The fornix conjunctiva is loose soft tissue lying at the junction between the palpebral conjunctiva (covering the inner surface of the eyelid) and the bulbar conjunctiva (covering the globe). Each eye has two fornices, the superior and inferior fornices. The fornix permits freedom of movement of...
The fornices are superior recesses of the vagina formed by the protrusion of the cervix into the vaginal vault. There is a large posterior fornix and a smaller anterior fornix with two small lateral fornices.
History and etymology
Fornix is Latin for 'arch'.
The fossa navicularis refers to a normal mild dilatation of the urethra. It occurs at the most distal/downstream portion of the urethra.
It is more evident in males, where it occurs in the penile/pendulous urethra, near the urethral meatus. There is also a fossa navicularis in women: the more f...
The fossa of Rosenmüller, also known as the posterolateral or pharyngeal recess, is the most common site of origin for nasopharyngeal carcinoma.
It is located superior and posterior to the torus tubarius (the posterior projection of the cartilaginous portion of the Eustachian tub...
The fossa ovale (or ovalis) is the small oval depression in the interatrial septum at the site of the closed foramen ovale, which closes once fetal circulation ceases in the first few minutes of postnatal life. It represents the overlapping primary and secondary septa of the interatrial septum. ...
The fourth ventricle is one of the components of the ventricular system in the brain, along with the lateral and third ventricles. It extends from the cerebral aqueduct (of Sylvius) to the obex and is filled with CSF.
CSF enters the ventricle via the cerebral aqueduct and leaves via one of four...
The fovea ethmoidalis is a portion of the ethmoid bone and represents its superior portion (part of the ethmoid roof) which is seen as a continuation of the superior orbital roof to the cribriform plate.
A foveola pharyngica recess is one of the variants of the inferior median clival canal, thought to represent a remnant of the notocord. It represents a blind ending recess in the anteroinferior surface (nasopharyngeal) surface of the clivus 1,2.
The frontal bone is a skull bone that contributes to the cranial vault. It contributes to form part of the anterior cranial fossa.
The frontal bone has two portions:
vertical portion (squama): has external/internal surfaces
horizontal portion (orbital): has superior/inferior su...
The frontal lobe is by far the largest of the four lobes of the cerebrum, and is responsible for many of the functions which produce voluntary and purposeful action.
The frontal lobe is the largest lobe accounting for 41% of the total neocortical volume 8. The frontal lobe resid...
The frontal nerve is a largest and main branch of the ophthalmic division of the trigeminal nerve. It divides off the ophthalmic division just before entering the orbit through the superior orbital fissure outside and superolateral to the tendinous ring, where it lies between the lacrimal nerve ...
The frontal pole is one of the three poles of the brain (along with the occipital pole and temporal pole), and corresponds to the anterior most rounded point of the frontal lobe.
It does not have easily defined boundaries, but is roughly equivalent to the frontopolar cortex, which in turn is co...
The frontal sinuses are the paranasal sinuses within the frontal bone. They are lined with mucosa and are most often two in number.
location: anterior frontal bones on either side of the midline behind the brow ridges
blood supply: supratrochlear, supraorbital and anterior ethmoidal a...
The frontoethmoidal suture is a short cranial suture located in the anterior cranial fossa, between the orbital process of frontal and orbital plate of ethmoid bones. It forms part of the medial wall of the orbit.
The anterior and posterior ethmoidal foramina are seen just superior to it, throu...
The frontolacimal suture is the cranial suture between the frontal and lacrimal bones.
The frontomaxillary suture is the site where the nasal process of frontal bone meets the frontal process of the maxilla.
The frontonasal suture is the cranial suture between the frontal bone and the two nasal bones. This suture meets the internasal suture at the nasion.
The frontopolar artery is a branch of the A2 segment of the anterior cerebral artery (ACA), commonly arising after the medial frontobasal artery and coursing obliquely across the medial surface of the cerebral hemisphere towards the frontal pole.
The frontopolar cortex is located at the frontal pole of each frontal lobe, and is comprised of three roughly horizontal gyri: superior, middle and inferior frontopolar gyri.
It contains Brodmann area 10, which is thought to contribute to many aspects of cognition 1,2.
Despite many studies re...
The frontozygomatic suture (or zygomaticofrontal suture) is between the frontal process of the zygomatic bone and the zygomatic process of the frontal bone.
Fundus (plural: fundi) is used as an anatomical term for many organs and is generally used in the sense of a part that is the lower part or is distant from the main aperture:
fundus (urinary bladder)
fundus (internal acoust...
The fusiform gyrus, also known as the temporo-occipital gyrus is a structure that lies on the basal surface of the temporal and occipital lobes. It forms part of Brodmann area 37, along with the inferior and medial temporal gyri. As its name suggests, it is composed of a temporal or anterior por...
The galea aponeurotica (also called the Galeal or epicranial aponeurosis or the aponeurosis epicranialis) is a tough fibrous sheet of connective tissue that extends over the cranium, forming the middle (third) layer of the scalp.
The gallbladder is a pear-shaped musculomembranous sac, lodged in a fossa on the undersurface of the right lobe of the liver, and extending from near the right extremity of the porta hepatis to the anterior border of the liver.
It typically measures from 7 to 10 cm in length and...
Agenesis of the gallbladder is a rare congenital anomaly.
The incidence is <0.1% (range 0.04-0.1%). There is strong female predominance present among the symptomatic cases.
Most patients with agenesis of the gallbladder are asymptomatic. Although some patie...
Gallbladder duplication is a rare anatomic anomaly characterised by the presence of an accessory gallbladder. There is no increased risk for malignancy or calculi compared to a single gallbladder.
Prevalence is estimated at 1 in 3000.
Boyden's classification divi...
Gallbladder triplication is an extremely rare anomaly. There are three types of gallbladder triplication are described according to the number of cystic duct and their insertion:
Three gallbladders and three cystic ducts which unite to form a common cystic duct before joining the common bile du...
Gastric lymph node stations were originally divided into 16 groups proposed by the Japanese Research Society for Gastric Cancer in 1963.
The areas of stomach which drain into regional lymph nodes:
cardia and proximal lesser curvature drain into left gastric lymph nodes, then int...
The gastrocnemius muscle is one of the calf muscles (triceps sure) in the superficial posterior compartment of the leg which sits superificial to the much larger soleus muscle. It gives the calf its distinctive two-headed appearance and is a primary plantarflexor.
origin: superior to a...
The gastroduodenal artery is a terminal branch of the common hepatic artery which mainly supplies the pylorus, proximal duodenum, and the head of the pancreas. Due to its proximity to the anterior wall of the first part of the duodenum, the gastroduodenal artery is one of the most important sour...
The gastrointestinal tract includes any part of the oral cavity, oropharynx, hypopharynx, oesophagus, stomach, small bowel, colon, rectum and anal canal.
The gastro-oesophageal junction (GOJ) (also known as the oesophagogastric junction) is the part of the gastrointestinal tract where the oesophagus and stomach are joined.
The GOJ is normally mostly intra-abdominal and is 3-4 cm in length. To some extent, the oesophagus slides in ...
The gastrosplenic ligament is a peritoneal ligament which is formed by ventral part of dorsal mesentery.
The gastrosplenic ligament extends from the greater curvature of the stomach to the hilum of the spleen. It contains the short gastric arteries.
General anatomy is best described as the study of general anatomic concepts and structures removed from the specific regional anatomy focus.
To facilitate clinical description, the general topography of the abdomen is divided into four quadrants or nine regions by lines on the surface of the anterior abdominal wall. The four quadrants are created by vertical and horizontal lines passing through the umbilicus, whereas the nine regions...
The geniculate ganglion contains fibres for taste and somatic sensation and is located in the petrous temporal bone.
It is located at the first genu of the facial nerve at the anterior most part of the Fallopian canal at the junction between the labyrinthine and tympanic segment...
The genioglossus muscle is a fan-shaped extrinsic muscles of the tongue which makes up the bulk of the tongue.
origin: superior mental spine of the symphysis menti (posterior surface of midline mandible)
insertion: entire tongue mass and body of the hyoid bone
nerve supply: hypogloss...
The geniohyoid muscle is one of the suprahyoid muscles of the neck that is innervated by the ventral ramus of C1. Geniohyoid draws the hyoid bone up and forward during mastication and assists the opening of the mandible.
origin: inferior mental spine of the mandible also known as the g...
The genitofemoral nerve is a branch of the lumbar plexus arising within the substance of the psoas major muscle from the union of anterior rami of L1 and L2 spinal nerves. The nerve descends in the retroperitoneum to give off genital and femoral terminal branches supplying the skin over the ante...
Gerdy's tubercle is the eponymous name for the lateral condyle of the proximal tibia (where it is located anterolaterally). It is where the iliotibial band and anterior tibialis muscle inserts.
The Giacomini vein or thigh extension of the short saphenous vein refers to a variation in lower limb venous anatomy where the short saphenous vein (SSV) continues through to the thigh as a distinct branch.
The persistence of this vein may play a contributory role in the development of chronic ...
Gilula three carpal arcs refer to the alignment described on posteroanterior or anteroposterior wrist radiographs and are used to assess normal alignment of the carpus:
first arc: is a smooth curve outlining the proximal convexities of the scaphoid, lunate and triquetrum
second arc: traces the...
The glabella is the smooth midline bony prominence between the supraciliary arches of the frontal bone, representing the most anterior part of the forehead when standing erect and look straight ahead. The metopic suture traverses the glabella, between the two frontal bones. Just below it is the ...
The glenohumeral joint is a synovial joint between the head of the humerus and the glenoid.
articulation: ball and socket joint between the head of the humerus and the glenoid
ligaments: glenohumeral, coracohumeral and transverse humeral ligaments
movements: arm flex...
There are three glenohumeral ligaments (GHL), which are thickenings of the glenohumeral joint capsule and are important passive stabilisers of the joint.
Superior glenohumeral ligament
runs from the superior aspect of the glenoid and coracoid process to the fovea capitis just s...
The glenoid or glenoid cavity or fossa is the shallow depression of the scapula found on the lateral angle.
glenoid labrum: the cavity has a fibrocartilaginous structure on its margin called the glenoid labrum which is continuous superiorly with the tendon of the lo...
The glenoid labrum is a fibrocartilaginous structure that attaches as a rim to the articular cartilage of the glenoid fossa and serves to deepen and increase the surface area. In this capacity, it acts as a static stabiliser of the glenohumeral joint, preventing dislocation and subluxation at th...
There are a number of glenoid labral variants, whose importance is mainly due to the fact that the unwary may misinterpret them as pathology (e.g. Bankart lesion or labral tear). These include:
superior sublabral sulcus
Glial cells, or neuroglia, are cells that surround the neurones of the central nervous system embedded between them, providing both structural and physiological support 1-3. Together they account for almost half of the total mass 1 and 90% of all cells of the central nervous system 3.
The globes or simply, the eyes are paired spherical sensory organs, located anteriorly on the face within the orbits, which house the visual apparatus.
The globe is suspended by the bulbar sheath in the anterior third of the bony orbit.
Each globe is an approxim...
The globus pallidus (plural: globus pallidi) is a paired structure and one of the nuclei that make up the basal ganglia. It is a subcortical structure at the base of the forebrain and in anatomical relation to the caudate nucleus and putamen. It forms the lentiform nucleus with the putamen.
The glomus body is a component of the dermis that is involved in thermoregulation.
It consists of a specialised arteriovenous anastomosis surrounded by a connective tissue capsule. They are most numerous in the fingers and toes and exist to shunt blood from the skin surface when...
The glossopharyngeal nerve is the ninth (IX) of the twelve pairs of cranial nerves. It exits the brainstem out from the sides of the upper medulla, just rostral to the vagus nerve and has sensory, motor, and autonomic components.
The sensory ganglion cells lie in the supe...
The superficial gluteal muscles lie within the gluteal region posterolateral to the bony pelvis and proximal femur. From superficial to deep lie the gluteus maximus, medius and minimus. The gluteus maximus is an important in hip extension and lateral rotation. Gluteus medius and minimus are hip ...
The gluteus maximus is the largest muscle in the gluteal region and overlies most of the other gluteal muscles.
gluteal surface of the ilium behind the posterior gluteal line
the lumbar fascia
lateral mass of sacrum
insertion: gluteal tuberosity of th...
The gluteus medius and gluteus minimus muscles are two muscles of the more superficial group in the gluteal region.
origin: gluteal surface of the ilium between the posterior and anterior gluteal line
insertion: posterolateral surface of the greater trochanter of femur
The gluteus minimus and gluteus medius muscles are two muscles of the more superficial group in the gluteal region.
origin: gluteal surface of the ilium between the anterior and inferior gluteal lines
insertion: anterior surface of the greater trochanter of femur
arterial supply: sup...
The glymphatic pathway has only recently been described and functionally represents the brain’s lymphatic system, although no anatomical structure equivalent to the peripheral lymphatic system is present within the brain parenchyma. It is believed to be a crucial normal homeostatic feature allow...
The gonadal arteries are the paired primary vascular supply to the ovaries in the female and the testes in the male. As the anatomy of the gonadal arteries differs substantially between the sexes, they are covered separately:
The gonadal veins are paired structures that drain the gonads in males and females. In males it is called the testicular vein and in females it is called the ovarian vein. The gonadal veins ascend with the gonadal arteries in the abdomen along the psoas muscle anterior to the ureters. Like the s...
The gracilis is the most superficial muscle in the medial compartment of the thigh and descends almost vertically down the medial side of the thigh.
origin: a line on the external surfaces of the body of the pubis, inferior pubic ramus, and the ramus of the ischium
insertion: medial s...
The great cardiac vein (GCV) runs in the anterior interventricular groove and drains the anterior aspect of the heart where it is the venous complement of the left anterior descending artery. It is the main tributary of the coronary sinus.
It begins on the anterior surface of th...
The greater auricular nerve is a cutaneous branch of the cervical plexus that innervates the skin of the auricle as well as skin over the parotid gland and mastoid process. The greater auricular nerve also supplies branches that innervate the deep layer of the parotid fascia.
The greater (descending) palatine artery is a branch of the third part of the maxillary artery which passes through the greater palatine foramen to supply most of the hard palate.
After branching off from the third (pterygopalatine) part of the maxillary artery, the greater palat...
The greater occipital nerve is a spinal nerve that innervates the skin of the occiput and upper neck.
The greater occipital nerve arises from the medial branch of the dorsal ramus of C2.
The greater occipital nerve emerges between axis (C2) and the obliquus capit...
The greater palatine foramen is the opening in the posterior hard palate of the greater palatine canal, which is formed between the articulation of maxillary bone and the greater palatine sulcus of palatine bone. The canal is also known as the pterygopalatine canal. A small accessory canal branc...
The greater palatine nerve (or anterior palatine nerve) is a branch of the maxillary division of the trigeminal nerve and contributes to the pterygopalatine ganglion.
The greater palatine nerve divides off the maxillary division just after emerging from the foramen rotundum to en...
The greater sciatic foramen is a foramen within the pelvis and is a major conduit of neurovascular structures from the pelvis to the lower limb.
In a clockwise fashion, its boundaries include:
superior: anterior sacroiliac ligament
posteromedial: sacrotuberous liga...
The greater sciatic notch is a large notch in the pelvis above the ischial spine. The addition of the sacrospinous ligament converts the notch into the greater sciatic foramen.
The greater (superficial) petrosal nerve originates at the geniculate ganglion, where the nervus intermedius and facial nerve join. It contains mainly preganglionic parasympathetic fibers and some sensory taste afferent from the soft palate.
It arises at the geniculate ganglion, passes through ...
The greater trochanteric bursa is located posterior to the greater trochanter of the femur, subjacent to the iliotibial band.
The clinical importance of the bursa lies in the fact that it commonly becomes inflamed (see: trochanteric bursitis).
The greater wing or ali-sphenoid of the sphenoid bone is a process which projects from either side of the lower part of the sphenoid body, at a common junction with the pterygoid process. 1 It is a paired structure, which curves upward, backward and laterally from each side of the sphenoid body,...
The great saphenous vein (GSV) forms part of the superficial venous system of the lower limb.
Origin and course
The GSV lies within the subcutaneous tissues of the leg in the thigh in the saphenous compartment, which is bounded posteriorly by the deep fascia and superficially b...
The great vessel space is the fourth retroperitoneal space along with the anterior and posterior pararenal spaces, and the perirenal space 1, 2. Unlike other retroperitoneal spaces, it is not well-defined by fascial planes and thus disease process affecting other retroperitoneal spaces can also ...
The Griffiths point (or Griffiths critical point) refers to the site of watershed anastomosis between the ascending left colic artery and the marginal artery of Drummond occurring in the region of the splenic flexure. Most anatomy texts describe the location as two-thirds along the transverse co...
Gudden’s commissure, also called the ventral supraoptic decussation, is one of three tracts that comprise the supraoptic commissure 1,2. The remaining two tracts that comprise the supraoptic commissure are Meynert's commissure (dorsal supraoptic commissure) and the anterior hypothalamic commiss...
Guyon’s canal is a fibro-osseous tunnel extending from the transverse carpal ligament at the proximal aspect of the pisiform to the origin of the hypothenar muscles at the hook of hamate. It is approximately 4 cm in length.
roof: palmar carpal ligament, palmaris brevi...
The gyrus rectus, or straight gyrus, is located at the medial most margin of the inferior surface of frontal lobe 1,2. Its function is unclear but it may be involved in higher cognitive function (e.g. personality) 3.
The gyrus rectus is bounded medially by the interhemispheric fi...
The habenula is part of the epithalamus and receives input from the brain via the stria medullaris. It outputs to many midbrain areas involved in releasing neuromodulators, such as dopamine, norepinephrine, and serotonin.
The habenula was traditionally divided into lateral (limbic) and medial (...
Haemorrhagic cholecystitis refers to an inflammatory process of the gallbladder, complicated by haemorrhage into the lumen.
The presenting features may mimic non-haemorrhagic acute cholecystitis, with right upper quadrant pain being a dominant feature. If the blood is pa...
Haller cells are also known as infraorbital ethmoidal air cells or maxilloethmoidal cells. They are extramural ethmoidal air cells that extend into the inferomedial orbital floor and are present in ~20% (range 2-45%) of patients, depending on their exact definition 1-3.
In most instances they a...
The Haller index (HI), also known as the pectus index, is a simple mathematical way to assess and describe the chest cage on CT of the thorax and is used in the detection of pectus excavatum, as well as preoperative and postoperative assessment 1,5.
The Haller index is calculated by ...
The hallux sesamoid bones are paired ossicles of the foot. They function as a fulcrum to increase the leverage of both flexor hallucis brevis and longus.
The hallux sesamoids are ovoid-shaped ossicles. There is a medial (tibial) and lateral (fibular) hallux sesamoid and are embe...
The hamate is one of the carpal bones, forms part of the distal carpal row and has a characteristic hook on its volar surface.
The hamate has a wedge-shaped body. It bears an uncinate (unciform) hamulus (hook of hamate) which projects in a volar fashion from the dista...
The hamstrings are the muscles of the posterior compartment of the thigh and include the:
lateral: biceps femoris
medial: semimembranosus and semitendinosus
Apart from the short head of biceps femoris, the muscles share two common features:
span both the hip and knee joints and therefore pro...
All the intrinsic muscles of the hand are innervated by the ulnar nerve, except four muscles which are supplied by the median nerve and are easily recalled with the mnemonic:
FOAL or LOAF
F: flexor pollicis brevis
O: opponens pollicis
A: abductor pollicis brevis
L: lateral two lum...
The hand is part of the upper limb below the forearm and wrist. In the supinated anatomical position, the palm is facing anteriorly. The bones of the hand are:
The hard palate is the anterior horizontal bony part of the palate that forms the roof of the oral cavity and floor of the nasal cavity. It is formed by the palatine processes of the maxillae and the horizontal plates of the palatine bones. On its inferior oral surface it is lined by oral mucosa...
The haustral folds represent folds of mucosa within the colon. They are formed by circumferential contraction of the inner muscular layer of the colon.
The outer longitudinal muscular layer is organised into three bands (taeniae coli) which run from the caecum to the rectum. These muscular band...
Head and neck anatomy is important when considering pathology affecting the same area. In radiology, the 'head and neck' refers to all the anatomical structures in this region excluding the central nervous system, that is, the brain and spinal cord and their associated vascular structures and en...
The heart is a hollow, muscular organ of the middle mediastinum, designed to pump oxygenated blood around the systemic circulation and de-oxygenated blood around the pulmonary circulation
The heart has a somewhat conical form and is enclosed by pericardium. It is positioned poste...
There are four heart chambers, the right atrium, left atrium, right ventricle and left ventricle. These receive blood from the body and lungs, and contract to transmit blood to the lungs for oxygenation and to the body for use in metabolism.
It is best to list the four chambers in order of the ...
The hemiazygos vein is the asymmetric counterpart to the azygos vein and forms part of the azygos venous system.
The hemiazygos vein is formed by the confluence of the left ascending lumbar and left subcostal veins.
The hemiazygos vein enters the thorax either ...