hypothenar eminence

What Is the Hypothenar Eminence?

The hypothenar eminence is the fleshy pad on the palm of the hand at the base of the little finger, formed by the muscles controlling the fifth digit. In polygraph testing, the hypothenar eminence is relevant as a potential site for electrodermal sensor placement and as a site rich in eccrine sweat glands that responds to emotional stimuli.

Electrodermal Sensor Placement

While the standard placement for polygraph electrodermal sensors is on the medial phalanges of the index and ring fingers, the hypothenar and thenar eminences are alternative palmar sites used in some research and clinical applications. These palmar sites have high eccrine gland density and respond to emotional rather than thermoregulatory sweating, making them suitable for electrodermal measurement.

Anatomical Distinction

The hypothenar eminence is on the ulnar (little finger) side of the palm; the thenar eminence is on the radial (thumb) side. Both are richly innervated by the sympathetic nervous system and contribute to the palmar sweating measured by the electrodermal channel.

Practical Application

Understanding this concept contributes to the comprehensive knowledge base required for competent polygraph practice. The APA Standards of Practice and Code of Ethics require that examiners maintain the theoretical and practical knowledge necessary to conduct examinations competently, interpret data accurately, and communicate findings clearly in examination reports and, when required, in legal proceedings.