Monday, 14 April 2014

Triceps Muscle

The TRICEPS muscle:

 The only muscle on the posterior (back of) your upper arm (humerus bone)

This muscle gets its name "tri" because it has 3 muscle 'heads', or attachment points on the upper arm.
A- LONG HEAD: attaches to the top edge of your shoulder blade (scapula)
B- LATERAL HEAD: lives nextdoor to the deltoid muscle (see last week!) attaching to the upper part of the back (posterior) humerus
C- MEDIAL HEAD: hiding under the other heads, attaching  onto the lower part of humerus bone (closer to the elbow!)

And guess what ? All THREE heads attach to the SAME place: the olecranon process of the ulna aka YOUR ELBOW!

So what muscle action is Triceps responsible for?

Well, together (all 3 heads - see previous post) (A) EXTEND THE FOREARM AT THE ELBOW JOINT (extend the elbow from a bend position into a straight position!)

*Pause for palpation*: feel triceps yourself!  Start with the elbow in a flexed (bent, closed) position- put your peace fingers just above your elbow (on the back of the arm) and feel triceps contract as you slowly extend your elbow (un-bend your arm!)

- continue to slowly  flex and extend the forearm at the elbow joint (bend & un-bend) as you follow the triceps with your fingers (feeling a muscle is called "palpating" :) all the way up the arm towards the armpit! Can you feel the different heads? (see previous post for anatomy!)

But wait there's TWO more muscle actions! the LONG head of triceps helps to (B) EXTEND THE ARM AT THE SHOULDER (glenohumeral) JOINT as well! (extension of the entire arm as opposed to just the forearm at the elbow.)

- The Long head of triceps also helps the arm (C) ADDUCT  the arm at the  shoulder (gleno-humeral) joint. Adduct means to bring the arm TOWARDS the midline of the body :)