Anat Cell Biol.  2023 Jun;56(2):288-292. 10.5115/acb.22.225.

Degenerated lumbricals in the feet of adult human cadavers: case series

• Krishna H
• Tandon R
• Jacob TG

• KMID: 2544094
• DOI: http://doi.org/10.5115/acb.22.225

Abstract

In the foot, the lumbricals flex the metatarsophalangeal joints and extend the interphalangeal joints. The lumbricals are known to be affected in neuropathies. It is not known whether they may degenerate in normal individuals. Here, we report our findings of isolated degenerated lumbricals in seemingly normal feet of two cadavers. We explored lumbricals in 20 male and 8 female cadavers that were 60–80 years of age at the time of death. As part of routine dissection, we exposed the tendons of the flexor digitorum longus and the lumbricals. From the degenerated lumbricals, we took some tissue for paraffin-embedding, sectioning, and staining by hematoxylin and eosin, and Masson’s trichrome technique. Of the 224 lumbricals studied, we found four apparently degenerated lumbricals in two male cadavers. In the first, the 2nd and 4th lumbricals in the left foot and the 2nd in the right foot were degenerated. In the second, the right 4th lumbrical was degenerated. Microscopically, the degenerated tissue was made of bundles of collagen. The lumbricals may have degenerated due to compression of their nerve supply. We cannot comment on whether the functionality of the feet were affected by these isolated degeneration of the lumbricals.

Keyword

Lumbrical muscle; Foot; Degeneration; Lateral plantar nerve

Figure

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  Fig. 1 Photographs of lumbricals of the foot showing: (A) degenerated 2nd and 4th lumbricals in the left and 2nd lumbrical in the right foot; (B) enlarged view of (A) showing degenerated 2nd and 4th lumbricals in the left and 2nd lumbrical in the right foot; (C) the degenerated fourth lumbrical of the right foot and normal lumbricals in the left foot; and (D) enlarged view of the right foot of (C) showing degenerated fourth lumbrical. 1, flexor accessorius; 2, tendon of flexor digitorum longus; 3, tendon of flexor hallucis longus; 4, first lumbrical; 5, second lumbrical; 6, third lumbrical; 7, fourth lumbrical; >, degenerated lumbrical.

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  Fig. 2 The photomicrographs of longitudinally sectioned lumbrical muscles, stained with hematoxylin and eosin, showing: (A) normal lumbrical muscle at low power (10×); (B) normal lumbrical muscle at high power (40×); (C) degeneration of lumbrical muscle at low power (10×); and (D) degeneration of lumbrical muscle at high power (40×). Scale bars=200 µm (A, C); scale bars=50 µm (B, D). F, muscle fascicle; N, nucleus; FC, fascicle of collagen fibers.

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  Fig. 3 The photomicrographs of longitudinally sectioned lumbrical muscles, stained with Masson’s trichrome technique, showing: (A) normal lumbrical muscle at low power (10×); (B) normal lumbrical muscle at high power (40×); (C) degeneration of lumbrical muscle at low power (10×); and (D) degeneration of lumbrical muscle at high power (40×). Scale bars=200 µm (A, C), scale bars=50 µm (B, D). F, muscle fascicle ; N, nucleus; FC, fascicle of collagen fibres; MF, muscle fibres.

Reference

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