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Concept: Flexor digitorum profundus muscle


PURPOSE: To compare the biomechanical and technical properties of flexor tendon repairs using a 4-strand cruciate FiberWire (FW) repair and a 2-strand multifilament stainless steel (MFSS) single cross-lock cable-crimp system. METHODS: Eight tests were conducted for each type of repair using cadaver hand flexor digitorum profundus tendons. We measured the required surgical exposure, repair time, and force of flexion (friction) with a custom motor system with an inline load cell and measured ultimate tensile strength (UTS) and 2-mm gap force on a servo-hydraulic testing machine. RESULTS: Repair time averaged less than 7 minutes for the 2-strand MFSS cable crimp repairs and 12 minutes for the FW repairs. The FW repair was performed with 2 cm of exposure and removal of the C-1 and A-3 pulleys. The C-1 and A-3 pulleys were retained in each of the MFSS cable crimp repairs with less than 1 cm of exposure. Following the FW repair, the average increase in friction was 89% compared with an average of 53% for the MFSS repairs. Six of the 8 MFSS specimens achieved the UTS before any gap had occurred, whereas all of the FW repairs had more than 2 mm of gap before the UTS, indicating that the MFSS was a stiffer repair. The average UTS appeared similar for both groups. CONCLUSIONS: We describe a 2-strand multifilament stainless steel single cross-lock cable crimp flexor repair system. In our studies of this cable crimp system, we found that surgical exposure, average repair times, and friction were reduced compared to the traditional 4-strand cruciate FW repair. While demonstrating these benefits, the crimp repair also produced a stiff construct and high UTS and 2-mm gap force. CLINICAL RELEVANCE: A cable crimp flexor tendon repair may offer an attractive alternative to current repair methods. The benefits may be important especially for flexor tendon repair in zone 2 or for the repair of multiple tendons.

Concepts: Stainless steel, Strength of materials, Knee, Force, Titanium, Flexor digitorum profundus muscle, Tensile strength, Steel


A previous ultrasound study showed inflammation around the extensor pollicis longus tendon and surrounding structures at 6 weeks after manipulation, with or without pin fixation, and immobilization for distal radius fracture. Ultrasound examination after plating of distal radius fracture followed by early active mobilization of the wrist showed a short-lived inflammatory response, evident at 2 weeks but not at 6 weeks, around the extensor pollicis longus tendon (26 wrists examined) and flexor pollicis longus tendon (18 wrists examined). Early active mobilization of the wrist appears to limit the duration of inflammation around these tendons.

Concepts: Flexor digitorum profundus muscle, Carpal tunnel, Flexor pollicis brevis muscle, Extensor pollicis longus muscle, Extensor pollicis brevis muscle, Flexor pollicis longus muscle, Distal radius fracture, Wrist


Recurrent volar displacement of the extensor digitorum communis tendon (EDC) at the metacarpophalangeal joint (MCPJ) more commonly occurs post-trauma or in the rheumatoid hand. This disabling condition of the hand results in painful swelling of the MCPJ, associated with “locking” of the extensor tendon. We report a simple surgical technique used to successfully ‘secure’ the EDC from recurrent displacement. This was performed for a 59-year-old man who developed the condition in his ring finger, following Vth ray amputation for severe Dupuytren’s disease. First, the EDC over the IIIrd and IVth MCPJ are exposed using a longitudinal incision. The junctura tendinum between the EDC tendons was next extended proximally by 2 cm on the radial side of the IVth EDC and then divided to create a distally based junctura slip. Next, a ‘lasso’ was created by passing the slip beneath the IVth EDC tendon and then securing it onto itself with a 5/0 Ethibond suture (Ethicon Inc.). This reconstruction was then tested in all ranges of MCPJ flexion, successfully preventing volar displacement of the extensor tendon. The ‘junctura lasso’ provided a satisfactory solution for the patient, who, over the next four years; for the duration of his follow-up, suffered no further displacement of the extensor tendon.

Concepts: Ring finger, Hand, Flexor digitorum profundus muscle, Surgery, Finger, Tendon, Extensor digitorum muscle, Lumbricals of the hand


Camptodactyly of the lesser digits is commonly seen in patients with arthrogryposis. The flexed posture of the digit can be functionally limiting and necessitate surgical treatment to improve grasp function. In digits with normal bony anatomy, a lateral stiletto-shaped transposition flap combined with flexor digitorum superficialis tendon release, can improve finger deformity and function.

Concepts: Flexor digitorum profundus muscle, Numerical digit, Finger, Physician


Despite their relatively low prevalence in the population, anomalous muscles of the forearm may be encountered by nearly all hand and wrist surgeons over the course of their careers. We discuss 6 of the more common anomalous muscles encountered by hand surgeons: the aberrant palmaris longus, anconeus epitrochlearis, palmaris profundus, flexor carpi radialis brevis, accessory head of the flexor pollicis longus, and the anomalous radial wrist extensors. We describe the epidemiology, anatomy, presentation, diagnosis, and treatment of patients presenting with an anomalous muscle. Each muscle often has multiple variations or subtypes. The presence of most anomalous muscles is difficult to diagnose based on patient history and examination alone, given that symptoms may overlap with more common pathologies. Definitive diagnosis typically requires soft tissue imaging or surgical exploration. When an anomalous muscle is present and symptomatic, it often requires surgical excision for symptom resolution.

Concepts: Flexor digitorum profundus muscle, Extensor carpi radialis brevis muscle, Flexor carpi radialis muscle, Surgery, Hospital, Forearm, Physician, Wrist


Transverse sections of the monkey cervical spinal cord from a previous study (Jenny and Inukai, 1983) were reanalyzed using Neurolucida to create a three-dimensional display of extensor digitorum communis (EDC) motoneurons and proximal dendrites that had been labeled with horse radish peroxidase (HRP). The EDC motoneuron pool was located primarily in the C8 and T1 segments of the spinal cord. Small motoneurons (cell body areas less than 500 μm2and presumed to be gamma motoneurons) comprised about ten percent of the motoneurons and were located throughout the length of the motoneuron pool. Most small motoneurons were oblong in shape and had one or two major dendrites originating from the cell body in the transverse plane of section. The majority of the HRP labeled dendritic trees were directed either superiorly, dorsal-medially to the mid zone area between the base of the dorsal horn and the upper portion of the ventral horn, or medially to the ventromedial gray matter. The longer HRP labeled dendrites usually continued in the same radial direction as when originating from the cell body. As such we considered the radial direction of the longer proximal HRP labeled dendrites to be a reasonable estimate of the radial direction of the more distal dendritic tree. Our data suggest that the motoneuron dendritic tree as seen in transverse section has direction-oriented dendrites that extend toward functional terminal regions.

Concepts: Synapse, Motor neuron, Flexor digitorum profundus muscle, Extensor digitorum muscle, Part, Neuron, Spinal cord, Dendrite


This study proposed an independent component analysis (ICA)-based framework for localization and activation level analysis of muscle-tendon units (MTUs) within skeletal muscles during dynamic motion. The gastrocnemius muscle and extensor digitorum communis were selected as target muscles. High-density electrode arrays were used to record surface electromyographic (sEMG) data of the targeted muscles during dynamic motion tasks. First, the ICA algorithm was used to decompose multi-channel sEMG data into a weight coefficient matrix and a source matrix. Then, the source signal matrix was analyzed to determine EMG sources and noise sources. The weight coefficient vectors corresponding to the EMG sources were mapped to target muscles to find the location of the MTUs. Meanwhile, the activation level changes in MTUs during dynamic motion tasks were analyzed based on the corresponding EMG source signals. Eight subjects were recruited for this study, and the experimental results verified the feasibility and practicality of the proposed ICA-based method for the MTUs' localization and activation level analysis during dynamic motion. This study provided a new, in-depth way to analyze the functional state of MTUs during dynamic tasks and laid a solid foundation for MTU-based accurate muscle force estimation, muscle fatigue prediction, neuromuscular control characteristic analysis, etc.

Concepts: Neuromuscular disease, Flexor digitorum profundus muscle, Acetylcholine, Independent component analysis, Extensor digitorum muscle, Source, Electromyography, Muscular system


Asymptomatic pisotriquetral arthroses caused ruptures of the flexor digitorum profundus tendon of the little finger in 2 elderly patients. Ruptures occurred with unnoticeable onset, and bilateral ruptures separately occurred with interval of several years in one patient. The tendon was ruptured in zone IV with perforation of the gliding floor through which the degenerative pisiform was visible. The gliding floor was repaired followed with excision of the pisiform, and the ruptured tendon was then transferred to the profundus tendon of the ring finger. Asymptomatic pisotriquetral arthrosis in old age can be an aspect of the pathological background of flexor tendon ruptures of the little finger that occur unnoticed.

Concepts: Little finger, Hand, Finger, Ring finger, Ageing, Gerontology, Old age, Flexor digitorum profundus muscle



The extensor indicis proprius (EIP) is a muscle of the forearm that originates from the posterior surface of the ulna and the adjacent interosseous membrane and attaches to the index finger. Many anatomical variations of this muscle have been reported in the literature. The extensor digitorum brevis manus (EDBM) is a variant muscle found on the back of the wrist and hand. These muscle variants should be considered in the context of clinical syndromes and reconstructive hand surgery. The aim of the present study was to describe in detail the normal and variant anatomy of these muscles and propose new systematic classifications.

Concepts: Flexor digitorum profundus muscle, Hand, Finger, Ulna, Index finger, Extensor indicis muscle, Wrist, Extensor digitorum muscle