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Posterior Lacrimal Crest
The posterior lacrimal crest is a vertical bony ridge on the orbital surface of the lacrimal bone. It divides the bone into two parts. It gives origin to the lacrimal part of the orbicularis oculi muscle. Structure The posterior lacrimal crest is a vertical bony ridge on the orbital (lateral) surface of the lacrimal bone. It divides the lacrimal bone into two parts. It is quite thin and fragile in most people. The lacrimal groove is in front of this crest. The inner margin of it unites with the frontal process of the maxilla to complete the fossa for the lacrimal sac. The portion of the lacrimal bone behind the posterior lacrimal crest is smooth, and forms part of the medial wall of the orbit. The lacrimal crest ends below in the lacrimal hamulus (a small hook-like projection), which articulates with the lacrimal tubercle of the maxilla. Relations The posterior lacrimal crest is just behind the lacrimal sac, and its upper part lodges the lacrimal sac. The lower part lodges ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lacrimal Bone
The lacrimal bone is a small and fragile bone of the facial skeleton; it is roughly the size of the little fingernail. It is situated at the front part of the medial wall of the orbit. It has two surfaces and four borders. Several bony landmarks of the lacrimal bone function in the process of lacrimation or crying. Specifically, the lacrimal bone helps form the nasolacrimal canal necessary for tear translocation. A depression on the anterior inferior portion of the bone, the lacrimal fossa, houses the membranous lacrimal sac. Tears or lacrimal fluid, from the lacrimal glands, collect in this sac during excessive lacrimation. The fluid then flows through the nasolacrimal duct and into the nasopharynx. This drainage results in what is commonly referred to a runny nose during excessive crying or tear production. Injury or fracture of the lacrimal bone can result in posttraumatic obstruction of the lacrimal pathways. Structure Lateral or orbital surface The lateral or orbital surface i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lacrimal Sac
The lacrimal sac or lachrymal sac is the upper dilated end of the nasolacrimal duct, and is lodged in a deep groove formed by the lacrimal bone and frontal process of the maxilla. It connects the lacrimal canaliculi, which drain tears from the eye's surface, and the nasolacrimal duct, which conveys this fluid into the nasal cavity. Lacrimal sac occlusion leads to dacryocystitis. Structure It is oval in form and measures from 12 to 15 mm. in length; its upper end is closed and rounded; its lower is continued into the nasolacrimal duct. Its superficial surface is covered by a fibrous expansion derived from the medial palpebral ligament, and its deep surface is crossed by the lacrimal part of the orbicularis oculi, which is attached to the crest on the lacrimal bone. Histology Like the nasolacrimal duct, the sac is lined by stratified columnar epithelium with mucus-secreting goblet cells, with surrounding connective tissue. The Lacrimal Sac also drains the eye of debris and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Le Fort Fracture Of Skull
A Le Fort fracture of the skull is a classic transfacial fracture of the midface, involving the maxillary bone and surrounding structures in either a horizontal, pyramidal or transverse direction. The hallmark of Lefort fractures is traumatic ''pterygomaxillary separation'', which signifies fractures between the pterygoid plates, horseshoe-shaped bony protuberances which extend from the inferior margin of the maxilla, and the maxillary sinuses. Continuity of this structure is a keystone for stability of the midface, involvement of which impacts surgical management of trauma victims, as it requires fixation to a horizontal bar of the frontal bone. The pterygoid plates lie posterior to the upper dental row, or alveolar ridge, when viewing the face from an anterior view. The fractures are named after French surgeon René Le Fort (1869–1951), who discovered the fracture patterns by examining crush injuries in cadavers. Signs and symptoms Le Fort I – Slight swelling of the upper ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Avulsion Fracture
An avulsion fracture is a bone fracture which occurs when a fragment of bone tears away from the main mass of bone as a result of physical trauma. This can occur at the ligament by the application of forces external to the body (such as a fall or pull) or at the tendon by a muscular contraction that is stronger than the forces holding the bone together. Generally muscular avulsion is prevented by the neurological limitations placed on muscle contractions. Highly trained athletes can overcome this neurological inhibition of strength and produce a much greater force output capable of breaking or avulsing a bone. Types Dental avulsion Traumatic complete displacement of a tooth from its socket in alveolar bone. It is a serious dental emergency in which prompt management (within 20–40 minutes of injury) affects the prognosis of the tooth. Tuberosity avulsion of the 5th metatarsal left, Proximal fractures of 5th metatarsa The tuberosity avulsion fracture (also known as pseud ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Journal Of Anatomy
The ''Journal of Anatomy'' is a monthly peer-reviewed scientific journal published by Wiley on behalf of the Anatomical Society. It covers all aspects of anatomy and morphology. The journal was first published in 1867 and was originally known as the ''Journal of Anatomy and Physiology'', obtaining its current title in October 1916. The editors-in-chief are Phil Cox (Hull York Medical School), Thomas H. Gillingwater (University of Edinburgh), Stefan Milz (Ludwig-Maximilians University), and Neil Vargesson (University of Aberdeen). According to the ''Journal Citation Reports'', the journal has a 2021 impact factor of 2.921. In conjunction with their centennial in 2009, the international Special Libraries Association included the ''Journal of Anatomy'' as one of the 100 most influential journals in biology and medicine over the past 100 years. History The journal was established in 1867 as the ''Journal of Anatomy and Physiology''. The journal was conceived at the 1866 meeting of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anterior Lacrimal Crest
The anterior lacrimal crest is a bony projection on the frontal process of the maxilla. It creates the lateral margin of the lacrimal sac fossa and is continuous with the orbital margin. The medial palpebral ligament is attached to anterior lacrimal crest. It is an important structure to avoid damaging during rhinoplasty. Structure The anterior lacrimal crest is a bony projection on the frontal process of the maxilla in the skull. It reaches the junction between the maxilla and the lacrimal bone. At its junction with the orbital surface is a small tubercle, the lacrimal tubercle, which serves as a guide to the position of the lacrimal sac. The anterior lacrimal crest is much thicker and stronger than the posterior lacrimal crest. It is one of the thickest parts of the orbit. It is nearly always quite prominent, whilst the posterior lacrimal crest may be less prominent in some people. Relations The lacrimal sac is directly behind the anterior lacrimal crest, which prote ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orbicularis Oris Muscle
In human anatomy, the orbicularis oris muscle is a complex of muscles in the lips that encircles the mouth. It is a sphincter, or circular muscle, but it is actually composed of four independent quadrants that interlace and give only an appearance of circularity.Saladin, "Anatomy & Physiology: The Unity of Form and Function". 5th edition. McGraw Hill. Page 330 It is also one of the muscles used in the playing of all brass instruments and some woodwind instruments. This muscle closes the mouth and puckers the lips when it contracts. Structure The orbicularis oris is not a simple sphincter muscle like the orbicularis oculi; it consists of numerous strata of muscular fibers surrounding the orifice of the mouth, but having different direction. It consists partly of fibers derived from the other facial muscles which are inserted into the lips, and partly of fibers proper to the lips. Of the former, a considerable number are derived from the buccinator and form the deeper stratum of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nasolacrimal Duct
The nasolacrimal duct (also called the tear duct) carries tears from the lacrimal sac of the eye into the nasal cavity. The duct begins in the eye socket between the maxillary and lacrimal bones, from where it passes downwards and backwards. The opening of the nasolacrimal duct into the inferior nasal meatus of the nasal cavity is partially covered by a mucosal fold ( valve of Hasner or ''plica lacrimalis''). Excess tears flow through the nasolacrimal duct which drains into the inferior nasal meatus. This is the reason the nose starts to run when a person is crying or has watery eyes from an allergy, and why one can sometimes taste eye drops. This is for the same reason when applying some eye drops it is often advised to close the nasolacrimal duct by pressing it with a finger to prevent the medicine from escaping the eye and having unwanted side effects elsewhere in the body as it will proceed through the canal to the Nasal Cavity. Like the lacrimal sac, the duct is lined by st ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lacrimal Hamulus
The lacrimal hamulus is a small, hook-like bony projection of the lacrimal bone. It is a continuation of the posterior lacrimal crest. It articulates with the lacrimal tubercle of the maxilla, and completes the upper orifice of the lacrimal canaliculus. It sometimes exists as a separate piece, and is then called the lesser lacrimal bone. Structure The lacrimal hamulus is a small, hook-like bony projection of the lacrimal bone. It is a continuation of the posterior lacrimal crest of the lacrimal bone. It articulates with the lacrimal tubercle of the maxilla. This completes the upper orifice of the lacrimal canaliculus. Relations The lacrimal hamulus is usually around 9 mm from the infraorbital foramen, around 20 mm from the inferior orbital fissure, and around 31 mm from the beginning of the posterior lacrimal crest. Variation The lacrimal hamulus develops from its own site of primary ossification of cartilage. Because of this, it sometimes exists as a separate piece, an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Skeletal System
A skeleton is the structural frame that supports the body of an animal. There are several types of skeletons, including the exoskeleton, which is the stable outer shell of an organism, the endoskeleton, which forms the support structure inside the body, and the hydroskeleton, a flexible internal skeleton supported by fluid pressure. Vertebrates are animals with a vertebral column, and their skeletons are typically composed of bone and cartilage. Invertebrates are animals that lack a vertebral column. The skeletons of invertebrates vary, including hard exoskeleton shells, plated endoskeletons, or Sponge spicule, spicules. Cartilage is a rigid connective tissue that is found in the skeletal systems of vertebrates and invertebrates. Etymology The term ''skeleton'' comes . ''Sceleton'' is an archaic form of the word. Classification Skeletons can be defined by several attributes. Solid skeletons consist of hard substances, such as bone, cartilage, or cuticle. These can be further ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orbit (anatomy)
In anatomy, the orbit is the cavity or socket of the skull in which the eye and its appendages are situated. "Orbit" can refer to the bony socket, or it can also be used to imply the contents. In the adult human, the volume of the orbit is , of which the eye occupies . The orbital contents comprise the eye, the orbital and retrobulbar fascia, extraocular muscles, cranial nerves II, III, IV, V, and VI, blood vessels, fat, the lacrimal gland with its sac and duct, the eyelids, medial and lateral palpebral ligaments, cheek ligaments, the suspensory ligament, septum, ciliary ganglion and short ciliary nerves. Structure 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."eye, human."Encyclopædia Britannica from Encyclopædia Britannica 2006 Ultimate Reference Suite DVD 2009 Openings There are two important foramina, or windows, two important fissu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fossa For Lacrimal Sac
A smooth, more deeply concave depression on the lacrimal bone, which forms the medial wall of the orbital cavity, in which the lacrimal sac that drains into the nasolacrimal duct is located, is referred to as the lacrimal fossa (or fossa for the lacrimal sac). See also * Fossa for lacrimal gland The lacrimal fossa (or fossa for lacrimal gland) is located on the inferior surface of each orbital plate of the frontal bone. It is smooth and concave, and presents, laterally, underneath the zygomatic process, a shallow depression for the lacrim ... References Bones of the head and neck {{musculoskeletal-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
