Myogale abductor subsp. pollicis

WHIDDEN, HOWARD P., 2000, Comparative Myology of Moles and the Phylogeny of the Talpidae (Mammalia, Lipotyphla), American Museum Novitates 3294, pp. 1-53 : 32

M. abductor pollicis brevis

ORIGIN: From a ridge on the medial side of the palmar surface of the radiale.

INSERTION: On the medial side of a sesamoid that lies on the palmar surface of the metacarpo­phalangeal joint of digit I.

REMARKS: This muscle has the same general form in Condylura , Desmana , Neurotrichus , Parascalops , Scapanus , Scaptonyx , Talpa , Uropsilus , and Urotrichus . It is apparently absent in Galemys and Scalopus . Reed (1951) found this muscle in Scapanus , but considered it to be the medial deep podial flexor for the pollex. However, in Uropsilus and in the soricids Crocidura (Haines, 1955) , Suncus (Sharma, 1958) , and Blarina (personal obs.), a muscle originating from a ridge on the radiale is present in addition to a full set of paired Mm. flexores breves to each digit. Such a muscle is also present in Desmana ,

which has an unpaired M. flexor brevis for each digit (see description of Mm. flexores breves below). It seems to me more likely that talpids other than Galemys and Scalopus have retained M. abductor pollicis brevis and (except for Uropsilus ) reduced or lost the set of deep podial flexors.