1. A rare variation of intrinsic and extrinsic hand muscles represented by a bi-ventered first lumbrical extending into the carpal tunnel combined with bilateral fifth superficial flexor digitorum tendon regression
- Author
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Sandeep Silawal, Karim Rayan Galal, and Gundula Schulze-Tanzil
- Subjects
musculoskeletal diseases ,0301 basic medicine ,Tendons ,03 medical and health sciences ,0302 clinical medicine ,Cadaver ,medicine ,Humans ,Carpal tunnel ,Carpal tunnel syndrome ,Muscle, Skeletal ,Aged, 80 and over ,030222 orthopedics ,business.industry ,Anatomic Variation ,Anatomy ,Medial epicondyle of the humerus ,musculoskeletal system ,medicine.disease ,Hand ,Carpal Tunnel Syndrome ,Median nerve ,Tendon ,Median Nerve ,body regions ,medicine.anatomical_structure ,Palmaris longus muscle ,030101 anatomy & morphology ,Plantaris muscle ,business - Abstract
A rare unilateral variation of the first left lumbrical muscle was discovered in a female Caucasian cadaver dissected during a first year anatomy course at the Paracelsus Medical University - Nuremberg, Germany. The muscle possessed two venters with the first originating near the medial epicondyle of the humerus together with the intramuscular tendon of the superficial flexor digitorum tendon, and the second presenting as a regular first lumbrical muscle with radial palmar origin from first tendon of the deep flexor digitorum muscle. Both muscle bellies were connected by a 1.42mm thick tendon that passed beneath the median nerve and ran through the carpal tunnel. The second belly was enlarged and entered the distal part of the carpal tunnel. Interestingly, the donor revealed further rare variations such as a bilateral regression of the fifth superficial flexor tendons to an obviously non functional connective tissue strand, lack of both palmaris longus muscles, a discoid lateral meniscus in the left knee, and reduction of the plantaris muscle to a fascia-like structure on the right leg. Lumbrical muscle variations extending into the carpal tunnel, especially those associated with auxiliary tendons, have significant clinical relevance due to their association with carpal tunnel syndrome.
- Published
- 2018