Welcome to Muscle Monday! We’re back with another WRIST/Forearm FLEXOR muscle: PALMARIS LONGUS !
(Remember that all wrist flexor muscles run along the ‘inside of the forearm’ (the softer feeling side that usually doesn’t have hair on it ;) it’s actually referred to as the “anterior forearm” - meaning ‘front’ (because that is the side that faces out when standing in ‘anatomical position’) the back of the forearm is referred to as POSTERIOR.
Palmaris Longus Attachment Points:
>ORIGINATES at the ‘common flexor tendon’ (where many of the forearm flexors originate) – this tendon is connected to the MEDIAL EPICONDYLE of the HUMERUS (the bump on the inside of your elbow)
> the actual muscle belly is shorter (ending about a 1/3 the way down the forearm – towards the elbow > then its just a long skinny muscle tendon that travels down the center of the anterior forearm, crosses the wrist..
> INSERTS onto the Flexor Retinaculum & Palmer Aponeurosis (which are fancy ways of saying ‘the connective tissue of the inside of the wrist & Palm
It’s actually the way this connective tissue spreads out that whenever I think of PALMARIS LONGUS I can’t help but think of SPIDERMAN shooting his web :)
Palmaris Longus Muscle Actions:
1) FLEXES the hand at the wrist joint
2) tenses the palmer fascia (scrunches up your palm)
3) It also helps to FLEX the forearm at the elbow joint - aka bend your arm (because it crosses onto the humerus (upper arm bone).
Fun Fact! Did you know that some people DON’T even have a Palmaris Longus muscle? Nothing to be alarmed about –absence of Palmaris Longus does not affect grip strength. I’ll betyou’re wondering right now if you have this muscle or not?
-To see it – look at your palm > flex your hand (like you’re trying to point your fingers towards your face > and look for the ‘cord like ‘ tendon in the midline (center) of the inside of your wrist.
(The Palmaris tendon lives between the Flexor Carpi Radialis and Flexor Carpi Ulnaris )