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.

2,616 results found
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≤11 ribs (differential)

≤11 ribs is associated with a number of congenital abnormalities and skeletal dysplasias, including: Down syndrome campomelic dysplasia kyphomelic dysplasias asphyxiating thoracic dysplasia (Jeune syndrome) short rib polydactyly syndromes trisomy 18 chromosome 1q21.1 deletion syndrome​ a...
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5th metacarpal pit

The 5th metacarpal pit refers to the normal exaggeration of the pit-like depression in the head of fifth metacarpal.  It should not be mistaken for a fracture (old or new) or an erosion.
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Abdominal hernia

Abdominal hernias (herniae also used) may be congenital or acquired and come with varying eponyms. They are distinguished primarily based on location and content. 75-80% of all hernias are inguinal. Content of the hernia is variable, and may include: small bowel loops mobile colon segments (s...
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Abdominal surface anatomy

The abdomen, when looking from in front, is divided into nine regions by imaginary planes (two vertical and two horizontal) forming abdominal surface anatomy. The nine regions are of clinical importance when examining and describing pathologies related to the abdomen. The horizontal planes are o...
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Abductor digiti minimi (foot)

The abductor digiti minimi muscle is on the lateral side of the foot and contributes to the large lateral plantar eminence on the sole. Summary origin: lateral and medial processes of calcaneal tuberosity, and band of connective tissue connecting calcaneus with base of metatarsal V insertion:...
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Abductor digiti minimi (hand)

The abductor digiti minimi muscle overlies the opponens digiti minimi. Summary origin: pisiform, the pisohamate ligament, and tendon of flexor carpi ulnaris insertion: 5th proximal phalanx action: abducts 5th finger at metacarpophalangeal joint arterial supply: ulnar artery innervation: de...
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Abductor hallucis muscle

The abductor hallucis muscle forms the medial margin of the foot and contributes to a soft tissue bulge on the medial side of the sole. Summary origin: medial process of calcaneal tuberosity insertion: medial side of base of proximal phalanx of great toe action: abducts and flexes great toe ...
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Abductor pollicis brevis

The abductor pollicis brevis is a thin subcutaneous muscle located laterally in the thenar eminence of the hand. Summary origin: mainly from the flexor retinaculum few fibres originate from the tubercles of scaphoid and trapezium and tendon of abductor pollicis longus accessory slips may ori...
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Abductor pollicis longus

The abductor pollicis longus (APL) is a muscle found in the deep layer of the posterior compartment of the forearm. As it descends, it becomes superficial and passes under the extensor retinaculum and through the 1st extensor compartment of the wrist before attaching distally. Summary origin: ...
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ABER position

The ABER position relates to MR arthrography of the shoulder joint and is a mnemonic for ABduction and External Rotation. In this position, labral tears are made conspicuous by tightening the inferior glenohumeral labroligamentous complex (which are also the most important glenohumeral ligament...
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Abnormal ultrasound findings in rheumatological diseases (definitions)

The OMERACT ultrasound group published a consensus in 2005 of widely accepted definitions of abnormal ultrasound findings in rheumatological diseases: erosion: an intra-articular discontinuity of the bone surface that is visible in two orthogonal planes joint effusion: abnormal hypoechoic or a...
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Abscess

Abscesses are focal confined collections of suppurative inflammatory material and can be thought of as having three components 1: a central core consisting of necrotic inflammatory cells and local tissue peripheral halo of viable neutrophils surrounded by a 'capsule' with dilated blood vessel...
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Absent bow tie sign (knee)

The absent bow tie sign represents the loss of the normal appearance of the menisci on parasagittal MRI images, and is suggestive of meniscal injury. Normally the medial and lateral menisci appear as low signal bow-tie-shaped structures between the femoral condyles and tibial plateaux. As the n...
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Absent patella

An absent patella is a rare finding and can be found with an equally rare set of associations: surgical removal of patella (patellectomy) nail patella syndrome 2 popliteal pterygium syndrome proximal focal femoral deficiency (PFFD) Meier-Gorlin syndrome 3
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Absent thumb

An absent thumb can have many associations. They include: Fanconi anaemia (pancytopenia-dysmelia syndrome) Franceschetti syndrome Holt-Oram syndrome phocomelia (e.g. thalidomide embryopathy) Poland syndrome (pectoral muscle aplasia and syndactyly) Rothmund-Thomson syndrome Seckel syndrome...
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Accessory navicular syndrome

Accessory navicular syndrome occurs when a type II accessory navicular (or "os tibiale externum") becomes painful due to movement across the pseudojoint between the ossicle and the navicular bone. Radiographic features Ultrasound It can be inferred on musculoskeletal ultrasound if a patient's...
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Accessory ossicle of the anterior arch of the atlas

The accessory ossicle of the anterior arch of the atlas is a normal variant and is best appreciated on a lateral cervical/sagittal study. It is observed as a circular and corticated osseous density that articulates with the inferior aspect of the anterior arch of the atlas.  It is not associate...
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Accessory ossicles

Accessory ossicles are secondary ossification centres that are separate from the adjacent bone. In most cases, they are congenital in origin, although they may occur as a result of trauma or local degenerative disease 2: shoulder and elbow os acromiale os supratrochleare dorsale wrist (mnemo...
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Accessory ossicles of the foot

Accessory ossicles of the feet are common developmental variants with almost 40 having been described. The more common ones include: os peroneum os subfibulare os subtibiale os tibiale externum (accessory navicular) os trigonum os calcaneus secundaris os intermetatarseum pars peronea met...
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Accessory ossicles of the wrist

Accessory ossicles of the wrist are commonly seen on plain radiographs of the wrist and associated cross-sectional imaging. Over 20 were originally described 2, although the more common include 1: lunula: between TFCC and triquetrum os styloideum (carpal boss): on dorsal surface of 2nd or 3rd ...
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Accessory ossicles of the wrist (mnemonic)

Accessory ossicles of the wrist can be easily recalled with the mnemonic: LOTTEO 1 HOTELS Mnemonic   L: lunula O: os styloideum (carpal boss) T: (os) triangulare T: (os) trapezium secondarium E: (os) epilunate O: os hamuli propriu Another useful mnemonic is HOTELS H: (os) hamuli propr...
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Accessory peroneal muscles

Accessory peroneal muscles are a group of accessory muscles that can occur in the foot region as a normal variant in some individuals. The peroneal compartment is known as the lateral compartment of the leg. Peroneus quartus muscle Originally, several accessory muscles were distinguished in th...
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Accessory soleus muscle

The accessory soleus muscle is an anatomical variant characterised by an additional distinct muscle encountered along a normal soleus muscle. It is uncommon with a prevalence of ~3% (range 0.7-5.5%). Summary origin: fibula, soleal line of the tibia, or the anterior surface of the soleus muscle...
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Accessory superior acetabular notch

An accessory superior acetabular notch is a normal variant of the acetabulum, which can be seen on radiographs. It may lead to diagnostic confusion, especially in younger patients.  Radiographic features MRI appear as bilateral symmetric fluid-filled pits in the roof of the acetabulum with sh...
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Acetabular angle

The acetabular angle is a radiographic measurement used when evaluating potential developmental dysplasia of the hip (DDH).  It is most useful in patients who have started to ossify the epiphysis since ossification diminishes the usefulness of ultrasound. The angle is formed by a horizontal lin...
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Acetabular foramen

The acetabular foramen is formed by the bony margins of the acetabular notch and completed by the transverse ligament of the hip. From its margins (both transverse ligament and acetabular notch) arises the ligamentum teres. Through it pass nutrient vessels to the femoral head epiphysis.
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Acetabular labral tears

Acetabular labral tears, as the name implies, are tears involving the acetabular labrum of the hip.   With the increasing use of hip arthroscopy in orthopaedic surgery since the 1970s pathologies of the acetabular labrum as a possible cause of chronic hip and groin pain have become more familia...
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Acetabular labrum

Acetabular labrum acts to deepen the acetabulum and increase contact between the pelvis and the femoral head. Its exact biomechanical role remains to be fully elucidated. Gross anatomy The acetabular labrum is a C-shaped fibrocartilaginous structure with an opening anteroinferiorly at the site...
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Acetabular notch

The acetablar notch is a depression in the margin of the acetabulum located anteroinferiorly. It is bridged by the transverse ligament, and thus forms the acteabular foramen. The ligamentum teres has part of its origin from the acetabular notch. 
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Acetabulum

The acetabulum (plural: acetabula) is the large cup-shaped cavity on the anterolateral aspect of the pelvis that articulates with the femoral head to form the hip joint. Gross anatomy All three bones of the pelvis (the ilium, ischium, and pubis) together form the acetabulum. The three bones ar...
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Acheiria

Acheiria refers to absence of one or both hands and can occur in a number of situations, including: amniotic band syndrome: particularly if unilateral Cornelia de Lange syndrome 1 fetal hydantoin syndrome 2  Epidemiology Rare defect occurring in 1:65 000 live births. See also absent thumb...
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Achilles tendinopathy

Achilles tendinopathy refers to a combination of pathological changes affecting the Achilles tendon usually due to overuse and excessive chronic stress upon the tendon. It can be seen both in athletes and non-athletes (weekend warriors). It is hard to differentiate clinically from a paratendinop...
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Achilles tendon ossification

Achilles tendon ossification (ATO) is an uncommon condition that consists of characteristic bone formation within the substance of the Achilles tendon.  Epidemiology Achilles tendon ossification is more common in males 4.  Pathology The aetiology is unknown but Achilles tendon ossification i...
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Achilles tendon tear

Achilles tendon tears are the most common ankle tendon injuries, and are most commonly seen secondary to sports-related injury, especially squash and basketball. Epidemiology There is strong male over-representation presumably as a result of the predominantly sport related aetiology. Patients ...
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Achilles tendon thickening

Achilles tendon thickening can occur for a number of reasons. The Achilles tendon has an average AP diameter of 6 mm 1. Thickening of the tendon is when it exceeds 8 mm in AP diameter and can result from: Achilles tendinosis/tear post-surgical thickening retrocalcaneal bursitis degeneration...
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Achilles tendon xanthoma

Achilles tendon xanthomas are painless soft tissue masses occurring most commonly at the distal one-third of the tendon and are usually bilateral and symmetrical. Pathology It is characterised by localised accumulation of lipid-laden macrophages, inflammatory cells and giant cells secondary to...
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Achondrogenesis

Achondrogenesis refers to a group of rare and extreme skeletal dysplasias. Epidemiology The estimated incidence is 1:40,000 with no recognised gender predilection. Pathology It is classified as an osteochondrodysplasia, meaning deficiency of both bone and cartilage development.  Subtypes T...
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Achondrogenesis 1A

Achondrogenesis type Ia, also known as the Houston-Harris subtype, is a subtype of achondrogenesis. It is an extremely rare lethal skeletal dysplasia (chondrodysplasia) with a characteristic severe disarrangement of endochondral ossification.  Pathology The growth plate cartilage completely la...
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Achondrogenesis 1B

Achondrogenesis type Ib, also known as Parenti-Fraccaro subtype, is a subtype of achondrogenesis and is an extremely rare skeletal dysplasia (chondrodysplasia).​​ Pathology Undersulphation has a pronounced effect on the composition of the extracellular matrix of cartilage, and this has been sh...
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Achondroplasia

Achondroplasia is a congenital genetic disorder resulting in rhizomelic dwarfism and is the most common skeletal dysplasia. It has numerous distinctive radiographic features.  Epidemiology It occurs due to sporadic mutations in the majority of cases but can be inherited as an autosomal dominan...
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Achondroplastic base of skull abnormalities

Achondroplasia is the most common cause of short-limb dwarfism. (For a general discussion, see the generic article on achondroplasia.) As the skull base forms by endochondral ossification whereas the skull vault by membranous ossification, there is a marked discrepancy in relative size as the s...
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Acro-osteolysis

Acro-osteolysis refers to resorption of the distal phalanx. The terminal tuft is most commonly affected but the shaft of the distal phalanx can also be affected in a few conditions. It is associated with a heterogeneous group of pathological entities and, some of which can be remembered by using...
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Acro-osteolysis (mnemonic)

The causes of acro-osteolysis can be remembered using the mnemonic: PINCH FO Mnemonic P: psoriasis/pyknodysostosis I: injury, e.g. thermal burn, frost bite N: neuropathy, e.g. diabetes, leprosy C: collagen vascular disease, e.g. scleroderma, Raynaud disease H: hyperparathyroidism F: fami...
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Acrocephalopolysyndactyly

Acrocephalopolysyndactyly (ACPS) syndrome is comprised of a rare group of disorders collectively characterised by: calvarial anomalies: e.g. craniosynostoses digital anomalies: syndactyly and polydactyly While there can be some overlap in features, they can be primarily classified into the fo...
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Acrocephalosyndactyly

Acrocephalosyndactyly syndromes (ACS) is a rare group of disorders collectively characterised by: calvarial anomalies, e.g. craniosynostoses digital anomalies, e.g. syndactyly Classification While there can be some overlap in features, they can be primarily classified into the following majo...
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Acrodysostosis

Acrodysostosis is a rare skeletal dysplasia characterised by growth retardation, nasal hypoplasia, brachydactyly, midfacial deficiency, mental retardation and deafness. Pathology Most cases are sporadic. Few cases with autosomal dominant transmission have been reported. It is believed to occur...
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Acromegaly

Acromegaly is the result of excessive growth hormone production in skeletally mature patients, most commonly from a pituitary adenoma. The same excess of growth hormone in individuals whose epiphyses have not fused will result in gigantism (excessively tall stature).   It is most commonly diagn...
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Acromial apophysiolysis

Acromial apohysiolysis is a finding on shoulder MRI that may be encountered in patients with an unfused acromial apophysis. It is associated with athletes in throwing sports. Clinical presentation Presents with superior shoulder tenderness in a patient <25 years old, often in a young throwing ...
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Acromial types

The shape of the acromion had been initially divided into three types (which was known as the Bigliani classification) 3, to which a fourth has been added 2. They are useful as a standardised way of describing the acromion, as well as predicting to a degree the incidence of impingement.  Classi...
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Acromioclavicular injury

Acromioclavicular joint injuries are common and range from a mild sprain to complete disruption of the acromioclavicular joint (ACJ) and injury to surrounding structures.  Pathology Mechanism Acromioclavicular joint injuries usually occur from a direct blow or following a fall onto the should...
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Acromioclavicular joint

The acromioclavicular (AC) joint is a plane synovial joint of the pectoral girdle. Gross anatomy The acromioclavicular joint is between the small facets of the convex distal clavicle and flat medial acromion. The articular surfaces are lined with hyaline cartilage 4. A fibrocartilaginous wedge...
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Acromioclavicular joint series

The acromioclavicular (AC) joint radiographic series is a used to evaluate the acromioclavicular joint and the distal clavicle. Indications AC radiographs are performed for a variety of indications including:  shoulder trauma direct blows to the should region following a fall onto adducted ...
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Acromioclavicular joint configuration

There is much variation in acromioclavicular (AC) joint configuration which may be confused with pathology.  The relationship of the acromion to the distal clavicle at the AC joint can be described in the coronal plane as 1, 2, 3: horizontal: normal low lying: associated with shoulder impinge...
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Acromiohumeral interval

Acromiohumeral interval is a useful and reliable measurement on AP shoulder radiographs and when narrowed is indicative of rotator cuff tear or tendinopathy.  Pathology Measurements of the acromiohumeral interval in the following intervals are suggestive of pathology 1-2: >12 mm: shoulder dis...
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Acromion

The acromion, also known as the acromial process, is a small section of the scapula that extends anteriorly from the spine of the scapula.  Gross anatomy It forms the acromioclavicular joint with the lateral third of the clavicle, and also connects with the coracoid process via the coraco-acro...
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Acroparesthesia

Acroparesthesia refers to tingling, pins-and-needles, burning or numbness or stiffness in the hands and feet, particularly the fingers and toes 1. Occasionally episodic pain is also present, which can be very severe 1.  Is one of the more common manifestations of Fabry disease (more common than...
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Adam's forward bend test

The Adam's forward bend test is clinical test to assess the presence of a scoliosis. Technique Exclusion of a limb length discrepancy is considered important prior to performing the test. The patient is asked to bend forward with feet together, arms hanging and knees extended until the back be...
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Adamantinoma

Adamantinomas are rare primary malignant bone tumours that in the vast majority of cases occur in the tibia of young patients. Terminology In the past, ameloblastomas, which are benign, locally aggressive bone tumours of the mandible, were also known as adamantinomas of the mandible. The two e...
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Adductor brevis muscle

The adductor brevis is a muscle in the medial compartment of the thigh that lies immediately deep to the pectineus and adductor longus. Summary origin: external surface of body of pubis and inferior pubic ramus insertion: posterior surface of proximal femur, linea aspera, medial supracondylar...
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Adductor canal

The adductor canal is a muscular tunnel in the thigh. It commences at the inferior end of the femoral triangle and terminates at the adductor hiatus.  Gross anatomy Boundaries anteriorly: sartorius muscle posteromedially: adductor longus and adductor magnus muscles laterally: vastus mediali...
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Adductor hallucis muscle

The adductor hallucis muscle arises by two heads, an oblique and transverse head. It is responsible for adducting the big toe. Summary origin transverse head: ligaments associated with metatarsophalangeal joints of lateral three toes oblique head: bases of metatarsals II to IV and from sheat...
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Adductor longus muscle

The adductor longus is a muscle in the medial compartment of the thigh that lies anterior to the adductor magnus. Summary origin: external surface of body of pubis (triangular depression inferior to pubic crest and lateral to pubic symphysis) insertion: linea aspera on middle one-third of sh...
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Adductor magnus muscle

The adductor magnus is the largest and deepest of the muscles in the medial compartment of the thigh. Like the adductor longus and brevis muscles, the adductor magnus is a triangular or fan shaped muscle anchored by its apex to the pelvis and attached by its expanded base to the femur. Summary ...
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Adductor pollicis

The adductor pollicis is a large triangular muscle anterior to the plane of the interossei that crosses the palm. Summary origin: transverse head: 3rd metacarpal oblique head: capitate and bases of 2nd and 3rd metacarpals insertion: base of proximal phalanx and extensor hood of thumb actio...
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Adhesive capsulitis of the shoulder

Adhesive capsulitis of the shoulder, also known as frozen shoulder, is a condition characterised by thickening and contraction of the shoulder joint capsule and surrounding synovium. Adhesive capsulitis can rarely affect other sites such as the ankle 8. Epidemiology The incidence in the genera...
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ADIR position

The ADIR (ADduction and Internal Rotation) position relates to MR arthrography of the shoulder joint. When added to a neutral-position shoulder protocol, MR arthrography in the ADIR position facilitates the diagnosis of labroligamentous lesions in patients with recurrent shoulder dislocations, ...
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Adventitious bursitis

Adventitious bursitis refers to inflammation associated with adventitious bursae. Adventitious bursae are not permanent native bursae. They can develop in adulthood at sites where subcutaneous tissue becomes exposed to high pressure and friction. Clinical presentation When present in the foot...
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Aggressive angiomyxoma

Aggressive angiomyxomas are rare tumours that arise in the pelvis and typically cross the the levator ani muscles. Despite its name, it is essentially a benign tumour and the term "aggressive" is given due to a predilection for local recurrence. Only rarely does it metastasize. Epidemiology It...
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Aggressive fibromatosis

Aggressive fibromatosis is a type of musculoskeletal fibromatosis. While it is a non-metastasising fibrous lesion, it is thought to be a true neoplasm that arises from the fascial and musculoaponeurotic coverings, sometimes at the site of a traumatic or post-surgical scar. Terminology The term...
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Aggressive granulomatosis post hip replacement

Aggressive granulomatosis post hip replacement is a potential complication of a hip joint replacement. Some authors use the same term for particle disease - if you are an expert on this we would love your help. Pathology Aggressive granulomas consist of well organised connective tissue contain...
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Ahlbäck classification of osteoarthritis of the knee joint

This classification was proposed by Ahlback et al in 1968. According to Ahlbäck system, knee joint osteoarthritis is classified as: grade 1: joint space narrowing (less than 3 mm) grade 2: joint space obliteration grade 3: minor bone attrition (0-5 mm) grade 4: moderate bone attrition (5-10...
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Ainhum

Ainhum ("dactylolysis spontanea") is a rare cutaneous condition in which a hyperkeratotic band partially or totally encircles a digit. The constriction thins the underlying bone, which is then prone to fracture. Some cases result in autoamputation. Epidemiology Some have suggested that the dis...
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Allen and Ferguson classification of subaxial cervical spine injuries

Allen and Ferguson classification is used for research purposes to classify subaxial spine injuries. It is based of the mechanism of injury and position of neck during injury. This classification was proposed by Allen and Ferguson in 19823 and at the time of writing (July 2016) remains the most ...
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Alpha angle

Alpha angle can refer to two different musculoskeletal measurements: alpha angle (developmental dysplasia of the hip) alpha angle (femoroacetabular impingement)
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Alpha angle (developmental dysplasia of the hip)

The alpha angle is a measurement used in the ultrasonographic assessment of developmental dysplasia of the hip (DDH). The angle is formed by the acetabular roof to the vertical cortex of the ilium and thus reflects the depth of the bony acetabular roof. This is a similar measurement to the acet...
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Alternating radiolucent and radiodense metaphyseal lines

Alternating radiolucent and radiodense metaphyseal lines can be seen with a number of conditions and the differential diagnosis is wide: growth arrest lines bisphosphonate therapy rickets: especially those on prolonged treatment, e.g. vitamin D dependent rickets osteopetrosis chemotherapy ...
Article

Alveolar rhabdomyosarcoma

Alveolar rhabdomyosarcomas are a type of rhabdomyosarcoma and accounts for 20-40% of all rhabdomyosarcomas 1-2. Unlike embryonal rhabdomyosarcomas, which are more common, these tumours occur in slightly older individuals, typically 10-25 years of age 1.  Pathology Location Although these tumo...
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American Academy of Orthopedic Surgeons classification of periprosthetic hip fractures

The American Academy of Orthopedic Surgeons classification of periprosthetic hip fractures divides the femur into three separate regions: level I: proximal femur distally to the lower extent of the lesser trochanter  level II: 10 cm of femur distal to level I  level III: femur distal to level...
Article

Amniotic band syndrome

Amniotic band syndrome (ABS) comprises of a wide spectrum of abnormalities, all of which result from entrapment of various fetal body parts in a disrupted amnion. Due to the randomness of entrapment, each affected individual has the potential to form a unique deficit. Epidemiology The phenomen...
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Amphiarthroses

Amphiarthroses are a functional class of joint that permit a small amount of movement under normal conditions. Examples symphyses (secondary cartilaginous joints) symphysis pubis intervertebral discs sternomanubrial joint  See also  synarthroses diarthroses
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Amputation

The term amputation refers to the disconnection of all or part of a limb from the body. Specifically amputation is defined as removal of the structure through a bone. This is in contrast to disarticulation, which is removal of the structure through a joint. Terminology When due to trauma, trau...
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Amsterdam wrist rules

The Amsterdam wrist rules are validated clinical decision rules for determining which patients require radiographic imaging (wrist radiography) for acute wrist pain following trauma. The initial study evaluated 882 patients and were published in 2015 1. The decision rules assessed different clin...
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Amyloid arthropathy

Amyloid arthropathy is the extracellular deposition of the fibrous protein amyloid within the skeletal system. It is a skeletal manifestation of amyloidosis and may involve either the axial skeleton (especially the cervical spine) or the appendicular skeleton. Clinical presentation Shoulder pa...
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Amyoplasia congenita

Amyoplasia congenita is a syndrome characterized by multiple specific congenital joint contractures, associated with substitution of muscular tissue by fibrosis and adipose tissue. Epidemiology The estimated incidence is at  1: 10000 live births. There may be a higher prevalence with twin preg...
Article

Anal sphincter

The anal sphincter is divided into an internal and external anal sphincter. It surrounds the anal canal.  Gross anatomy Internal anal sphincter continuation of inner rectal muscle thickened, circular muscle fibres, up to 5 mm thick composed of visceral muscle External anal sphincter Compo...
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Anaplastic rhabdomyosarcoma

An anaplastic rhabdomyosarcoma is a subtype of embryonal rhabdomyosarcoma, characterised by extensive anaplastic cells seen throughout the tumour 1.
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Anatomical snuff box

The anatomical snuff box is a surface anatomy feature. It appears as a triangular depression on the lateral surface of the wrist on full extension of the thumb. Gross anatomy Boundaries medial: tendons of the extensor pollicis longus lateral: tendons of the extensor pollicis brevis and mor...
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Anatomy curriculum

The anatomy curriculum is one of our curriculum articles and aims to be a collection of articles that represent the core anatomy knowledge for radiologists and imaging specialists. General anatomy Neuroanatomy Head and neck anatomy Thoracic anatomy Abdominal and pelvic anatomy Spinal anat...
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Anconeus

The anconeus is a small muscle in the posterior compartment of the arm at the lateral aspect of the elbow. It has little functional significance but should be differentiated from the variably present anconeus epitrochlearis at the medial aspect of the elbow. Summary origin: lateral epicondyle ...
Article

Anconeus epitrochlearis

Anconeus epitrochlearis is an accessory muscle at the medial aspect of the elbow. It is also known as the accessory anconeus muscle and should not be confused with the anconeus muscle which is present at the lateral aspect of the elbow.  Epidemiology The muscle may be unilateral but has been f...
Article

Anderson and D'Alonzo classification of odontoid process fracture

The Anderson and D'Alonzo classification is the most commonly used classification of fractures of the odontoid process of C2. Classification type I rare fracture of the upper part of the odontoid peg above the level of the transverse band of the cruciform ligament usually considered stable...
Article

Andersson lesion

Andersson lesions refer to an inflammatory involvement of the intervertebral discs by spondyloarthritis. Epidemiology Rheumatic spondylodiscitis is a non-infectious condition that has been shown to occur in about 8% of patients with ankylosing spondylitis, as detected at radiography. Patholog...
Article

Aneurysmal bone cyst

Aneurysmal bone cysts (ABC) are benign expansile tumour-like bone lesions of uncertain aetiology, composed of numerous blood filled channels, and mostly diagnosed in children and adolescents. Epidemiology Aneurysmal bone cysts are primarily seen in children and adolescents, with 80% occurring ...

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