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27-443: The orbits are conical or four-sided pyramidal cavities, which open into the midline of the face and point back into the head. Each consists of a base, an apex and four walls. There are two important foramina , or windows, two important fissures , or grooves, and one canal surrounding the globe in the orbit. There is a supraorbital foramen , an infraorbital foramen , a superior orbital fissure , an inferior orbital fissure and

54-689: A foramen ( / f ə ˈ r eɪ m ən / ; pl. : foramina , / f ə ˈ r æ m ɪ n ə / or foramens / f ə ˈ r eɪ m ən z / ; from Latin  'an opening produced by boring') is an opening or enclosed gap within the dense connective tissue ( bones and deep fasciae ) of extant and extinct amniote animals , typically to allow passage of nerves , arteries , veins or other soft tissue structures (e.g. muscle tendon ) from one body compartment to another. The skulls of vertebrates have foramina through which nerves , arteries , veins , and other structures pass. The human skull has many foramina, collectively referred to as

81-444: A mosaic of seven embryologically distinct structures: the zygomatic bone laterally , the sphenoid bone , with its lesser wing forming the optic canal and its greater wing forming the lateral posterior portion of the bony orbital process, the maxillary bone inferiorly and medially which, along with the lacrimal and ethmoid bones , forms the medial wall of the orbital canal . The ethmoid air cells are extremely thin, and form

108-496: A small part of the body of the sphenoid. It is the thinnest wall of the orbit, evidenced by pneumatized ethmoidal cells. The lateral wall is formed by the frontal process of zygomatic and more posteriorly by the orbital plate of the greater wing of sphenoid. The bones meet at the zygomaticosphenoid suture. The lateral wall is the thickest wall of the orbit, important because it is the most exposed surface, highly vulnerable to blunt force trauma. The base, orbital margin, which opens in

135-423: A structure known as the lamina papyracea , the most delicate bony structure in the skull, and one of the most commonly fractured bones in orbital trauma. The lacrimal bone also contains the nasolacrimal duct . The superior bony margin of the orbital rim, otherwise known as the orbital process , is formed by the frontal bone. The roof (superior wall) is formed primarily by the orbital plate frontal bone , and also

162-402: Is a crucial structure in the orbit, as it is often the only source of collateral blood to the brain in cases of large internal carotid infarcts , as it is a collateral pathway to the circle of Willis . In addition, there is the optic canal , which contains the optic nerve, or cranial nerve II, and is formed entirely by the lesser wing of the sphenoid, separated from the supraorbital fissure by

189-413: Is a paired bone - the two maxillae unite with each other at the intermaxillary suture. The maxilla consists of: It has three surfaces: Features of the maxilla include: Each maxilla articulates with nine bones: frontal , ethmoid , nasal , zygomatic , lacrimal , and palatine bones, the vomer , the inferior nasal concha , as well as the maxilla of the other side. Sometimes it articulates with

216-471: The Le Fort classification . Sometimes (e.g. in bony fish), the maxilla is called "upper maxilla", with the mandible being the "lower maxilla". Conversely, in birds the upper jaw is often called "upper mandible". In most vertebrates, the foremost part of the upper jaw, to which the incisors are attached in mammals consists of a separate pair of bones, the premaxillae . These fuse with the maxilla proper to form

243-448: The inferior orbital and pterygomaxillary . -When the tender bones of the upper jaw and lower nostril are severely or repetitively damaged, at any age the surrounding cartilage can begin to deteriorate just as it does after death. A maxilla fracture is a form of facial fracture . A maxilla fracture is often the result of facial trauma such as violence , falls or automobile accidents . Maxilla fractures are classified according to

270-495: The optic canal , each of which contains structures that are crucial to normal eye functioning. The supraorbital foramen contains the supraorbital nerve, the first division of the trigeminal nerve or V1 and lies just lateral to the frontal sinus . The infraorbital foramen contains the second division of the trigeminal nerve, the infraorbital nerve or V2, and sits on the anterior wall of the maxillary sinus . Both foramina are crucial as potential pathways for cancer and infections of

297-445: The optic nerve ) within the cone formed by the horizontal rectus muscles produce axial protrusion (bulging forward) of the eye. Graves disease may also cause axial protrusion of the eye, known as Graves' ophthalmopathy , due to buildup of extracellular matrix proteins and fibrosis in the rectus muscles. Development of Graves' ophthalmopathy may be independent of thyroid function. Foramen In anatomy and osteology ,

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324-402: The optic strut . Injury to any one of these structures by infection, trauma or neoplasm can cause temporary or permanent visual dysfunction, and even blindness if not promptly corrected. The orbits also protect the eye from mechanical injury. In the orbit, the surrounding fascia allows for smooth rotation and protects the orbital contents. If excessive tissue accumulates behind the ocular globe,

351-414: The bone are each greater than the vertical. The frontal process is well-marked and the body of the bone consists of little more than the alveolar process, the teeth sockets reaching almost to the floor of the orbit. The maxillary sinus presents the appearance of a furrow on the lateral wall of the nose. In the adult the vertical diameter is the greatest, owing to the development of the alveolar process and

378-404: The bone found in humans, and some other mammals. In bony fish , amphibians , and reptiles , both maxilla and premaxilla are relatively plate-like bones, forming only the sides of the upper jaw, and part of the face, with the premaxilla also forming the lower boundary of the nostrils . However, in mammals, the bones have curved inward, creating the palatine process and thereby also forming part of

405-458: The cranial foramina. Within the vertebral column (spine) of vertebrates, including the human spine , each bone has an opening at both its top and bottom to allow nerves, arteries, veins, etc. to pass through. Maxilla In vertebrates , the maxilla ( pl. : maxillae / m æ k ˈ s ɪ l iː / ) is the upper fixed (not fixed in Neopterygii ) bone of the jaw formed from

432-407: The eye can protrude, or become exophthalmic . Enlargement of the lacrimal gland , located superotemporally within the orbit, produces protrusion of the eye inferiorly and medially (away from the location of the lacrimal gland). Lacrimal gland may be enlarged from inflammation (e.g. sarcoid ) or neoplasm (e.g. lymphoma or adenoid cystic carcinoma ). Tumors (e.g. glioma and meningioma of

459-494: The face, has four borders. The following bones take part in their formation: The orbit holds and protects the eyes . The movement of the eye is controlled by six distinct extraocular muscles, a superior , an inferior , a medial and a lateral rectus, as well as a superior and an inferior oblique . The superior ophthalmic vein is a sigmoidal vessel along the superior margin of the orbital canal that drains deoxygenated blood from surrounding musculature. The ophthalmic artery

486-402: The fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth . The two maxillary bones are fused at the intermaxillary suture, forming the anterior nasal spine . This is similar to the mandible (lower jaw), which is also a fusion of two mandibular bones at the mandibular symphysis . The mandible is the movable part of the jaw. The maxilla

513-404: The increase in size of the sinus. The alveolar process of the maxillae holds the upper teeth, and is referred to as the maxillary arch. Each maxilla attaches laterally to the zygomatic bones (cheek bones). Each maxilla assists in forming the boundaries of three cavities: Each maxilla also enters into the formation of two fossae: the infratemporal and pterygopalatine , and two fissures ,

540-400: The lesser wing of sphenoid near the apex of the orbit. The orbital surface presents medially by trochlear fovea and laterally by lacrimal fossa. The floor (inferior wall) is formed by the orbital surface of maxilla , the orbital surface of zygomatic bone and the minute orbital process of palatine bone . Medially, near the orbital margin, is located the groove for nasolacrimal duct . Near

567-403: The middle of the floor, located infraorbital groove, which leads to the infraorbital foramen. The floor is separated from the lateral wall by inferior orbital fissure , which connects the orbit to pterygopalatine and infratemporal fossa . The medial wall is formed primarily by the orbital plate of ethmoid , as well as contributions from the frontal process of maxilla, the lacrimal bone , and

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594-407: The ocular globe at the lateral wall of the maxillary sinus. It is not as important in function, though it does contain a few branches of the maxillary nerve and the infraorbital artery and vein. Other minor structures in the orbit include the anterior and posterior ethmoidal foramen and zygomatic orbital foramen . The bony walls of the orbital canal in humans do not derive from a single bone, but

621-476: The optic canal, and is formed at the junction of the lesser and greater wing of the sphenoid bone . It is a major pathway for intracranial communication, containing cranial nerves III , IV , VI which control eye movement via the extraocular muscles , and the ophthalmic branches of cranial nerve V , or V1. The second division of the trigeminal nerve enters the skull base at the foramen rotundum , or V2. The inferior orbital fissure lies inferior and lateral to

648-443: The orbit to spread into the brain or other deep facial structures. The optic canal contains the ( cranial nerve II ) and the ophthalmic artery , and sits at the junction of the sphenoid sinus with the ethmoid air cells , superomedial and posterior to structures at the orbital apex. It provides a pathway between the orbital contents and the middle cranial fossa . The superior orbital fissure lies just lateral and inferior to

675-427: The orbital surface, and sometimes with the lateral pterygoid plate of the sphenoid . The maxilla is ossified in membrane. Mall and Fawcett maintain that it is ossified from two centers only, one for the maxilla proper and one for the premaxilla. These centers appear during the sixth week of prenatal development and unite in the beginning of the third month, but the suture between the two portions persists on

702-428: The palate until nearly middle life. Mall states that the frontal process is developed from both centers. The maxillary sinus appears as a shallow groove on the nasal surface of the bone about the fourth month of development, but does not reach its full size until after the second dentition. The maxilla was formerly described as ossifying from six centers, viz.: At birth the transverse and antero-posterior diameters of

729-431: The roof of the mouth. Birds do not have a maxilla in the strict sense; the corresponding part of their beaks (mainly consisting of the premaxilla) is called "upper mandible". Cartilaginous fish , such as sharks, also lack a true maxilla. Their upper jaw is instead formed from a cartilaginous bar that is not homologous with the bone found in other vertebrates. [REDACTED] This article incorporates text in

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