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Functional Anatomy and Biomechanics
Published in Emeric Arus, Biomechanics of Human Motion, 2017
The other two extensors are musculus extensor carpi radialis longus and extensor carpi radialis brevis. For both of these muscles, the original insertion is on the lateral epicondyle of the humerus. They are very long muscles. The distal insertion of the extensor carpi radialis longus is on the base of the second metacarpal bone. The distal insertion of the extensor carpi radialis brevis is on the base of the third metacarpal bone. Their action is the extension of the wrist. Figure 3.7 shows the extensor muscles from the dorsal part of the forearm (they are mostly superficial muscles).
Quantifying wrist angular excursion on impact for Jab and Hook lead arm shots in boxing
Published in Sports Biomechanics, 2021
Ian Gatt, Thomas Allen, Jonathan Wheat
In boxing, carpometacarpal instability of the hand has been identified as the most common injury, incurring the highest time loss from training (Loosemore et al., 2017; Loosemore, Lightfoot, Palmer-Green et al., 2015). As little movement occurs at the index and middle finger carpometacarpal joints (Morgan & Carrier, 2013), they are loaded when a punch is thrown correctly. Loading of the carpometacarpal joints is supported through investigations of proportional distribution of impact forces, using pressure films placed over the knuckles (Loosemore, Lightfoot, Meswania et al., 2015). The middle and ring finger knuckle displayed the largest and lowest proportion of impact forces, respectively (Loosemore, Lightfoot, Meswania et al., 2015). Higher force transmission towards the radial side of the wrist is supported by the literature, as observed when a load is applied to the hand using a rigid body spring model (Schuind et al., 1995). Index and middle finger carpometacarpal injuries are more common than those at the other fingers (Loosemore et al., 2017; McDougall, 1972; Melone et al., 2009; Nazarian et al., 2014). Concomitant avulsion of the tendons attaching at the base of the index and middle metacarpal joints, extensor carpi radialis longus and extensor carpi radialis brevis, respectively, are also identified from clinical practice (Mundell et al., 2014; Najefi et al., 2016; Turner et al., 2012). Extensor carpi radialis longus and extensor carpi radialis brevis muscles are typically described to perform combined extension with radial deviation of the wrist (Tanrıkulu et al., 2014), the opposing action of ulnoflexion motion. It is, therefore, proposed that as the hand contacts on the radial side during a punch, the wrist moves towards ulnoflexion, following the path described in dart-throwing motion.