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Anatomy
Published in Peter Houpt, Hand Injuries in the Emergency Department, 2023
The extensors of the thumb form the borders of the anatomical snuff box. The m. extensor pollicis longus lies on the dorsal side of the thumb, inserts onto the distal phalanx and extends the IP joint. The m. abductor pollicis longus and m. extensor pollicis brevis are positioned on the radial side of the anatomical snuff box and provide abduction and extension of the first metacarpal, respectively. Positioned just ulnar to the anatomical snuff box are the two radial extensors of the wrist, the m. extensor carpi radialis longus and brevis, which insert at the base of the second and third metacarpal, respectively. The m. extensor carpi ulnaris is the most ulnar positioned tendon at the level of the wrist. It inserts onto the base of the fifth os metacarpal. The mm. extensor digitorum communis extend the fingers. The index finger has an additional extensor which is located on the ulnar side of the EDC; the m. extensor indicis proprius.
Upper Limb Muscles
Published in Eve K. Boyle, Vondel S. E. Mahon, Rui Diogo, Handbook of Muscle Variations and Anomalies in Humans, 2022
Eve K. Boyle, Vondel S. E. Mahon, Rui Diogo
Extensor digitorum originates from the lateral epicondyle of the humerus and the neighboring intermuscular septum (Standring 2016). It typically inserts via four tendons onto the extensor expansions, and thus to the middle and distal phalanges, of digits two through five (Standring 2016). Intertendinous connections between the terminal tendons are referred to as juncturae tendinae (Standring 2016; Akita and Nimura 2016b).
Upper Limb
Published in Rui Diogo, Drew M. Noden, Christopher M. Smith, Julia Molnar, Julia C. Boughner, Claudia Barrocas, Joana Bruno, Understanding Human Anatomy and Pathology, 2018
Rui Diogo, Drew M. Noden, Christopher M. Smith, Julia Molnar, Julia C. Boughner, Claudia Barrocas, Joana Bruno
As its name indicates, the extensor digitorum inserts on various digits: As explained above, because of the high mobility and freedom of the thumb, the extensores and flexores digitorum in humans insert on digits 2, 3, 4, and 5, but not 1. Also, the simple name “extensor digitorum” indicates that, unlike the anterior compartment of the forearm that contains both a flexor digitorum superficialis and a flexor digitorum profundus, the posterior compartment contains only one long extensor muscle for digits 2, 3, 4, and 5. Logically, this single muscle is the antagonist of the two flexor digitorum muscles of the anterior compartment: That is, it performs the opposite action (extension vs. flexion) and can extend both the middle and the distal phalanges of digits 2, 3, 4, and 5. The extensor digitorum and all the other extensors of the forearm that attach onto fingers (digits 2 to 5) are able to reach the middle and distal phalanges because they are associated with the extensor expansions (or dorsal expansions, or dorsal hoods) attached to the phalanges of these digits (Plate 4.14). The extensor digitorum passes deep (anterior or ventral) to the extensor retinaculum, and its four distal tendons are tied together by intertendinous connections at the hand region. Just medially to the extensor digitorum lies the extensor digiti minimi, which as its name indicates inserts only onto digit 5 (the littlest finger, thence the designation “minimi”). Medially to this muscle lies the extensor carpi ulnaris, which as indicated by its name goes to the ulnar side of the carpal region and thus extends and adducts the hand.
Radial nerve palsy following humeral shaft fracture: a theoretical PNF rehabilitation approach for tendon and nerve transfers
Published in Physiotherapy Theory and Practice, 2022
Lauren Fader, John Nyland, Hao Li, Brandon Pyle, Kei Yoshida
During Phase II, the individual performs high-frequency (hourly), low-intensity donor muscle group activation “fisting,” and low-intensity PNF isometric “position and hold” exercises. Long-term treatment effectiveness is directly related to the motor learning developed during this phase. Early use of high intensity manually resisted scapular PNF patterns at the ipsilateral and contralateral upper extremity may facilitate involved side proximal-to-distal overflow to the wrist and finger extensors, and thumb extensors-abductors. Manually resisted scapular PNF patterns may be safely applied with high intensity at both upper extremities as no direct load is applied to the healing humerus fracture site. Distally, at the involved upper extremity hand and wrist, a passive rhythmic initiation PNF technique can be used within specific ranges of motion in conjunction with verbal cues to open the hand, and extend the wrist, or close the hand, and flex the wrist following a quick stretch stimulus (Adler, Beckers, and Buck, 2008; Saliba, Johnson, and Wardlaw, 1993). Manually applied wrist, metacarpophalangeal, or interphalangeal joint approximation, or slight traction may improve joint stability or mobility, respectively. These techniques should improve extensor carpi radialis brevis generated wrist extension-abduction, extensor digitorum communis generated proximal and distal interphalangeal joint and wrist extension, extensor digiti minimi generated little finger metacarpophalangeal joint extension, and extensor carpi ulnaris generated wrist extension-adduction.
Biomechanical evaluation of the stability of extra-articular distal radius fractures fixed with volar locking plates according to the length of the distal locking screw
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2021
Gyung-Hwan Oh, Hak-Sung Kim, Jung Il Lee
Distal radius fractures (DRFs) are a common injury encountered by orthopedic surgeons. Recently, an operative treatment using a volar locking plate (VLP) has emerged as a popular treatment for unstable DRFs. (Chung et al. 2009; Obert et al. 2013) However, the increased use of VLP has led to various postsurgical complications. Extensor tendon complications such as extensor tenosynovitis, extensor pollicis longus rupture, and extensor digitorum rupture after VLP fixation have been extensively reported. (Benson et al. 2006; Soong et al. 2011; Bentohami et al. 2014; Caruso et al. 2015; Azzi et al. 2017; Thorninger et al. 2017) These complications related to extensor tendons can occur due to inappropriate surgical technique (injury by depth gauge or drill bit) or dorsal protrusion of the distal screw.
Effects of Mental Effort on Premotor Muscle Activity and Maximal Grip Force
Published in Journal of Motor Behavior, 2021
Yosra Saidane, Ross Parry, Chama Belkhiria, Sofia Ben Jebara, Tarak Driss, Giovanni de Marco
Flexor digitorum superficialis (FDS) and extensor digitorum communis (EDC) muscles were identified by palpation as participants flexed and extended the fingers of their right hand. The surface of the skin over each muscle belly was shaved, then cleaned using alcohol wipes. Electrodes were placed on the muscle belly parallel to the main direction of muscle fibers. Each sensor was placed taking into consideration the anthropometric proportions of the individual, corresponding with the zones identified by Barbero et al. (2012). One further electrode was placed upon the lateral epicondyle of the elbow to serve as a reference. Prior to the commencement of the experimental protocol all subjects were placed in a lying down position, with the upper limb along the body and the wrist in the neutral position, neither pronation nor supination.