The anterior cerebral artery along with the middle cerebral artery forms at the termination of the internal carotid artery. It is the smaller of the two, and arches anteromedially to pass anterior to the genu of the corpus callosum, dividing as it does so into its two major branches; pericallosa...
Anterior cerebral artery (ACA) territory infarcts are much less common than either middle or posterior cerebral artery territory infarcts.
ACA territory infarcts are rare, comprising ~2% of ischemic strokes 1,2.
ACA stroke syndrome presents as 1-3:
Anterior cervical discectomy and fusion (ACDF) is a commonly performed spinal fusion procedure for the decompression of the cervical cord due to disc protrusions and posteriorly projecting osteophytes.
It is not to be confused with an ACDA (anterior cervical disc arthroplasty).
The anterior cervical space is a small infrahyoid compartment of the head and neck. It is a fat containing space and is not enclosed by fascia 1.
posterior: carotid space
medial: visceral space
superior: submandibular space
The anterior choroidal artery (AChA) supplies several crucial anatomical structures of the brain important for vision and motor control. Identification of AChA is important because of its strategic and extensive area of supply as well as large variations in the territorial distribution.
Anterior choroidal artery (AchA) syndrome is a rare entity characterized by the triad of hemiplegia, hemianaesthesia and contralateral hemianopia as a result of cerebral infarction in the anterior choroidal artery territory.
The syndrome may also be associated with neuropsychological disorders,...
The anterior cingulate cortex (ACC), previously known as the precingulate, is a region of the brain surrounding the anterior corpus callosum. It is involved in the limbic system and the prefrontal cortex.
location: it is located superior to the anterior corpus callosum, more specifical...
The anterior circulation is the blood supply to the anterior portion of the brain, including most of the supratentorial structures excluding the occipital lobes.
The anterior circulation is supplied by the internal carotid arteries which each divide into two the large terminal branches, the ant...
The anterior commissure (AC) is a transversely oriented commissural white matter tract that connects the two cerebral hemispheres along the midline. It is a very important anatomical landmark that connects different parts of the limbic system on both sides and plays a role in the interhemispheri...
The anterior commissure of the larynx is the anterior junction point of the true vocal cords. It is bounded anteriorly by the thyroid cartilage and is part of the laryngeal glottis.
The anterior commissure - posterior commissure line (AC-PC line), also known as the bicommissural line, has been adopted as a convenient standard by the neuroimaging community, and in most instances is the reference plane for axial imaging in everyday scanning. The creation of a standard image p...
The anterior communicating artery (ACOM) arises from the anterior cerebral artery and acts as an anastomosis between the left and right anterior cerebral circulation. Approximately 4 mm in length, it demarcates the junction between the A1 and A2 segments of the anterior cerebral artery.
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 ...
The anterior corticospinal tract is formed at the level of the of the medullary pyramids, where the majority (90%) of descending corticospinal tract fibers decussate to form the lateral corticospinal tract. The majority of the remaining non-decussating 10% of fibers form the much smaller anterio...
The anterior cranial fossa constitutes the floor of the cranial vault which houses the frontal lobes of the brain.
Structures present in the midline of the anterior cranial fossa from anterior to posterior are:
groove for superior sagittal sinus
groove for anterior meningeal v...
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...
Anterior cruciate ligament (ACL) ganglion cysts, commonly referred to simply as ACL cysts, along with ganglion cysts arising from the alar folds that cover the infrapatellar fat pad, make up the vast majority of intra-articular ganglion cysts of the knee.
Anterior cruciate ligamen...
Anterior cruciate ligament (ACL) mucoid degeneration, along with tears and anterior cruciate ligament ganglion cysts, is a relatively common cause of increased signal within the anterior cruciate ligament (ACL). The appearance can mimic acute or chronic interstitial partial tears of the ACL. How...
Anterior cruciate ligament (ACL) reconstruction is a common procedure post ACL tear. It aims to reduce knee joint instability and thus prevent any further meniscal and/or cartilage damage.
There are numerous surgical techniques for ACL reconstruction 1-3:
Anterior cruciate ligament (ACL) reconstruction complications are common, occurring in 10-25% of patients.
Patients with complications of ACL reconstruction can present with decreased range of motion (impingement or arthrofibrosis) and/or laxity (graft rupture or stretchi...
Anterior cruciate ligament (ACL) tears are the most common knee ligament injury encountered in radiology and orthopedic practice.
Patients typically present with symptoms of knee instability, usually after acute trauma. The following signs and symptoms are common:
Anterior hip dislocation is much less common than a posterior hip dislocation. It constitutes only 5-18% of all hip dislocations.
While the posterior dislocation is often associated with fractures, the anterior dislocation is mostly an isolated injury 1.
It can be classifi...
The anterior division of the mandibular division of the trigeminal nerve has four branches, which are all motor branches except one. The four branches are:
deep temporal nerves
lateral pterygoid nerves
The anterior epitympanic recess, also known as the supratubal recess, is a small discrete space in the epitympanum anterior to the malleus. It is separated from the epitympanum proper by the cog.
The anterior ethmoid artery is a branch of the ophthalmic artery. It supplies the anterior and middle ethmoidal sinuses, frontal sinus, the lateral nasal wall and the nasal septum (see nasal cavity).
It traverses the anterior ethmoidal foramen with the anterior ethmoidal nerve (w...
The anterior ethmoid foramen is a small opening in the ethmoid bone. It is the anatomical border of anterior and posterior ethmoid air cells. It transmits the anterior ethmoidal artery, vein and nerve.
The anterior ethmoid foramen is situated 25 mm away from the lacrimal crest, 12 mm anterior t...
The anterior ethmoidal nerve is an extraconal branch of the nasociliary nerve, a branch of the ophthalmic division of the trigeminal nerve. Some authors describe it as either the terminal branch or a direct continuation of the nasociliary nerve. It branches off distal to the infratrochlear nerv...
The anterior ethmoidal notch contains the anterior ethmoidal artery and has significant rates of anatomic variation that put the artery during function endoscopic sinus surgery (FESS).
The anterior ethmoidal notch lies in the medial wall of the superomedial orbit, adjacent to the...
The anterior or frontal fontanelle (or fontanel) is the diamond-shaped soft membranous gap at the junction of the coronal and sagittal sutures. It persists until approximately 18-24 months after birth, after which it is known as the bregma. The precise timing of the anterior fontanelle closure i...
Anterior fontanelle inclusion cysts, also commonly referred to as congenital dermoid inclusion cysts, are cystic lesions overlying the anterior fontanelle without communication with the underlying intracranial compartment.
Although the term congenital dermoid inclusion cyst is mor...
Anterior glenolabral injuries are common in the setting of anterior shoulder dislocation and comprise a number of closely related entities:
bony Bankart lesion
anterior labroligamentous periosteal sleeve avulsion (ALPSA)
glenolabral articular disruption (GLAD)
Causes of anterior hip pain include:
pigmented villonodular synovitis (PVNS)
inflammatory arthropathy (e.g. rheumatoid arthritis)
Anterior horn syndrome is a fairly generic term used to refer to flaccid paralysis and areflexia due to involvement of the anterior grey matter horns of the spinal cord. Sensation is typically preserved.
Causes of anterior horn syndrome include:
anterior spinal artery ischemia
The anterior humeral circumflex artery is a vessel arising from the axillary artery at the proximal part of the arm. It is smaller in size relative to the posterior humeral circumflex artery.
origin: branch of the axillary artery at the proximal part of the arm
location: proximal arm...
The anterior humeral line is key to demonstrating normal elbow alignment and should be used whenever reading a pediatric elbow radiograph to exclude a subtle supracondylar fracture.
A line drawn down the anterior surface of the humerus should intersect the middle third of the capitell...
The anterior inferior cerebellar artery (AICA) is one of three vessels that provides arterial blood supply to the cerebellum. It has a variable origin, course and supply, with up to 40% of specimens not having an identifiable standard AICA. The amount of tissue supplied by the AICA is variable (...
Anterior inferior cerebellar artery (AICA) territory infarcts are much less common than posterior inferior cerebellar artery (PICA) infarcts. AICA generally arises from the caudal third of the basilar artery and supplies the lateral pons, inner ear, middle cerebellar peduncle and the anterior in...
The anterior inferior iliac spine (AIIS) is bony prominence on the anterior border of the ilium forming the superior border of the acetabulum.
Attachments include the Iliacus, origin of straight head of the rectus femoris, and also the proximal ileofemoral ligament (Y-ligament or ligament of Bi...
Anterior inferior iliac spine (AIIS) avulsion injuries are one of the six main types of pelvic apophyseal avulsion fractures. Subacute or chronic avulsion injuries can be mistaken for a pseudotumor.
As with many pelvic avulsion injuries, they most often occur in adolescents (most...
The intercostal spaces are supplied by pairs of posterior and anterior intercostal arteries.
The 1st to 6th anterior intercostal arteries arise directly from the lateral aspect of the internal thoracic artery. The 7th to 9th arise from the musculophrenic artery, a branch of the i...
The anterior interosseous artery is one of the two branches of the short common interosseous artery (from the ulnar artery). The artery courses deep in the anterior compartment of the forearm on the anterior surface of the interosseous membrane along with the anterior interosseous nerve (from th...
The anterior interosseous nerve also known as the volar interosseous nerve arises from the median nerve in the forearm, and supplies the flexor pollicis longus, pronator quadratus and the lateral portion of flexor digitorum profundus.
The anterior interosseous nerve conti...
Anterior interosseous nerve syndrome (AINS), also known as Kiloh-Nevin syndrome, is one of three common median nerve entrapment syndromes; the other two being pronator teres syndrome and the far more common carpal tunnel syndrome.
AINS is a rare entrapment syndrome, with comparati...
The anterior jugular vein is a paired tributary of the external jugular vein.
It arises beneath the chin in the region of the hyoid bone or suprahyoid neck.
Origin and course
The anterior jugular vein has its origin as the confluence of several small superficial subma...
The anterior junction (or junctional) line is a feature of frontal chest radiographs and chest CTs. It is a result of the parietal and visceral pleura meeting anteromedially. It normally contains a small amount of fat but can form a stripe of variable thickness if there is a lot of fat present o...
There are three anterior knee fat pads 1:
infrapatellar fat pad (of Hoffa)
fills the space between the patella ligament and the anterior intercondylar area of the tibia 2
posterior suprapatellar (prefemoral or supratrochlear) fat pad
anterior suprapatellar (quadriceps) fat pad
fills the spa...
Anterior knee pain is common with a variety of causes which can be divided anatomically using a layered approach1 from superficial to deep:
Superficial soft tissues
quadriceps tendinosis / partial tear
An anterior labroligamentous periosteal sleeve avulsion (ALPSA) lesion is similar to a Bankart lesion, in that it too is usually due to anterior shoulder dislocation and involves the anterior inferior labrum.
It is often the result of chronic injury rather than acute dislocation;...
The anterior lacrimal crest is a bony projection on the frontal process of the maxilla continuous with the orbital rim which creates the lateral margin of the lacrimal sac fossa. The medial palpebral ligament is attached to anterior lacrimal crest.
Immediately anterior to the anterior lacrimal ...
The anterior lateral malleolar artery is the counterpart to the anterior medial malleolar artery, supplies the lateral aspect of the ankle.
Origin and course
branch of anterior tibial artery
runs posterior to the tendons of extensor digitorum longus and fibularis tertius to th...
The anterior left perihepatic (or subhepatic) space is a potential space located between the diaphragm and the anterosuperior aspect of the left lobe of the liver.
The anterior left perihepatic space is separated from the posterior left perihepatic space by the left lobe of the ...
The anterior left subphrenic space is a potential space between the fundus of the stomach and the left hemidiaphragm 1,2.
The anterior left subphrenic space is a subcompartment of the left supramesocolic space.
medial: falciform ligament (separates it from the anter...
Anterior lenticonus is present when the anterior surface of the ocular lens assumes a conical shape.
It can be unilateral or bilateral. Bilateral anterior lenticonus is associated with Alport syndrome.
Decreased visual activity and irregular refraction that...
The anterior longitudinal ligament (ALL) runs along the anterior surface of the vertebral bodies (firmly united to the periosteum) and intervertebral discs (attaching to the anterior annulus). It ascends from the anterosuperior portion of the sacrum superiorly to the become the anterior atlanto-...
Anterior lumbar interbody fusion (ALIF) is a spinal fusion procedure usually performed at L5/S1 or L4/5.
It is carried out either via a transabdominal or lateral retroperitoneal approach. A discectomy is performed, an interbody spacer introduced and fixed in place with screws with or without a...
Anterior medial malleolar artery is the counterpart to the anterior lateral malleolar artery, and supplies the medial aspect of the ankle.
Origin and course
branch of anterior tibial artery
arises approximately 5 cm proximal to the ankle
passes posterior to the tendons of exte...
Germ cell tumors are one of the causes of anterior mediastinal mass, and any of the germ cell histologies may be identified. They can therefore be divided histologically into:
non-seminomatous germ cell tumors (NSGCT)
embryonal cell carcinoma
yolk sac tumor
Getting a film with an anterior mediastinal mass in the exam is one of the many exam set-pieces that can be prepared for.
The film goes up and after a couple of seconds pause, you need to start talking:
There is a left sided mediastinal mass that makes obtuse angles with the mediastinal c...
The anterior mediastinum is the portion of the mediastinum anterior to the pericardium and below the thoracic plane.
It forms the anterior part of the inferior mediastinum, and contains the thymus, lymph nodes, and may contain the portions of a retrosternal thyroid.
The anterior (or external) nares (singular: naris) (or nostrils) form the entrance to the nose. Each naris is formed by a ring of structures:
medially the columella (soft tissue anteroinferior portion of the nasal septum)
laterally and superiorly the nasal ala
inferiorly the nasal sill
The anterior pararenal space is the portion of the retroperitoneum that lies between the posterior surface of the parietal peritoneum and the anterior reflection of the perirenal fascia.
It contains the duodenum, pancreas and retroperitoneal segments of the ascending and descendi...
The anterior perforated substance, or substantia perforata anterior, is an area in the basal forebrain that plays an important role with regards to the blood supply of deep grey matter structures of the brain.
Located within the basal forebrain, the anterior perforated substance...
The anterior pituitary (or adenohypophysis) is by far the largest part of the pituitary gland, and is responsible for synthesis and release of most pituitary hormones (with the exception of oxytocin and antidiuretic hormone (ADH) which are released by the posterior pituitary).
It consists of 3 ...
The anterior pontine membrane is an arachnoid membrane located anteriorly in the posterior fossa to the side of the basilar artery, separating the prepontine cistern (medially) form the cerebellopontine cistern (laterally) 1.
The anterior ramus of the lateral sulcus, is located at the very anterior end of the lateral sulcus (sylvian fissure), just anterior to the ascending ramus, and passes superiorly into the inferior frontal gyrus separating the pars orbitalis form the pars triangularis of the frontal operculum.
Anterior resection syndrome refers to wide spectrum of symptoms which develop post-sphincter preserving rectal resection for rectal cancer.
Pelvic radiotherapy is a known risk factor to develop anterior resection syndrome.
Symptoms include but are not limited to:
The anterior right subhepatic space is a potential space between the inferior surface of the right lobe of the liver and the transverse colon.
The anterior right subhepatic space is separated from Morison’s pouch (also known as the posterior right subhepatic space) by the transve...
Anterior sacral meningocele is a congenital defect seen in the anterior aspect of the spine. It is defined as a meningeal cyst that occurs in the presacral space secondary to agenesis of a portion of the anterior sacrum.
In approximately 50% of cases, associated malform...
The anterior capsular insertion, unlike the posterior aspect of the shoulder joint capsule which has a constant scapular attachment along the margins of the glenoid labrum, inserts a variable distance from the labrum.
The capsular insertions are classified as follows:
type I: at or very near t...
Anterior shoulder dislocation is by far the commonest type of dislocation and usually results from forced abduction, external rotation and extension 1.
Broadly speaking, anterior shoulder dislocations occur in a bimodal age distribution. The first, and by far the more prevalent a...
The anterior spinal artery supplies the anterior portion of the spinal cord and arises from the vertebral artery in the region of the medulla oblongata. The two vertebral arteries (one of which is usually bigger than the other) anastamose in the midline to form a single anterior spinal artery at...
The anterior spinal commissure connects the left and right sides of the spinal cord anteriorly. It is located between the posterior-most extent of the anterior median fissure anteriorly and the ventral grey matter commissure posteriorly 1.
It is composed of anterior and lateral spinothalamic t...
The anterior spinothalamic tract, also known as the ventral spinothalamic fasciculus, is an ascending pathway located anteriorly within the spinal cord, primarily responsible for transmitting coarse touch and pressure.
The lateral spinothalamic tract (discussed separately), in contrast, primar...
Anterior subluxation of the cervical spine, also known as hyperflexion sprain, is a ligamentous injury of the cervical spine.
Patients present with severe, focal neck pain. There may be neurological symptoms due to spinal cord injury.
Anterior subluxation of t...
The anterior superior alveolar canal courses through the anterior wall of the maxillary sinus, and contains the anterior superior alveolar nerve, artery and vein. Usually, it shares a common channel with the infraorbital canal but when seen separately should not be confused for a fracture.
The anterior superior alveolar nerve, also known as the anterior superior dental nerve, is the third branch of the infra-orbital nerve, from the maxillary division of the trigeminal nerve. It is the largest of the superior alveolar nerves and contributes to the superior dental plexus.
The anterior superior iliac spine is an important bony surface landmark and is the prominence is the most anterior part of the ilium. It can be palpated at the lateral end of the inguinal fold. Attachments include the inguinal ligament, sartorius and depending on which resource you read, the ten...
Anterior superior iliac spine (ASIS) avulsion injuries typically occur in athletes during forceful muscular contraction. ASIS is the site of attachment for sartorius and tensor fascia latae muscles.
ASIS avulsion, like other pelvic avulsion injuries, is a stable fracture.
The anterior talofibular ligament (ATFL) is part of the lateral collateral ligament complex of the ankle. Its role is to stabilize the talus. It is also the weakest of the lateral collateral ankle ligaments.
The ATFL is an intracapsular flat two-banded ligament that arises from ...
Anterior talofibular ligament (ATFL) injury is the most common of the ligament injuries that can occur as part of the lateral ligament complex injuries 2. The injuries can comprise either soft tissue tears, avulsion fractures or both.
ATFL injuries typically occur with an inversion i...
The anterior temporal artery is usually a branch of the M1 segment of the middle cerebral artery (MCA) that curves out of the Sylvian fissure and runs over the temporal lobe to supply the anterior third of the superior, middle and inferior temporal gyri.
The temporopolar arter...
Anterior temporal lobe perivascular spaces are recently recognized special variants of tumefactive perivascular spaces, which can mimic cystic tumors with surrounding edema.
A predilection for women has been reported 1. Age range is wide, from 24 to 86 years old reported 1.
The anterior tibial artery is the main arterial supply of the anterior compartment of the leg.
The anterior tibial artery arises from the popliteal artery in the popliteal fossa and continues distally as the dorsalis pedis artery.
The popliteal artery usually divides at...
The anterior tibial translocation sign or anterior drawer sign (a.k.a. anterior translation of tibia) is seen in cases of complete rupture of the anterior cruciate ligament, and refers to anterior translocation (anterior tibial subluxation) of the tibia relative to the femur of >7 mm 1.
The anterior tibial veins, continuations of the venae comitantes of the dorsalis pedis artery, leave the anterior compartment of the leg between the tibia and fibula and pass through the proximal end of the interosseous membrane. They unite with the posterior tibial veins to form the popliteal v...
The anterior triangle forms the anterior compartment of the neck and is separated from the posterior triangle by the sternocleidomastoid muscle. The triangles of the neck are surgically focused, first described from early dissection-based anatomical studies which predated cross-sectional anatomi...
The anterior tympanic artery is the second named branch of the first part of the maxillary artery. The vessel passes through the petrotympanic fissure to supply the lining of the middle ear and accompanies the chorda tympani in its course.
The anterior ulnar recurrent artery is a recurrent branch of the proximal ulnar artery that ascends in the anterior medial aspect of the elbow, anterior to the medial epicondyle of the humerus to anastomose with the inferior ulnar collateral artery (from the brachial artery) and contribute to th...
Anterior vertebral body beaking occurs in a number of conditions and may emanate from the central portion or the lower third of the vertebral body.
Morquio syndrome 1 (middle for Morquio)
Hurler syndrome 2