Hand Web Space Tethers
The web space between your fingers is very complex in appearance and functional demands. It is formed by a relatively large, three-dimensional inclined triangle extending all the way from the distal palm to the dorsal metacarpophalangeal (MCP) joint. Accordion-like tethers running between the metacarpal heads from the palm to the dorsal skin facilitate MCP finger flexion by storing skin folds in extension. These attachments also serve to anchor the proximal apex of the triangular web space. We found oblique, dense fibrous attachments between the palmar and dorsal skin along the whole length and width of the web spaces. They extend into the fingers in continuity with the midaxial, longitudinal ligaments (Cleland’s and Grayson’s) tethering the dermis to the periostea, joint capsules and tendon sheaths. The tethers are so strong that we can lift the hand up by holding onto them. They form an elastic matrix that facilitates finger abduction (spreading apart) and adduction (moving fingers together). As you spread your fingers, you will see the functional advantage conferred by the uniquely tethered shape of the webs.
Although the web spaces are essentially dorsal hand structures, the skin is thick, smooth, pale, non-hair-bearing and is tightly held by the subcutaneous endoskeleton. These are characteristics of palmar skin along with increased vascularity and reflexive posturing protecting them from injury. This is distinct from the thinner, darker, more loosely held hair-bearing skin on the remainder of the dorsal hand. Looking at the top of your hand, it is clear that the palmar skin extends onto the dorsal web. The difference becomes especially relevant when treating deep hand burns. Palmar burns and dorsal web spaces often heal better without surgery for all of the reasons stated above. Additionally, the Cinderella Layer within the web spaces is almost impossible to re-create. Surgical reconstruction typically leads to distortion in appearance and function.
The web spaces are uniquely contoured by an underlying collagenous endoskeleton.
A complex array of tethers extending from the palm toward the dorsal webspace facilitates spreading of the fingers.
Web-like structure of tethers.
The digital neurovascular bundle runs through the hand web space tethers.
Tethers between the metacarpal heads help store skin for MCP flexion and also serve to anchor the proximal web spaces.
Matrix of tethers between the palmar fascia and skin help shape the web space and facilitate finger abduction and recoil.