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Head and Neck
Published in Rui Diogo, Drew M. Noden, Christopher M. Smith, Julia Molnar, Julia C. Boughner, Claudia Barrocas, Joana Bruno, Understanding Human Anatomy and Pathology, 2018
Rui Diogo, Drew M. Noden, Christopher M. Smith, Julia Molnar, Julia C. Boughner, Claudia Barrocas, Joana Bruno
The orbital margin is formed by the frontal bone superiorly, zygomatic bone laterally (which includes the frontal process and temporal process) and the maxillary bone (or maxilla) medially, which also spans a good portion of the skull. The maxilla includes a frontal process along this orbital margin, an alveolar process above the teeth, an anterior nasal spine located at the bottom of the nasal region protruding out, an incisive foramen, and palatine process along the roof of the oral cavity, an anterior lacrimal crest bordering the anterior portion of the lacrimal groove, an infraorbital groove located on the floor of the orbit, and an infraorbital foramen just inferior to the orbital margin. The anterior nasal aperture is bounded by the nasal bones and maxillae. The nasal septum and the lacrimal bone (which includes the posterior lacrimal crest and lacrimal groove, all so-named because of their proximity to the lacrimal duct, which drains the tears of happiness that you will shed on completing your degree) can be seen in a frontal view of the anterior nasal aperture (Plates 3.7a and c and 3.8a and c).
Disorders of the Orbit
Published in John C Watkinson, Raymond W Clarke, Louise Jayne Clark, Adam J Donne, R James A England, Hisham M Mehanna, Gerald William McGarry, Sean Carrie, Basic Sciences Endocrine Surgery Rhinology, 2018
Nithin D. Adappa, James N. Palmer
The medial wall is most relevant to otorhinolaryngologists due to the proximity of the paranasal sinuses. From an anterior to posterior direction, the boney contribution of anterior lacrimal crest originates at the frontal process of the maxilla. The lacrimal bone makes up the second one half of the lacrimal sac fossa and the posterior lacrimal crest. The lamina papyracea (arising from ethmoid bone) makes up the majority of the medial orbital wall. The paper-thin bone overlies the ethmoid sinuses.2 The anterior and posterior ethmoid foramina are found in the superior aspect of the orbit along the fronto-ethmoidal suture line. The anterior ethmoid foramen is a useful landmark and is identified 20–25 mm posterior to the anterior lacrimal crest and the posterior ethmoid foramen is 30–35 mm posterior to the anterior lacrimal crest.3 The thick bone of the sphenoid body forms the most posterior portion of the medial orbital wall adjoining the optic canal.
Orbital Fractures
Published in Jeffrey R. Marcus, Detlev Erdmann, Eduardo D. Rodriguez, Essentials of CRANIOMAXILLOFACIAL TRAUMA, 2014
Regina M. Fearmonti, Jeffrey R. Marcus
Composed of the lacrimal bone and lamina papyracea of the ethmoid, the medial orbital wall occupies a vertical position with a slightly lateral slant. Anteriorly, it houses the lacrimal sac between the frontal process of the maxilla (anterior lacrimal crest) and the lacrimal bone (posterior lacrimal crest). A fracture in this anterior third (the medial rim) is typically classified as a nasoorbital ethmoid fracture, whereas a fracture of the weak lamina papyracea connotes a pure medial wall injury. Because the medial wall separates the orbit from the ethmoid sinus, epistaxis and orbital emphysema are commonly seen with floor fractures that involve the medial wall.
Correction of severe medial ectropion using a novel osseous fixation technique
Published in Orbit, 2023
Ivan Vrcek, David Seamont, Ashtyn Zapletal, Marie Somogyi, Alison Huggins Watson, Tanuj Nakra
A transcaruncular orbitotomy is then used to identify the posterior lacrimal crest and anterior ethmoidal bone. This technique, described in 1998 by Garcia, Goldberg, and Shorr, offers wide exposure to the medial and inferior orbit.9 An external caliper is used to measure the distance between the proximal swage and the tip of an RB2 needle on a 5–0 double armed polypropylene suture (Figure 1). The caliper is set with this measurement, which is then used to create two holes in the ethmoid bone just posterior to the posterior lacrimal crest (Figures 2 and 3). The prolene suture is then passed through the medial cut edge of the lower eyelid. One arm of the double-armed suture is easily passed through the two puncture holes in the ethmoid bone created by the external caliper. The caliper ensures that the holes and the distance between the tip and swage of the needle are identical, facilitating the pass of the suture through the bone (Figure 4). The two arms of the suture are then tied down creating a posterior vector for the medial lower eyelid and medial canthal tendon. A supplementary video demonstrating the intraoperative procedure has been added for reference. The initial sizing of the caliper against the prolene suture is shown before the caliper is used to create the two “puncture holes.” The suture is first passed through the superior hole, and subsequently the inferior hole of the ethmoid bone before the two ends of the suture are brought up to be tied.
Magnetic Resonance Imaging Features of Medial Canthal Tendon in Centurion Syndrome
Published in Current Eye Research, 2021
Md. Shahid Alam, Andrea Tongbram, Olma Veena Noronha
The MCT was considered the medial canthal ligament or just an adhesion to the periosteum of the frontal process of the maxilla,5 was later reconsidered to be a tendon of the orbicularis oculi muscle in the 1970s by Jones and Wobig.6 Since then this peculiar structure has remained an area of interest for many researchers and has seen many changes in its concept and application. Traditionally the MCT is thought to have an anterior and a posterior limb.7 The anterior limb is more prominent, but it is the posterior limb which actually supports the medial canthus.8 The anterior limb is like a triangular band inserting predominantly at the anterior lacrimal crest, the anterior-most extent ending just behind the nasomaxillary suture. It is about 11.7 mm in length, 2 to 4 mm in width, and 4.9 mm thick, in the anteroposterior plane. The posterior limb extends as a thin band and inserts at the posterior lacrimal crest. Its thickness varies from 1.0 to 3.3 mm.9 Whether the posterior limb actually exists has been a matter of some debate. Studies on Asians and Caucasians cadavers have demonstrated that the Horner’s muscle and the fibrous lacrimal diaphragm is actually what was originally considered to be the posterior limb of the MCT, both of which get inserted at the posterior lacrimal crest.10,11 The posterior limb was not detected in any of the cadaveric specimens.10,11 The lacrimal diaphragm around the posterior lacrimal crest ran almost parallel to the Horner's muscle and was difficult to distinguish from the tendon of the Horner’s muscle. The Horner’s muscle was found to be anterior to the lacrimal canaliculus, except in the medial part near the ostium of the common canaliculus where it was found separated from the canaliculus, going further posteriorly to attach at the posterior lacrimal crest.11 The common canaliculus is covered by the anterior limb of the MCT.11 Though Kakizaki et al have questioned the existence of the posterior limb of the MCT and have said that it was the fibrous lacrimal diaphragm which was mistaken as the posterior limb,10 we are of the opinion, that it is still preferable to call this structure as the posterior limb to avoid any confusion with the nomenclature.