Compressor naris forms the transverse component of nasalis muscle, is one of the muscles of the nose, a subset of the muscles of facial expression.
origin: frontal process of maxilla
insertion: medial insertion into a transverse aponeurosis
innervation: facial nerve (VII)
Concha bullosa (plural: conchae bullosae) (also known as middle turbinate pneumatisation) is a common finding and although associated with deviation of the nasal septum, it is usually of little clinical importance.
Concha bullosa is a normal variant and is one of the most common v...
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, i.e. does the artery run between big pulsating objects - right ventricular outflow tract / ...
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 hep...
Congenital portosystemic shunts are rare, extrahepatic or intrahepatic, anatomical abnormalities shunting blood from the portal venous system to the systemic venous system and, thus, avoiding passage through the hepatic acinus.
The term “portosystemic shunt” can be used to refer t...
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.
The incidence in cadaveric studies is about ...
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 conjunctiva is a transparent membrane is attached at the margins of the cornea. It is loosely attached to the sclera and thence reflected over the inner surface of the eyelids. It is firmly attached to the tarsal plates and blends with the skin at the margins of the lids.
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 lateral surface of the base of the coracoid process
runs laterally across the glenohumeral capsule and covers the long head of bicep...
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 cornea forms the fibrous layer of the anterior portion of the eye. It functions to refract light entering the eye.
location: anterior one-sixth of the eyeball
blood supply: avascular
innervation: long ciliary nerves
relations: continuous with the sclera posteriorly and covered...
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 thi...
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 three groups:
cardiac veins which drain into the coronary sinus:
great cardiac ...
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 is the largest of the commissural fibres, linking the cerebral cortex of the left and right cerebral hemisphere. It is the largest white matter tract in the brain.
located inferior to the cerebral cortices, and superior to the thalamus
connects left and right cereb...
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 within the basal ganglia.
History and etymology
The term originates from the Latin "striatus", meaning "striped", referring to the caudatolenticar bridges of grey matter crossing the internal capsule fr...
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 white matter tract primarily concerned with motor function extending from the motor cortex down to synapse with motor neurones of the spinal cord in the anterior horns.
Corticospinal fibres are axons from upper motor n...
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...
The costoclavicular ligament or rhomboid ligament is the major stabilising factor of the sternoclavicular joint.
The costoclavicular ligament binds the inferior medial clavicle (via the rhomboid fossa) to the first costal cartilage and adjacent end of the first rib. It is compose...
The costoclavicular space is the anterior portion of the superior thoracic aperture, between the clavicle and first rib. The subclavian vessels and brachial plexus pass though the space related to the scalene muscles. Proximally, the plexus passes through the interscalene space, and distally thr...
The costovertebral joint is an articulation between the ribs and the vertebral column.
The ribs articulate with the thoracic vertebrae via two distinctly different joints:
costovertebral joint - articulation between the head of the rib and the vertebral body
The costoxiphoid ligaments, also known as the chondroxiphoid ligaments, are inconstant fibrous structures joining the anterior and posterior surfaces of the xiphoid to the respective surfaces of the adjacent seventh and, occasionally, sixth costal cartilages.
The Couinaud classification (pronounced kwee-NO) is currently the most widely used system to describe functional liver anatomy. It is the preferred anatomy classification system as it divides the liver into eight independent functional units (termed segments) rather than relying on the tradition...
Pauli et al published a "handy" way to remember the Couinaud classification of hepatic segments 1.
Make a fist with your right hand. The fingers should be wrapped around the flexed thumb and the fist should face you. The segments are represented by the following:
segment I: (caudate): the thum...
A coumadin ridge, also called warfarin ridge or left lateral ridge, is a band-like embryological remnant in the left atrium between the left superior pulmonary vein and the left atrial appendage. It is considered an anatomical variant.
The ridge is formed by the coalition of the left superior ...
The cranial foramina are the holes that exist in the base of skull to allow the passage of structures into and out of the cranium:
anterior ethmoidal foramen
The cranial nerves are the 12 paired sets of nerves that arise from the cerebrum or brainstem and leave the central nervous system through cranial foramina rather than through the spine. The cranial nerves are numbered one to twelve using the Roman numerals, I to XII.
The first and se...
There are many cranial nerve mnemonics that can be memorable and rude/lewd. Either way, they can be helpful for remembering the names of the twelve cranial nerves, as well as remembering which nerves are sensory, motor, or both.
Remembering cranial nerve names in order of CN I to CN XII:
The cranial vault, also known as the skull vault, skullcap or calvaria, is the cranial space that encases and protects the brain together with the base of the skull (chondrocranium). The cranial vault and the base of skull together form the neurocranium.
Although commonly seen in r...
The cremasteric artery is a small branch of the inferior epigastric artery that enters the deep inguinal ring of the inguinal canal and supplies the layers of the spermatic cord and also the skin of the scrotum, including the cremaster muscle.
History and etymology
The word "cremaster" derives...
The cremaster muscle is the thin fascial muscle of the spermatic cord made of skeletal muscle. It is also referred to as cremaster fascia or simply the cremaster. Its action is to retract the testes, important in thermoregulation and spermatogenesis.
It is derived from the inter...
The crests of Duret attach the most numerous superficial breast lobes by their summit to the superficial layer of fascia. The deepest crests connect the anterior lobes to the deep layer through the Cooper's ligament.
Breast lobe groups about one hundred lobules separated by interlobular connect...
The cribriform plate is a sieve-like structure between the anterior cranial fossa and the nasal cavity. It is a part of ethmoid bone and supports the olfactory bulb, which lies in the olfactory fossa. It is perforated by foramina for the passage of the olfactory nerves and the anterior ethmoidal...
The cricoid cartilage is a ring shaped structure that sits just below the thyroid cartilage. It is the only complete cartilaginous ring of the whole airway.
The anterior portion is called the arch and the posterior quadrangular shaped portion is the lamina. It articulates with th...
The crista galli is a thick, midline, smooth triangular process arising from the superior surface of the ethmoid bone, projecting into the anterior cranial fossa. It separates the olfactory bulbs, which lie either side of it in the olfactory fossae of the cribriform plate. It serves as an anteri...
The crista terminalis is a smooth muscular ridge in the superior aspect of right atrium. It represents the junction between the sinus venosus and the heart. It divides the pectinate muscle origin and the right atrial appendages in the right atrium.
Its identification is significant in the deter...
The critical zone of the rotator cuff is an area approximately 8-15 mm from the insertion of the rotator cuff tendons onto the greater tubercle of the humeral head, mainly within the supraspinatus tendon. This is a watershed zone between the anterior and posterior circumflex humeral, thoracoacro...
Crossed fused renal ectopia refers to an anomaly where the kidneys are fused and located on the same side of the midline.
The estimated incidence is around 1 out of 1000 births 1. There is a recognised male predilection with a 2:1 male to female ratio. More than 90% of crossed ren...
Crossed renal ectopia is said to be present when the kidney is seen in the opposite retroperitoneal space. It is more common for the left kidney to be ectopically located on the right side. More than 85% of these get fused resulting in crossed fused renal ectopia. Less than 15% cases are non-fus...
The cruciate ligament of the atlas (also known as the cruciform ligament) is an important ligamentous complex that holds the posterior dens of C2 in articulation at the median atlantoaxial joint. It lies behind a large synovial bursa (surrounded by loose fibrous capsule) and consists of two band...
The crystalline lens (or simply, the lens, plural: lenses) is in the ocular globe between the posterior chamber and the vitreous body. It is transparent and biconvex in morphology, and aids the focusing of light onto the retina.
The lens lies in the globe at the poster...
Multi-slice CT angiography of the splanchnic vessels is a powerful minimally invasive technique for evaluation of the splanchnic vascular system.
The actual procedure will vary depending on institutional protocol/guidelines but below is a typical description 2, 4:
CT cerebral venography is a contrast enhanced examination with an acquisition delay providing an accurate detailed depiction of the cerebral venous system.
Rapid diagnosis of cerebral venous thrombosis.
general CT contraindications such as pregnancy, etc.
The cubital fossa is a triangular space which forms the transition between the arm and the forearm. It is located anterior to the elbow joint.
superior: the line joining the medial and lateral humeral epicondyles
lateral: medial border of brachioradialis
The cubital tunnel is a space through which the ulnar nerve passes posterior to the medial epicondyle of the humerus.
cubital tunnel retinaculum (also known as ligament or band of Osborne), extends from the olecranon to the medial epicondyle
The cuboid bone is one of the tarsal bones located lateral to the lateral cuneiform bone and has an important articulation with the calcaneus.
The cuboid is a wedge shaped bone, being widest at its medial edge and narrow at its lateral edge. It has three main articular...
The cuneate fasciculus, also known as the fasciculus cuneate or column of Burdach, 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 cuneiform cartilage is a small, paired cartilage which resides in the aryepiglottic fold. It takes the form of a club-like nodule, visible as an elevation beneath the mucosa (the cuneiform tubercle) anterosuperior to the corniculate cartilages.
History and etymology
The word cuneiform deri...
The cuneus is a wedge-shaped region on the medial surface of the occipital lobe.
Anterosuperiorly the parieto-occipital sulcus separates the cuneus from the precuneus of the parietal lobe.
Posteroinferiorly the cuneus abuts the calcarine sulcus which separates it from...
A cyamella is a rare sesamoid bone that exists as a normal variant within the popliteus tendon, characteristically located at the lateral aspect of the distal femur in the popliteal groove.
Cyamella is best seen on the AP view of plain radiograph as opposed to fabella, which is best appreciated...
The cystic artery represents the main blood supply to the gallbladder. It most commonly arises from the right hepatic artery within Calots triangle 1.
The cystic artery passes posterior to the cystic duct to reach the neck of the gallbladder. At this point, it gives off two-to-fo...
The cystic duct connects the neck of the gallbladder to the common hepatic duct (CHD), draining bile to and from the biliary tree.
The confluence of the cystic duct and the common hepatic duct forms the common bile duct. The cystic duct is approximately 2-3 cm long and 2-3 mm in ...
The danger space is a potential space located behind the true retropharyngeal space, which connects the deep cervical spaces to the mediastinum.
anteriorly: alar fascia
posteriorly: prevertebral layer of the deep cervical fascia
The dartos muscle is the thin rugated fascial muscle of the scrotum made of smooth muscle. Hence it is also referred to as dartos fascia or simply the dartos. It forms from the subcutaneous tissue of the scrotum and base of the penis and attaches to the scrotal skin and fibrous midline septum be...
The deep auricular artery is the first named branch of the maxillary artery and passes through the bony or cartilaginous wall of the external acoustic meatus to supply the skin of that canal and part of the tympanic membrane. It can sometimes contribute a small branch to the arterial supply of t...
The deep brachial artery or profunda brachii artery is a large branch of the brachial artery, located in the arm.
origin: brachial artery
location: posterior aspect of the arm
supply: triceps brachii
main branches: middle collateral and radial collateral arteries
Deep bursae are those bursae that are located deep to the fibrous fascia and are normally located between muscles or muscle and bone. These bursae form in utero alongside synovial joint formation 1.
In contrast, superfical bursae are located superficial to the fibrous fascia.
The deep cerebral veins drain the deep white matter and grey matter that surround the basal cisterns and ventricular system. The deep veins are responsible for the outflow of approximately the inner 80% of the hemisphere. They provide useful landmarks for skull base and intraventricular surgery ...
The deep cervical fascia consists of 3 separate but related fascial layers that encircle structures in the neck and allow anatomic compartmentalisation. These layers cannot be visualized directly by cross sectional imaging. All 3 layers meet to form the carotid sheath. From superficial to deep, ...
The deep circumflex iliac artery arises from the external iliac artery.
origin: lateral aspect of the external iliac artery above the inguinal ligament, almost opposite to the inferior epigastric artery
course: travels superiorly parallel to the inguinal ligament towards the ant...