The paracingulate sulcus is a secondary sulcus running anteroposteriorly in the medial surface of the frontal lobe above and parallel to the cingulate sulcus 1. It is only found in the great apes and only identified in 70-89% of humans 1.
The depressor labii inferioris muscle, also known as quadratus labii inferioris muscle, is one of the facial muscles.
origin: oblique line of the mandible, medial to the mental foramen
modiolus at the angle of the mouth
ascends to medially insert into lower lip
Scapulothoracic bursae refer to a number of bursae that allow for the gliding movement of the scapulothoracic joint.
Two major bursae have been reliably described 1,3:
infraserratus (scapulothoracic) bursa: between the serratus anterior muscle and the chest wall
supraserratus (subscapularis) ...
The superior cervical ganglion (plural: ganglia) is the largest ganglion of the cervical sympathetic trunk, providing innervation to the head and neck region 1.
The superior cervical ganglion is formed by embryologically fused C1 to C4 sympathetic ganglia. It is elongated, cylind...
The ciliary muscle (TA: musculus ciliaris) is located within the ciliary body of the eye. It acts to facilitate lens accommodation for near vision, and receives parasympathetic innervation from short ciliary nerves, arising from the oculomotor nerve via the ciliary ganglion.
The dilator pupillae muscle is a ring of contractile cells within the iris. These cells are arranged radially, such that their contraction facilitates pupillary dilation (mydriasis). The dilator pupillae muscle receives innervation from the sympathetic nervous system.
The sphincter pupillae is a circular ring of smooth muscle within the iris responsible for constriction of the pupil (miosis). The structure is stimulated by the parasympathetic nervous system causing the muscle to decrease in diameter as it contracts.
The sphincter pupillae is ...
There are multiple pharyngeal muscles that make up the structure of the pharynx. They comprise circular and longitudinal muscles whose overall function is to propel food into the esophagus.
These muscles comprise the outer layer of musculature and act to c...
Persistent primitive olfactory artery (PPOA) is a rare variant of the proximal anterior cerebral artery 1,2. It is proposed to be more prone to aneurysms due to its sharp hairpin-like turn. Embryologically, the PPOA is the rostral division of the primitive internal carotid artery.
Ovary size and volume is frequently determined with ultrasound. The volume estimate is calculated by the formula for an ellipsoid, where D1, D2, and D3 are the three axial measurements:
D1 x D2 x D3 x 0.52
The normal, adult, non-pregnant, mean ovary volume of women who are not postmenopausal i...
The suboccipital cavernous sinuses are paired venous plexuses that surround the horizontal (distal V3) portion of the vertebral arteries at the craniocervical junction. Its name derives from its resemblance to the cavernous sinus as it is a venous cushion surrounding a large arterial loop at the...
The supraodontoid space, also known as the supradental space or apical cave, is an extradural space at the anterior craniocervical junction superior to the odontoid process of C2 (dens axis).
The space is a cave-shaped region facing posteriorly with the following boun...
Hair (TA: pilus/pili) remains important physiologically and psychologically for humans. The hair shaft develops from a structure known as the hair follicle. Each hair has an arrector pili muscle and both sensory and sympathetic neural connections.
The hair shaft (TA: stipes pili)...
The posterior superior aortic recess, (also known as the superior pericardial recess or the superior sinus) is one of the variable invaginations of the superior aortic recess and is located posterior to the ascending aorta.
It may mimic mediastinal lymphadenopathy or a bronchogenic cyst.
The posterior pericardial recess is one of the pericardial recesses forming a small space within the pericardium. It arises from the superior margin of the oblique pericardial sinus, posterior to the right pulmonary artery and medial to the bronchus intermedius.
It may mimic mediastinal lymphad...
Talar tilt is a measurement of the angle between the talus and the distal tibia, used in the assessment of ankle instability and ankle osteoarthritis (OA).
Talar tilt is an important measurement in the assessment of ankle osteoarthritis. It is measured as part of the Kellgren and Lawrenc...
The nasal septal cartilage, also known as quadrangular cartilage, forms most of the anterior portion of the nasal septum, and is one of five named nasal cartilaginous components supporting the external nose.
Most of the anterior one-third of the nasal septum is formed by the sept...
The superficial epigastric vein (TA: vena epigastrica superficialis) is an important tributary of the great saphenous vein that drains the anterior abdominal wall inferior to the level of the umbilicus.
The superficial epigastric vein drains into the great saphenous vein at the saphenous openin...
The lateral thoracic vein (TA: vena thoracica lateralis) is a tributary of the axillary vein. It provides venous drainage for the axilla, anterolateral chest wall, including serratus anterior and pectoralis muscles and breast, and the supraumbilical abdominal wall.
In some texts, t...
The long head of the biceps tendon (LHBT) is the proximal tendon of the long head of the biceps muscle and encircles the humeral head on its course. It has an intraarticular extrasynovial and an extraarticular portion.
insertion: supraglenoid tubercle of the scapula...
The autonomic nervous system (ANS) is a subdivision of the peripheral nervous system. The autonomic system provides innervation of the involuntary muscles, i.e. myocardium and smooth muscle, and glands, through which fine control of homeostasis is maintained.
The afferent innervation of the aut...
The peripheral nervous system (PNS) consists of the nerves (cranial nerves III-XII and spinal) and their related ganglia outside the central nervous system (CNS). The latter comprising the brain and spinal cord. The central nervous system and peripheral nervous system together form the nervous s...
The neurocranium (plural: neurocrania) is the name given to the portion of the skull that encloses the brain. It comprises the skull base and the skull vault. The neurocranium and facial bones (viscerocranium) together form the skull.
The nasolacrimal canal is the short bony passage along which the nasolacrimal duct courses in the face.
lacrimal groove of the medial maxilla
lacrimal hook of the lacrimal bone
superiorly: lacrimal bone
inferiorly: lacrimal process of the inferior n...
The carotid cistern is one of the basal (subarachnoid) cisterns that surrounds the supraclinoid internal carotid artery.
Relations and/or Boundaries
The carotid cistern lies between these brain structures:
medially: the optic chiasm and nerve
laterally: the mesial temporal lob...
The central nervous system (CNS) is the part of the nervous system that includes the brain and spinal cord.
The main components of the CNS are the brain and spinal cord. In addition, the CNS includes the optic nerves (cranial nerve II), retinas, olfactory nerves (cranial nerve I)...
The oropharyngeal isthmus, a.k.a. isthmus of fauces, is the relative constriction of the anterior oropharynx that borders the oral cavity. The isthmus is sometimes described as the passage that transitions between the oral cavity and pharynx, but strictly speaking, it is part of the oropharynx.
The modiolus (plural: modioli) may refer to one of two different anatomical structures, both in the head and neck region:
History and etymology
The Latin word, "modiolus" means hub of a wheel, and is well-named, as in both the cochlea and at the angle of t...
The modiolus (plural: modioli), also known as the modiolus anguli oris or commissural modiolus, is a small fibromuscular structure at the corner of the mouth where fibers from multiple facial muscles converge, and helps coordinate the action of these muscles.
The convergence of t...
A gomphosis (plural: gomphoses), also known as the dentoalveolar syndesmosis, is the specific name for the fibrous joint between the teeth and the alveolar bone of the maxilla/mandible 1,2.
The incisivus labii inferioris muscle (TA: pars labialis musculi orbicularis oris) is one of the facial muscles. It acts as a supplementary muscle to the orbicularis oris muscle.
The incisivus labii inferioris muscle is often omitted from major anatomical texts or articles on the f...
A commissure (TA: commissura) is a location at which two anatomical structures are united. Though the term most commonly refers to the commissures in the brain, there are a number which exist in the human body:
central nervous system
The right atrial appendage, also known as the right auricule (TA) or auricle, is a trapezoidal pouch forming the anterosuperior part of the right atrium. Pacemaker/defibrillator leads are often placed at this site.
The right atrial appendage is delineated from the rest of the rig...
"Egyptian eye sign" or "sonographic eye sign" refers to the normal appearance of great saphenous vein on ultrasound, in transverse view 1-2.
Ultrasound examination of the great saphenous vein shows echogenic fascia surrounding it, with the saphenous fascia superiorly and the muscular fascia inf...
The trochlea is a cartilaginous structure acting as a pulley for the superior oblique muscle of the eye.
The trochlea inserts on the trochlear fovea and spine located on the anteromedial part of the orbital roof. The tendon of superior oblique muscle passes through it 1.
The interstitial cells of Cajal are mesenchymal cells closely apposed to neural and smooth muscle cells of the gut. They form a heterogeneous group with differing ultrastructure and functions. One cell type has an ancillary neural function as a gastrointestinal pacemaker, generating electrical s...
Scapular medial rotation describes the rotation of the scapula (scapulothoracic joint) such that the glenoid fossa faces downwards - thus it may also be called downward rotation. It is the opposite of scapular lateral rotation - similarly, this motion requires motion at the sternoclavicular and ...
Scapular lateral rotation describes the rotation of the scapula (scapulothoracic joint) such that the glenoid fossa faces upwards - thus it may also be called upward rotation. This motion allows elevation of the humerus as seen in abduction of the arm. It is almost always associated with scapula...
Scapular retraction describes the backward movement of the scapula about the thoracic wall (scapulothoracic joint). As the scapula moves towards the midline it can also be referred to as scapular adduction. The opposite motion is scapular protraction.
The muscles that act as primary movers are ...
Scapular protraction describes the forward movement of the scapula about the thoracic wall (scapulothoracic joint). As the scapula moves away from the midline it can also be referred to as scapular abduction. This motion usually occurs in conjunction with some scapular lateral rotation. This mov...
Scapular depression refers to the caudal motion of the scapula (scapulothoracic joint). In most instances, depression of the scapula is a passive process (due to gravity) that is facilitated by movement at the acromioclavicular joint. Occasionally some muscular attachments serve as active depres...
Scapular elevation refers to the cranial motion of the scapula (scapulothoracic joint), commonly described as “shrugging the shoulders”. This movement is facilitated by several muscles and it is useful to distinguish these as primary movers and stabilizers. It is important to note that no one mo...
A subseptate uterus is a mild form congenital uterine anomaly (often considered as a normal variant) where there is a presence of a partial septum within the uterus not extending to the cervix and with the central point of the septum at an acute (<90°) angle. The external uterine contour is unif...
The deep artery of the penis, also known as cavernosal artery, is one of the two terminal branches of the internal pudendal artery.
The internal pudendal artery bifurcates terminally into the deep artery of the penis and the dorsal artery of the penis at the anterior marg...
The dorsal artery of the penis is one of the two terminal branches of the internal pudendal artery.
The internal pudendal artery bifurcates into the deep artery of the penis and the dorsal artery of the penis at the anterior margin of the perineal membrane 1.
The artery to the bulb of the penis (male) or vestibule (female) is a branch of the internal pudendal artery. It differs slightly in males and females.
Artery to the bulb of the penis
Origin: internal pudendal artery, distal to the perineal artery1.
a common penile artery, serving as the or...
The pes anserinus (rare plural: pedes anserini) is the name given to two different anatomical structures:
pes anserinus (facial nerve): a.k.a. parotid plexus
pes anserinus (knee)
Both structures are so named due to their similarity to a goose's foot, which is what 'pes anserinus' means in Lat...
The marginal mandibular nerve (TA: ramus marginalis mandibularis nervi facialis) is a branch of the extratemporal (terminal) segment of the facial nerve. It supplies the depressor anguli oris, depressor labii inferioris and mentalis muscles. It is of greater clinical importance than the other fa...
The mentalis muscles (TA: musculus mentalis) are paired muscles, one on each side of the mouth, important as elevators of the chin and lower lip; the muscles are one of the facial muscles.
origin: incisive fossa of the mandible
insertion: skin of the chin
innervation: facial nerve
The common iliac lymph nodes are found surrounding the common iliac artery and vein which is located above the bifurcation of the external and internal iliac vessels and distal to the aortic bifurcation (in a majority of patients at the L4 level and a minority at the L3 or L5 level) and medial t...
The antebrachial fascia or deep fascia of the forearm is a thick connective tissue fascia investing the muscles of the forearm. It also formes the lateral intermuscular septum which divides the forearm muscle into the two following compartments of the forearm together with the radius, ulna and i...
The perineal artery arises from the internal pudendal artery and supplies some of the perineal musculature and external genitalia.
Origin: branches off the internal pudendal artery, arising at the level of the posterior angle of the perineal membrane
Branches: it has two branches:
The middle genicular artery (MGA) is one of the arteries of the knee joint and is a major supplicant of the anterior and posterior cruciate ligaments.
origin: popliteal artery
supply: cruciate ligaments
The middle genicular artery originates from the an...
The cystic veins (TA: venae cysticae) are the main venous drainage of the gallbladder. They subsequently drain into the portal vein.
The cystic veins begin as venules running over the surface of the fundus and body of the gallbladder which merge proximate to the neck of the gallb...
The heart is one of the first organs in the developing embryo to form and function. By the start of week 4, a primitive heart has begun to pump blood and by week 7 most of the gross development of the heart is complete. Its development is complex, with several events occurring simultaneously.
The superior medial genicular artery (SMGA) is the medial counterpart of the superior lateral genicular artery and participates in the supply of the superomedial structures of the knee and the vascularization of the patella.
origin: popliteal artery
branches: anterior ...
The superior lateral genicular artery (SLGA) is the lateral counterpart of the superior medial genicular artery and supplies the superolateral structures of the knee and participates in the vascularization of the patella.
origin: popliteal artery
branches: anterior and...
The inferior medial genicular artery (IMGA) is the medial counterpart of the inferior lateral genicular artery and supplies the inferomedial structures of the knee including the medial tibial condyle and participates in the supply of the patella.
origin: popliteal arter...
The inferior lateral genicular artery (ILGA) is the lateral counterpart of the inferior medial genicular artery and supplies the inferolateral structures of the knee and the patella.
origin: popliteal artery
branches: cutaneous perforating branches
A sphincter (TA: musculus sphincter) is a term used in anatomy to refer a ring of muscle which narrows a tube or closes off a bodily orifice 1.
external anal sphincter
internal anal sphincter
lower esophageal sphincter
The buccolabial muscles form a subgroup of the facial muscles.
Elevators, retractors and evertors of the upper lip:
levator labii superioris alaeque nasalis (LLSAN) muscle
levator labii superioris muscle
zygomaticus major muscle
zygomaticus minor muscle
levator anguli oris...
The crural fascia or deep fascia of the lower leg is a thick connective tissue fascia that invests the muscles of the lower leg and divides them into the four compartments of the lower leg 1,2:
lateral or peroneal compartment
deep posterior compartment
A thyrolinguofacial trunk is a very rare pattern of branching of the anterior branches of the external carotid artery. Rather than the facial artery, lingual artery, and superior thyroid artery having their own distinct origins, all three vessels originate from a common trunk of the external car...
A linguofacial trunk is a rare variation of the anterior branches of the external carotid artery. The lingual artery and facial artery share a common trunk rather than branching independently from the external carotid artery 1. Unlike the thyrolingual or thyrolinguofacial variations in which the...
A thyrolingual trunk is an anatomical variant in which the superior thyroid artery and lingual artery share a common trunk 1. This is in contrast to the typical pattern of both vessels emerging independently from the external carotid artery. Other variations of origin include a linguofacial trun...
The submental artery is the largest branch of the facial artery. The vessel supplies the floor of the mouth and sublingual gland while also connecting the circulation of the tongue and the floor of the mouth 1,3.
origin: facial artery 2
course: emerges from the facial artery at the s...
The submasseteric space, also known as the masseteric space, is the inferolateral subcompartment of the masticator space located between the mandible and masseter muscle.
Relations and/or Boundaries
The submasseteric space has the following boundaries 1:
medially: mandible (ram...
The pterygomandibular space is the inferomedial subcompartment of the masticator space located between the mandible and pterygoid muscles.
The pterygomandibular space contains loose areolar tissue, the sphenomandibular ligament, and the following named neurovascular str...
The coronary microcirculation comprises several anatomically and functionally different coronary vascular compartments with a small diameter (<500 µm) that play a crucial role in the regulation of myocardial perfusion.
location: epicardium, myocardium, endocardium
blood supply: epicar...
The dual stream language processing models (dorsal and ventral) have replaced the historic model that only included the Broca's and Wernicke's areas and the arcuate fasciculus 1.
The dorsal stream is responsible for phonological processing and language production (sound/sign to actio...
The levator anguli oris muscle, also known as caninus or triangularis labii superioris muscles, is a buccolabial muscle, a subdivision of the facial muscles.
origin: canine fossa of the maxilla
insertion: modiolus and merges with depressor anguli oris muscle
Tubercle of Assaki (also known as tubercle of Asskay 3) is a small bony protuberance of the central part of glenoid fossa with accompanying thinning of articular cartilage in this location 1.
It is presumably caused by constant pressure of the humeral head exerted on the inferior gle...
The lesser palatine artery is a small branch of the descending palatine artery (branch of the 3rd part of the maxillary artery). The vessel supplies the soft palate with small branches to the palatine tonsils 1,2. The vessel emerges through the lesser palatine foramen before traveling posterior ...
The descending palatine artery is a branch of the maxillary artery that supplies both the soft palate and hard palate as well as the palatine tonsils 1.
origin: 3rd part of the maxillary artery
course: descending through the pterygopalatine fossa before its branches enter either the ...
The ascending palatine artery is a branch of the facial artery that supplies part of the soft palate. In addition, the vessel also supplies the tensor veli palatini, uvular muscle, palatine tonsils, and palatopharyngeus 1,2. The posterior branch supplies the posterior and inferior soft palate es...
The aerodigestive tract is a non-TA descriptive collective term for the respiratory tract and proximal portion of the digestive tract. As it is a non-standard term, its precise components vary somewhat with the context in which the term is being employed.
Definitions of what precis...
The frontalis muscle (TA: musculus frontalis) is a paired muscle extending from the supraorbital region to the level of the coronal suture. Flat and quadrilateral in shape, it is one of the facial muscles. Along with the occipitalis muscle, it forms the occipitofrontalis muscle due to a common t...
The anterior tarsal tunnel is a fibro-osseous canal found in the anterior aspect of the ankle.
The anterior tarsal tunnel is beneath the inferior extensor retinaculum of the foot and bordered by the following structures 1,2:
roof: inferior extensor retinaculum
The risorius muscle (TA: musculus risorius) is one of the muscles of the mouth, a subset of the facial muscles. It is often absent and has been described as an accessory muscle.
origin: fascia overlying the parotid, masseter and/or platysma muscles
insertion: modiolus at the angle of...
Glenoid bare spot also known as glenoid bare area is a small central or slightly eccentric area of inferior glenoid fossa, where the articular cartilage is markedly thinner or completely absent 2. It is considered to be a normal aging-related phenomenon 1.
Glenoid bare spot can be...
The levator labii superioris (LLS) muscle (TA synonym: musculus levator labii superioris) is one of the elevators of the upper lip, a subset of the facial muscles.
It is not to be confused with the levator labii superioris alaeque nasalis muscle, which has a very similar name, at least partiall...
The medial capsuloligamentous complex of the knee is comprised of three layers 1-3:
superficial layer (layer 1)
deep crural fascia
intermediate/middle layer (layer 2)
superficial medial collateral ligament
posterior oblique ligament
medial patellofemoral ligament
The interosseous (or interossei) muscles of the hand are a group of intrinsic hand muscles that lie near the metacarpals.
There are two sets:
dorsal interossei muscles (hand)
palmar interossei muscles (hand)
The palmar aponeurosis is the thickened strong part of the palmar fascia in the hand which is continuous with the flexor retinaculum and the tendon of palmaris longus tendon. It is superficial to the long flexor tendons and is an inverted triangle in shape, fanning over the palm and thinning med...
Muscles of the hand can be divided into:
extrinsic muscles whose tendons, which attach to structures within the hand, arise from muscle bellies from the forearm or distal humerus
intrinsic muscles (mnemonic) whose muscle bellies and tendons are located solely within the hand
A central vein refers to a major vein close to the center of the circulation, i.e. the heart. It originally referred to those large veins in which the distal tip of a catheter could lie for central venous pressure monitoring. To accurately measure the central venous pressure, which is the pressu...
Skeletal muscles, skeletal striated muscles or plainly muscles are an integral part of the locomotor system responsible for movements. The musculoskeletal system of the human body has more than 600 muscles 1 making up around 40% of the body weight. They are very heterogeneous and have different ...
A non-recurrent laryngeal nerve is an uncommon anatomical variant in which the recurrent laryngeal nerve takes a course that is deviant to its usual descent into the thorax. The non-recurrent laryngeal nerve rather enters the larynx directly from the cervical Vagus nerve instead of coursing infe...
Additional radial wrist extensors are normal anatomical variants and accessory muscles of the forearm and the wrist. The following additional wrist extensors have been described 1-6:
extensor carpi radialis intermedius
extensor carpi radialis accessorius
extensor carpi radialis tertius
The accessory flexor carpi ulnaris (AFCU) is a rare accessory muscle of the forearm and wrist and a normal anatomical variant that can be found in addition to a normal flexor carpi ulnaris muscle.
The accessory flexor carpi ulnaris muscle is considered very rare 1,2.
The flexor carpi radialis brevis (FCRB) vel profundus muscle is an accessory muscle of the forearm and wrist and a normal anatomical variant.
The flexor carpi radialis brevis vel profundus muscle has been found in 2-8% of anatomical dissections 1-3.
origin: anterior surf...
The anterior meniscofemoral ligament (aMFL) inserts to the lateral aspect of the medial femoral condyle and runs between the anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) to its' distal attachment to the posterior horn of the lateral meniscus 1-3. It is one of two varia...
Ligaments are connective tissue structures that arch over joints connecting one bone to another bone with primary functions as stabilizers of articulations. The scientific study of ligaments is called syndesmology.
Ligaments are ultimately formed from numerous ligamental fibrils. The...