A Strong Supporter: Evidence for the Role of the Fifth Finger in Habitual Gripping Activity

The fifth finger plays a key role in manual dexterity, yet its habitual use and functional integration within the hand remain poorly understood. This study investigates the contribution of the fifth ray to habitual gripping activities and its synergistic relationship with the thumb.

The "Validated Entheses-based Reconstruction of Activity" (VERA) method and multivariate statistical analyses were applied to the hand bones of 43 adult male/probable male individuals from three post-Medieval skeletal collections in the Netherlands. Principal component and pairwise correlation analyses were used to assess covariation among entheseal attachment sites, with particular focus on the opponens digiti minimi (ODM) and third palmar interosseous (PI3).

Both analyses reproduced functional patterns established in previous VERA studies that distinguish precision from power gripping. The ODM clustered with thumb muscles involved in precision grasping, especially the opponens pollicis (OP), suggesting habitual coordination between the fifth finger and thumb. In contrast, the PI3 formed an independent axis of variation and showed weak correlations with other entheses once overall size effects were removed.

The findings indicate that the fifth finger functions as a stabilizing and supportive element across both grip types, contributing to object control and manual stability through its opposition to the thumb and flexion at the MCP joint. This study underscores the functional significance of the fifth ray in habitual manual activity and highlights the value of size-adjusted VERA analyses for detecting subtle patterns of hand use in past populations.