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Umbilical folds

The umbilical folds are a series of 5 folds of parietal peritoneum on the deep surface of the anterior abdominal wall and consist of: a single midline median umbilical fold, bilateral medial umbilical folds, and bilateral lateral umbilical folds

Umbilicus

The umbilicus is the fibrous remnant of the fetal attachment of the umbilical cord after birth. Gross anatomy All layers of the anterior abdominal wall fuse at the umbilical ring, a small round defect in the linea alba located just inferior to the midpoint between the xiphoid process of the st...

Dorsal intercarpal ligament

The dorsal intercarpal ligament is one of the extrinsic wrist ligaments. Gross anatomy The dorsal intercarpal ligament has a horizontal orientation, however, together with the dorsal radiotriquetral ligament, it is said to have a zig-zag configuration. It runs from the dorsal tubercle of the ...

Cystic lymph node of Lund

The cystic lymph node of Lund (also known as the Calot or Mascagni node) is the sentinel node for the gallbladder, and one of the structures in Calot triangle. It lies in close proximity to the cystic artery and is one of the structures removed during cholecystectomy. History and etymology The...

Circular sulcus

The circular sulcus, or peri-insular sulcus is a deep sulcus that surrounds the lateral surface of the insular cortex and separates it from the operculum of the frontal, temporal and parietal lobes. In this sulcus, the M2 segment of the middle cerebral artery (MCA) completes a downward turn at t...

Incudostapedial joint

The incudostapedial joint is the articulation between the incus and stapes bones in the middle ear. It is one of the three joints in the ossicular chain.

Venous circle of Trolard

The anastomotic venous circle of the base of the brain 1, also referred to as the venous circle of Trolard 2,3,5, is an inconsistently found venous homologue of the better-known arterial circle of Willis. It should not be confused with other venous structures also described by Trolard such as t...

Adenoid tonsil

The adenoid tonsils, or often just simply the adenoids (also known as the nasopharyngeal or pharyngeal tonsils), are paired foci of lymphatic tissue located on the superoposterior wall of the nasopharynx and form part of Waldeyer's ring.

Triangular space (disambiguation)

The triangular space may refer to: medial (upper) triangular space in the axilla lateral (lower) triangular space in the axilla

Circumduction

Circumduction is the orderly combination of shoulder movements so that the hand traces a circle and the arm traces a cone. In order it is produced by shoulder flexion, abduction, extension and abduction (or the reverse). It is hence produced by co-ordination of all the muscles that produce thes...

Arm adduction

Arm adduction represents movement of the arm towards the midline of the body in the coronal plane. Most individuals can manage 40° of isolated adduction. It is the opposite of arm abduction and contributes to the combined movement of shoulder circumduction. It is produced by: pectoralis major ...

Arm abduction

Arm abduction represents movement of the arm away from the midline of the body in the coronal plane and, in most cases, isolated abduction can be achieved to 160-180°. It is the opposite of arm adduction and contributes to the combined movement of shoulder circumduction. It is produced by: del...

Arm external rotation

External or lateral rotation of the arm represents the movement of the humerus when an arm flexed to 90° at the elbow is externally rotated around the longitudinal plane of the humerus such that the hand moves away from the midline of the body. It is the opposite of arm internal rotation. As wi...

Arm internal rotation

Internal or medial rotation of the arm represents the movement of the humerus when an arm flexed to 90° at the elbow is internally rotated around the longitudinal plane of the humerus such that the hand moves towards the midline of the body. The degree of rotation is dependant on the degree o...

Arm extension

Arm extension represents the opposite movement to arm flexion where the arm moves posteriorly. Only about 40° of movement posteriorly from the anatomic position is achievable in most individuals. It is the opposite of arm flexion and contributes to the combined movement of shoulder circumduction...

Arm flexion

Arm flexion represents rotation in the anatomic plane such that the distal humerus moves ventrally. It represents raising the arm and isolated flexion can achieve approximately 150-170° of movement. The opposite movement is arm extension and contributes to the combined movement of shoulder circu...

Annular ligament (disambiguation)

The annular ligament can refer to: annular ligament of the stapes annular ligament of the proximal radio-ulnar joint

Movements of the forearm

The elbow joint is a modified hinge joint resulting in a wide range of movements of the forearm. Forearm flexion Forearm flexion is rotation in the anatomic plane such that the radius and ulna move anteriorly. It occurs primarily in the articulation between the humerus and ulna and can achiev...

Myrtiformis muscle

Myrtiformis muscle, also known as depressor alae nasi, is one of the muscles of the nose, a subset of the facial muscles. Terminology Myrtiformis is often omitted from classic anatomy tomes. Some texts describe this muscle as two separate components, the medial fibers forming the depressor se...

Accessory maxillary ostium

Accessory maxillary ostia are a common anatomic variant, and are usually found incidentally on CT scans of the paranasal sinuses. Accessory ostia of the maxillary sinus are common, occurring in up to 40% patients 1. No significant association has been found between the presence of accessory osti...

Lunotriquetral ligament

The lunotriquetral ligament joins the lunate and triquetrum of the carpals. Gross anatomy The lunotriquetral ligament arises from the volar aspect of the distal lunate and triangular fibrocartilage to distally attach to the medial margin of the hamate. Similar to the scapholunate ligament, it ...

Trigeminal ganglion

The trigeminal ganglion, also known as the Gasser, Gasserian or semilunar ganglion, is the large crescent-shaped sensory ganglion of the trigeminal nerve located in the trigeminal cave (Meckel cave) surrounded by cerebrospinal fluid. The ganglion contains the cell bodies of the sensory root of ...

Petrous apex

The petrous apex is the pyramid-shaped anteromedial part of the petrous part of the temporal bone. It is oriented obliquely in the skull base and articulates with the posterior aspect of the greater wing of the sphenoid and occipital bones. The lateral boundary is the inner ear, medially the pe...

Endolymphatic duct

The endolymphatic duct is a small epithelial-lined channel, part of the membranous labyrinth that passes through the vestibular aqueduct in the bony labyrinth of the petrous temporal bone. It arises from the utricle and saccule via the utriculosaccule duct and drains endolymph. The distal end is...

Perilymphatic duct

The perilymphatic duct is a small epithelial-line channel that passes through the cochlear aqueduct in the bony labyrinth of the petrous temporal bone. It arises from the scala tympani of the cochlea and drains perilymph into the cerebrospinal fluid of the subarachnoid space of the posterior cra...

Inferior calcaneal nerve

The inferior calcaneal nerve (or Baxter nerve) is a mixed nerve in the foot. Gross anatomy Origin Originates from the lateral plantar nerve at the level of the medial malleolus. Course Courses between the abductor hallucis muscle and the quadratus plantae and along the medial border of the...

Membranous labyrinth

The membranous labyrinth or endolymphatic labyrinth is the part of the inner ear housed in the osseous labyrinth. It comprises 3 distinct, but joined, sensory sacs and ducts supplied by the vestibulocochlear nerve (CN VIII): cochlear duct (scala media) in the cochlea, responsible for hearing u...

Semicircular duct

The semicircular ducts are the part of the membranous labyrinth that are contained in the semicircular canals of the osseous labyrinth, concerned with rotational equilibrium. Like the other parts of the membranous labyrinth, the ducts contain endolymph and are surrounded by perilymph. The crura...

Interventricular septum

The interventricular septum divides the right and left ventricles, running in the plane of the anterior and posterior interventicular grooves. Septation of the ventricles occurs in the fetus within 7 weeks of gestation, achieved by the formation of this embryologically heterogenous structure 6. ...

Fallopian (disambiguation)

The eponym fallopian may refer to: fallopian canal (facial nerve canal) fallopian tube (uterine duct) fallopian ligament (inguinal ligament) History and etymology It is named after Gabriele Falloppio (also known by his Latin name Fallopius), Italian anatomist (1523-1562). Despite the eponym...

Accessory muscle

Accessory muscles are a form of anatomic variation that refers to supplementary discrete muscles that are found alongside the normal expected musculature. They have been described in the neck, thorax, pelvis, upper and lower limbs. See also accessory muscles of respiration

Cochlear aqueduct

The cochlear aqueduct or canaliculus is a small canal in the bony labyrinth of the petrous temporal bone that contains the perilymphatic duct, which drains perilymph into the cerebrospinal fluid of the posterior cranial fossa subarachnoid space. It runs inferior and parallel to the internal audi...

Saccule (disambiguation)

The saccule may refer to: saccule of the inner ear saccule of the larynx

Utricle (disambiguation)

The utricle may refer to: utricle of the inner ear utricle of the prostatic urethra

Labyrinth of the inner ear

The labyrinth of the inner ear is the combined sensory organ of hearing and balance and its surrounding bony cavity located in the petrous temporal bone, consisting of two components: the osseous labyrinth, the bony cavity, which houses the membranous labyrinth, a tubular sac filled with endol...

Labyrinth (disambiguation)

The labyrinth can refer to: labyrinth of the inner ear osseous labyrinth membranous labyrinth labyrinth of the ethmoid bone

Angular artery (facial artery branch)

The angular artery is the terminal branch of the facial artery. It becomes the angular artery after the lateral nasal artery branch from the facial artery. It courses superiorly along the lateral border of the external nose to the medial canthus. It is accompanied by the angular vein which drai...

Accessory abductor digiti minimi muscle (hand)

An accessory abductor digiti minimi (ADM) muscle is the commonest accessory muscle of the hand and wrist, found in 24% of individuals on the hypothenar eminence. When present it is one of the intrinsic muscles of the hand. Summary origin: antebrachial fascia passing anteriorly to Guyon canal ...

Extrinsic muscles of the hand

The extrinsic muscles of the hand are the muscles of the hand that originate outside the hand but insert into structures within the hand 1,2. Most of the extrinsic muscles have their origins within the forearm, with several solely/also originating from the humerus: flexor carpi radialis muscle ...

Intrinsic muscles of the hand

The intrinsic muscles of the hand (also known as the small (or short) muscles of the hand) is a term used to refer to those muscles of the hand that structurally are wholly within the hand: palmaris brevis muscle short muscles of the thumb thenar muscles opponens pollicis muscle flexor poll...

Nasal cartilages

The nasal cartilages make up the skeleton of the external nose, along with the nasal bones, maxilla, frontal bone and bony nasal septum. They are formed from hyaline cartilage and responsible for maintaining the shape of the flexible part of the external nose and vestibule and consist of five na...

Sinus tympani

The sinus tympani of the petrous temporal bone is a small recess in the posterior wall of the mesotympanum medial to the pyramidal eminence and stapedius muscle origin. Lateral to the pyramidal eminence is the facial recess. It is of surgical importance due to its invasion by cholesteatoma and ...

Facial recess

The facial recess of the petrous temporal bone is a small recess in the posterior wall of the mesotympanum lateral to the pyramidal eminence and stapedius muscle origin. The upper mastoid portion of the facial nerve runs immediately posterior to it, giving it its name. Medial to the pyramidal em...

Pyramidal process

The pyramidal process or eminence of the petrous temporal bone is a small hollow anterior osseous protrusion from the posterior wall of the mesotympanum that separates the sinus tympani medially from the facial recess laterally. The stapedius muscle arises from the hollow of the pyramidal proces...

Deltopectoral groove

The deltopectoral groove is located between the superolateral aspect of the pectoral region and the deltoid muscle. It runs obliquely from superomedial to inferolateral and contains the cephalic vein which at the upper margin of the groove dives deep to pierce the clavipectoral fascia and enter ...

Pectoral region

The pectoral region is the anterior region of the upper chest where there are four thoracoappendicular muscles (also known as the pectoral muscles): pectoralis major pectoralis minor subclavius serratus anterior The breast is located superficial to the muscles. The lateral border of the pec...

Intraparotid lymph nodes

The intraparotid lymph nodes are groups of cervical lymph nodes located within the parenchyma of each of the parotid glands. Gross anatomy Among the salivary glands, only the parotid glands have their own internal lymph nodes due to the late encapsulation of the parotids during embryologic dev...

Artery of Bernasconi and Cassinari

The artery of Bernasconi and Cassinari, also known as medial or marginal tentorial artery (of Bernasconi–Cassinari), commonly arises from the cavernous segment of the internal carotid artery. Gross anatomy The artery of Bernasconi and Cassinari is ~2 cm long and is an important branch of the m...

Alar thoracic artery

The alar thoracic artery is a rare variant arterial glandular branch of the axillary artery (usually the second part) that supplies the axillary fat, lymph nodes and skin of the axilla.

Suboccipital triangle

The suboccipital triangles are a paired triangular-shaped space formed by the configuration of three paired muscles in the posterior neck between the occipital bone, C1 and C2. Gross Anatomy The suboccipital triangle has an inferomedial pointing apex (pointing towards the nuchal ligament) form...

Extensor retinaculum (wrist)

The extensor retinaculum of the wrist is the broad ligamentous sheet located at the dorsal aspect of the wrist and functions to keep the extensor tendons in alignment and prevent bowstringing during movement. Gross anatomy It is obliquely oriented and attaches proximally to the lateral surface...

Extensor retinaculum (disambiguation)

The extensor retinaculum can refer to the: extensor retinaculum of the wrist extensor retinaculum of the foot

Rhomboid muscles

The rhomboid muscles, or simply the rhomboids, refers to the scapulothoracic group of rhomboid muscles, named because of their shape and consist of: rhomboid major muscle rhomboid minor muscle

Transverse humeral ligament

The transverse humeral ligament (also known as the Brodie ligament) is a small broad ligament that extends between the lesser and greater tubercles of the humerus superior to the epiphyseal line. It encloses the tendon of the long head of biceps brachii and its sheath in the bicipital groove, fo...

Rhomboid fossa (disambiguation)

The rhomboid fossa can refer to two different structures: rhomboid fossa of the clavicle rhomboid fossa of the floor of the fourth ventricle

Interthalamic adhesion

The interthalamic adhesion, or massa intermedia, is a small variably present connection between the medial apposing surfaces of the two thalami that passes through the third ventricle. It is not a commissure as once thought, as it does not contain neurons; instead, it is composed of glial tissue...

Supraoptic commissure

The supraoptic commissure consists of: Gudden commissure Meynert commissure Gasner commissure

Suprapineal recess

The suprapineal recess is a small angular recess or diverticulum that forms the posterior wall of the third ventricle superior to the habenular commissure and the larger pineal recess. Some anatomists describe a single pineal recess rather than separate pineal and suprapineal recesses.

Agenesis of the appendix

Agenesis of the appendix is extremely rare, with an incidence at surgery of approximately 1 in 100,000 laparotomies 1. It is most commonly due to a sporadic etiology. However in the rare genetic condition, familial apple peel jejunal atresia, absence of the appendix is a recognized feature. Also...

Kugel's artery

An uncommon variant of coronary arterial anatomy, Kugel's artery was originally described as an anastomotic communication between branches of the proximal left circumflex artery with the distal right coronary artery. These coronary trunks often communicate indirectly through atrial anastomotic n...

Rhomboid fossa

The rhomboid fossa is the shallow, diamond shaped depression on the dorsal surface of the pons and medulla oblongata that forms the floor of the fourth ventricle 1. It is covered by grey matter which is continuous with the spinal cord. It may be divided into two parts: superior upward triang...

Stria terminalis

The stria terminalis, also known as the terminal stria, is a fascicle of nerve fibers that runs across the lateral wall of the lateral intra-ventricular surface in a groove formed by the head of the caudate superiorly and the thalamus inferiorly. The stria terminalis overlies the superior thalam...

Vallecula

The epiglottic valleculae are paired depressions in the oropharynx located anterior to the epiglottis and posterior to the base of tongue. They are located between the lateral glossoepiglottic folds and the median glossoepiglottic fold. Etymology Vallecula is Latin for "small valley", a combi...

Emissary veins (skull)

Emissary veins (also known as the vena emissaria) are veins which pass through foramina in the skull to provide a venous communication between the dural venous sinuses and veins of the scalp or veins inferior to the skull base (cranial-cerebral anastomosis). They are thin-walled and valveless. ...

Isthmus (disambiguation)

Isthmus (plural: isthmi) is an anatomical term and refers to a slender structure joining two larger components. Some of these uses of the word isthmus are now rarely used or only seen in older texts and articles: isthmus (aorta) isthmus (auditory tube) isthmus (auricle of the ear) isthmus (c...

Inferior salivatory nucleus

The inferior salivatory (or salivary) nucleus is the nucleus associated with the visceral efferent innervation of the parotid gland. It is one of the four nuclei of the glossopharyngeal nerve. Gross anatomy The inferior salivatory nucleus is located within the dorsal aspect of the pons just su...

Inferior tympanic canaliculus

The inferior tympanic canaliculus is a small bony passageway that lies within the petrous portion of the temporal bone, between the carotid canal and jugular foramen. Gross anatomy The inferior tympanic canaliculus is a bony canal that separates the opening of the carotid canal anteromedially ...

Wrist ligaments

The intrinsic and extrinsic wrist ligaments play a vital role in the stability of the wrist joint. There are numerous ligaments but included below are the most clinically significant. Wrist ligaments are best assessed with dedicated wrist MRI. Gross anatomy intrinsic ligaments (only attach to ...

Carotid tubercle

The carotid tubercle or tubercle of Chassaignac refers to the paired anterior tubercles of the transverse processes of the sixth cervical vertebrae 1. The carotid tubercle serves as an important landmark with respect to performing regional anesthesia such as a brachial plexus and cervical plexus...

Martin-Gruber anastomosis

Martin-Gruber anastomosis is the most common type of four inter neural communication between median nerve and ulnar nerve in forearm and hand. Its prevalance has been reported between 11- 27%. Motor fibers from median, most commonly from anterior interosseous nerve cross to join ulnar nerve. Mot...

Gantzer muscle

The Gantzer muscle is an anomalous head of the flexor pollicis longus muscle, an accessory muscle of the forearm. Some authors 1 suggest that this muscle is present in ~70% of limbs and should be considered a normal anatomical pattern rather than an anatomical variation. Summary origin: deep s...

Perinephric bridging septa

Perinephric bridging septa or septa of Kunin are composed of numerous fibrous lamellae which traverse the perinephric fat 1,2 where they suspend the kidneys within the perirenal space. The septa may act as a barrier or conduit for the spread of pus, blood, urine, and neoplasms in the perinephric...

Multicentric ossification

Multicentric ossification refers to normal, or variant of normal, ossification at more than one site within a single epiphysis or apophysis. It is important to be aware of common sites where multicentric ossification may occur, to avoid confusion with fracture, apophysitis and other entities. t...

Jugulodigastric lymph nodes

The jugulodigastric lymph nodes, also known as subdigastric lymph nodes, are deep cervical nodes located below the posterior belly of the digastric muscle and anterior to the internal jugular vein. They are located in neck node level IIa and receive lymphatic drainage from the tonsils, pharynx,...

McConnell’s capsular arteries

McConnell’s capsular arteries (MCCA) are one of the three major branches of the cavernous segment of the internal carotid artery (ICA). Gross anatomy They arise from the medial wall of the cavernous ICA distal to both the meningohypophyseal trunk and the inferolateral trunk. The McConnell’s c...

Tracheal bifurcation angle

The tracheal bifurcation angle can have a wide range of normal values in patients and can vary significantly in serial radiographs. It is of poor diagnostic value due to the lack of sensitivity and specificity in identifying the underlying pathology. Terminology The interbronchial angle is th...

Epidural ligaments

The epidural ligaments, also known as meningovertebral ligaments, are variably thick bands of connective tissue located within the spinal epidural space attaching the outer surface of the theca to the inner borders of the spinal canal (vertebrae and ligaments). They are somewhat variable in nu...

Carotid plate

The carotid plate is a thin (0.5 mm) bony plate that separates the carotid canal from the middle ear cavity. Gross anatomy The caroticotympanic artery perforates the carotid plate normally. Related pathology Disruption or dehiscence of the carotid plate may be seen in aberrant internal caro...

Thin postcentral gyrus sign

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...

Bifid postcentral gyrus sign

The bifid postcentral gyrus sign, also known as the pars deflection sign, is a landmark useful for identifying the central sulcus on cross-sectional imaging. The medial aspect of the postcentral gyrus splits in two before meeting the interhemispheric fissure. The two legs straddle the pars marg...

Iris (eye)

The iris (plural: irises or irides) is a pigmented muscular structure which modifies the amount of light entering the eye, by controlling the size of the pupil, its central aperture. Summary location: between the anterior and posterior chambers of the globe function: controls the amount of l...

Basis pontis

The basis pontis, or basilar/basal part of the pons, refers to the ventral portion of the pons, which contains white matter fibers of the corticospinal tract. Related pathology lacunar infarct in this region may result in pure motor hemiparesis, ataxic hemiparesis, or dysarthria-clumsy hand sy...

Nasal ala

The nasal ala (plural alae) forms the lateral part (wing) of the nasal vestibule. The alar cartilage on each side provides a skeleton for the other soft tissue components.

Muscles of the nose

The muscles of the nose form a distinct subgroup within the muscles of facial expression. Some of the muscles, e.g. orbicularis oris muscle, are in more than one subgroup. nasalis muscle compressor naris muscle dilator naris muscle procerus muscle myrtiformis muscle depressor septi...

Dilator naris muscle

Dilator naris muscle forms the alar component of nasalis muscle, and is one of the muscles of the nose, a subset of the facial muscles. Summary origin: maxilla insertion: nasal ala innervation: facial nerve (VII) action: flaring of the nostril Gross anatomy Origin fibers originate fr...

Zygomaticus minor muscle

The zygomaticus minor muscle is a member of the buccolabial muscle group of the facial muscles. Together with the levator labii superioris alaeque nasi and levator labii superioris muscles it is one of the main elevators of the lip, exposing the maxillary teeth 1. Along with its other action of ...

Zygomaticus major muscle

The zygomaticus major muscle is a member of the buccolabial muscle group of the upper lip, a subset of the facial muscles 1. It joins with the muscle fibers of levator anguli oris, orbicularis oris and the more deeply placed muscular bands to move the side of the mouth upwards and sideways durin...

Fascia lata

The fascia lata is part of the deep fascia, and envelopes the thigh analogous to a stocking, but with an over large proximal end. Within the femoral triangle, the great saphenous vein passes through the saphenous hiatus to drain into the femoral vein.

Compressor naris muscle

Compressor naris muscle forms the transverse component of nasalis muscle, and is one of the muscles of the nose, a subset of the facial muscles. Summary origin: frontal process of maxilla insertion: medial insertion into a transverse aponeurosis innervation: facial nerve (VII) action: s...

Nasalis muscle

Nasalis muscle is one of the muscles of the nose, a subset of the facial muscles, consisting of two main parts: compressor naris dilator naris These two parts have opposing actions, the compressor narrows the nostrils and dilator flares them. Both parts are supplied by the buccal branch of t...

Alar fascia

The alar fascia is a thin fibroareolar membrane separating the (anterior) true retropharyngeal space from the (posterior) danger space. It is the ventral component of the deep layer of the deep cervical fascia. Notably, in the well patient, the alar fascia is not usually visible on cross-sectio...

Nomina Anatomica

The Nomina Anatomica (NA) was the standard lexicon of anatomic nomenclature from 1955 until 1998 when it was replaced by the new Terminologia Anatomica. The Nomina Anatomica was originally signed off by the Sixth International Congress of Anatomists held in Paris, France, in 1955, and became kno...

Paraglottic space

The paraglottic space is a fat-containing space located on either side of the larynx. Gross anatomy Boundaries and/or relations laterally: thyroid cartilage superomedially: pre-epiglottic space inferomedially: conus elasticus posteriorly: pyriform sinus The space surrounds the laryngeal v...

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