um the wrist motion happened in two planes um one is uh fraction extension uh within the uh sagittal plan with a a a frontal axis the other is a frontal plan uh with radial oner deviation uh with the sagittal axis and in some textbook um they uh describe radio deviation as abduction and on deviation as adduction um but they're really the same thing so and don't be surprised you will um see some descriptions uh for the risk motion as flection extension and abduction adduction um um some um people may confused uh with um circumduction with rotation um like when we are drawing a circle uh we will call the rist would do a rotation but it is in fact uh is a c C conduction and what is circumduction then circumduction is a combination of uh all the uh movements that uh the rist perform so starting from the anatomical position um we can do a wrist extension and then radial deviation and then flexion and then owner deviation and then back to uh the neutral so that look like u a rotation but it is not because you can see that it's really really the uh the rolling and gliding we don't have any spinning going on inside the bat so please don't um um uh mix up with the uh rotation with the U the circumduction um when we talk about the mid corer joints we uh mentioned um using the citate as a reference to look at uh radio on deviation and this is a uh uh further um exploration for us to see that um this kind arth kinematics happen within the coule bones so again when we are um use the capit as a reference you can we can see that uh when we do honor deviation um the whole um um set of the coule bones going to roll to the on side and glide to the radial side and same thing we can observe when we do uh radial deviation U the whole set of the Caro bone kind of rolled toward the radio side and then uh they slide toward oner side and this can be confirmed through the X-ray picture right here you can see when we do uh owner deviation the whole set of the coule bones kind of kind of uh roll and slide to um in to form this shape and why does this happen because um this region is secure by a lot of ligaments so uh because of the the tightness of the ligaments that with forc all the bones going to move all together so you can imagine when uh we got ligament in damaged we lose that stability that would cause a lot of uh problems within the hand and we also know that ligament is formed by the uh type one uh collagen it's uh it takes time to heal so uh our client will experience um a lot of inconvenience using their hand you know when they have this kind of ligament injury within their wrist or the hand so this something uh we should uh be more considerate and then be much more prepared and do a better job in educate our clients um for the muscles um all muscles within this region contribute to the wrist motion which is wrist flection extension and deviation um but I want to focus on the muscles specifically for the wrist uh for wrist flexors we can see we have uh flexor carai onys on the on side and flexor carai radiatus that um insert on the radio side and you can see that I did not put the pomis longus in this picture because not everybody has uh palaras longest like I don't have this muscle so I'm biased in in this way so I'm not going to show you uh the pl okay so um um so when we uh want to do a pure uh rist flection we can and um expect that both FCU and fcr will contract together to do this um risk faction however we also need to cancel the deviation I the effect of the deviation which will come from the extensors um extension part we will uh talk more about that for risk extensors again all muscles passing through this region U contribute to uh risk extension but specifically uh from um the um uh uh The Superficial layer we have extensor carpine radiatus longus um that originated from the humoral bone and ends at you can see here the second uh the base of the second Meto bone okay and then extensor carpi radi brevis that um originally also from the hum bomber lower to the longus and it inserted at the base of the third meno bone you can see these two muscles insert at different um bones so when you do uh the man muscle test think about which muscle that uh we are testing on the on side we have extensor carai onara you can see again it originated from the humal bone and ends at the base of the fifth U um medou bone so all these three muscles uh work together to produce a pure wrist extension you may ask so what muscle are or muscles are responsible for R radio and owner deviation well if we want to do um Aller deviation we will recruit uh extensors and uh flexors on the owner side if we want to do radial deviation we will recruit um the uh flexor and extensors on the radio signs so for example to do owner deviation we will recruit ECU and FCU and for radial deviation we recruit ecrl ecrb and FC y so and this um photo um shows um the the actual uh test the lab test that um that would help the surgeon to decide or help us to know uh the role of each muscles and how and help the surgeon to decide if they need to cut something and then to for uh uh reconstruction for example for extensor careras you we can see that it has strong role in or deviation and uh it help in um um risk extension but not as strong as the two um um extensors on the radial side right but the two strong extens on the radial side they're not as uh as a strong radio deviator as the ECU same thing we can U observe here um flexor car by onys um is good for uh RIS flection and owner deviation but not as strong as extensor car by onys and flexor car by radialis it has strong role in flection but not so strong in radial deviation so that being said that that when um the surgeon needs to decide when they need to do some kind of repairment because of some um nerve injury they a lot of time they choose to uh um cut a muscle and then do a transfer uh for the nerve um to um to heal or to become an a new structure for that um you can see um the pomis longus um it has it it it is a pure RIS uh factors right um but it has very little role in either radial deviation or onal deviation um and taking this out um this person doesn't lose too much in Risk flections because we don't do many uh functional task that require us to do uh risk flection in this sense PL is often time uh being used to you know to cut and then to do some tender transfer right if we cut the extensor carai uh radius bravis what would happen then um this person uh will become weaker in uh risk extension because uh ecrl and ECU are not as strong as ecrb right so if this person hurt the ecrb then we can expect that uh their uh risk extension will become much weak weer and they will definitely need some rehab or um some uh compensatory uh training to compensate the Lost function of ecrb