Flexor Digiti Minimi Brevis (Manus)

This muscle is extremely variable and is frequently united with, or replaced by, the abductor and sometimes by opponens digiti minimi. It may also be replaced by a tendinous band that arises from flexor carpi ulnaris and inserts onto the base of the fifth proximal phalanx and hook of the hamate. The muscle may be doubled and the absence of flexor digiti minimi brevis has been reported (Cloquet). Flexor brevis may be associated with an accessory palmaris slip joined to it. It was found with an unciform (os hamatum) origin alone. The muscle may send a slip to the head of the metacrpal bone. It may be united with the abductor.

Macalister reported the variations of opponens digiti minimi as follows:

1. The muscle may be split into an upper and lower part
2. It may be absent
3. It may be inseparably united with abductor digiti minimi.

Tensor capsularis articulationis metacarpophalangei digiti minimi is a small muscle that arises from the ligaments joining the pisiform and hamate bones. It inserts into the palmar surface of the metacarpophalangeal joint of the fifth digit. Calori (1867) found a small muscle passing from the hamate to the pisiform bone. The tendon of palmaris longus may give rise to an additional muscle, accessorius ad flexorem digiti minimi, which usually inserts on the body and head of the fifth metacarpal between abductor digiti minimi and flexor digiti minimi brevis. see also Palmaris longus .

Palmaris brevis may join flexor digiti minimi brevis Although not an intrinsic hand muscle, the rare ulnaris externus brevis arises about 6.5 cm proximal to the distal end of the ulna. It inserts onto the fifth metacarpal not unlike opponens digiti minimi, which inserts onto the fifth metacarpal, to which it may be functionally related.

Syn.: m. Flexor brevis digiti quinti.

Riferimenti dell’opera originale

Elenco riportato come compare nella fonte, senza normalizzazione dei formati bibliografici.

• Calori, L. (1867) Di alcuni varieta muscolari dell'avambraccio e dell' eminenza ipothenar. Mem. Accad. R. Sci Istituto di Bologna. S. 2. 7:359-381.
• Carr, N.D., O'Callaghan, J.D. and R. Vaughn. (1977) An unusual flexor of the fifth finger. Acta Anat. 98:376-379.
• Flower, W.H. and J. Murie. (1867) Account of the dissection of a Bush woman. J. Anat. Physiol. 1:202-208.
• Gloobe, H. and P. Pecket. (1973) An anomalous muscle in the canal of Guyon (A possible ulnar compression). Anat. Anz. 133:477-479.
• Macalister, A. (1875) Additional observations on muscular anomalies in human anatomy (third series), with a catalogue of the principal muscular variations hitherto published. Trans. Roy. Irish Acad. Sci 25:1-134
• Morrison, J.T. (1916) A palmaris longus muscle with a reversed belly, forming an accessory flexor muscle of the little finger. J. Anat. Physiol. 50:324-326.
• Saadeh, F.A. and R.A. Bergman. (1986) Doubled palmaris longus muscle with an associated accessorius ad flexorem digiti minimi muscle. Anat. Anz. 161:393-395.
• Saadeh, F.A. and R.A. Bergman. (1988) An unusual flexor (opponens) digiti minimi accessorius. Anat. Anz. 165:327-329.
• Thomas, Jr., C.G. (1958) Clinical manifestations of an accessory palmaris muscle. J. Bone Joint Surg. (A) 40:929-930.