Variation archive

854 published articles

• Encyclopedia entry8 August 2026

  Adductor Pollicis

  Adductor pollicis is a triangular muscle that shows a tendency to split into radial parts. The relative extent of the division and the closeness of their connection is variable. Occasionally, fasiculi are seen arising from the palmar metacarpophalangeal ligaments, forming a transversus manus (Hallett). Mori describes the variations of this muscle as follows: Origin : The transverse head arises from the third and fourth metacarpal bones in 76 %. The transverse head arises from the third metacarpal bone only in 24%. The Belly of the Muscle. Two heads are completely separated in 82%.

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• Encyclopedia entry8 August 2026

  Adductor Minimus (Henle, Günther)

  Adductor minimus is a small flat muscle that constitutes the lateral and upper part of adductor magnus. It inserts proximal to the linea aspera. Because it is primarily a separate entity it is considered independent of adductor magnus (see above). Adductor magnus and adductor minimus are frequently separated by a branch of the superior perforating branch of the profunda artery. Syn.: m. adductor femoris minimus (Günther) and Diemerbröck termed it adductor quartus.

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• Encyclopedia entry8 August 2026

  Adductor Magnus

  Adductor magnus may be inseparable from quadratus femoris. In this particular case the terminal branch of the internal (medial) circumflex artery appeared to pierce the upper part of the muscle. Irregular slips from adductor magnus may insert onto the adductor tubercle. Adductor magnus varies in its degree of segmentation, its condyloid part Macalister found to be quite distinct. A similar slip has been reported by Weber and by Hildebrandt. A separate slip into the lower piller of the tendinous arch of insertion is described by Henle.

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• Encyclopedia entry8 August 2026

  Adductor Longus

  Adductor longus may be doubled, it may be split in two and it may be bilaminar. It may receive a slip from pectineus over the profunda artery (Wood). It may send a small muscular fascicle over the femoral artery into the anterior wall of the Hunterian canal (adductor canal). The muscle may extend as far as the knee, with its tendon of insertion inseparable from that of adductor magnus. Syn.: m. adductor femoris longus, Second adducteur superficiel (Cruveilhier), m. adductor triceps, first or long head. References Henle, J.

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• Encyclopedia entry8 August 2026

  Adductor Hallucis, Caput Transversum (Transversalis Pedis Casserii)

  The slip from the little toe is frequently absent; more rarely, other slips or the entire muscle may be absent. In a study of 91 bodies it was absent in 67% of limbs. Muscle arising from the base of the second metatarsal may receive substantial contributions from peroneus longus prior to the latters' usual insertion. This head may appear as a separate fascicle. Syn.: m. Abducteur (Cruveilhier).

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• Encyclopedia entry8 August 2026

  Adductor Hallucis, Caput Obliquum

  A slip has been observed passing from this muscle to the base of the first phalanx of the second or even the third toe. It may be attached to the opponens or to the lateral head of flexor hallucis brevis. It is of theoretical interest when this head is considered as a separate muscle fasiculus because it may represent a vestige of a plantar adductor of the second toe. A slip from the adductor is occasionally found ending on the metatarsal bone of the great toe. It may arise entirely from the sheath of the long peroneal tendon.

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• Encyclopedia entry8 August 2026

  Accessory Supinator

  The accessory supinator was found in 21 of 63 forearms, bilaterally in 8 of 27 cadavers, and in 8 of 20 males and in 7 of 16 female cadavers. With only one exception, the muscle was always found lateral to the annular ligament. The muscle originates from the coronoid process of the ulna just lateral to the ulnar tuberosity, and inserts onto the radial tuberosity, posterior to the insertion of the biceps tendon. Its action is to assist in the supination of the forearm. LeDouble mentions that these accessory supinator muscles have been overlooked by recent, nineteenth century, anatomists.

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• Encyclopedia entry8 August 2026

  Abductor Pollicis Brevis

  The abductor pollicis brevis is often divided into outer and inner parts, or it may receive slips from the navicular bone or styloid process of the radius. A third head arising from opponens pollicis has been reported. An accessory slip is frequently found joining the muscle with abductor pollicis longus. More rarely, accessory slips connect abductor pollicis with palmaris longus, extensor carpi radialis longus, accessory extensor carpi radialis, opponens or flexor pollicis brevis.

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• Encyclopedia entry8 August 2026

  Abductor Manus

  This rare muscle arises from the common extensor origin, and courses between extensor carpi radialis longus and brachioradialis to insert onto the trapezium. Reference Wood, J . (1864) On some varieties in human myology. Proc. Roy. Soc. Lond. B. 13:299-303.

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• Encyclopedia entry8 August 2026

  Abductor Hallucis

  This muscle occasionally sends a slip to the base of the first phalanx of the second and third toe. It may be inserted into the long flexor tendon of the great toe. Its tendon of insertion is sometimes joined by a musclular slip arising from the skin on the medial border of the foot, somewhat in front of the ankle. Lepine (1864) found a slip passing to the skin of the ball of the great toe. Syn.: m. adducteur hallucis (Cruveilhier).

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• Encyclopedia entry8 August 2026

  Abductor Digiti Minimi (pedis)

  A slip of this muscle may insert onto the base of the fifth metatarsal and is known as abductor ossis metatarsi quinti . Most of the muscle glides over the tuberosity of the lateral surface of the proximal phalanx. The abductor ossis may be adherent to the abductor of the small toe and it has been found to extend to the middle or even anterior part of the metatarsal. This has been reported in 40% of cases studied.

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• Encyclopedia entry8 August 2026

  Abductor Digiti Minimi (manus)

  This muscle is occasionally divided into two or even three slips; in other cases it is united with flexor digiti minimi brevis. Its absence has been reported, as has the doubling of the entire hypothenar muscle mass. An accessory head, accessorius ad abductorem digiti minimi manus is frequently present. It may arise from the tendon of flexor capri ulnaris, from the flexor retinaculum, the tendon of palmaris longus, fascia of the forearm, the ulna, or even the radius.

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• Encyclopedia entry8 August 2026

  Vertebre di transizione lombosacrali: inquadramento (contenuto dimostrativo)

  Contenuto dimostrativo. Questo testo serve a verificare il funzionamento del portale e non costituisce una fonte scientifica. Questa voce mostra come sarà presentata una variazione scheletrica, con l’indicazione dei sistemi di classificazione impiegati in letteratura.

  • Editorially checked — what this means
• Encyclopedia entry8 August 2026

  Arteria succlavia: varianti di origine (contenuto dimostrativo)

  Contenuto dimostrativo. Questo testo serve a verificare il funzionamento del portale e non costituisce una fonte scientifica. Questa voce mostra come sarà trattata una variazione di origine vascolare, con attenzione alla terminologia e alla provenienza delle informazioni.

  • Editorially checked — what this means