The Common Vein
Copyright 2010
Definition
The lumbricals of the musculoskeletal system are characterized by having different innervations depending upon the phalanx.
They are part of the 2nd layer of plantar muscles of the lower leg and consists of skeletal muscle fibers.
Its unique structural features include that it intimately related to the flexor digitorum longus.
The origin is the tendons of the flexor digitorum longus.
The insertion is the medial side of the proximal phalanx and into the tendon of the extensor digitorum longus of the 2nd to the 5th toes.
The blood supply is from distal branches of the posterior tibial artery.
The innervation is from the lateral plantar nerve to the 2nd, 3rd, and 4th lumbricals and from the medial plantar nerve to the 1st lumbrical.
The lumbrical muscles as well as all other bones, muscles, and ligaments of the body are derived of mesodermal origin in embryo.
The function of the lumbricals are to flex the proximal phalanges and to extend the middle and distal phalanges of the lateral 4 toes. The lumbricals work synergistically with the flexor digitorum brevis and flexor digitorum longus for metatarsophalangeal movement, the extensor digitorum longus and brevis for extension, and the dorsal and platar interossei.
There are no common diseases.
Commonly used diagnostic procedures include clinical history, physical exam, and MRI.
References
Lieberman J (ed), AAOS Comprehensive Orthopaedic Review, American Academy of Orthopaedic Surgeons, 2008.
Moore K, Dalley A (eds), Clinically Oriented Anatomy (5th edition), Lippincott Williams & Wilkins, Philadelphia, PA, 2006.
Wheeless’ Textbook of Orthopaedics: Foot Lumbricals (http://www.wheelessonline.com/ortho/foot_lumbricals)