Chest x-ray lines and stripes are important to recognise on chest radiographs.
Lines are usually less than 1mm in width and are comprised of tissue outlined on either side by air and typically represent pleural-covered structures within the middle and superior mediastinum 1, 2:
The chordae tendineae are thin strong inelastic fibrous chords that extend from the free edge of the cusps of the atrioventricular valves (the tricuspid and mitral valves) to the apices of the papillary muscles within the right and left ventricles respectively. They transmit the force of the co...
The Chorda tympani is a nerve that arises from the mastoid segment of the facial nerve, carrying afferent special sensation from the anterior two-thirds of the tongue via the lingual nerve, as well as efferent parasympathetic secretomotor innervation to the submandibular and sublingual glands.
The chorion is one of the embryonic membranous structures than encloses both the fetus as well as the amnion. The chorion begins to form chorionic villi towards its outer surface, which initially serves to provide nutrition to the developing embryo.
Part of the chorionic villi arborize more ex...
The chorionic plate is a synonym for the fetal side of the placenta. The maternal side of the placenta is termed the basal plate.
Some pathologies and processes are localized to the chorionic plate, and evaluation of the chorionic plate is a part of placental grading.
The choroidal fissure is a thin C-shaped cleft of the lateral ventricle, located along the medial wall, and to which choroid plexus is attached. It runs between the fornix and the thalamus, and it separates the temporal lobe from the optic tract, midbrain and hypothalamus.
The choroid plexus is located within the cerebral ventricles and is made of epithelial cells, loose connective tissue (tela choroidea) and permeable capillaries. It produces cerebrospinal fluid.
roof of the temporal horns of the lateral ventricles, extending along the ...
Chromaffin cells are neuroendocrine cells found predominantly in the medulla of the adrenal gland. They are also found in other ganglia of the sympathetic nervous system and are derived from the embryonic neural crest.
They arise in the fifth week of fetal development when neuroblas...
The ciliary ganglion is one of four parasympathetic ganglia of the head and neck. It receives parasympathetic fibres from the oculomotor nerve.
smallest of the ganglia (2mm in size)
located posterolaterally in the intraconal space of the orbit (towards the orbital apex) between ...
The cingulate gyrus lies on the medial aspect of the cerebral hemisphere. It forms a major part of the limbic system which has functions in emotion and behaviour. The frontal portion is termed the anterior cingulate gyrus (or cortex) 1-2.
The cingulate gyrus extends from the sub...
The cingulate sulcus is situated directly superior to the cingulate gyrus, which is formed by the medial surface of the cerebral hemisphere that is directly above the corpus callosum.
The Circle of Willis is an arterial polygon formed as the internal carotid and vertebral systems anastomose around the optic chiasm and infundibulum of the pituitary stalk in the suprasellar cistern. This communicating pathway allows equalization of blood-flow between the two sides of the brain,...
Circumaortic left renal vein, also known as circumaortic renal collar is an anomaly of left renal vein when a supernumerary or accessory left renal vein passes posterior to the aorta, apart from the normal renal vein passing anterior to the aorta. This anomaly is potentially hazardous, if unreco...
A circumcaval ureter, or retrocaval ureter, is a developmental anomaly of the inferior vena cava (IVC). Unfortunately both terms suggest that the ureter is at fault, whereas in reality it is the IVC. They are of two types:
Many patients with this anom...
The circumflex artery (Cx) is a major coronary artery that divides off the left main coronary artery (the other branch being the left anterior descending (LAD) artery).
The circumflex artery is referred to by multiple terms:
circumflex artery (Cx)
ramus circumflex artery (RCx)
The circumflex fibular artery is a minor artery of the leg.
Origin and course
Most often arises from the posterior tibial artery, passes laterally round the neck of the fibula through the soleus to anastomose with the lateral inferior genicular, medial genicular and anterior tib...
The cisterna chyli (CC), also known as the receptaculum chyli, is a normal anatomical structure seen as a saccular area of dilatation in the lymphatic channels that is located in the retrocrural space, usually to the immediate right of the abdominal aorta 4.
The claustrum is a vertical curved sheet of subcortical grey matter oriented sagittally between the white matter tracts of the external capsule and extreme capsule. It is lateral to the putamen and medial to the insular cortex. It is not part of the basal ganglia.
There are lateral and medial t...
The clavicle (or informally collar bone) is the only bone connecting the pectoral girdle to the axial skeleton and is the only long bone that lies horizontally in human skeleton.
The clavicle is roughly "S-shaped" with a flattened, concave, lateral one-third and a thi...
The clavipectoral fascia is a sheet of loose connective tissue which is the deep layer of fascia in the pectoral region. It acts to suspend the floor of the axilla.
The clavipectoral fascia lies below the clavicular head of the pectoralis major. It fills in the space between the...
Cleft epiphysis is a normal variant of an epiphysis. It can be either unilateral or bilateral. The most common site is the epiphysis of the first proximal phalanx of the foot.
Plain radiographs will demonstrate a lucent defect in the epiphysis. The borde...
The clivus is the sloping midline surface of the occipital bone anterior to the foramen magnum. Specifically it is located in the basiocciput. At the clivus, the occipital bone has articulations with the sphenoid and petrous part of temporal bone1.
Inferiorly the clivus is flanked be the rounde...
The cloaca is the terminal portion of the hindgut. It is an embryonic structure (weeks 4-7) in which the distal ends of the gastrointestinal tract and urogenital system share a common channel. The most distal aspect of the cloaca is termed the cloacal membrane.
The cloaca, or portions of it, ca...
Cloquet's canal, also known as the hyaloid canal or Stilling's canal, is a transparent canal that runs from the optic nerve disc to the lens traversing the vitreous body. It serves as a perivascular sheath surrounding the hyaloid artery in the embryonic eye.
The coccygeus, also known as the ischiococcygeus, is a remnant muscle of the pelvic floor.
The coccygeus is a paired muscle which is triangular in shape and overlies the sacrospinous ligament. The coccygeus lies parallel to the inferior border of the piriformis, but is separated ...
The coccyx is the series of rudimentary vertebrae forming the caudal termination of the vertebral column and is positioned inferior to the apex of the sacrum. The coccyx is one leg of the tripod formed in conjunction with the ischial tuberosities for support in a seated position. Additionally, i...
The cochlea is part of the inner ear osseous labyrinth found in the petrous temporal bone.
The cochlea is a shell-shaped spiral that turns between two-and-a-half and two-and-three-quarters times around the modiolus (a central column of porous bone).
The spiral of the cochlea is...
The cochlear promontory is the name given to the bone that overlies the basal turn of the cochlea protruding into the middle ear cavity.
glomus tympanicum paragangliomas typically arise in the region of the cochlear promonotory
Coeliac artery (also known as the coeliac axis or trunk) is a major visceral artery in the abdominal cavity.
Arises anteriorly from abdominal aorta at the T12 level, behind the median arcuate ligament, just as the aorta enters the abdomen.
It is typically a sho...
The collateral ligaments of the foot are attached to the dorsal tubercles on the metatarsal heads and the corresponding side of the phalangeal bases.
The collateral sulcus, also known as the medial occipitotemporal sulcus, runs anteroposteriorly on the inferior surface of the temporal lobe and occipital lobe. Anteriorly it is sometimes continuous with the rhinal sulcus 1-3.
Anteriorly, it separates the fusiform gyrus laterally, from the par...
The colliscalene triangle is an important anatomical region of the neck, situated medial to the scalenus anterior muscle.
medial: lateral border of longus colli
lateral: medial border of scalenus anterior
inferior: first part of the subclavian artery
apex: carotid ...
The columella is the inferior portion of the nasal septum. It is a single midline structure composed of cartilage and overlying skin, the lateral aspects of which form the medial wall of each nostril.
History and etymology
From the Latin word for little column.
The column of Burdach, also known as the cuneate fasciculus or fasciculus cuneate, represents the lateral portion of the dorsal columns and carries input from between and including C1 and T6 1.
The cuneate fasciculus is responsible for transmitting vibration, conscious proprioception...
The column of Goll, also known as the gracile fasciculus or fasciculus gracilis, represents the medial portion of the dorsal columns and carries input from below and including T7 1.
The gracile fasciculus is responsible for transmitting vibration, conscious proprioception, and fine (d...
There are a number of white matter tracts that cross the midline, connecting the two cerebral hemispheres. These are known as commissures and include:
hippocampal commissure (psalterium)
The common bile duct (CBD), which is sometimes simply known as the bile duct, is formed by the union of the cystic duct and common hepatic duct.
The CBD is approximately 8 cm long and usually <6 mm wide in diameter but this can be dependent on a number of factors including age a...
The common carotid artery is a paired structure that supplies blood to the head and neck.
left: branch of the aortic arch
right: branch of the brachiocephalic trunk
course: posterior to sternoclavicular joint, lateral to thyroid and trachea
supply: head and neck
The common facial vein is formed by the joining of the facial vein and anterior branch of the retromandibular vein. It is part of the venous drainage system of the face.
origin and termination: the facial vein (along with the facial artery) pierces the deep investing fascia of the neck...
The common femoral artery is the continuation of the external iliac artery at the level of the inguinal ligament. As well as supplying oxygenated blood to the leg, it gives off smaller branches to the anterior abdominal wall. The artery lies medial to the midpoint of the inguinal ligament, halfw...
The common hepatic artery (CHA) is a terminal branch of the coeliac artery.
Origin and course
The CHA is a terminal branch of the coeliac artery, it passes to the right in the lesser sac, and enters the lesser omentum to pass slightly upwards towards the porta hepatis. It gives ...
The common hepatic duct is formed by the junction of the right and left hepatic ducts. It joins the cystic duct to form the common bile duct. It is approximately 4 cm long and 4 mm in diameter.
Together with the cystic duct (laterally) and cystic artery (superiorly), they form Calot's triang...
The common iliac arteries (CIA) are the large paired terminal branches of the abdominal aorta.
The abdominal aorta bifurcates anterolateral (to the left side) of the L4 vertebra, into the right and left common iliac arteries.
The common iliac arteries enter the ...
The common iliac vein, corresponding with the common iliac artery, drains venous blood from the pelvis, lower limbs and their associated structures.
location: pelvis, anterior to the sacroiliac joint
origin and termination: union of internal and external iliac veins; into the inferior...
The common interosseous artery is a branch of the proximal part of the ulnar artery at the level of the pronator teres in the distal part of the cubital fossa. It is a short vessel that dives laterally and deeply before bifurcating into anterior and posterior interosseous arteries.
The common peroneal nerve, also known as common fibular nerve, forms the lateral part of the sciatic nerve and supplies the leg.
origin: one of two terminal branches of the sciatic nerve
course: diverges laterally to enter the lateral compartment of the leg
The condylar canal, or canalis condylaris, is a skull base canal in the posterior cranial fossa, located in the condylar fossa.
location: in the condylar fossa of the posterior cranial fossa, posterior to the occipital condyles
emissary veins, connecting the sigmoid sinus to...
Condyloid joints are a type of synovial joint where the articular surface of one bone has an ovoid convexity sitting within an ellipsoidal cavity of the other bone.
Condyloid joints allow movement with two degrees of freedom much like saddle joints. They allow flexion/extension, ab...
The confluence of sinuses, also known as the torcula or torcular Herophili is the site of the confluence of:
superior sagittal sinus
The anatomy is highly variable and three types can be distinguished:
type 1: superior sagittal sinus drains...
Congenital absence of a spine pedicle is a rare congenital condition, but awareness of its characteristic imaging appearance is important to avoid misdiagnosis.
Failure to recognise this entity can lead to misdiagnosis of unilateral facet subluxation/dislocation, leading to unnecessary treatmen...
Congenital absence of the internal carotid artery (ICA) is a rare anomaly that occurs in less than 0.01% of the population. It encompasses agenesis, aplasia, and hypoplasia 1.
The most common type of collateral flow is through the circle of Willis, through the anterior communicating artery (ACO...
Congenital anomalies of the posterior arch of the atlas (C1) are relatively common anomalies. They may range from partial defects presenting as clefts to complete absence of the posterior arch (aplasia).
These anomalies are classified according to Currarino (see below). It should not be confuse...
Congenital coronary artery anomalies (CCAAs) are not common, found only in ~1% (range 0.1-2%) of patients 1,3.The most important finding to look for is the "malignant" course of anomalous coronary artery, namely, does the artery run between big pulsating objects - RVOT and pulmonary artery on on...
This congenital intrahepatic portosystemic shunt classification was proposed by Park et al in 1990 1:
type 1: single large vessel of constant diameter connecting the right portal vein to the Inferior vena cava
type 2: localised, peripheral shunt with one or more communications in a single hepa...
Congenital portosystemic shunts are rare anatomical abnormalities linked to abnormal embryological venous development. They can be extrahepatic or intrahepatic. In either case, the underlying abnormality is shunting of blood from the portal venous system to the systemic venous system thus avoid...
Congenital pulmonary venolobar syndrome is a condition comprised of a rare group of cardiac and pulmonary congenital abnormalities occurring variably in combination. The abnormalities include:
anomalous pulmonary venous drainage
particularly scimitar syndrome with hypogenic right lung
Congenital urachal anomalies are a spectrum of potential anomalies that can occur due to incomplete involution of the urachus.
A urachal remnant occurs in approximately 1 in 5000 patients.
The urachus connects the dome of the bladder to the umbilical cord during fetal ...
There are many classification systems for congenital utero-vaginal anomalies. These include:
Buttram and Gibbons classification 2
American Fertility Society (AFS) classification
Modified Rock and Adam - AFS classification
Modified Rock and Adam - AFS classification
This classification divid...
A conjoined root is a type of developmental anomaly involving a nerve root.
It is the most common nerve root developmental anomaly of the cauda equina being twice as common as two roots in the same foramen, the next most common anomaly 1.
The incidence in cadaveric studies is abo...
The conjoint tendon forms when the medial fibres of the internal oblique aponeurosis unite with the deeper fibres of the transversus abdominis aponeurosis. The conjoint tendon then turns inferiorly and attaches onto the pubic crest and pecten pubis 1. It forms part of the posterior wall of the i...
The conoid ligament is one of two components forming the coracoclavicular (CC) ligament. The trapezoid ligament is the other component.
The conoid ligament takes the shape of an inverted cone. It is the posteromedial part of the coracoclavicular ligament. Its apex originates from...
The conoid tubercle also known as the coracoid tuberosity (not to be confused with the coracoid process of the scapula) is a bony prominence on the inferior surface of the lateral third of the clavicle.
It marks the insertion of the conoid ligament (which along with the trapezoid ligament) for...
A useful mnemonic to remember the contents of the cubital fossa is, from medial to lateral:
My Brother Throws Rad Parties
M: median nerve
B: brachial artery
T: tendon of biceps
R: radial nerve
P: posterior interosseous branch of radial nerve
The conus artery is a small early branch off the right coronary artery (RCA) circulation.
The artery has a variable distribution, but usually supplies a region of the anterior interventricular septum and the conus of the main pulmonary artery (hence its name).
The conus medullaris is the terminal end of the spinal cord.
After the cord terminates, the nerve roots descend within the spinal canal as individual rootlets, collectively termed the cauda equina. The conus medullaris most commonly terminates at the L1/2 intervertebral disc leve...
Cooper ligaments are the fibrous connections between the inner side of the breast skin and the pectoral muscles. Working in conjunction with the fatty tissues and the more fibrous lobular tissues, they are largely responsible for maintaining the shape and configuration of the breast. They play a...
The coracoacromial ligament is a flat triangular band that plays a supportive role for the shoulder joint.
originates from the medial border of the acromion
attaches to the lateral border of the coracoid process
overlies the subacromial bursa
indirectly supports the head of th...
The coracobrachialis is one of the three muscles of the anterior compartment of the arm. It sits beneath the biceps brachii, inserting via a flat tendon into the medial shaft of the humerus.
origin: coracoid process of scapula
insertion: via a flat tendon onto the midportion of the medial surf...
The coracoclavicular joint is a normal variant of the pectoral girdle, where the conoid tubercle of the clavicle appears enlarged or elongated, with a flattened inferior surface where it approximates the coracoid process of the scapula to form an articulation.
More common in Asia...
The coracoclavicular (CC) ligament is the major vertical stabilising factor of the acromioclavicular joint.
The coracoclavicular ligament can be divided into two parts, the more medial conoid ligament and trapezoid ligament.
origin: knuckle of the coracoid proc...
The coracohumeral ligament (CHL) is a strong supportive ligament of the shoulder joint and is a part of rotator cuff interval.
originates from the coracoid process base (lateral surface)
runs laterally across the glenohumeral capsule and covers the long head of biceps tendon su...
The coracoid process is an anteriorly projecting hook-like process on the superolateral edge of the scapula that projects anterolaterally.
coracobrachialis from the medial apex
short head of biceps brachii from the lateral apex
pectoralis minor from the m...
The corniculate cartilages are paired, elastic and accessory cartilages of the larynx that lie superior to and articulate with the apices of the arytenoid cartilages. They are components of the laryngeal cartilages. The word 'corniculate' comes from the latin word 'cornu' meaning horn-like.
The coronal suture is the cranial suture formed between the two parietal bones and the frontal bone. At the junction of coronal, sagittal and frontal sutures is the anterior fontanelle which is open at birth and usually fuses at around 18-24 months after birth.
Fusion of the coronal suture occu...
Corona mortis, Latin for "crown of death", is a common variant vascular anastomosis between the external iliac artery or deep inferior epigastric artery with the obturator artery. It is reported to be present in a third of patients on routine multi-detector CT examination 1, 4.
Knowledge of th...
The corona radiata refer to a pair of white matter tracts seen at the level of the lateral ventricles. Superiorly they are continuous with the centrum semiovale. Inferiorly these tracts converge as the internal capsule.
Coronary arterial dominance is defined by the vessel which gives rise to the posterior descending artery (PDA), which supplies the myocardium of the inferior 1/3rd of the interventricular septum.
Most hearts (80-85%) are right dominant where the PDA is supplied by the RCA. The remaining 15-20% ...
The coronary arteries arise from the coronary sinuses immediately distal (superior) to the aortic valve and supply the myocardium with oxygenated blood. They branch and encircle the heart to cover its surface with a lacy network resembling perhaps a slightly crooked crown.
The coronary sinus is the major coronary vein. It returns the majority of the left ventricular blood flow to the right atrium.
The coronary sinus courses along the posterior wall of the left atrium into the left atrioventricular groove. It normally drains into the right atrium. T...
The coronary veins return deoxygenated blood from the myocardium back to the right atrium. Most venous blood returns via the coronary sinus. Coronary venous anatomy is highly variable, but is generally comprised of 3 groups of veins:
cardiac veins which drain into the coronary sinus:
Coronoid process can refer to a number of different anatomical structures:
coronoid process (mandible)
coronoid process (ulna)
The corpora quadrigemina (Latin for "quadruplet bodies") are the four colliculi, two inferior and two superior, that sit on the quadrigeminal plate on the posterior surface of the midbrain.
The corpora quadrigemina are reflex centres involving vision and hearing:
superior colliculi: involved i...
The corpus albicans is a fibrous scar that results from the involution of the corpus luteum if fertilisation does not occur. When seen on ultrasound, it is a small, lobulated echogenic intra-ovarian lesion.
History and etymology
It is Latin for "whitening body", after the white appearance of ...
The corpus callosum (CC) is the largest of the commissural fibres, linking the cerebral cortex of the left and right cerebral hemisphere. It is the largest fibre pathway in the brain.
The corpus callosum is approximately 10 cm in length and is C-shaped, like most of the supratent...
The corpus luteum is a temporary endocrine structure involved in ovulation and early pregnancy.
During ovulation, the primary follicle forms the secondary follicle and subsequently the mature vesicular follicle.
At ovulation the follicle ruptures expelling the ovum into the fallopian tube. The...
The corpus striatum is a collective name given to the caudate nucleus and lentiform nucleus.
History and etymology
The term originates from the Latin "striatus", meaning "striped", referring to the caudatolenticar bridges of grey matter crossing the internal capsule from the putamen to the cau...
The corrugator supercilii are two small, triangular muscles that allow facial expression through movement of the eyebrows, including frowning. They originate from the medial end of the supraorbital margins and insert deep to and can cause traction on the skin over the middle of the supraorbital ...
The outer shell of compact bone is called cortical bone or cortex.
Cortical bone contains Haversian systems (osteons) which contain a central Haversian canal surrounded by osseous tissue in a concentric lamellar pattern.
Two fibrovascular layers surround the cortical bone which...
The corticorubral tract contains neurons that connect the primary motor and sensory areas to the red nucleus. The rubrospinal tract then descends through the spinal cord.
The tract is thought to excite flexor muscles and inhibit extensor muscles.
The corticospinal tract is a descending neural pathway primarily concerned with motor function extending from the motor cortex down to synapse with motor neurones of the spinal cord.
Corticospinal fibres arise from neurones in the cerebral cortex. Most of th...
The costal cartilages form part of the thoracic cage and anterior chest wall. There are 10 costal cartilages, one for rib 1-10, with each of which forms a costochondral joint. Costal cartilages 1-7 articulate with the sternum at sternocostal joints, and costal cartilages 8-10 are attached to eac...
The costocervical trunk is one of the branches of the second part of the subclavian artery. It arises from the posterior wall of the subclavian artery, posterior or medial to the anterior scalene muscle and courses posterosuperiorly across the suprapleural membrane where it divides into 2 branc...
The costochondral joints are the joints between each rib and its costal cartilage. They are primary cartilaginous joints. These joints represent the demarcation of the unossified and ossified part of the rib 1. The joint is held together by periosteum, with the lateral aspect of the costal ca...