Innominate artery compression syndrome, also known as brachiocephalic artery compression syndrome, is a rare cause of tracheal stenosis that occurs in the pediatric population.
The brachiocephalic artery usually takes its origin to the left of the trachea. The artery subs...
An interarterial course of the left coronary artery is defined as origination of the left main or left anterior descending coronary artery from the right coronary sinus of Valsalva, with a course between the ascending aorta and the pulmonary artery trunk.
An interarterial course i...
Interarterial course of the right coronary artery, may occur if the right coronary artery (RCA) has an aberrant origin from the left coronary sinus. The interarterial course occurs because the artery passes between the ascending aorta and the pulmonary trunk.
It is an uncommon anatomic variant ...
The intercavernous sinuses (anterior, posterior, and inferior) are variable dural venous sinuses that connect the left and right cavernous sinuses. Some authors also include in this group the basilar venous plexus (basilar sinus) and sinus of the dorsum sellae 2. The anterior, posterior, and inf...
The internal carotid artery (ICA) is a terminal branch of the common carotid artery.
It arises most frequently between C3 and C5 vertebral level, where the common carotid bifurcates to form the internal carotid and the external carotid artery (ECA). Just superior to its ...
Internal carotid artery (ICA) dissection, like arterial dissection elsewhere, is a result of blood entering the media through a tear in the intima 1 and is a common cause of stroke in younger patients.
Dissection may occur at any age but is a common cause of stroke in young patien...
The internal carotid artery segments, according to the Bouthillier classification, can be recalled by the following mnemonic:
C'mon Please Learn Carotid Clinical Organizing Classification
C: cervical segment
P: petrous segment
L: lacerum segment
C: cavernous segment
C: clinoid se...
Internal carotid artery venous plexus of Rektorzik (also known as the petro-occipital venous plexus) is a plexus of small veins that surrounds the petrous segment internal carotid artery proximal to the cavernous sinus as it passes through the base of skull.
It is believed that the plexus serv...
The internal cerebral veins are paired, paramedian veins which course posteriorly along the roof of the third ventricle, between the two leaves of the velum interpositum.
Each is formed at the foramen of Monro by the confluence of the choroidal vein (draining the choroid plexus o...
The internal iliac artery (also known as the hypogastric artery, but internal iliac is the accepted term in the TA) is the smaller terminal branch of the common iliac artery. It supplies the pelvic walls, pelvic viscera, external genitalia, perineum, buttock and medial part of the thigh.
The internal iliac vein (IIV) represents the union of veins and venous plexuses draining the pelvic viscera, pelvic wall, external genitalia, perineum, buttocks, and medial thigh.
Above the greater sciatic notch.
Course and termination
Ascends out of pelvis to meet th...
The internal jugular vein (IJV) is the major venous return from the brain, upper face and neck.
Origin and course
It is formed by the union of inferior petrosal and sigmoid dural venous sinuses in or just distal to the jugular foramen (forming the jugular bulb). It descends in t...
A useful mnemonic to remember the branches of the internal jugular vein is:
Medical Schools Let Fun People In
From inferior to superior:
M: middle thyroid vein
S: superior thyroid vein
L: lingual vein
F: facial vein
P: pharyngeal vein
I: inferior petrosal sinus
The internal palpebral arteries, or medial palpebral arteries, are branches of the ophthalmic artery, with superior and inferior medial palpebral branches arising opposite the trochlear of the superior oblique muscle.
The internal palpebral arteries enter the superior and inferio...
The internal pudendal artery is a branch of the anterior division of the internal iliac artery and is the primary supply of the perineum. It is a larger vessel in males than in females.
origin: anterior division of internal iliac artery
location: pelvis, gluteal region, perineum
The internal pudendal veins are the set of accompanying veins to the internal pudendal artery draining the perineal region to empty into the internal iliac vein.
inferior rectal veins
penile bulb and scrotum vein
clitoris and posterior labial vein
The internal thoracic artery (previously called the internal mammary artery) supplies the anterior body wall and its associated structures from the clavicles to the umbilicus.
The internal thoracic artery arises from the first part of the subclavian artery in the base of ...
The internal thoracic vein (previously known as the internal mammary vein) arises from the superior epigastric vein. It drains the chest wall and breasts.
The internal thoracic vein arises from the superior epigastric vein. It forms venae comitantes to the internal thoracic arte...
The interosseous recurrent artery is a branch of the posterior interosseous artery just after its origin, within the proximal aspect of the posterior compartment of the forearm. It courses proximally between the lateral epicondyle of the humerus and olecranon of the ulna to anastomose with the m...
Interrupted aortic arch (IAA) is an uncommon congenital cardiovascular anomaly where there is a separation between the ascending and descending aorta. It can either be complete or connected by a remnant fibrous band. An accompanying large ventricular septal defect (VSD) and/or patent ductus arte...
An interscalene brachial plexus block is indicated for procedures involving the shoulder and upper arm.
Ultrasound-guided brachial plexus nerve blocks entered the literature in 1989, when Ting et al. detailed their success with axillary nerve blocks in 10 patients 3.
This is a basic article for medical students and other non-radiologists
Intestinal ischemia refers to vascular compromise of the bowel which in the acute setting has a very high mortality if not treated expediently. Diagnosis is often straight forward provided appropriate imaging is obtained. T...
The intestinal trunk (TA: truncus intestinalis) is an unpaired lymphatic trunk which drains lymph (and chyle) from those portions of the GI tract which receive their blood supply from the celiac and superior mesenteric arteries.
In the majority of individuals, the intestinal trunk drains into t...
Intimal hyperplasia is not a true disease, but a physiologic healing response to injury to the blood vessel wall. It is the bane of endovascular intervention and vascular surgery.
When the endothelium is injured, endothelial cells release inflammatory mediators that trigger platelet aggregatio...
Intima-media thickness (IMT) is an indirect sonographic assessment of the degree of atheromatous vascular disease of end organs. The thickness of the media and the intima of the vessels changes following many conditions and it can be easily and reliably assessed with ultrasound on B mode in the ...
Intra-aortic balloon pumps (IABP) are used in the intensive care setting to provide hemodynamic assistance to patients in cardiogenic shock.
Function and physiology
The device is comprised of a catheter introduced via a femoral artery sheath, which extends retrogradely to the proximal descendi...
Intra-atrial course of the right coronary artery is an uncommon anatomic variation in the course of the right coronary artery, usually involving the mid and distal segments, where the vessel partially or completely courses through the right atrial chamber. It is the most common intracavitary (in...
Intracranial aneurysms, also called cerebral aneurysms, are aneurysms of the intracranial arteries. The most common morphologic type is the saccular aneurysm.
There is not a universal classification for the types of intracranial aneurysms, resulting in a heterogeneous mix of terms ba...
Intracranial arteries have a unique structure when compared to extracranial vessels of similar size: see general histology of blood vessels entry.
Proximal larger arteries
The proximal arteries, arising from the internal carotid and vertebral arteries have differing distribution of elastic fib...
Intracranial arterial variants, of which there are many, are collectively common. Their clinical significance may be variable but knowledge and recognition of these variants is fundamental, especially if surgical or endovascular treatments (e.g. for acute stroke, aneurysms or other vascular path...
Intracranial atherosclerotic disease (ICAD) is the term applied to atherosclerosis of the large intracranial arteries and is a cause of ischemic stroke.
ICAD is an important cause of stroke in certain racial groups particularly Asians, but also Hispanics and Black people. ICAD is ...
Intracranial mycotic aneurysms, or intracranial infectious aneurysms, describe aneurysms arising from infection of the arterial wall of intracranial vessels.
See mycotic aneurysm for a general discussion on infectious aneurysms.
The epidemiology of intracerebral mycotic aneurysms...
Intrahepatic arteriovenous shunts, also referred to as intrahepatic arteriovenous malformations (AVMs) or hepatic arteriosystemic venous shunts, represent a spectrum of abnormal communications between the hepatic arterial system and the hepatic veins.
Please note that arterioportal shunts, whi...
Intrapelvic cup migration is a serious complication after total hip arthroplasty, in which the prosthetic acetabular cup migrates or drifts into the pelvic inlet.
Fortunately, this complication is very rare. There seems to be a female predisposition 1-3.
Intratesticular varicocele is a rare entity, occurring in ~2% of symptomatic population.
It is defined as dilated intratesticular veins seen in relation to the mediastinum testis and extending peripherally. It is usually seen in the presence of ipsilateral extratesticular varicocele....
Intravenous leiomyomatosis (IVLM) is characterized by the extension into venous channels of histologically benign smooth muscle tumor arising from either the wall of a vessel or from a uterine leiomyoma.
Intravenous leiomyomatosis should not be confused with benign metastasizing le...
This is a basic article for medical students and other non-radiologists
Limb ischemia is a relatively uncommon, but potentially limb (and life) threatening situation. There are many potential causes.
This is a summary article; we do not have a more in-depth reference article...
Ischemic colitis refers to inflammation of the colon secondary to vascular insufficiency and ischemia. It is sometimes considered under the same spectrum as intestinal ischemia. The severity and consequences of the disease are highly variable.
Ischemic bowel is typically a disease...
Ischemic stroke results from a sudden cessation of adequate amounts of blood reaching parts of the brain. Ischemic strokes can be divided according to territory affected or mechanism.
Stroke is the second most common cause of morbidity worldwide (after myocardial infarction) and i...
The Isikoff's view is a sonographic view which demonstrates the origins of the right and left renal arteries. It is taken in the longitudinal plane with the patient in the left lateral decubitus position 1.
Isolated periaortitis is a non-aneurysmal form of chronic periaortitis.
mesenteric arterial ischemia: abdominal pain, diarrhea, and gastrointestinal hemorrhage
renal artery stenosis: renovascular hypertension
vascular impairment ...
Isolated unilateral absence of the pulmonary artery (IUAPA) is the congenital absence of the left or right pulmonary artery. When found in combination with other congenital vascular abnormalities it is known as unilateral absence of the pulmonary artery (UAPA).
The ISSVA classification of vascular anomalies encompasses all vascular malformations and tumors in a framework of internationally consistent nomenclature. ISSVA is the International Society for the Study of Vascular Anomalies. It is based on the initial classification published by Mulliken and...
Isthmus (plural isthmi) is an anatomical term and refers to a slender structure joining two larger components. Some of these uses of the word isthmus are now rarely used or only seen in older texts and articles:
isthmus (auditory tube)
isthmus (auricle of the ear)
The ivy sign refers to the MRI appearance of patients with moyamoya disease or moyamoya syndrome. Prominent leptomeningeal collaterals result in vivid contrast enhancement and high signal on FLAIR due to slow flow. The appearance is reminiscent of the brain having been covered with ivy.
The jejunal and ileal branches of the superior mesenteric artery are variable in number.
They pass in the two layers of the mesentery to the jejunum and ileum and progressively divide and join in a series of anastomosing arcades. From the arcades, straight arteries (also known as the vasa recta...
A jet hematoma or flame hemorrhage is a term used to describe an intraparenchymal hematoma adjacent to a ruptured intracranial berry aneurysm caused when the ruptured aneurysm abuts a lobe of the brain and the pressure of the blood leaving the aneurysm dissects into the brain parenchyma.
The jugular bulb is the connection between the sigmoid sinus and the internal jugular vein.
The sigmoid and inferior petrosal sinuses empty into the jugular bulb, which continues as the internal jugular vein. It lies in the pars vascularis, which occupies the posterolateral aspe...
The jugular trunks are small short paired lymphatic trunks, each one draining one side of the head and neck, forming an important terminal part of the lymphatic system 1-3.
the left and right jugular trunks are found in the root of the neck
the organs of the he...
The internal jugular vein is a preferred site for venous access for large lumen, long-term central venous catheters for chemotherapy, hemofiltration and plasma exchange. These are commonly referred to as (internal) jugular venous (IJV) catheters.
Typically, the right internal jugular is used as...
Kaposiform hemangioendothelioma is a rare, locally invasive vascular tumor that often presents in infancy, most commonly as an enlarging cutaneous mass 1,2.
Kaposiform hemangioendothelioma is a rare disease of childhood. The exact incidence and prevalence has not been accurately ...
Kaposiform lymphangiomatosis (KLA) is a rare lymphatic anomaly associated with a poor prognosis. Disease hallmarks include multifocal, intra- and extra-thoracic lymphatic malformations, thrombocytopenia and consumptive coagulopathy.
The exact prevalence and incidence of kaposiform...
Kasabach-Merritt syndrome, also known as hemangioma thrombocytopenia syndrome, is a rare life-threatening disease found in infants in which a rapidly growing vascular tumor is responsible for thrombocytopenia, microangiopathic hemolytic anemia and consumptive coagulopathy.
Kawasaki disease (KD) is a small to medium vessel vasculitis predominantly affecting young children. It can affect any organ but there is a predilection for the coronary vessels.
Japan has the highest incidence in the world, with an annual incidence of 300/100,000 children under t...
Kawashima procedure is a palliative surgical procedure performed in cases of:
left isomerism and azygos continuation of the inferior vena cava
single functional ventricle
single atrium and common atrioventricular valve with or without regurgitation
It is performed by crea...
Kiesselbach plexus (Kiesselbach area or Little's area) is a vascular region of the anteroinferior nasal septum that comprises four arterial anastomoses:
anterior ethmoidal artery
a branch of the ophthalmic artery
a branch of the maxillary artery
greater palatine artery...
The term kissing carotids refers to tortuous and elongated vessels which touch in the midline. They can be found in:
within the pituitary fossa
within sphenoid sinuses
within sphenoid bones
The significance of kissing carotids is two-fold:
may mimic intrase...
Klippel-Trénaunay-Weber syndrome (KTWS) is a syndrome combination of capillary malformations, soft-tissue or bone hypertrophy, and varicose veins or venous malformations. It is considered an angio-osteo-hypertrophic syndrome.
KTS classically comprises a triad of:
port wine nevi
bony or soft t...
Kommerell diverticula occur in some anomalies of the aortic arch system. It usually refers to the bulbous configuration of the origin of an aberrant left subclavian artery in the setting of a right-sided aortic arch. However, it was originally described as a diverticular outpouching at the origi...
This article lists a series of labeled imaging anatomy cases by system and modality.
CT head: non-contrast axial
CT head: non-contrast coronal
CT head: non-contrast sagittal
CT head: angiogram axial
CT head: angiogram coronal
CT head: angiogram sagittal
CT head: venogram axial
The labyrinthine artery, also known as the auditory artery or internal auditory artery, is a long and slender artery that is the main arterial supply to the vestibular apparatus and cochlea. It also vascularizes the VII and VIII cranial nerves.
It usually originates from the AICA (~85%), althou...
The lacrimal artery is a branch of the ophthalmic artery that supplies the lacrimal gland.
The lacrimal artery travels along the upper border of the lateral rectus muscle with the lacrimal nerve to supply the lacrimal gland as well as the eyelids and conjunctiva.
The term large vessel vasculitis (LVV) usually denotes the spectrum of primary vasculitides that causes chronic granulomatous inflammation predominantly involving the aorta and its major branches.
The two major entities in this group are
giant cell arteritis (GCA): affects older ind...
The Lasjaunias classification, at the time of writing (mid 2016), is one of the two commonly used systems for classifying vein of Galen malformations. It relies on dividing the entity into choroidal or mural types, depending on the number and origin of feeding arteries.
The lateral circumflex femoral artery is a branch of the profunda femoris that arises from its lateral aspect just after the medial circumflex femoral artery.
While the medial circumflex runs posteriorly around the femoral neck, the lateral circumflex courses laterally from its origin and anter...
The lateralized internal carotid artery is an anatomic variation of the course of the petrous segment of the internal carotid artery (ICA). It can be visualized on CT by its more posterolateral entrance to the skull base and protrusion into the anterior mesotympanum.
The lateral lenticulostriate arteries arise from the proximal middle cerebral artery (MCA), usually from M1 segment, more rarely from the postbifurcation or M2 segment. They supply the lateral portion of the putamen and external capsule as well as the upper internal capsule.
They are longer (al...
The lateral marginal vein (also known as the vein of Servelle or the Klippel-Trenaunay vein) is one of two known persisting embryonic veins of the leg, the persistent sciatic vein being the other. The lateral marginal vein is the principle tributary forming the small saphenous vein.
The lateral posterior choroidal artery may be a singular vessel or exist as multiple lateral posterior choroidal arteries. In either case, they usually arise from the P2 segment of the PCA, just distal (and lateral) to the medial posterior choroidal arteries. In some cases, they may arise from o...
The lateral sacral artery is one of three branches of the posterior division of the internal iliac artery.
origin: from the posterior division of the internal iliac artery in the pelvis
branches: superior and inferior sacral arteries
supply: sacral meninges, pirifor...
The lateral tentorial artery also known as lateral tentorial arcade, is a branch of the meningohypophyseal trunk (MHT) which arises from the cavernous segment of the internal carotid artery. The lateral tentorial artery runs along the lateral edge of the tentorium cerebelli.
The lateral thoracic artery is a branch of the second part of the axillary artery.
Origin and course
The lateral thoracic artery originates from the medial surface of the axillary artery, posterior to the distal part of pectoralis minor. It courses inferomedially along the infe...
The lateral umbilical folds are bilateral raised ridges of parietal peritoneum in the deep aspect of the anterior abdominal wall overlying the inferior epigastric vessels. The paired folds originate medial to the deep inguinal ring and end at the arcuate line on the posterior aspect of the anter...
The left anterior descending (LAD) artery, also known as the anterior interventricular branch, is one of the two branches of the left coronary artery (the other branch being the circumflex (Cx) artery).
It descends along the interventricular groove.
It can be divided into proxim...
The left colic artery is the first branch of the inferior mesenteric artery and supplies the marginal artery.
It ascends retroperitoneally to the left, dividing into two branches:
passes anteriorly to the left kidney, then enters the transverse mesocolon, and passes s...
The left gastric artery is the smallest and first branch of the celiac artery.
It passes superiorly over the left crus of the diaphragm, approaching the esophageal opening of the diaphragm, giving off an esophageal branch to the distal esophagus, then enters the lesser omentum to pass along t...
The left gastric vein (also known as the coronary vein) drains both gastric walls. It forms a loop with the right gastric vein at the lesser curvature of the stomach. The left gastric vein travels in the lesser omentum to drain in the portal vein. It also communicates with the lower esophageal v...
The left gastroepiploic artery (LGA) is one of the branches of the splenic artery.
The LGA arises from the splenic artery, and runs within the gastrosplenic ligament. It then runs within the two layers of the greater omentum to the right along the greater curvature of the...
The left hepatic artery (LHA) is formed when the proper hepatic artery (PHA) bifurcates. The hepatic arteries provide 25% of the blood supply and 50% of the oxygen supply to the liver.
The proper hepatic artery bifurcates into the left and right hepatic arteries at or before reac...
The left main coronary artery (LMCA) or left coronary artery (LCA) is one of the two main coronary arteries that supply the heart with oxygenated blood.
It is a branch of the ascending aorta, with its normal origin in the left aortic sinus, just superior to the aortic val...
When a central venous catheter that is supposed to terminate in the superior vena cava or right atrium is abnormally located to the left of the mediastinum and below the level of the brachiocephalic vein, a limited differential of left paramediastinal catheter position should be considered 1:
The left pulmonary artery (LPA) is one of the branches of the pulmonary trunk, branching at the level of the transthoracic plane of Ludwig. It is shorter than the right pulmonary artery and represents a direct posterior continuation of the pulmonary trunk. It arches posterosuperiorly over the su...
A left-sided superior vena cava (SVC) is the most common congenital venous anomaly in the chest, and in a minority of cases can result in a right-to-left shunt 3,4.
A left-sided SVC is seen in 0.3-0.5% of the normal population and in ~5% of those with congenital heart disease 3. I...
The left superior intercostal vein drains the left posterosuperior hemithorax and is considered to be part of the azygos venous system even though it does not directly drain into the azygos vein.
Origin and course
The left superior intercostal vein forms by the union of the 2nd...
Left ventricular assist devices (LVAD) are mechanical circulatory support device that are surgically implanted to aid pumping blood in patients with severe refractory cardiac failure. It may be used as a bridge to cardiac transplantation, or as destination therapy in patients who are not a trans...
In patients with a left ventricular assist device (LVAD), spectral Doppler waveforms are altered due to continuous flow provided by the pump in the device:
waveforms are monophasic with a constant antegrade flow and no flow below the baseline
the waveform is typically parvus-tardus with a slow...
Left ventricular pseudoaneurysms are false aneurysms that result from contained myocardial rupture, and are a rare complication of myocardial infarction (MI). They should not be confused with left ventricular aneurysms, which are true aneurysms containing all the layers (endocardium, myocardium,...
Leiomyosarcomas are extremely rare malignant neoplasms that originate from smooth muscle cells and may be considered the malignant counterpart of a leiomyoma. They are classified as a soft tissue tumor and account for ~8% of malignant soft tissue tumors 10.
Lemierre syndrome (also known as postanginal septicemia) refers to thrombophlebitis of the internal jugular vein(s) with distant metastatic sepsis in the setting of initial oropharyngeal infection such as pharyngitis/tonsillitis with or without peritonsillar or retropharyngeal abscess.
The lenticulostriate arteries, also known as anterolateral central arteries, are a collection of small perforating arteries arising from the anterior part of the circle of Willis and supplying the basal ganglia.
They are divided into:
medial lenticulostriate arteries
The Lie classification of vasculitis was proposed in 1994 1.
affecting large, medium, and small blood vessels (see large vessel vasculitides)
temporal arteritis (giant cell arteritis)
isolated angiitis of the central nervous system
The ligamentum arteriosum (or arteriosus) is the small fibrous remnant of the fetal ductus arteriosum, located between and connecting the proximal left pulmonary artery and the undersurface of the junction of the aortic arch and descending aorta, at the aortic isthmus. The left recurrent larynge...
The ligamentum teres or round ligament is the fibrous cord formed by the obliterated fetal umbilical vein that runs in the free edge of the falciform ligament from the umbilicus into the left lobe of the liver.