Monday, 9 June 2014

Abductor Pollicis Longus : (2 of 4) Long thumb muscles

Abductor: hint that this muscle does the action of  Abduction which means to 'take away from the mid-line of the body'

Pollicis: referring to the thumb

Longus:  there is likely a shorter version of this muscle (when we cover the four short muscles of the thumb - you will meet the 'short version' of this muscle: Abductor Pollicis Brevis)

This long muscle of the thumb starts from about half way up the back of the forearm (the posterior side) then turns into a skinny tendon that attaches right where the wrist meets the thumb (aka carpo-metacarpal joint) 

Official Attachment Points:

Origin: Posterior surface of the radius and ulna & the interosseous membrane
Insertion: Base of the first metacarpal

Break it down:
radius and ulna = forearm bones
interosseous membrane = is a connective tissue between the radius and ulna
metacarpal = our metacarpals are our finger bones between the wrist and the actual fingers (phalanges) so the metacarpals are located pretty much in the palm of your hand!)

Also, this muscle is deep to (meaning it lives underneath) the wrist extensors!

 Muscle Action(s): 
a) Abducts the thumb at the carpo-metacarpal joint
b) extends the thumb at the carpo-metacarpal joint
 Thumb muscle abduction and extension look verrry similar at first glance. But remember, Abduction is bringing thumb away from hand whereas extension is more like pointing your thumb towards yourself.  Thumb muscle Extension is basically a thumbs up !

It's safe to say this muscle helps you give a good ol' fashioned Thumbs UP! Verry nice!