There are technically 8 compartments – 9 if you count Manoli’s calcaneal compartment
Medial: Abductor hallucis Lateral: Abductor digiti minimi
Flexor hallucis brevis Flexor digiti minimi
Superficial: Flexor digitorum brevis
Adductor: Adductor hallucis
Distal tendons of flexor digitorum longus
Four interosseous compartments Calcaneal: Quadratus plantae – (Manoli)
There are 9 compartments in total (if you count Manoli’s calcaneal compartment). The superficial, lateral, and medial compartments run the length of the foot. The adductor and 4 interossei compartments are confined to the forefoot. The calcaneal compartment is a separate hindfoot/midfoot compartment consisting of the quadratus plantae.
Manoli feels that the clawing from compartment syndrome is due to the contracture of quadratus – pulls on the flexor digitorum longus tendons.
The described technique of decompressing the compartments is two dorsal longitudinal incisions to decompress the interosseous compartments, then a medial curved incision to decompress the medial, superficial, lateral, adductor, and calcaneal. Beware the lateral and medial plantar nerves that run deep to the flexor digitorum brevis, between the 1st and 2nd muscular layers of the foot. (1st layer: flexor digitorum brevis, abductor hallucis, abductor digiti minimi. 2nd layer: quadratus plantae, tendons of FDL, tendon of FHL, lumbricals)