The supravesical fossae are concave depressions of peritoneum in the paravesical space bounded by the median umbilical fold and the medial umbilical folds. It partially overlies the inguinal (Hesselbach’s) triangle. The supravesical fossae are usually occupied by small bowel loops and the urinar...
The supreme intercostal arteries, or superior intercostal arteries, are formed as a direct result of the embryological development of the intersegmental arteries. These arteries are paired structures of the upper thorax which normally form to provide blood flow to the first and second intercosta...
The supreme meatus is an air passage of the lateral nasal cavity located between the supreme nasal concha and lateral nasal wall. The ostium of a posterior ethmoidal air cell may be seen in the supreme meatus.
The plural of meatus is meatus (Latin noun of the fourth declension) or ...
The supreme nasal concha or turbinate is one of the conchae in the nose and is a bony projection, arising from the medial surface of the labyrinth of the ethmoid above the superior nasal concha. Its presence is variable and has been reported in up to 52% of subjects 1.
The air passage between t...
The suspensory ligament of the axilla is the inferior extension of the clavipectoral fascia on each side of the thorax.
The suspensory ligament of the axilla originates from the inferior border of pectoralis minor, where the 'leaflets' of the clavipectoral fascia have fused again...
The sustentaculum tali is a horizontal shelf that arises from the anteromedial portion of the calcaneus. The superior surface is concave and articulates with the middle calcaneal surface of the talus. The inferior surface has a groove for the tendon of flexor hallucis longus.
There are many sutures of the skull, which are where skull bones meet. In general, sutures don't fuse until brain growth is complete, therefore allowing the skull to increase in size with the developing brain.
Sutures are fibrous joints with the periosteum externally and outer la...
The Sylvian cistern, also known as the insular cistern, is one of the CSF-filled subarachnoid cisterns.
There are two paired cisterns on either side. It is the transitional subarachnoid space between the rest of the basal cisterns and the Sylvian fissure (lateral sulcus) 2.
The Sylvian fissure, also known as the lateral sulcus, separates the frontal and parietal lobes superiorly from the temporal lobe inferiorly. The insular cortex is located immediately deep to the Sylvian fissure.
Anteriorly the fissure courses medially to form the 'stem' of the lateral fissure...
The sympathetic chain is a component of the autonomic nervous system and is composed of general visceral afferent and efferent axons that allow for involuntary control of bodily functions via the hypothalamus.
The overarching function of the sympathetic system is to control the 'fight, fright o...
Symphalangism refers to ankylosis of the interphalangeal joints (i.e. fusion of the phalanges) in either the toes or the fingers. Less commonly, the metacarpophalangeal joints may be affected.
One study reports symphalangism of the fifth toe in ~55% (range 40-75%) of the populatio...
Symphyses (singular: symphysis) are secondary cartilaginous joints composed of fibrocartilage (and hence also known as fibrocartilaginous joints). They are considered amphiarthroses, meaning that they allow only slight movement and are all found at the skeletal midline.
Synarthroses are a functional class of joint that permit very little or no movement under normal conditions.
fibrous joints such as cranial sutures
synchondroses (primary cartilaginous joints) such as growth plates
Synchondroses (singular: synchondrosis) are primary cartilaginous joints mainly found in the developing skeleton, but a few also persist in the mature skeleton as normal structures or as variants.
Synchondroses are cartilaginous unions between bone composed entirely of hyaline cartil...
Syndesmoses (singular: syndesmosis) are a type of fibrous joint where strong collagen rich connective tissue holds two portions of bone together allowing very little movement. They consist of an interosseous membrane and ligamentous thickenings.
distal tibiofibular syndesmosis
Synovial cysts are para-articular fluid-filled sacs or pouch-like structures containing synovial fluid and lined by synovial membrane. They can occur around virtually every synovial joint in the body and also around tendon sheaths and bursae. Communication with the adjacent joint may or may not ...
Synovial joints are a type of joint with an articular capsule, consisting of an outer fibrous layer and an inner synovial membrane, which surrounds a fluid-filled synovial cavity. The articulating surfaces are covered by hyaline cartilage, designed to slide with little friction and to absorb com...
Synovial plicae are folds of synovium, thought to represent embryologic remnants. They are common, present in ~90% of arthroscopies 3.
They have been implicated in anterior knee pain and possibly in chondromalacia patellae although their role remains controversial 1,3.
T11 is an atypical thoracic vertebra. In contrast to typical thoracic vertebrae, it contains a single costal facet that articulates with the atypical eleventh rib. There are no facets on the transverse processes.
T12 is an atypical thoracic vertebra. In contrast to typical thoracic vertebrae, it contains a single costal facet with no facets on transverse processes.
T1 is an atypical thoracic vertebra. In contrast to typical thoracic vertebrae, it contains a complete facet for the 1st rib and a demifacet for the 2nd rib. It contains lips on the upper surface of the body. T1 also has a spinous process more horizontal than other thoracic vertebrae.
The taeniae coli are the three outer muscular bands of the colon. They sit on top of the inner circumferential layer and result in the classical appearance of the colon: the haustral markings are interrupted unlike the valvulae conniventes within the small bowel.
The talar declination angle is drawn on the weightbearing lateral foot radiograph between the mid-talar axis and the supporting surface. It should usually measure approximately 21°.
If the first metatarsal axis is steep, the mid-talar axis approaches the horizontal and is projected above the fi...
Talocalcaneal coalition is one of the two most common sub-types of tarsal coalition, the other being calcaneonavicular coalition. It accounts for 45% of all tarsal coalitions, and although all three facets of the talocalcaneal joint can be involved, the middle facet is most commonly involved.
The talocalcaneal joint, also called the clinical subtalar joint, is an important and complex joint in the hindfoot that allows articulation of the talus and calcaneus.
It comprises three articulations between talus and calcaneus 1:
anterior: head of talus with anterior facet o...
The talonavicular joint is an important part of the Chopart joint between the talus of the hindfoot and the navicular of the midfoot.
The talonavicular joint primarily consists of the articulation between the head of the talus and the concavity produced by the posterior aspect of...
The talus is a tarsal bone in the hindfoot that articulates with the tibia, fibula, calcaneus, and navicular bones. It has no muscular attachments and around 60% of its surface is covered by articular cartilage.
The talus has been described as having three main components: head,...
Tanycytes are one of the three types of ependymal cells, themselves a type of glial cell. They are found lining the floor of the third ventricle overlying the median eminence of the hypothalamus 1.
It is believed that these specialized cells are involved in the feedback mechanisms on the ante...
The tarsal bones are the seven bones of the foot excluding the metatarsals and phalanges. They are collectively known as the tarsus. The seven bones are:
There are several mnemonics for the tarsals.
Mnemonics of the tarsal bone are numerous and useful for memorizing the order and location of tarsal bones. They usually describe the position of the tarsal bones from superior to inferior, medial to lateral in a right foot:
The Cab in New Mexico Is Land Cruiser
The Cure of Nemaline Myopathy I...
Tarsal coalition describes the complete or partial union between two or more bones in the midfoot and hindfoot. Tarsal coalition refers to developmental fusion rather than fusion that is acquired secondary to conditions such as rheumatoid arthritis, trauma or post-surgical.
The tarsal plates of the eye are formed by dense fibrous tissue representing thickened extensions of the orbital septum, molded to the curvature of the eyeball. Each eye has a superior tarsal plate and an inferior tarsal plate.
The plates anchor the roots of the eyelashes and contain tarsal (M...
The tarsal sinus (or sinus tarsi) is a cylindrical cavity located between the talus and calcaneus on the lateral aspect of the foot. MRI is the investigation of choice for evaluating the tarsal sinus structures.
The tarsal sinus is situated on the lateral side of the foot; distal...
The tarsal tunnel is a fibro-osseous canal found in the medial aspect of the ankle.
roof: flexor retinaculum
from the tip of the medial malleolus to the medial calcaneal process and plantar aponeurosis
floor: medial surfaces of the tibia, talus and calcaneus 1, 2
The tectorial membrane is the thin superior continuation of the posterior longitudinal ligament from the body of the axis. It joins the axis body to the clivus on the anterior half of the foramen magnum, and ascends as high as the spheno-occipital synchondrosis and laterally extends to the hypog...
The teeth (singular: tooth; collective term: dentition) can be both primary and secondary, with the eruption of permanent teeth occurring over a long period between the ages of 6 and 24 years. When an individual has a complete set of teeth, they are said to be dentate, if some are missing they a...
The tegmen is the thin osseous plate that separates the middle cranial fossa from the tympanic and mastoid cavities of the temporal bone. It is comprised of two or three parts 1,2:
tegmen tympani (roof of the tympanic cavity)
tegmen mastoideum (roof of the mastoid cavity)
tegmen antri (roof o...
The tegmentovermian angle is an important measurable parameter in the assessment of posterior fossa abnormalities in the fetus. The angle is constructed on midsagittal images of the fetal brain, ideally on MRI.
The angle is formed by the intersection of the following two lines 1:
line 1: along...
The tegmentum is one of the areas of the brainstem. It is a phylogenetically old part of the brainstem and, in adults, is the location of the brainstem nuclei.
In the midbrain, it sits between the quadrigeminal plate and cerebral peduncles. In the pons, it is posterior to the basilar part of t...
The tegmen tympani, also known as the tegmental wall or roof of the tympanic cavity, is a thin plate of the petrous part of the temporal bone that separates the intracranial compartment and middle ear.
Relations and/or Boundaries
anteriorly, roof of the canal for the tensor tymp...
The tela choroidea is the thin, highly vascularized, loose connective tissue portion of pia mater that gives rise to the choroid plexus. Thus, it is basically the lamina propria of the ependyma and lies directly adherent to it, without any tissue in between the two 6.
Being part ...
The telencephalon (plural: telencephala or telencephalons) is the most anterior region of the primitive brain.Together with the diencephalon, the telencephalon develops from the prosencephalon, the primitive forebrain 1.
The inferior boundaries of the telencephalon are found at the diencephalo...
The temporal bone is situated on the sides and the base of the cranium and lateral to the temporal lobe of the cerebrum. The temporal bone is one of the most important calvarial and skull base bones.
The temporal bone is very complex and consists of five parts 1,2:
The temporal fossa is located in the temporal region and communicates inferiorly with infratemporal fossa deep to the zygomatic arch.
The temporal fossa is bounded by a few anatomical landmarks, anteriorly the frontal process of the zygomatic bone, superiorly and posteriorly the...
The temporalis muscle is one of the muscles of mastication. It is responsible for both closing the mouth and retraction (posterior fibers).
origin: temporal fossa between the infratemporal crest and inferior temporal line on the parietal bone
insertion: coronoid process and ramus of m...
The temporal lobe is one of the four lobes of the brain (along with the frontal lobe, parietal lobe, and occipital lobe), and largely occupies the middle cranial fossa.
The temporal lobe is the second largest lobe, after the larger frontal lobe, accounting 22% of the total neocor...
The temporal pole is an anatomical landmark that corresponds to the anterior end of the temporal lobe, lying in the middle cranial fossa.
It corresponds to Brodmann area 38 and has strong connections with the amygdala and orbital prefrontal cortex, and is sometimes recognized as a component of...
The temporomandibular joint (TMJ) is an atypical synovial joint located between the condylar process of the mandible and the mandibular fossa and articular eminence of the temporal bone. It is divided into a superior discotemporal space and inferior discomandibular space by the TMJ disc (or meni...
The temporopolar artery is usually a dorsolateral branch from the M1 segment of the middle cerebral artery (MCA) and supplies the polar and anterolateral portions of the temporal lobe.
This artery may arise as a branch from the anterior temporal artery 1.
The temporozygomatic suture (or zygomaticotemporal suture) is between the zygomatic process of the temporal bone and the temporal process of the zygomatic bone.
It can mimic a zygoma fracture.
The tendinous ring, also known as the annulus of Zinn, is the common origin of the four rectus muscles (extraocular muscles).
The tendinous ring straddles the superior orbital fissure and through it (from superior to inferior) pass:
superior division of the oculomotor nerve (CN III)
The Tenon capsule, also known as fascia bulbi or bulbar sheath, functions as an extraocular muscle pulley. It also provides a socket which separates the globe from the surrounding fat and allows free movement. It merges posteriorly with the dural sheath of the optic nerve and extends anteriorly ...
The tensor fasciae latae muscle is the most anterior of the superficial group of muscles in the gluteal region and overlies the gluteus minimus and the anterior part of the gluteus medius.
origin: lateral aspect of crest of ilium between anterior superior iliac spine and tubercle of cr...
The tensor fasciae suralis muscle is an uncommon accessory muscle in the popliteal fossa. It can be an unusual cause of a popliteal fossa soft-tissue swelling or mass.
origin: may arise from the distal aspect of any of the hamstring muscles, in the majority of reported cases it origin...
The tensor tympani muscle is a short muscle in the middle ear that arises from the superior surface of the cartilaginous part of the Eustachian tube, the greater wing of the sphenoid, and the petrous part of the temporal bone. It passes across the tympanic cavity and inserts into the upper end o...
The tensor-vascular-styloid fascia is a part of the middle layer of the deep cervical fascia that has been suggested to divide the prestyloid and poststyloid compartments of the parapharyngeal space. It is an extension of, and previously sometimes referred to as, the tensor veli palatini fascia ...
The tensor veli palatini muscle is one of the 5 paired muscles of the soft palate. It is triangular in shape and its tendon wraps around the pulley of pterygoid hamulus to alter the shape of the soft palate.
origin: it has 3 sites of origin:
scaphoid fossa of the medial pterygoid plat...
The tentorial nerve is the first branch of the ophthalmic division of the trigeminal nerve (CN Va) which is the dominate dural nerve supplying most of the supratentorial dura. It specifically supplies the falx, calvarial dura and superior surface of the tentorium.
The tentorium cerebelli (plural: tentoria cerebellorum) is the second largest dural fold after the falx cerebri. It lies in the axial plane attached perpendicularly to the falx cerebri and divides the cranial cavity into supratentorial and infratentorial compartments 1. It has free and attached ...
Teres major muscle is one of the seven scapulohumeral muscles that act around the glenohumeral joint to facilitate shoulder movement.
origin: caudal two thirds of lateral border and inferior angle of scapula
insertion: medial border of the intertubercular groove, which is the crest of...
The teres minor muscle is one of the four muscles that make up the rotator cuff, the others being: supraspinatus, infraspinatus, and subscapularis.
origin: middle third of the lateral border of the scapula
insertion: inferior facet of the greater tubercle of the humerus
The terminal bronchioles are a continuation of the bronchi and are the last divisions of the conducting airways.
Terminal bronchioles are confusingly named, as they are not the final branches but rather the distal bronchioles that do not bear alveoli. The first 19 divisions fr...
Each breast lobe is drained by a collecting duct terminating in the nipple. The collecting duct has several branches, which ends in a terminal ductal-lobular unit (TDLU), the basic functional and histopathological unit of the breast. The TDLU is composed of a small segment of the terminal duct a...
The terminal ileum is the most distal segment of small bowel. It immediately precedes the small bowel's connection with the colon through the ileocecal valve. It is of particular interest since a number of infectious and inflammatory processes preferentially involve the segment.
location: the m...
The terminal tuft is the most distal part of a distal phalanx (toe or finger), comprising the flared bone distal to the shaft.
spade phalanx sign
terminal tuft masses
as it is close to the nail, pathology or injuries of one can affect the oth...
The Terminologia Anatomica (TA) is the global standard for correct gross anatomical nomenclature in humans 1. The second edition was published by the Federative International Programme for Anatomical Terminology in 2019 4.
The standard anatomical terms are from Latin and Ancient Greek roots. T...
Testicular and epididymal appendages are remnants of embryonic ducts and are quite common, with one or more being present in ~70% of patients 1.
Four such appendages have been described:
testicular appendix (hydatid of Morgagni)
it is a Müllerian duct remnant (paramesonephric d...
A testicular appendix (alternatively called appendix of testis or appendix testis, and historically also known as hydatid of Morgagni) represents a developmental remnant of the paramesonephric duct (Müllerian duct) which is situated in the upper pole of the testis inside a groove between the tes...
The testicular arteries (also known as the spermatic arteries) are the long, small-diameter gonadal arteries in the male that supply the testis alongside the cremasteric artery and the artery to the ductus deferens.
As paired structures they arise symmetrically, slightly...
Testicular descent occurs after the fourth month of fetal life. The testes are derived from the gonadal ridge medial to the mesonephric ridge of the intermediate cell mass. An elongated diverticulum of the peritoneal cavity, the processus vaginalis precedes the testis through the inguinal canal ...
The testes, also known as the testicles, are the male gonads and are contained within the scrotum. The testes are responsible for the production of sperm and testosterone.
At birth, testes measure approximately 1.5 cm (length) x 1 cm (width), reaching ~4 mL volume at puberty 1.
The thalamencephalon is an anatomic region that includes the thalamus, metathalamus and epithalamus. It is one of the components that form the diencephalon.
Thalamostriate veins are formed by the joining of anterior caudate vein and the vein of stria terminalis. They join the septal veins and form internal cerebral veins.
The thalamostriate veins can be compressed in preterm neonates who have had germinal matrix hemorrhage. This ...
The thalamus (plural: thalami) is the largest of the structures comprising the diencephalon.
The thalamus acts as a relay center, receiving and distributing information between the peripheries and higher centers such as the cerebral cortices. It contributes to functions such as:
The thenar eminence is the muscular bulge on the radial side of the palm due to the thenar muscles. They are innervated by median nerve, except FPB which also provided by ulnar nerve. Together the muscle group primarily acts to oppose the thumb. The four muscles are:
Thigh refers to the portion of the lower limb between the hip and knee joints. Note that in an anatomical context "leg" refers to the portion between the knee and ankle joints and not to the entire lower limb.
The thin postcentral gyrus sign is an anatomic landmark useful for identifying the central sulcus on cross-sectional imaging.
The anteroposterior dimension of the postcentral gyrus surface is less than that of the precentral gyrus surface, as seen in the axial or sagittal planes. Identifying tw...
The third condyle, also known as condylus tertius or median occipital condyle, is a rare anatomic variant of the occipital condyles. It is a small separate ossicle at the anteromedial margin of the occipital condyle formed by the failure of the embryonic proatlas (4th occipital sclerotome) to un...
The third occipital nerve (TON) is a branch of the posterior root of C3, which provides cutaneous sensation to a small portion of the occipital scalp.
Occipital region of the scalp close to the midline.
The posterior root of C3 (the third cervical nerve) gives...
The third ventricle is one of the four CSF-filled cavities that together comprise the ventricular system.
The third ventricle is a median cleft between the two thalami and is bounded laterally by them anteriorly and the hypothalamus and subthalamus posteriorly. Its anterior wall ...
Thoracic anatomy encompasses the anatomy of all structures of the thorax.
This anatomy section promotes the use of the Terminologia Anatomica, the international standard of anatomical nomenclature.
The thoracic aorta is the most superior division of the aorta and is divided into three sections:
The thoracic aorta begins at the aortic valve, located obliquely just to the left of the midline at the level of the third intercostal space. It term...
The thoracic cage refers to the skeleton of the thorax:
thoracic vertebral column
12 pairs of ribs
The thoracic duct is the main lymphatic vessel for the return of chyle/lymph to the systemic venous system. It drains lymph from both lower limbs, abdomen (except the convex area of the liver), left hemithorax, left upper limb and left face and neck.
The thoracic duct is the supe...
Thoracic lymph nodes are divided into 14 stations as defined by the International Association for the Study of Lung Cancer (IASLC) 1, principally in the context of oncologic staging. For the purpose of prognostication, the stations may be grouped into 7 zones. The IASLC definitions leave some a...
The thoracic plane, also known as the transthoracic plane or the plane of Ludwig is an artificial horizontal plane used to divide the mediastinum into the superior mediastinum and the inferior mediastinum.
It is defined as a horizontal line that runs from the manubriosternal joint (sternal angl...
A handy mnemonic to remember the structures found at the level of the thoracic plane (also known as the plane of Ludwig) is:
C: cardiac plexus
L: ligamentum arteriosum
A: aortic arch (inner concavity)
P: pulmonary trunk
T: tracheal bifurcation (carin...
The thoracic spine (often shortened to T-spine) forms the middle part of the vertebral column. It extends from below C7 of the cervical spine to above L1 of the lumbar spine. There are 12 thoracic vertebra, termed T1-T12.
The thoracic spine is unique due to its articulation with ribs via costal...
The thoracoacromial artery is a vessel arising from the axillary artery at the axilla.
origin: first branch of the second part of the axillary artery 1
supply: pectoralis major and minor, anterior part of the deltoid, and dermal sensation overlying the clavipectoral ...
A useful mnemonic to remember the branches of the thoracoacromial artery is:
The thoracodorsal nerve also known as the middle subscapular or long subscapular nerve arises from the posterior cord of the brachial plexus and supplies the latissimus dorsi muscle.
The thoracodorsal nerve arises from the posterior cord of the brachial plexus with fibers...
The thoracoepigastric vein provides a communication between the superficial epigastric vein and the lateral thoracic vein as it ascends superficially on the anterolateral chest and abdominal wall. It, therefore, drains into both the superior vena cava via the axillary vein and the inferior vena ...
The thymus (plural: thymi) is a T-cell producing lymphoid organ in the anterior mediastinum that plays a role in the development of the immune system, particular the maturation of T-cells. It typically has a retrosternal location and hence can mimic retrosternal pathology.
It is ...