fascia is a series of fibrous layers. During embryological life,
the layer called mesoderm develops into many components of the body, including bones, muscles, blood vessels. Cells which do not differentiate form a surrounding investment for these structures. The superficial fascia lies beneath the skin over the entire body. In many places it contains fat - often considerable amounts. It helps skin to be mobile, conducts vessels and nerves to the skin, and retains body heat.
- Superficial fascia is very thin over the back of the hands and
feet, but is extremely dense over the palms, soles of the feet and scalp
where it has a cushioning effect.
- Deep fascia is dense and fibrous with no fat. It lies directly
on the outer surface of the muscle groups (like a stocking around limb muscles)
and may form a) thick septa between different groups and b) thin surrounds
to individual muscles.
All of this maximises the efficiency of muscle contraction by isolating
individual muscles and groups from their neighbours. fascia may form specialisations
including a) retinacula which hold down muscle tendons (e.g. around the
ankle) and b) bursae and synovial tendon sheaths which reduce friction. |
