Clinical Assessment of the Congenital Absence of Palmaris Longus and Flexor Digitorum Superficialis Muscles in Young Saudi Population

Abstract

Introduction. Congenital Palmaris Longus (PL) absence was found in 15%–20.25% of population globally. This condition and Flexor Digitorum Superficialis (FDS) tendon absence in little finger are not known in Saudi Arabia. We studied prevalence of PL and FDS agenesis in Saudi Arabian population. Methods. A random cross-sectional study was carried out after an ethical approval in the Riyadh universities. Schaeffer's test was used to examine PL absence. The Modified test was used to examine FDS absence. Data was analyzed using Microsoft Excel and the SPSS Software version 22. Results. The volunteers, 331, males 164 (49.5%) and females 167 (50.5%), mean age of 23 (SD ± 5.3), showed right hand dominance in 294 (88.8%) and bilateral absence of PL and FDS in 15.1% and 14.8%, respectively. The hand dominance showed no significant relation between PL and FDS absence, p value = 0.788, 0.835, respectively. Generally, we found a weak correlation between absence of the PL and FDS, p value ≥ 0.595. Conclusion. The bilateral absence of PL and FDS was found as 15.1% and 14.8%, respectively. Variation of the FDS tendon absence was an independent entity for the PL absence. The dominance of hands was not related to the tested variables found in PL and FDS agenesis.

Bilateral Congenital Absence of Small Finger Flexor Digitorum Superficialis Tendons in a Trauma Patient

“…The flexor digitorum superficialis (FDS) is the only muscle in the intermediate layer of the anterior forearm [1]. It has three heads originating from the medial epicondyle of the humerus, coronoid process of the proximal ulna, and anteroproximal radius [2].…”

“…It has three heads originating from the medial epicondyle of the humerus, coronoid process of the proximal ulna, and anteroproximal radius [2]. The humeral and ulnar heads typically fuse to form the humeroulnar head [1][2]. Fibers from these three heads form a central belly in the proximal half of the forearm and then diverge into four beams [2].…”

“…Fibers from these three heads form a central belly in the proximal half of the forearm and then diverge into four beams [2]. The tendons of these beams insert into the radial and ulnar aspects of the proximal half of the middle phalanx at Camper's chiasm of each digit except for the thumb [1]. The FDS is innervated by the median nerve and receives its blood supply from the ulnar artery.…”

“…The primary action of FDS is to flex the middle phalanx at the proximal interphalangeal (PIP) joints and can also flex the metacarpal phalangeal (MCP) joints and wrist joint with sustained action [1,3]. This allows the human hand to make skilled, grasping movements necessary for fine motor skills [3][4].…”

“…The origin of these muscles migrated proximally to establish the present separate forearm and intrinsic hand muscle arrangements, giving the organism more control over hand movements [4]. The evolutionary role of the FDS tendon to the small finger warrants further investigation, as its small structure has limited functional consequence [1,6] and its absence may represent evolutionary progression with improved independent flexion of the ring and small finger PIP joints [1,3,6].…”