What makes up the orbital complex

Whitaker, Neil R. Instant Anatomy. ISBN: 4. Last's anatomy, regional and applied. Churchill Livingstone. Read it at Google Books - Find it at Amazon. Related articles: Anatomy: Head and neck. Promoted articles advertising. Figure 1: bony orbit Figure 1: bony orbit.

Figure 2: bony orbit photo Figure 2: bony orbit photo. Loading more images In the frontal plane it slopes downward from medial to lateral with an intermediate convexity at the midorbit level. Behind the postentry concavity, the floor is separated from the lateral wall by the inferior orbital fissure. In the sagittal plane the floor has a lazy S shape with the upper ledge at the height of the orbital process of the palatine bone posteriorly and extending downward to the infraorbital margin anteriorly.

In a surface view the posteromedial convexity has a sphere-like appearance that levels off inferior-laterally but maintains its height posteriorly and diverges into the medial wall. It also provides its main support. The medial wall has a convex rectangular shape and runs parallel to the sagittal plane. This convexity becomes particularly prominent in the midorbit at the maxillary-ethmoidal suture line, where it transitions into the posterior medial bulge of the maxillary surface of the orbital floor.

The medial wall is paper thin Lamina papyracea but reinforced along the maxillary-ethmoidal suture forming an internal orbital buttress. Many fractures of the posterior medial bulge abruptly break off along this line and do not cross over into the lamina papyracea of the medial wall.

The lateral wall roughly forms a triangle with an anterior base. It is a flat surface bounded by the zygomaticofrontal, frontosphenoid suture and lateral edge of the superior orbital fissure superiorly and the inferior orbital fissure. The superior wall is triangular and has a domed contour in the anterior orbital one third and the midorbit.

It is mainly comprised of the horizontal orbital plate of the frontal bone. It can be extremely thin, frequently with dehiscent spots in elderly individuals. In such cases the periorbita can become confluent with the dura. In the apex the orbital roof terminates into the lesser wing of the sphenoid, where the vertically oriented oval shaped optic foramen forms the orbital opening of the optic canal.

The posterior third or the apex of the orbit is made up by the sphenoid bone. The 4 paranasal sinuses surround the floor maxillary sinus and the medial wall ethmoidal and sphenoid sinuses of the orbit Fig The frontal sinus has a variable relationship to the anterior orbital roof. The other major structures around the orbit are the anterior cranial fossa superiorly containing the frontal lobe and the temporal fossa laterally containing the temporalis muscle. The roof of the ethmoidal complex, delineated by the frontal ethmoidal suture top of the ethmoidal bone, or lamina papyracea , marks the inferior boundary of the anterior cranial fossa.

It is important to realize that surgical intervention above this anatomical landmark—as occurs, for example, during endoscopic sinus surgery—can result in entry into the anterior cranial fossa or a cerebrospinal fluid CSF leak. The sphenoid sinus forms the medial wall of the optic canal Fig Surgery within the sphenoid sinus has the potential to damage the optic nerve; alternatively, the sphenoid sinus is a surgical route facilitating decompression of the optic chiasm.

The pterygomaxillary area, which contains the sphenopalatine ganglion and the internal maxillary artery, underlies the apex of the orbit. This area communicates posteriorly through the foramen rotundum and the vidian canal to the middle cranial fossa, anteriorly through the infraorbital canal to the cheek and lower eyelid, and superiorly through the inferior orbital fissure to the orbit.

The orbit communicates with the surrounding areas through several bony canals and fissures. Posteriorly, the orbit is contiguous with the cavernous sinus through the superior orbital fissure see Fig The medial wall of the orbit continues as the lateral wall of the sphenoid bone, marking the medial extent of the cavernous sinus.

Therefore, when sharp objects enter the medial orbit, they are directed through the superior orbital fissure, where they can lacerate the carotid artery. The orbit is connected superiorly and posteriorly to the anterior cranial fossa by way of the optic canal see Fig B , which transmits the optic nerve, ophthalmic artery, and some sympathetic fibers.

Inferiorly at the apex, the orbit is connected to the pterygopalatine area —and thus the temporal and inferotemporal regions—through the inferior orbital fissure. This fissure, formed by the greater wing of the sphenoid, maxillary, zygomatic, and palatine bones, carries the maxillary branch of CN V CN V2 , infraorbital vessels, the inferior ophthalmic vein, branches from the pterygopalatine ganglion, parasympathetic fibers that innervate the lacrimal gland, and collateral meningeal arteries that help connect the external and internal carotid circulation.

Anteriorly, the orbit connects to the inferior meatus of the nose beneath the inferior turbinate through the nasolacrimal duct, which carries tears into the nasal cavity. In addition, numerous variable bony canals carry blood vessels that travel to and from the orbit and surrounding structures. Malar asymmetry is a frequent complication of zygoma fractures resulting from inadequate three-dimensional reduction. Methods for accurate reduction and stabilization, indications for closed and open reduction, and management of the fractured infraorbital rim are emphasized.

The indications for miniplates vs wire ligatures for the infraorbital rim are discussed. Long-term follow up and evaluation of the results with regard to the fracture pattern, complications, maxillary sinus dysfunction, and facial and orbital symmetry are presented. Arch Otolaryngol Head Neck Surg. Coronavirus Resource Center.

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