Monday, 14 July 2014

Adductor Pollicis (1 of 4 Short muscles of thumb)

We've covered all 4 LONG muscles of the thumb. Now it's time to explore the 4 SHORT muscles of the thumb! The main difference being that the attachment points for the short muscles Begin (originate) and End (insert) in the hand whereas the long muscles of the thumb originate just above the wrist joint and into the forearm.

Our first short muscle of the thumb:


 Adductor: hinting that this muscle performs the action of Adduction
Pollicis: referring to the Thumb.

Muscle Attachments:

Origin: capitate, 2nd, and 3rd metacarpals
Insertion: base of proximal phalange of the thumb

Adductor Pollicis is strong and the largest of the 4 short thumb muscles!

Muscle Action(s):
a) Adducts the thumb at the carpo-metacarpal & metacarpo-phalangeal joints (see image below)
b)  also assists in Flexion of the thumb at the metacarpo-phalangeal joints

at the what-what joints?
Here's a visual:

An example of thumb flexion (the secondary action for this muscle) would actually be the last two thumb joints in the above image (MCP & IP joints)

See you next week! 3 more short muscle to go ! Can you believe our thumbs have so many muscles? (8!)