial pterygoid plate of the sphenoid bone  The Bony Orbit B. Palatine Bone II. Perpendicular plate Ø 4 borders of the perpendicular plate 3. Superior border - articulates with the body of the sphenoid bone  The Bony Orbit B. Palatine Bone II. Perpendicular plate Ø 4 borders of the perpendicular plate 4. Inferior border - is continuous with the lateral border of the horizontal plate  The Bony Orbit C. Maxillary Bone - also known as the upper jaw, is a vital viscerocranium structure of the skull Ø Function: a) holds the upper teeth b) plays an important role for mastication c) communication  The Bony Orbit C. Maxillary Bone - also known as the upper jaw, is a vital viscerocranium structure of the skull Ø Consists of five major parts, one being the “Body” and four being projections named “Processes” 1. Body of maxilla 2. Alveolar process 3. Frontal process 4. Zygomatic process 5. Palatine process  The Bony Orbit C. Maxillary Bone Ø Five major parts 1. Body of maxilla - the largest part of the maxillary bone (ashaped like a pyramid) Ø Contributes to the: a) anterior margin b) floor of the bony orbit c) anterior wall of the nasal cavity d) inferior part of the infratemporal fossa  The Bony Orbit C. Maxillary Bone Ø Five major parts 1. Body of maxilla - Contains: maxillary sinuses which extend from the orbital ridge to the alveolar process and drain to the middle meatus of the nose.  The Bony Orbit C. Maxillary Bone Ø Five major parts 2. Alveolar process - is an inferior extension of the maxilla with a porous structure. - It forms the maxillary dental arch containing eight cavities where the upper teeth are held.  The Bony Orbit C. Maxillary Bone Ø Five major parts 3. Frontal process - has a vertical ridge which constitutes the medial border of the orbit (anterior lacrimal crest). - Posteriorly - it forms the lacrimal groove together with the lacrimal bone. - Superomedially - it is in close contact with the anterior ethmoidal sinuses.  The Bony Orbit C. Maxillary Bone Ø Five major parts 4. Zygomatic process - grows laterally and meets the zygomatic bone  The Bony Orbit C. Maxillary Bone Ø Five major parts 5. Palatine process - is a horizontal extension on the medial side of the bone constitutingthe roof of the mouth and the floor of the nasal cavity. - Together with the palatine bone it forms the hard palate.  The Bony Orbit D. Zygomatic Bone - an irregularly shaped bone of the skull. - often referred to as the cheekbone. - quadrangular in shape Ø Features: 3 surfaces 5 borders 2 processes  The Bony Orbit D. Zygomatic Bone - an irregularly shaped bone of the skull. - often referred to as the cheekbone. - quadrangular in shape Ø Function/contributes to the formation of: 1) Prominence of the cheek 2) Zygomatic arch 3) Walls of the temporal and infratemporal fossae 4) Floor and lateral wall of the bony orbit  The Bony Orbit D. Zygomatic Bone Ø Features: 3 surfaces 5 borders 2 processes  The Bony Orbit D. Zygomatic Bone Ø Three surfaces: I. Lateral (facial) surface II. Posteromedial (Temporal) surface III. Orbital surface  The Bony Orbit D. Zygomatic Bone Ø Three surfaces: I. Lateral (facial) surface - Faces towards the outside - Smooth surface - Convex in shape - Small opening called the zygomaticofacial foramen (transmits: 1. zygomaticofacial nerve, 2. artery and 3. vein between the orbit and the face.)  The Bony Orbit D. Zygomatic Bone Ø Three surfaces: I. Lateral (facial) surface Ø Function/ serves as the attachment area: Zygomaticus major muscle on its anterior half Zygomaticus minor muscle on its posterior half  The Bony Orbit D. Zygomatic Bone II. Posteromedial (temporal) surface - Faces towards the temporal and infratemporal fossae - Its anteriormost portion is rough - Articulation with the zygomatic (malar) process of maxilla via the zygomaticomaxillary suture - Zygomaticotemporal foramen: Transmits the zygomaticotemporal nerve from the orbit to the temporal fossa  The Bony Orbit D. Zygomatic Bone III. Orbital surface- Faces towards the temporal and - Infratemporal fossae - Smooth - Concave in shape - Faces towards the orbit Ø Forms: Anterolateral part of its floor Anterior part of its lateral wall  The Bony Orbit D. Zygomatic Bone III. Orbital surface- Faces towards the temporal and Features: zygomatico-orbital foramen, which is a gateway to the bony canal found within the zygomatic bone  The Bony Orbit D. Zygomatic Bone III. Orbital surface Five borders of the zygomatic bone: 1. Anterosuperior (orbital) border 2. Anteroinferior (maxillary) border 3. Posterosuperior (temporal) border 4. Posteroinferior border 5. Posteromedial border  The Bony Orbit D. Zygomatic Bone Five borders of the zygomatic bone: I. Anterosuperior (orbital) border II. Anteroinferior (maxillary) border III. Posterosuperior (temporal) border IV. Posteroinferior border V. Posteromedial border  The Bony Orbit D. Zygomatic Bone Five borders of the zygomatic bone: I. Anterosuperior (orbital) border - Concave and smooth - It is the border between the lateral and orbital surfaces of the zygomatic bone  The Bony Orbit D. Zygomatic Bone Five borders of the zygomatic bone: 2. Anteroinferior (maxillary) border - Articular surface for the zygomaticomaxillary suture. - Serves as an attachment site for the levator labii superioris muscle.  The Bony Orbit D. Zygomatic Bone Five borders of the zygomatic bone: 3. Posterosuperior (temporal) border - Continuous with the superior border of zygomatic arch and the posterior border of the frontal process - It serves as an attachment point for the temporal fascia  The Bony Orbit D. Zygomatic Bone Five borders of the zygomatic bone: 4. Posteroinferior border - Rough surface - Serves as the attachment site for the masseter muscle  The Bony Orbit D. Zygomatic Bone Five borders of the zygomatic bone: 5. Posteromedial border - Ø Serrated and articulates with the: 1.) Greater wing of sphenoid bone superiorly via the sphenozygomatic suture 2.) Orbital surface of maxilla inferiorly  The Bony Orbit D. Zygomatic Bone 2 Processes of the Zygomztic bone 1. Temporal process - Originates from the lower half of the zygomatic bone. - Oriented posteriorly and slightly superiorly towards the temporal bone - Oblique and jagged - Articulates with the zygomatic process of temporal bone with which it comprises the zygomatic arch.  The Bony Orbit D. Zygomatic Bone 2 Processes of the Zygomztic bone 1. Temporal process - Originates from the lower half of the zygomatic bone. - Oriented posteriorly and slightly superiorly towards the temporal bone - Oblique and jagged - Articulates with the zygomatic process of temporal bone with which it comprises the zygomatic arch.  The Bony Orbit D. Zygomatic Bone 2 Processes of the Zygomztic bone 2. Frontal process - Originates from the upper margin of the zygomatic bone - Oriented superiorly - It articulates with the zygomatic process of frontal bone superiorly via the zygomaticofrontal suture and with the greater wing of sphenoid bone posteriorly via the sphenozygomatic suture  The Bony Orbit D. Zygomatic Bone 2 Processes of the Zygomztic bone 3. Maxillary process of zygomatic bone - Arises from the anterosuperior angle of the zygomatic bone - It extends anteriorly, comprising the inferolateral margin of the orbit - The inferior margin of this process participates in the joint with the maxilla - Posteriorly, it is continuous with the orbital surface of the bone  The Bony Orbit D. Zygomatic Bone Zygomatic bone Fractures - The second most common area of fracture in the face (especially of the left frontal process). Happens during a car accident or punched in the face with a fist.  The Bony Orbit D. Zygomatic Bone Zygomatic bone Fractures Clinically, one should check for the following symptoms: a. Pain b. Flattened cheek bone c. Swelling d. Subconjunctival hemorrhage e. None displacement and mobility  The Bony Orbit D. Zygomatic Bone Zygomatic bone Fractures Clinically, one should check for the following symptoms: f. Diplopia g. Paresthesia(burning or prickling sensation) h. Lowered lateral portion of the palpebral fissure (due to the downward displacement of the lateral canthal ligament and ecchymosis)  The Bony Orbit UNPAIRED BONES OF THE ORBIT  The Bony Orbit A. Frontal Bone - Smooth curvature of the forehead Ø Protects: a) The frontal lobe of the brain b) Ethmoid bone's horizontal plate (cribriform plate) “Cribriform plate” - allows the olfactory nerve bundles to pass through its perforated surface and bring the ceiling of the nasal cavity.  The Bony Orbit A. Frontal Bone Ø Three regions/parts Sqaumos part (Forehead) Orbital part (Ortbit) Nasal Part (Nose)  The Bony Orbit A. Frontal Bone Ø Three regions/parts 1. Sqaumos part (Forehead) - most anterior neurocranium bone - one of the skull bones enclosing the brain (neurocranium) bordered by: a) Neurocranial bones (Cranial Bones) b) Viscerocranial bones (Facial Bones)  The Bony Orbit A. Frontal Bone Ø Three regions/parts 1. Sqaumos part (Forehead) - The largest area of the frontal bone Ø Parts: ü Frontal sinuses - located superior to the orbit ü Supraorbital notch - superior border of the orbit (supraorbital margin) - where the supraorbital vessels and nerve pass through  The Bony Orbit A. Frontal Bone Ø Three regions/parts 1. Sqaumos part (Forehead) - The largest area of the frontal bone Ø Parts: ü Superciliary arches - a ridge on the frontal bone above the eye socket  The Bony Orbit A. Frontal Bone Ø Three regions/parts 1. Sqaumos part (Forehead) Ø Parts: ü Superciliary arches - a ridge on the frontal bone above the eye socket ü Glabella - smooth and slightly elevated surface above the nasal root  The Bony Orbit A. Frontal Bone Ø Three regions/parts 1. Sqaumos part (Forehead) Ø Parts: Zygomatic processes - a long arched process, projecting from the lower part of the squamous part of temporal bone.  The Bony Orbit A. Frontal Bone Ø Three regions/parts 2. Orbital Part - forms the roof of the orbit and the ethmoidal sinuses ü Trochlear spine - as a site of insertion for the superior oblique muscle at the medial eye angle.  The Bony Orbit A. Frontal Bone Ø Three regions/parts 2. Orbital Part - forms the roof of the orbit and the ethmoidal sinuses ü Trochlear spine - as a site of insertion for the superior oblique muscle at the medial eye angle.  The Bony Orbit A. Frontal Bone Ø Three regions/parts 2. Orbital Part - forms the roof of the orbit and the ethmoidal sinuses ü Ethmoidal notch - location of the ethmoid air cells  The Bony Orbit A. Frontal Bone Ø Three regions/parts 2. Orbital Part - forms the roof of the orbit and the ethmoidal sinuses Comprises two openings: 1. Anterior ethmoidal foramen ( for the anterior ethmoidal vessels and nerve) 2. Posterior ethmoidal foramen (for the posterior ethmoidal vessels and nerve)  The Bony Orbit A. Frontal Bone Ø Three regions/parts 3. Nasal part - Is connected to the frontal processes of the maxilla and the nasal bones, forming the stem of the nose.  The Bony Orbit B. Ethmoid Bone - Singular porous bone that makes up the middle area of the viscerocranium - Forms the midfacial region of the skull Ø Contributes to the moulding of: a) Orbit b) Nasal cavity c) Nasal septum d) Floor of the anterior cranial fossa  The Bony Orbit B. Ethmoid Bone Relation: Allows the olfactory fibers to pass through in order for you to smell things  The Bony Orbit B. Ethmoid Bone Ø Ethmoidal labyrinths - Lie on both lateral sides - Contain numerous little cavities with ethmoidal cells which arereferred to as the ethmoidal sinus.  The Bony Orbit B. Ethmoid Bone Ø Two structures in the nasal cavity: 1. Superior nasal concha 2. Middle nasal concha.  The Bony Orbit C. Sphenoid Bone - The most complex bone of the human body because of its shape - Known as the "wasp bone". - It makes up most of the middle part of the base of the skul Ø Contributes to the : 1. Floor of the middle cranial fossa of the skull 2. Forming of the foramina 3. Forming of the canals of the cranium.  The Bony Orbit C. Sphenoid Bone Ø Four main parts to the sphenoid bone: 1. Body (corpus) 2. Lesser wings of sphenoid 3. Greater wings of sphenoid 4. Pterygoid processes  The Bony Orbit C. Sphenoid Bone Ø Contributes to the : Floor of the middle cranial fossa of the skull Forming of the foramina Forming of the canals of the cranium.  The Bony Orbit C. Sphenoid Bone Ø Four main parts to the sphenoid bone: 1. Body (corpus) 2. Lesser wings of sphenoid Body 3. Greater wings of sphenoid 4. Pterygoid processes  The Bony Orbit C. Sphenoid Bone Ø I. Body(Corpus) - the most centrally positioned portion Anteriorly - contributes to the nasal cavity Laterally - builds the medial wall of the optic canal Superiorly - forms the sella turcica, the hypophyseal fossa and the dorsum sellae Posterior to the body - clivus slopes is located Sphenoidal sinuses - located in the sphenoid body behind the nasal cavity and divided by a septum  The Bony Orbit C. Sphenoid Bone Optic Nerve Ø II. Lesser wings of sphenoid Arise superolaterally from the sphenoid body where they form the optic canal (→ optic nerve, ophthalmic artery) The inferior surface participates in the lateral margin of the orbit Superior surface forms part of the cranial cavity  The Bony Orbit Optic Nerve C. Sphenoid Bone Ø II. Lesser wings of sphenoid Arise superolaterally from the sphenoid body where they form the optic canal (→ optic nerve, ophthalmic artery) The inferior surface participates in the lateral margin of the orbit Superior surface forms part of the cranial cavity  The Bony Orbit Optic Nerve C. Sphenoid Bone III. Greater wings of sphenoid - The greater wings arise posterolaterally from the body - Lateral surfaces form the infratemporal surfaces - Anterior surfaces make up part of the posterior aspect of the lateral wall of the orbit  The Bony Orbit Optic Nerve C. Sphenoid Bone III. Greater wings of sphenoid Ø Three important openings near their roots: 1. Foramen rotundum - transmits the maxillary nerve 2. Foramen ovale - allows the passage of the Mandibular nerve, Accessory meningeal artery, Lesser petrosal nerve and Emissary vein (mnemonic "MALE") 3. Foramen spinosum - traversed by the middle meningeal vessels, spinous nerve [branch of mandibular nerve]) lies at the posterior margin of the greater wings.  The Bony Orbit C. Sphenoid Bone Ø Borders -The sphenoid bone has a common border: 1) Frontal bone (via the sphenofrontal suture) 2) Parietal bone (via the the sphenoparietal suture) 3) Squamous part of the temporal bone (via the sphenosquamosal suture) 4) Occipital bone (via the spheno-occipital suture) Note: As the sphenoid and occipital bone fuse during p uberty ("tribasilar bone") the spheno- occipital suture di sappears by the age of 25 The Bony Orbit WALLS OF THE ORBIT  The Bony Orbit WALLS OF THE ORBIT 1. ROOF/VAULT 2. MEDIAL WALL 3. LATERAL WALL 4. FLOOR  The Bony Orbit WALLS OF THE ORBIT 1. ROOF/VAULT - Triangular in shape - Formed by the following bones: a. Frontal bone b. Lesser wing of sphenoid  The Bony Orbit WALLS OF THE ORBIT 1. ROOF/VAULT Structures found on the roof: 1. Lacrimal fossa/ Fossa for the lacrimal gland - Depression at supero - lateral of frontal bone 2. Fovea for the throchlea of the superior oblique - Depression near the nasal part of inferior surface of the orbital plate for the attachment of the cartilaginous pulley of the Obliqus oculi superior. - Serves as pulley for tendon of Superior Oblique  The Bony Orbit WALLS OF THE ORBIT 1. ROOF/VAULT Structures found on the roof: 3. Frontal spenoid suture - Cranial suture between the lesser wing of sphenoid bone and the frontal bone.  The Bony Orbit WALLS OF THE ORBIT 2. MEDIAL WALL - Formed primarily by: 1. Orbital plate of ethmoid 2. Contributions from the frontal process of maxilla 3. Lacrimal bone 4. Small part of the body of the sphenoid - It is the thinnest of the orbital bones (2-4mm) - Quadrilateral in shape  The Bony Orbit WALLS OF THE ORBIT 2. MEDIAL WALL Strucure present: Fossa for lacrimal sac - a depression on nasal side formed by maxilla and lacrimal bone  The Bony Orbit WALLS OF THE ORBIT 3. FLOOR - It is triangular in shape and it slopes downward and laterally - It has a measurement of 47.6 mm - It is the shortest orbital boundary  The Bony Orbit WALLS OF THE ORBIT 3. FLOOR Ø Formed by the following bones: - Orbital plate of the maxilla - Orbital surface of the zygomatic bone - Orbital process of the palatine bone  The Bony Orbit WALLS OF THE ORBIT 3. FLOOR Ø Strucure present: Maxillary antrum/sinus - a cavity in the maxillary bone communicating with the middle meatus of the nasal cavity.  The Bony Orbit WALLS OF THE ORBIT 4 LATERAL WALL - A triangular shape, its base is anterior. - It makes an angle of 45deg. within the median plane. - Thickest and strongest wall Ø It is formed by: - Orbital surface of the greater wing of the sphenoid (po sterior) - Orbital surface of the zygomatic bone (anterior)  The Bony Orbit WALLS OF THE ORBIT 4 LATERAL WALL Structure present: Lateral orbital tubercle - A small elevation on the orbital surface of the zygomatic bo ne just behind and within the orbital margin - 11 mm below the frontozygomatic suture  The Bony Orbit WALLS OF THE ORBIT 4 LATERAL WALL Structure present: Lateral orbital tubercle It serves as an attachment for the: a. Check ligament of the lateral rectus muscle b. Lateral palpebral ligament c. Suspensory ligament of Lockwood d. Levator palpebrae superioris muscle  The Bony Orbit Blood supply of the orbit: Ø Opthalmic artery - - (arteria ophthalmica) is the major blood supply of the orbit. - It enters the orbital cavity through the optic foramen, - Located below and lateral to the optic nerve. - Passes over the nerve (in 85% of cases) to reach the medial wall of the orbit.  The Bony Orbit Innervation of the lateral/outer wall: I. Motor Nerves: Ø CN#3 (oculomotor nerve) Three main motor functions: 1. Innervation to the pupil and lens (autonomic, parasympathetic) 2. Innervation to the upper eyelid (somatic) 3. Innervation of the eye muscles that allow for visual tracking and gaze fixation (somatic)  The Bony Orbit Innervation of the lateral/outer wall: I. Motor Nerves: Ø CN#4 (Trochlear nerve) One of the ocular motor nerves that controls eye movement Is a somatic efferent (motor) nerve Controls the abduction and intorsion of the eye  The Bony Orbit Innervation of the lateral/outer wall: I. Motor Nerves: Ø CN#6 (Abducens nerve) Somatic nerve Carry somatic efferent nerve axons to innervate the lateral rectus muscle which then abducts the eye on the ipsilateral side. Also secondarily involved in innervation of the contralateral medial rectus muscle so that both eyes move laterally  The Bony Orbit Innervation of the lateral/outer wall: II. Sensory Nerves: Ø CN#5 (trigeminal nerve) Provide sensory and motor innervation to the face. Sensory information conducted by this nerve includes touch, pain, and temperature  The Bony Orbit Innervation of the lateral/outer wall: II. Sensory Nerves: Ø CN#5 (trigeminal nerve) 1. ) Opthalmic Division Purely sensory (afferent) nerve Smallest division of the trigeminal nerve. It runs forward in the lateral wall of the cavernous sinus below the oculomotor and trochlear nerves. Ø Fxn: Provides sensory innervation to the lacrimal gland, conjunctiva, and the upper eyelid.  The Bony Orbit Innervation of the lateral/outer wall: II. Sensory Nerves: Ø CN#5 (trigeminal nerve) 2.) Maxillary Division Second branch of the trigeminal nerve Passes through the lateral wall of the cavernous sinus, before leaving the skull through the foramen rotundum. Innervates: skin, mucous membranes and sinuses of derivatives of the maxillary prominence  The Bony Orbit Innervation of the lateral/outer wall: II. Sensory Nerves: Ø CN#5 (trigeminal nerve) 3.) Mandibular Division The mandibular nerve (V3) is the largest branch of the trigeminal nerve. V3 is the only branch of the trigeminal nerve that has both sensory and motor components. V3 receives sensory information from the lower third of the face, the floor of the mouth and jaw, and the tongue. The Bony Orbit  The Bony Orbit v Openings/Aperture of the Orbit 1. Optic Foramen & canal 2. Superior orbital fisure 3. Inferior orbital fissure 4. Anterior and posterior ethmoidal foramen 5. Nasolacrimal canal  The Bony Orbit v Openings/Aperture of the Orbit I. Optic foramen and Canal - Located at lesser wing of sphenoid - Measures 4-10mm Ø Transmits the following structures: 1. Optic nerve (CN#2) 2. Opthalmic artery 3. Sympathetic nerve  The Bony Orbit v Openings/Aperture of the Orbit II. Superior orbital fissure - Medial to the eye - Lateral to the optic foramen - Devides the sphenoid into greater and lesser wing  The Bony Orbit Openings/Aperture of the Orbit II. Superior orbital fissure Ø Transmits the following structures: 1. CN#3 Oculomotor nerve 2. CN#4 Trochlear nerve 3. CN#5 Trigeminal nerve (Opthalmic division) Frontal Branch Nasocilliary branch Lacrimal branch 4. CN#6 Abducens nerve  The Bony Orbit Openings/Aperture of the Orbit III. Inferior orbital fissure/ shpenomaxillary fissure - located inferiorly the superior orbital fissure Ø Transmits the following structures: a. CN#5 Trigeminal nerve - Maxilallary division via zygomatic nerve and infraorbital nerve Infraorbital nerve - exits through the infraorbital foramen to carry sensory to the: Lower eyelids Lower lips Upper teeth Cheek  The Bony Orbit Openings/Aperture of the Orbit III. Inferior orbital fissure/ shpenomaxillary fissure - located inferiorly the superior orbital fissure Ø Transmits the following structures: b. Infraorbital artery c. Inferior ophthalmic vein d. Sympathetic nerve  The Bony Orbit Openings/Aperture of the Orbit IV. Anterior and posterior ethmoidal foramen - Located at the fronto-ethmoidal suture - Transmited strucutre: Ethmoidal nerve Ethmoidla artery Ethmoidal vein  The Bony Orbit Openings/Aperture of the Orbit V. Nasolacrimal canal - extends from lacrimal fossa to inferior meatus of the nose - Stracture passing: Nasolacrimal duct The Bony Orbit Other Structure’s in the Bony Orbit  The Bony Orbit Other Structure’s in the Bony Orbit I. Periorbita -Also called the orbital periosteum or orbital fascia, -Covers the bones of the orbit -Derived from dura mater of optic nerve meninges -Loosely adherent to orbit Ø Function: - Serves as an attachment site for muscles, tendons, and ligaments - Support structure for the blood supply to the orbital bones  The Bony Orbit Other Structure’s in the Bony Orbit II. Orbital septum/palpebral fascia - An important anatomic barrier in the eyelids - A thin fibrous layer arising from the periosteum along the inferior and superior orbital rims - Fuses into the upper and lower eyelid retractors Ø Function: prevents contiguous spread of infection posteriorly from the eyelids into the orbital tissues  The Bony Orbit Other Structure’s in the Bony Orbit III. Bulbar fascia/Tenons capsule - Thin fascial sheath that surrounds the eyeball. - Extends from entrance of optic nerve to limbus together with bulbar conjunctiva where they are firmly adherent - Thickens at the lower portion of the eyeball together with muscle sheath or fascia of Inferior Oblique and Inferior Rectus, forms the Ligament of Lockwood (suspensory ligaments of the eyeball).  The Bony Orbit Other Structure’s in the Bony Orbit III. Tenons capsule/ bulbar fascia Function: Separates the eyeball from the orbital fat and other orbital contents  The Bony Orbit Other Structure’s in the Bony Orbit IV. Paransal sinuses/ Anthrum - air-filled extensions of the nasal cavity. Ø Function of the paranasal sinuses 1. Lightening the weight of the head 2. Supporting immune defence of the nasal cavity 3. Humidifying inspired air 4. Increasing resonance of the voice  The Bony Orbit Other Structure’s in the Bony Orbit IV. Paransal sinuses/ Anthrum Ø Four paired sinuses: named according to the bone in which they are located: 1. Maxillary sinus 2. Frontal sinus 3. Sphenoid sinus 4. Ethmoid sinus *Note: Each sinus is lined by a ciliated pseudostratified epithelium, interspersed with mucus- secreting goblet cells.  The Bony Orbit Other Structure’s in the Bony Orbit IV. Paransal sinuses/ Anthrum I. Maxilarry sinus - Also known as Anthrum of highmore - Paired pyramid-shaped paranasal sinus within the maxillary bone - Largest cavity/sinus - Drain into the nasal cavity at the hiatus semilunaris, underneath the frontal sinus opening - This is a potential pathway for spread of infection – fluid draining from the frontal sinus can enter the maxillary sinus.  The Bony Orbit Other Structure’s in the Bony Orbit IV. Paransal sinuses/ Anthrum II. Frontal sinus - Located in the frontal bone, separated by septum - The most superior(above) of the paranasal sinuses - Triangular in shape - Drainage is via the frontonasal duct - Sensation is supplied by the supraorbital nerve (a branch of the ophthalmic nerve) - Arterial supply is via the anterior ethmoidal artery (a branch of the internal carotid)  The Bony Orbit Other Structure’s in the Bony Orbit IV. Paransal sinuses/ Anthrum III. Ethmoidal sinus - Located within the ethmoid bone - “Honeycomb” of air cells forming spongy network Ø Three ethmoidal sinuses 1. Anterior – Opens onto the hiatus semilunaris (middle meatus) 2. Middle – Opens onto the lateral wall of the middle meatus 3. Posterior – Opens onto the lateral wall of the superior meatus  The Bony Orbit Other Structure’s in the Bony Orbit IV. Paransal sinuses/ Anthrum III. Ethmoidal sinus Ø Innervation: 1. Anterior and posterior ethmoidal branches of the nasociliary nerve 2. Maxillary nerve Ø Blood supply: anterior and posterior ethmoidal arteries  The Bony Orbit Other Structure’s in the Bony Orbit IV. Paransal sinuses/ Anthrum IV. Sphenoidal Sinus - Situated within the body of the sphenoid bone - Spheno-ethmoidal recess - open out into the nasal cavity in an area supero-posterior to the superior cocha.  The Bony Orbit Other Structure’s in the Bony Orbit IV. Paransal sinuses/ Anthrum IV. Sphenoidal Sinus Ø Innervatation: 1. Posterior ethmoidal nerve - a branch of the ophthalmic nerve 2. Branches of the maxillary nerve  The Bony Orbit Other Structure’s in the Bony Orbit IV. Paransal sinuses/ Anthrum IV. Sphenoidal Sinus Ø Blood supply: - from pharyngeal branches of the maxillary arteries. Ø Strutures above sphenoidal sinus: 1. Pituitary/master glands 2. CN#2 - involved in sphenoidal sinusitis (retrobular neuritis)