Insertions of the Lumbrical and Interosseous Muscles in the Human Foot

Abstract

Summary: The lumbrical and interosseous muscles in twenty-five feet of Japanese adult cadavers were dissected. The lumbrical muscles mainly continued into the dorsal aponeuroses or the terminal tendons of the extensor digitorum longus muscle, though they occassionally issued some accessory and slender tendons inserting into the bases of the proximal phalanges. Rarely, the lumbrical muscle showed an atavistic anomaly. In this anomaly, the lumbrical muscle was divided into two tails which continued into the bases of the proximal phalanges of the contiguous toes. The plantar and dorsal interosseous muscles were mainly attached to the bases of the proximal phalanges. Frequently, the plantar and dorsal interosseous muscles issued some accessory and small tendons continuing into the dorsal aponeuroses.This fact suggests that the plantar and dorsal interosseous muscles in the foot, like the palmar and dorsal interosseous muscles in the hand, are composite muscles derived from the flexor brevis, contrahens and other muscles.The lumbrical muscles of the human foot are generally regarded as being inserted into the proximal phalanges (Henle, 1871; Frohse and Frãnkel, 1913; Paturet, 1951;Mortenson and Pettersen, 1966;Gardner, Gray and O'Rahilly, 1971; Tillman and TOndury, 1987). However, our recent dissection of Japanese feet has revealed that the lumbrical muscles mainly end in the dorsal aponeuroses. These are reported in the present paper. The insertions of the interosseous muscles are also described and discussed in relation to their phylogenetic compositions. Materials and MethodsTwenty-five feet of Japanese adult cadavers of both sexes, which had been fixed with 10% formalin by vascular perfusion and dehydrated with 60-70% ethanol, were dissected with sharpened forceps under a dissection light microscope. ResultsThere were four lumbrical, four dorsal interosseous and three plantar interosseous muscles in the human foot (Fig. 1, 2, 3). These muscles were numbered from the medial side of the foot (Figs. 1, 2, 3). No morphological difference of the lumbrical, dorsal interosseous and plantar interosseous muscles was observed between the male and female cadavers and also between the right and left feet.The dorsal aponeurosis of the toe consisted of the tendons of the extensor digitorum longus and brevis muscles and the outer and inner tendinous membranes arising, together with the deep plantar metatarsal ligaments, from the plantar aspect of the neck of the metatarsal bone (Figs. 4, 5, 6). The inner tendinous membranes ran around the neck of the metatarsal bone, and enclosed the tendons of the extensor digitorum longus and brevis muscles at a level between the neck of the metatarsal bone and the head of the proximal phalanx (Fig. 5). Thus, the inner tendons extended bilaterally along the proximal phalanx (wing tendons) (Figs. 4, 6). The outer tendinous membrane was thick and band-like, and firmly surrounded the plantar and dorsal interosseous muscles and the enclosed tendons of the extensor muscles (see above) (Figs. 5, ...

Early embryonic development of long tendons in the human foot

“…In adult human cadavers, the foot planta contains much frequently and greater types of flexor tendon anomalies than in the hand palmar aspect (Bergman et al, 1988). Moreover, in contrast to the hand, lumbrical muscles are poorly developed in the adult foot (Oukouchi et al, 1992). Therefore, in the common plate in human embryos and fetuses, much or less, some connections between tendons seemed to remain even after birth.…”

Extensor Apparatus of the Lesser Toes

“…Sarrafian and Topouzian 38 and other authors 6,29,33,36 state that the lumbrical muscles insert into the extensor apparatus (medial and middle slip) via a triangular structure formed by oblique fibers known as the extensor wing (Figure 8). Some authors report that the lumbrical muscles can also insert via tendinous fibers on the phalangeal tuberosity, at the base of the proximal phalanx.…”

“…The tendons from both the plantar and dorsal interossei muscles course distally before running dorsal to the deep transverse metatarsal ligament-in contrast with the lumbrical muscles, which do so plantarly-to reach the metatarsophalangeal joint and insert in the plantar area of the proximal phalanx and plantar plate. 8,15,27,31,33,36,38,39 At their insertion, they are covered by the extensor sling (Figure 11). 37,38 According to the description of the extensor apparatus proposed by Sarrafian and Topouzian, 38 the tendons of the interossei muscles are closely associated with the capsule, into which some fibers insert.…”

“…The vast majority of authors report that the interossei muscles insert at the phalangeal tuberosity on the base of the proximal phalanx. 8,15,27,31,33,36,41 The area of greatest confusion is the direct contribution of the tendons of the interossei muscles to the extensor apparatus. Some authors describe this contribution without specifying how it is produced.…”

Fasciae of the Lower Limb

“…Similar results may be possible with some manual techniques as suggested by Davis (2012). proximal to the tarsometatarsal joints and from the fascia of adjacent muscles. Oukouchi et al (1992) revealed that the plantar and dorsal interosseous muscles often contain some accessory smaller tendons that continue into the dorsal fascia. Due to these fascial connections, it is possible that the tension created by the contraction of one muscle triggers the contraction of others, so that they function as a unit in a coordinated manner.…”