The adductor hallucis muscle arises by two heads, an oblique and transverse head. It is responsible for adducting the big toe.
transverse head: ligaments associated with metatarsophalangeal joints of lateral three toes
oblique head: bases of metatarsals II to IV and from sheat...
The adductor longus muscle is a muscle in the medial compartment of the thigh that lies anterior to the adductor magnus muscle.
origin: external surface of body of pubis (triangular depression inferior to pubic crest and lateral to pubic symphysis)
insertion: linea aspera on middle o...
The adductor magnus muscle 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.
The adductor minimus muscle is a small, variably present muscle in the medial compartment of the thigh.
Due to confusion about this muscle over the years it has ended up with a variety of names, which include pars lateralis, adductor quartus muscle, premier faisceau du grand addu...
The adductor pollicis muscle is a large triangular muscle anterior to the plane of the interossei that crosses the palm of the hand. It is deep to the thenar eminence, forming part of the short muscles of the thumb, and the intrinsic muscles of the hand.
transverse head: 3rd m...
The adductor tubercle is a bony protuberance on the medial condyle of the femur and is located superior to the medial epicondyle. It demarcates the inferior most aspect of the medial supracondylar line. The adductor tubercle is the point of insertion for the adductor minimus and the hamstrings p...
Adhesive capsulitis of the shoulder, also known as frozen shoulder, is a condition characterized by thickening and contraction of the shoulder joint capsule and surrounding synovium. Adhesive capsulitis can rarely affect other sites such as the ankle 8.
The incidence in the genera...
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, ...
Adnexa is a general term that refers to the accessory structures of an organ.
Adnexa have been described in relation to:
hair follicles, sweat glands, nails
structures in the mastoid (posterior) wall of the middle ear, e.g. mastoid antrum, aditus ad an...
Adult acquired flatfoot disease is a common condition that results in foot pain and disability.
Most commonly affects middle-aged and elderly females 1.
Adult acquired flatfoot disease is a combination of:
flattened medial arch (pes planus)
Whenever you look at an adult elbow x-ray, review:
Check the anterior humeral line:
drawn down the anterior surface of the humerus
should intersect the middle 1/3 of the capitellum
if it doesn't, think distal humeral fracture
Adult fibrosarcomas are rare, malignant and highly aggressive fibroblastic soft tissue tumors. They constitute a diagnosis of exclusion.
Adult fibrosarcomas by more recent definition are rare and make up for around 1% of soft tissue sarcomas. They are mostly seen in the middle-age...
Adult-onset Still disease is a rare multisystem inflammatory disorder, and was originally thought to be a variant of Still disease, a pediatric arthropathy.
Still disease in adults is rare affecting around 1.5 per 100,000 people, it occurs in a bimodal distribution with one peak a...
Adventitial bursae are those bursae that develop later in life in response to pressures developed as a result of acquired bony prominences or deformities 1. These bursa can become inflamed resulting in adventitious bursitis.
Adventitious or adventitial 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.
Aggressive angiomyxomas are rare tumors that arise in the pelvis and typically cross the levator ani muscles. Despite its name, it is essentially a benign tumor and the term "aggressive" is due to a predilection for local recurrence. Only rarely does it metastasize.
It is seen pre...
Aggressive fibromatosis is a type of musculoskeletal fibromatosis. While it is a non-metastasizing 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.
Aggressive granulomatosis post hip replacement (also known as particle disease) is a potential complication of a hip joint replacement.
Aggressive granulomas consist of well organized connective tissue containing histiocytic-monocytic and fibroblastic reactive zones. They can be high...
Aggressive vertebral hemangiomata are a rare form of vertebral hemangiomata where significant vertebral expansion, extra-osseous component with epidural extension, disturbance of blood flow, and occasionally compression fractures can be present causing spinal cord and/or nerve root compression 1...
The Ahlbäck classification is one of many ways to grade knee osteoarthritis.
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 mm)
grade 5: severe bone attrition (mo...
Ainhum, also known as 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.
Some have suggested ...
Alar ligament calcification is rare. The alar ligaments arise bilaterally from the upper portion of the odontoid process and run obliquely cephalad and laterally to insert on the medial surface of the occipital condyles. They stabilize the head during rotatory movements.
Alban Köhler (1874-1947) was a German radiologist best known for both his work in describing avascular necrosis of the navicular (now known as Köhler disease) and the publication of ‘Roentgenology - The Borderlands of the Normal and Early Pathological in the Skiagram’ a textbook exploring anatom...
Albright hereditary osteodystrophy (AHO) is a form of osteodystrophy and is also classified as a phenotype of pseudohypoparathyroidism (i.e. type 1a).
Typical clinical spectrum includes
short, stocky build
round facies with a low, flat nasal bridge
Allen and Ferguson classification is used for research purposes to classify subaxial spine injuries. It is based ofn the mechanism of injury and position of the neck during injury. This classification was proposed by Allen and Ferguson in 19823 and at the time of writing (July 2016) remains the ...
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...
Alpha angle can refer to two different musculoskeletal measurements:
alpha angle (in developmental dysplasia of the hip) in children
alpha angle (in femoroacetabular impingement)
The alpha angle is a radiological measurement proposed for the diagnosis and evaluation of surgical treatment in cam-type femoroacetabular impingement (FAI).
When initially described in 2002, Notzli et al. suggested that the pathological value was >50°.
According to one study, a value measure...
Alternating radiolucent and radiodense metaphyseal lines can be seen with a number of conditions and the differential diagnosis is wide:
growth arrest lines
rickets: especially those on prolonged treatment, e.g. vitamin D dependent rickets
Alveolar rhabdomyosarcomas are a type of rhabdomyosarcoma and account for 20-40% of all rhabdomyosarcomas 1-2.
Unlike embryonal rhabdomyosarcomas, which are more common, these tumors occur in slightly older individuals, typically 10-25 years of age 1.
Alveolar soft part sarcoma (ASPS) is a rare, highly vascular, deep soft tissue mesenchymal malignancy that is classically seen in the lower extremities of young adults. They account for <1% of all soft tissue sarcomas.
There is a slight female predilection in patients less than 30...
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...
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.
Amphiarthroses are a functional class of joint that permit a small amount of movement under normal conditions.
symphyses (secondary cartilaginous joints)
The term amputation refers to the disconnection of all or part of a limb from the body. Specifically, amputation is defined as the removal of the structure through a bone. This is in contrast to disarticulation, which is the removal of the structure through a joint.
When due to trauma, traumati...
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...
Amyloid arthropathy results from the extracellular deposition of the fibrous protein amyloid within the skeletal system and is a skeletal manifestation of amyloidosis particularly in patients on long term haemodialysis. It may involve either the axial skeleton (especially the cervical spine) or ...
Amyopathic dermatomyositis (ADM) is recognized as a distinct subtype of dermatomyositis where there is a typical skin rash of classic dermatomyosiytis but without muscle involvement.
This form may be further divided into
anti-melanoma differentiation-associated gene 5 (MDA5) antibo...
Amyoplasia congenita is a syndrome characterized by multiple specific congenital joint contractures, associated with substitution of muscular tissue by fibrosis and adipose tissue.
The estimated incidence is at 1: 10000 live births. There may be a higher prevalence with twin preg...
The anal sphincter is divided into internal and external anal sphincters. It surrounds the anal canal.
Internal anal sphincter
continuation of inner rectal muscle
thickened, circular muscle fibers, up to 5 mm thick
composed of visceral muscle
External anal sphincter
An anaplastic rhabdomyosarcoma is a subtype of embryonal rhabdomyosarcoma, characterized by extensive anaplastic cells seen throughout the tumor 1.
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.
medial: tendons of the extensor pollicis longus
lateral: tendons of the
extensor pollicis brevis
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.
Head and neck anatomy
Abdominal and pelvic anatomy
The anconeus epitrochlearis is an accessory muscle at the medial aspect of the elbow. It is also known as the accessory anconeus muscle or epitrochleoanconeus muscle and should not be confused with the anconeus muscle which is present at the lateral aspect of the elbow.
The anconeus muscle 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.
origin: lateral epic...
The Anderson and D'Alonzo classification is the most commonly used classification of fractures of the odontoid process of C2.
fracture of the upper part of the odontoid peg (generally oblique)
above the level of the transverse band of the cruciform ligament
The Anderson and Montesano classification of occipital condyle fractures is the most widely used scheme for describing occipital condyle fractures and divides injuries into three types based on morphology and mechanism of injury 1,2,3.
type I - comminuted (3-15%)
An Andersson lesion, also known as rheumatic spondylodiskitis, refer to an inflammatory involvement of the intervertebral discs by spondyloarthritis.
Rheumatic spondylodiskitis is a non-infectious condition that has been shown to occur in about 8% of patients with ankylosing spond...
Aneurysmal bone cysts (ABC) are benign expansile tumor-like bone lesions of uncertain etiology, composed of numerous blood-filled channels, and mostly diagnosed in children and adolescents.
Aneurysmal bone cysts are primarily seen in children and adolescents, with 80% occurring in...
Angiofibromas of soft tissue are benign fibroblastic soft tissue neoplasms permeated by a vascular network that might be found in the periarticular and articular areas of the lower extremities that have been included as a separate entity into the WHO classification of soft tissue tumors in 2020....
Angioleiomyoma also known as angiomyoma or vascular leiomyoma is a benign pericytic or perivascular soft tissue tumor.
Angioleimyomas are rare and have been observed in a wide age range with a peak in the 4th to 6th decades of life. Generally, women are more commonly affected 1-...
Angiolipomas (also sometimes known as haemangiolipomas, vascular lipomas, and fibromyolipomas) are rare soft tissue tumors composed of mature adipocytes and vessels. They can occur essentially anywhere and can be subclassified into infiltrating and non-infiltrating variants 1.
Please refer to ...
Angiomatoid fibrous histiocytomas (AFH) or angiomatoid fibrous malignant histiocytomas are neoplasms of intermediate biologic potential and are classified as soft tissue tumors of uncertain differentiation.
Angiomatoid fibrous histiocytomas a rare and account for about 0.3% of all...
Angiomyofibroblastomas are benign mesenchymal neoplasms usually found in the pelvis or perineum especially the vulva.
Angiomyofibroblastomas are uncommon tumors predominantly found in adult women usually between menarche and menopause. Approximately 10% of these tumors have been d...
Angiosarcoma of bone is a malignant vascular tumor of bone. These are rare and account for less than 1% of malignant bone tumors. The majority of these tumors arising in bone are primary; however, a tiny percentage are either radiation-induced or associated with bone infarction
The angle of the longitudinal arch (calcaneal–fifth metatarsal angle) is one of the angles drawn on the weight-bearing lateral foot radiograph.
The angle is formed between the calcaneal inclination axis and a line drawn along the inferior edge of the 5th metatarsal:
pes planus: >170°
Anisotropy is an artefact encountered in ultrasound, notably in muscles and tendons during a musculoskeletal ultrasound. In musculoskeletal applications, the artefact may prompt an incorrect diagnosis of tendinosis or tendon tear.
When the ultrasound beam is incident on a fibrillar structure as...
Ankle and foot radiography is the plain radiographic investigation of the distal tibia and fibula, the tarsal bones and metatarsals. Radiographic examination of the foot and ankle are often requested together, however, there is a plethora of literature to aid in the correct request of x-ray exam...
The ankle AP view is part of a three view series, and visualizes the distal tibia, distal fibula, proximal talus and proximal fifth metatarsal.
The true anteroposterior view of the ankle is often performed in the setting of ankle trauma and suspected ankle fractures in addition to ...
Ankle fractures account for ~10% of fractures encountered in trauma, preceded only in incidence by proximal femoral fractures in the lower limb. They have a bimodal presentation, involving young males and older females. Ankle injuries play a major part in post multitrauma functional impairment t...
The ankle horizontal beam lateral view is a modified lateral view part of a three view ankle series.
This projection is used to assess the distal tibia and fibula, talus, navicular, cuboid, the base of the 5th metatarsal and calcaneus. It is a highly adaptable projection that can b...
There are several ankle impingement syndromes. They are characterized by a limited range of motion and pain on attempting specific movements about the joint and often in a load-bearing position. They have variable etiology and pathogenesis. They are best classified according to location.
Ankle injection is a general term which can refer to an intra-articular ankle injection but also other injections, particularly by patients, which include:
Achilles hydrodilation and microtenotomy
ankle joint injection
extensor tendon she...
The ankle joint (also known as the tibiotalar joint or talocrural joint) forms the articulation between the foot and the leg. It is a primary hinge synovial joint lined with hyaline cartilage.
The ankle joint is comprised of the tibia, fibula and talus as well as the supporting l...
The ankle lateral view is part of a three view ankle series; this projection is used to assess the distal tibia and fibula, talus, navicular, cuboid, the base of the 5th metatarsal and calcaneus.
This projection aids in evaluating fractures, dislocations and joint effusions surroun...
The ankle AP mortise (mortice is equally correct) view is part of a three view series of the distal tibia, distal fibula, talus and proximal 5th metatarsal.
This projection is the most pertinent for assessing the articulation of the tibial plafond and two malleoli with the talar do...
The MRI ankle protocol encompasses a set of MRI sequences for the routine assessment of the ankle joint.
Note: This article aims to frame a general concept of an MRI protocol for the assessment of the ankle. Protocol specifics will vary depending on MRI scanner type, specific hardware and softw...
Ankle radiographs are frequently performed in emergency departments, usually, after trauma, the radiographic series is comprised of three views: an anteroposterior, mortise, and a lateral. They may be performed to assess degenerative or inflammatory arthritis as well as to look for the sequela o...
The ankle 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.
The ankle series is comprised of an anteroposterior (AP), mortise and lateral radiograph. The series is often used in emergency departments to evaluate the distal tibia, distal fibula, and the talus; forming the ankle joint.
See approach to an ankle series.
Ankle radiographs are p...
The AP stress view of the ankle is a highly specialized view used to assess the integrity of the syndesmosis and deltoid ligament. It can be performed one of two ways, with gravity or via manual external rotation.
In intermediate ankle injuries that have no syndesmotic widening on...
This is a basic article for medical students and other non-radiologists
An ankle x-ray, also known as ankle series or ankle radiograph, is a set of two x-rays of the ankle joint. It is performed to look for evidence of injury (or pathology) affecting the ankle, often after trauma.
Ankylosing spondylitis (less commonly known as Bechterew disease or Marie Strümpell disease) is a seronegative spondyloarthropathy, which results in fusion (ankylosis) of the spine and sacroiliac (SI) joints, although involvement is also seen in large and small joints.
Thoracic manifestations of ankylosing spondylitis can be varied. For a general discussion of the condition refer to the parent article on ankylosing spondylitis.
It can affect the tracheobronchial tree and the lung parenchyma, and the disease spectrum includes:
upper lobe fibrocystic changes -...
Annular fissures are a degenerative deficiency of one or more layers that make up the annulus fibrosus of the intervertebral disc.
Many authors prefer the term annular fissure over annular tear, as the latter seems to imply acute injury 1,2. In the setting of severe trauma with di...
The annular ligament can refer to:
annular ligament of the stapes
annular ligament of the proximal radio-ulnar joint
The annulus fibrosus (plural: annuli fibrosi) surrounds the nucleus pulposus and together they form the intervertebral disc.
The annulus comprises 15 to 20 collagenous (type I) laminae which run obliquely from the edge of one vertebra down to the edge of the vertebra below. The d...
Anomalous insertion of the medial meniscus (AIMM) is an anatomical variation of the insertion of the anterior root of the medial meniscus.
Defined as a congenital variation in the insertion of the anterior root of the medial meniscus onto the anterior cruciate ligament (ACL). The...
Anorexia nervosa is a psychiatric disorder characterized by distorted self-perception of body weight leading to starvation, obsession with remaining underweight, and an excessive fear of gaining weight. One in five patients with anorexia dies due to complications of the disease.
The anteater nose sign refers to an anterior tubular elongation of the superior calcaneus which approaches or overlaps the navicular on a lateral radiograph of the foot. This fancifully resembles the nose of an anteater and is indicative of calcaneonavicular coalition 1,2.
History and etymolog...
The anterior abdominal wall forms the anterior limit of the abdominal viscera and is defined superiorly by the xiphoid process of the sternum and costal cartilages and inferiorly by the iliac crest and pubic bones of the pelvis.
In general, the anterior abdominal wall has nine la...
Anterior (or ventral) abdominal wall hernias (herniae also used) are a subgroup of abdominal wall herniae that are differentiated by the location of the hernia.
port site hernia
Anterior angulation of the coccyx may be a normal variant but poses a diagnostic challenge for those considering coccygeal trauma.
Four types of coccyx have been described:
type I: the coccyx is curved slightly forward, with its apex pointing caudally (~70%)
type II: the coccy...
Anterior ankle impingement (AAI) syndrome is the result of chronic repetitive trauma with impingement of the anterior tibia against the talus.
Common in soccer players and ballet dancers 1.
Clinical features of anterior ankle impingement syndrome include pa...
A mnemonic that refers to the order of the anterior ankle tendons around the ankle is:
Tom Hates Dick
The mnemonic can be used to remember the order of the tendons from medial to lateral as they pass under the extensor retinaculum of the ankle.
T: tibialis anterior
H: extensor hal...
The anterior center-edge angle, also known as the vertical-center-anterior (VCA) angle, is a radiographic measurement of the anterior coverage of the femoral head by the acetabulum. It is used in assessing acetabular dysplasia and pincer type of femoroacetabular impingement.
The MRI anterior chest wall protocol encompasses a set of MRI sequences for the routine assessment of the sternoclavicular joints and/or the anterior chest wall.
Note: This article aims to frame a general concept of an MRI protocol for the assessment of sternoclavicular joints and/or the anteri...
The anterior compartment of the arm is one of the two compartments of the arm.
A sheath of deep fascia surrounds the arm, the brachial fascia. Two intermuscular septa (medial and lateral) extend from it to attach to the humerus at the medial condylar ridge and lateral supracondylar ridge, respe...
The forearm is divided into the anterior compartment and the posterior compartment by the deep fascia, lateral intermuscular septum and the interosseous membrane between the ulna and radius.
The eight muscles located in the anterior compartment of the forearm can be divided into three...
The anterior compartment of the leg is one of the four compartments in the leg between the knee and foot. Muscles within this compartment primarily produce ankle dorsiflexion and toe extension.
The leg is separated into anterior, lateral, superficial posterior and deep posterior compartments by...
The anterior compartment of the thigh is one of the three compartments in the thigh. Muscles within this compartment primarily produce hip flexion and knee extension.
The thigh is separated into anterior, posterior and medial (adductor) compartments by intermuscular septa and surrounded by the ...
Anterior cruciate ligament (ACL) is one of the two cruciate ligaments that stabilize the knee joint.
The ACL arises from the anteromedial aspect of the intercondylar area on the tibial plateau and passes upwards and backwards to attach to the posteromedial aspect of the lateral ...
Anterior cruciate ligament (ACL) avulsion fracture or tibial eminence avulsion fracture is a type of avulsion fracture of the knee. This typically involves separation of the tibial attachment of the ACL to variable degrees. Separation at the femoral attachment is rare 5.
It is mor...