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Articles

Articles are a collaborative effort to provide a single canonical page on all topics relevant to the practice of radiology. As such, articles are written and edited by countless contributing members over a period of time. A global group of dedicated editors oversee accuracy, consulting with expert advisers, and constantly reviewing additions.

3,511 results found
Article

Volar intercalated segment instability

Volar intercalated segment instability (VISI) is a type of instability involving the wrist. It is less often encountered than dorsal intercalated segment instability (DISI). Clinical presentation It presents in most cases with nonspecific wrist pain and a "clunking" on the ulnar deviation of t...
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Volar plate avulsion injury

Volar plate avulsion injuries are a type of avulsion injury. The volar plate of the proximal interphalangeal (PIP) joint is vulnerable to hyperextension injury, in the form of either a ligament tear or an intra-articular fracture. Gross anatomy The volar plate forms the floor of the PIP joint ...
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Volar radioulnar ligament

The volar radioulnar ligament is one of the primary stabilizers of the distal radioulnar joint (DRUJ) and forms part of the triangular fibrocartilage complex (TFCC) 1,2. Summary location: extending from the anterior margin of the ulnar notch at the distal radius to the anterior portion of the ...
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Volkmann ischemic contracture

A Volkmann ischemic contracture refers to a complex and variable flexion deformity involving distal limbs (typically the wrist and fingers) resulting from fibrosis and contracture of flexor muscles. Fracture of hinge joint (elbow) or arm outcomes this contracture. It is associated with supracond...
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Wackenheims line

Wackenheims line (also known as the clivus canal line or basilar line) is formed by drawing a line along the clivus and extending it inferiorly to the upper cervical canal. Normally the tip of the dens is ventral and tangential to this line. In basilar invagination odontoid process transects th...
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Wagstaffe-Le Fort fracture

A Wagstaffe-Le Fort fracture refers to an avulsion fracture of the medial aspect of the distal fibula due to avulsion of the anterior tibiofibular ligament attachment. See also lower extremity fractures
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Walch classification of glenoid morphology

The Walch classification of glenoid morphology is the most commonly used system describing glenohumeral pathology in primary osteoarthritis. It was initially measured on 5 mm thick slices on axial CT scans of the shoulder 1, which had mixed results for inter- and intra-observer agreement but th...
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Waldenström classification of Perthes disease

The Waldenström classification of Perthes disease refers to x-ray abnormalities, and represents four temporal phases of the disease. These stages have been further subdivided in the modified Elizabethtown classification 2. stage I: early asymmetric femoral epiphyseal size (smaller on the affec...
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Waldenström sign (hip)

Waldenström sign is the increased distance between the pelvic teardrop and the femoral head. It is a highly specific sign of a hip joint effusion. Radiographic features Plain radiograph >11 mm total distance or >2 mm difference compared to contralateral hip 1,2 measured between the lateral a...
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Ward triangle

Ward triangle refers to a radiolucent area between principal compressive, secondary compressive and primary tensile trabeculae in the neck of femur. It should be differentiated from Babcock triangle. History and etymology Named for F O Ward after his original description of the region in 1838.
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Wartenberg syndrome

Wartenberg syndrome also known as cheiralgia paresthetica is due to compression of the superficial branch of the radial nerve in the distal forearm. It can be secondary to tight watch band or handcuffs, compression from distal radius fracture or idiopathic.  Clinical presentation Patients pres...
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Wasp-waist sign (spine)

The wasp-waist sign is a radiographic appearance seen in patients with Klippel Feil syndrome. It results from fusion of the vertebral bodies such that the anteroposterior diameter at the level of the affected discovertebral joint is smaller than the diameter at the superior and inferior limits o...
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Water-lily sign (hydatid cyst)

The water-lily sign, also known as the camalote sign, is seen in hydatid infections when there is detachment of the endocyst membrane which results in floating membranes within the pericyst that mimic the appearance of a water lily. It is classically described on plain radiographs (mainly chest...
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Weber classification of ankle fractures

The Weber ankle fracture classification (or Danis-Weber classification) is a simple system for classification of lateral malleolar fractures, relating to the level of the fracture in relation to the ankle joint. It has a role in determining treatment.  Classification type A below the level of...
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Wedge fracture

Wedge fractures (also known as compression fractures) are hyperflexion injuries to the vertebral body resulting from axial loading. Most commonly affecting the anterior aspect of the vertebral body, wedge fractures are considered a single-column (i.e. stable) fracture.  Less commonly wedge frac...
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Weightbearing foot series (an approach)

Reporting a weightbearing foot series can be a daunting process if you are inexperienced and often results in the films being left for somebody else to report. This article attempts to demystify the whole process by providing a structured approach to their reporting. Technique The weightbearin...
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Weil osteostomy

A Weil osteotomy is a from of osteotomy performed in the foot. It is considered a common technique used in the treatment of lesser metatarsal deformities of the forefoot. It is designed to make a controlled shortening of the length of the metatarsal in the transverse plane. Radiographic feature...
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Weiss classification of lateral humeral condyle fractures

The Weiss classification is one of the classification systems used for lateral humeral condyle fractures and is based on the degree of displacement measured on an internal oblique view of the elbow: type 1: <2 mm displacement type 2: 2-4 mm displacement type 3: >4 mm displacement The degree ...
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Werner syndrome

Werner syndrome is a progeroid rare autosomal recessive condition attributed to chromosome 8. It should not to be confused with similarly sounding Wermer syndrome. Pathology Werner syndrome is characterized by premature senescence cataracts short stature scleroderma-like skin changes such ...
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WHO classification of tumors of bone

The World Health Organization (WHO) classification of bone tumors is the most widely used pathologic classification system for such disorders. The current revision, part of the 4th edition of the WHO series, was published in 2013 and is reflected in the article below 1. Classification Chondrog...
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WHO classification of tumors of soft tissue

The World Health Organization (WHO) classification of soft tissue tumors is the most widely used pathologic classification system for such disorders. The current revision, part of the 4th edition of the WHO series, was published in 2013 and is reflected in the article below 1. Classification A...
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Wiberg classification of patella shape

Wiberg classification is a system used to describe the shape of the patella based mainly on the asymmetry between the patellar medial and lateral facets on axial views of the patella. Increasing number type indicates a larger degree of asymmetry. Classification Wiberg type 1 or a roughly symm...
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Widened intercondylar notch

A widened intercondylar notch on knee radiographs is a sign associated with: haemophilic arthropathy (most commonly bilateral) juvenile rheumatoid arthritis (most commonly bilateral) tuberculous arthropathy (usually unilateral) 3
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Widening of interpedicular distance

The interpedicular distance, which is the distance measured between the pedicles on frontal/coronal imaging, can be widened in a number of situations. Pathology Etiology diastematomyelia syringomyelia conditions that can cause dural ectasia (can potentially cause widening) Marfan syndrome ...
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Widening of the diploic space

Widening of the diploic space refers to expansion of the cancellous (spongy) bone between the inner and outer tables of the calvaria. The diploic space is the medullary cavity of the skull, and a location of normal physiologic hematopoiesis in adults. Thus, expansion of this structure most commo...
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Wilson disease

Wilson disease, also known as hepatolenticular degeneration, is a rare autosomal recessive disorder of copper metabolism affecting multiple systems.  Epidemiology Wilson disease is commonly found in Japan. It affects 1 in 30,000-40,000 individuals 12. 1 in 90 individuals are a heterozygous car...
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Wilson disease (musculoskeletal manifestations)

Wilson disease, also known as hepatolenticular degeneration, is a multisystem disease, which rarely has musculoskeletal manifestations secondary to the accumulation of copper in the articular cartilage.  Radiographic features Plain radiographs Reported manifestations include 1-3 premature os...
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Wiltse classification (spondylolisthesis)

Spondylolisthesis can be classified according to broad etiologies as described by Wiltse in 1981 1. Typically when reporting studies with spondylolisthesis the Wiltse type is merely stated without referring to its number, whereas the grade of spondylolisthesis is explicitly stated: e.g. "Grade 1...
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Wimberger ring sign

Wimberger ring sign, often simply just called Wimberger ring, refers to a circular calcification surrounding the osteoporotic epiphyseal center of ossification in scurvy, which may result from bleeding. It must not be confused with Wimberger sign, pathognomonic for congenital syphilis. History...
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Wimberger sign

The Wimberger sign, also called Wimberger corner sign, refers to localized bilateral metaphyseal destruction of the medial proximal tibias. It is a pathognomonic sign for congenital syphilis. It must not be mixed up with Wimberger ring sign seen in scurvy, which is sometimes also confusingly re...
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Windswept pelvis

Windswept pelvis fracture is a complex bony pelvic injury caused by a combination of unilateral AP compression (open book) injury with a contralateral lateral compression injury.  It occurs when the internal rotation of one iliac wing causes a unilateral sacral compression fracture, while the s...
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Winking owl sign (spine)

The (absent) pedicle sign, also called the winking owl sign, occurs on plain radiograph of the spine when a pedicle is absent 5. The term, winking owl sign, where the missing pedicle corresponds to the closed eye, the contralateral pedicle to the other round open eye, and the spinous process to...
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Winquist classification of femoral shaft fractures

The Winquist classification of femoral shaft fractures is based on fracture comminution and was proposed by Winquist in 1980. This classification is used with regards to management decision making, in determining whether a fracture requires an intramedullary nail or open reduction.  Type 0: no ...
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Wolff's law

Wolff's law summarizes the dynamic nature of the 3D microarchitecture of bone. Mechanical forces (or the lack of them) dynamically alter the thickness of cortical bone and the thickness and orientation of trabeculae.  Lack of sufficient mechanical loading (e.g. bed rest) results in resorption a...
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Wormian bone

Wormian bones (also knows as intrasutural bones) is the name given to the additional small bones sometimes found between the cranial sutures of the bones of the skull vault, most commonly in relation to the lambdoid suture. Some reserve the term Wormian bones to just the intrasutural bones proxi...
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Wormian bones (mnemonic)

A mnemonic to remember ten of the numerous conditions associated with Wormian bones is: PORKCHOPS Mnemonic P: pyknodysostosis O: osteogenesis imperfecta R: rickets K: kinky hair syndrome C: cleidocranial dysostosis H: hypothyroidism/hypophosphatasia O: otopalatodigital syndrome P: prim...
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Wrisberg rip

Wrisberg rips, also known as zip tears or zipper tears, are longitudinal vertical meniscal tears. They occur at the junction of the ligament of Wrisberg and the posterior horn of the lateral meniscus and are commonly associated with anterior cruciate ligament tears 1.  Pathology The ligament o...
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Wrist (carpal bridge view)

The carpal bridge view an additional view to the three view series of the wrist and carpal bones. It is used to assess the dorsal aspect of the scaphoid, lunate and the triquetrum. Patient position the patient is seated alongside the table dorsal aspect of affected wrist is placed on the dete...
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Wrist (carpal tunnel view)

The carpal tunnel view is an axial projection to demonstrate the medial and lateral prominences and the concavity. It can be utilized to investigate potential hook of hamate, pisiform and trapezium factures. Patient position patient stands with the back facing the table palmar surface of hand...
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Wrist (clenched fist view)

The clenched fist view is an additional projection used to evaluate suspected widening of the scapholunate interval, often performed bilaterally it is a functional view that requires the patient to clench both hands.  Patient position patient is seated in front of the table  both hands are pl...
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Wrist (horizontal beam lateral view)

The horizontal beam lateral wrist view is a modified lateral projection when performing the three view series of the wrist and carpal bones in trauma. It is the orthogonal projection of the PA wrist without any patient movement, making it the most appropriate projection for patients in pain. Pa...
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Wrist (lateral view)

The lateral wrist view is part of a three view series of the wrist and carpal bones. It is the orthogonal projection of the PA wrist. Patient position patient is seated alongside the table the affected arm if possible is flexed at 90° so the arm and wrist can rest on the table abduct the hum...
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Wrist ligaments

The intrinsic and extrinsic wrist ligaments play a vital role in the stability of the wrist joint. There are numerous ligaments but included below are the most clinically significant. Wrist ligaments are best assessed with dedicated wrist MRI. Gross anatomy intrinsic ligaments (only attach to ...
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Wrist (oblique view)

The oblique wrist view is part of a three view series of the wrist and carpal bones. It is not generally performed in follow-up studies unless specifically requested. Patient position patient is seated alongside the table the affected arm if possible is flexed at 90° so the arm and wrist can ...
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Wrist (PA view)

The PA wrist view is part of a three view series of the wrist and carpal bones. Although performed PA the view can often be referred to an AP view. Patient position patient is seated alongside the table the affected arm if possible is flexed at 90° so the arm and wrist can rest on the table ...
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Wrist protocol (MRI)

The MRI wrist protocol encompasses a set of MRI sequences for the routine assessment of the wrist joint. Note: This article aims to frame a general concept of an MRI protocol for the assessment of the wrist. Protocol specifics will vary depending on MRI scanner type, specific hardware and softw...
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Wrist (radial deviation view)

The wrist PA radial deviation view is specialized projection employed to better demonstrate the carpal bones that lay on the ulnar aspect of the wrist. Patient position patient is seated alongside the table the affected arm if possible is flexed at 90° so the arm and wrist can rest on the tab...
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Wrist radiograph

Wrist radiographs are ubiquitous in the emergency departments. They are commonly performed in the pediatric and elderly populations after a fall on an outstretched hand as well as in patients after higher force trauma. Moreover, they may be performed as part of a skeletal survey looking for meta...
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Wrist radiograph (an approach)

Wrist radiographs are ubiquitous on any night of the week in emergency departments, especially when pavements are icy!  Systematic review Choosing a search strategy and utilizing it consistently is a helpful method to overcome common errors seen in diagnostic radiology. The order in which you ...
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Wrist radiograph (approach)

Wrist x-rays are commonly used for the assessment of the wrist following trauma. This is usually a fall onto an outstretched hand. Systematic review It is useful to have a systematic approach; I tend to start proximally and work distally looking at structures on both views together: distal ra...
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Wrist radiograph (checklist)

The wrist radiograph checklist is just one of the many pathology checklists that can be used when reporting to ensure that you always actively exclude pathology that is commonly missed; this is particularly helpful in the examination setting, e.g. the FRCR 2B rapid-reporting. Radiograph Wrist ...
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Wrist radiograph (summary approach)

This is a basic article for medical students and other non-radiologists Wrist radiographs are commonly used for the assessment of the wrist following trauma.  Summary approach alignment AP distal radius and ulna have smooth joint surface carpal arcs are smooth carpal bones do not overlap ...
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Wrist series

The wrist series is comprised of a posteroanterior, oblique, and lateral projection. The series examines the carpal bones that are consisting of the scaphoid, lunate, triquetrum, pisiform, trapezium, trapezoid, capitate and hamate. It also examines the radiocarpal and distal radiocarpal joint al...
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Wrist series (summary)

This is a basic article for medical students and other non-radiologists A wrist series (or wrist x-ray) may be performed for a multitude of reasons. However, they are most commonly used in the assessment of trauma, by clinical teams within the Emergency Department or Orthopedic service. Refere...
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Xiphisternal joint

The xiphisternal joint (or more rarely, the sternoxiphoid joint) is a symphysis between the inferior margin of the body of the sternum and the superior margin of the xiphoid process. In most people it ossifies with age, usually becoming fully fused by the age of 40 years, forming a synostosis.  ...
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Xiphoid shape variations

There is considerable anatomic variation in the shape of the xiphoid of the sternum: xiphoid ending is classified as single, double, or triple. xiphoid size varies (e.g. elongated process) xiphoid morphology (e.g. ventral or dorsal deviation, hook-like, reverse S-shape). Clinical presentatio...
Article

Yaws

Yaws, also known as framboesia, is a tropical disease produced by the Treponema pallidum subspecies pertenue. Epidemiology Yaws is a tropical disease. Infections have declined dramatically over the last century, however the disease is still present in several countries in Africa and Asia 1. Y...
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Young and Burgess classification of pelvic ring fractures

The Young and Burgess classification is a modification of the Tile classification 1. It is the recommended 5 and most widely used classification system for pelvic ring fractures. It takes into account force type, severity, and direction, as well as injury instability. Three basic mechanistic ...
Article

Yo-yo on a string sign (Stener lesion)

The yo-yo on a string sign denotes the characteristic appearance of the torn, proximally retracted and superficially displaced ulnar collateral ligament (UCL) due to a Stener lesion. Mechanism The sign occurs as a consequence of the tear of the ulnar collateral ligament of the thumb (gamekeepe...
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Yunis-Varón syndrome

Yunis Varón syndrome is a rare skeletal dysplasia. It is thought to be autosomal recessive. Radiographic features severe neurologic impairment include small cerebellar vermis and dandy walker malformation cleidocranial dysplasia absent clavicles macrocrania diastasis of sutures micrognath...
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Z deformity

The Z deformity is one of the musculoskeletal manifestation of rheumatoid arthritis in hand: radial deviation at the wrist ulnar deviation of the digits, and often palmar subluxation of the proximal phalanges
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Z deformity (mnemonic)

A mnemonic to remember the features of Z deformity of the hand in rheumatoid arthritis is: WRD UPP Mnemonic Consider mnemonic to be pronounced "word up" to help remember it. WR: wrist radial deviation  DU: digits ulnar deviation PP: proximal phalanges palmar subluxation See also Z deform...
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Zebra stripe sign (bones)

The zebra stripe sign occurs where children with osteogenesis imperfecta have been treated with cyclical bisphosphonate therapy, e.g. pamidronate. When the drug is delivered in cycles, dense bone is formed while treatment is being given. This results in dense stripes across the metaphyses of bon...
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Zimmerman-Laband syndrome

Zimmerman-Laband syndrome is a rare congenital syndrome, characterized primarily by gingival hypertrophy and skeletal abnormalities.  Pathology The molecular basis of the syndrome is currently unknown. An autosomal dominant mutation with a high mutation rate and rare instances of germinal mosa...
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Zona orbicularis

The zona orbicularis are circular fibers of the hip joint capsule and form a collar around the femoral neck. Though partly blended with the pubofemoral and ischiofemoral ligaments, these fibers are not directly attached to bone. 
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Zone classification of flexor tendon injury

The zone classification of flexor tendon injuries divides injuries into five zones based on anatomical location. It is the most widely used flexor tendon injury classification system (c. 2007) 1. Classification Flexor tendon injuries were classified into five zones by Kleinart and Verdan in 19...
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Z-score

Z-scores are a way to translate individual data points into terms of a standard deviation.  Z = (X - Xbar) / σ X: individual data point Xbar: the arithmetic mean σ: the standard deviation The purpose of the Z-score is to allow comparison between values in different normal distributions. Two...
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Zygoma

The zygoma (also known as zygomatic bone or malar bone) is an important facial bone which forms the prominence of the cheek. It is roughly quadrangular in shape. Gross anatomy Zygoma has three surfaces, five borders, and two processes. Surfaces anterolateral surface is convex, pierced at its...
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Zygomaticus major muscle

The zygomaticus major muscle is a member of the buccolabial muscle group of the upper lip1. It joins with the fibers of levator anguli oris, orbicularis oris and the more deeply placed muscular bands to move the side of the mouth upwards and sideways during facial movements such as laughing. Su...
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Zygomaticus minor muscle

The zygomaticus minor muscle is a member of the buccolabial muscle group of the muscles of facial expression. Together with the levator labii superioris alaeque nasi and levator labii superioris muscles it is one of the main elevators of the lip, exposing the maxillary teeth 1. Along with its o...

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