The Plantar aponeurosis is the modification of Deep fascia, which covers the sole. It is a thick connective tissue, that functions to support and protect the underlying vital structures of the foot. The fascia is thick centrally, known as aponeurosis and is thin along the sides. The fascia consists of three parts, medial, lateral and the central part, respectively.
The aponeurosis is triangular in shape. The central portion, is attached to the medial tubercle of the calcaneal , proximal to the attachment of the Flexor digitorum brevis and it divides into five processes, near the head of the metatarsal bones, one for each of the toes. Each of these processes further divides opposite to the MTP articulation into two strata, superficial and deep. The superficial strata is attached to the skin, which separates the toes from the sole. The deep strata, divides into two slips which embrace the side of the Flexor tendons of the toes, blend with the sheaths of the tendons, and with the deep transverse metatarsal ligament. The intervals left between the five processes gives passage to the digital vessels and nerves.
The lateral and medial portions of the aponeurosis are thin compared to the central portion, and cover the sides of the sole of the foot. The lateral portion covers the Abductor digiti minimi, and medial portion covers the under surface of Abductor hallucis.
The aponeurosis is important for
- Protecting deeper structures of the foot, such as nerves and vessels.
- To maintain the longitudinal arches of the foot.
- For muscular attachment.
- Prevent excessive dorsiflexion.
- Distribute plantar pressure during static and dynamic loading.
The plantar aponeurosis supports the arch of the foot and distribute the plantar loading. Overstretching of this fascia, may lead to Plantar Fascitis.
- Chen DW, Li B, Aubeeluck A, Yang YF, Huang YG, Zhou JQ, Yu GR. Anatomy and biomechanical properties of the plantar aponeurosis: a cadaveric study. Plos one. 2014 Jan 2;9(1):e84347.