Table 3b.
Origin, insertion and function of the intrinsic foot muscles of Pan paniscus
| Muscles | Origin | Insertion | Form | Function |
|---|---|---|---|---|
| (a) Hallucal muscles | ||||
| AbdH | medial side of the tuber calcanei, tuberosity of the naviculare, and plantar aponeurosis | strong, broad tendon to medial sesamoid bone and base of proximal phalanx of the hallux | thick, pennate; fused with FHBm | hallucal abduction and flexion |
| AddHo | plantar side of the metatarsal III base | lateral sesamoid bone of the first metatarsal | pennate; short tendon at insertion | hallucal adduction and flexion |
| AddHt | plantar side of the metatarsal II, III and IV heads | massive, parallel head | ||
| (b) Short flexors | ||||
| FHBm | plantar side of the medial cuneiform bone | tendon to the medial sesamoid bone of the first metatarsal | thick, pennate, superficial head; fused with AbdH tendon | slight flexion of the first metatarsal |
| FHBl | lateral sesamoid bone of the first metatarsal | elongated, pennate, deep head; tendon at origin | ||
| FDB I | medio-plantar side of the tuber calcanei | perforated tendons to the plantar side of the middle phalanges of digits II (and III) | superficial head; unipennate (proximally fused bellies); variable distribution | flexion of digit(s) II (and III) |
| FDB II | from the latero-plantar side of the FT tendon | perforated tendons to the plantar side of the middle phalanges of digits (III and) IV | deep head; slender, unipennate; variable distribution | flexion of digit(s) (III and) IV; foot plantar flexion |
| (c) Short extensors | ||||
| EHB | dorso-lateral side calcaneus; trochlea peronealis, near the sinus tarsi | tendon into the dorsal aponeuroses of digit I | bipennate; proximally fused with EDB | hallucal extension and foot supination |
| EDB | 2–3 tendons into the dorsal aponeuroses of digits II (III) and IV | 2–3 bipennate muscle bellies; proximally fused with FDB | digital extension (digits II–IV) | |
| (d) Other | ||||
| Lumbr II | medial side of the FT tendon to digit II | tendons to the dorsal side of the proximal phalanges of digit II, III, IV and V | small, unipennate | assists in flexion of digital (proximal) phalanges |
| Lumbr III and IV | medial side of the FF tendons to digit III and IV | |||
| Lumbr V | lateral side of the FF tendon to digit IV | |||
| AbdV | plantar side of the tuber calcanei; ligament between the tuberosity of metatarsal V and the lateral malleolus | 2 tendons to the plantar base of the proximal phalanx of digit V | thick, bipennate; distally fused with FlexV | flexion and abduction of digit V |
| FlexV | along metatarsal V and from the AbdV belly | separate insertion onto the AbdV tendon and to the metatarso-phalangeal joint | pennate; 2 separate muscle bellies; fused with AbdV | slight flexion of digit V |