Wrist and fingers kinesiology and predilection of hand configuration in Brazilian Sign Language

Abstract

In this paper, we identify the prevalence (and inexistence) of hand configurations in Brazilian Sign Language (Libras) in which only one of the fingers is extended, and we discuss the findings from the anatomical and muscular system of the wrist and finger joints. The kinesiology of upper limbs can justify some movement combinations and hand configuration patterns in sign languages (CRASBORN, 2012; MENDEL, 1979; SMITH, WEISS e LEHMKUHL, 1997; WOOKWARD, 1982; 1987). Our corpus of analysis was the Trilingual Illustrated Encyclopedic Dictionary of Brazilian Sign Language (CAPOVILLA; RAPHAEL, 2001). From the data, we observed that Libras has extended thumb, extended index, and extended little finger configurations, and does not have extended middle and extended ring finger. This pattern of manifestation in Libras is predicted typologically and can be justified from the physiology of wrist and finger movements. The independent extension movement of the ring finger and middle finger requires greater effort, as there are no specific muscles that allow the isolated and independent movement of these segments. Moving them generates the recruitment of a single muscle that tends to move the other fingers. Differently, the distending movement of the thumb, extension of the index finger and extension of the little finger, independently, is performed by specific (and individual) muscles for these actions. Still in relation to Libras, the extended index hand configuration is more prevalent, followed by extended thumb and extended little finger. The findings and suggestions presented in this paper are restricted to the analyzed data.