Download Activity – Analyzing the Brachialis Elbow (Humeroulnar) Joint

Activity – Analyzing the Brachialis
In this activity we will use the "3 Rules of Muscles" to determine the joint actions of the biceps
brachialis. Answer the questions below:

Hints in Blue
http://upload.wikimedia.org/wikipedia/commons
Elbow (Humeroulnar) Joint Actions Word Bank
Action
Plane
Flexion
Extension
Sagittal
Sagittal
© 2014 Brent Brookbush
1. Since this muscle runs up and down in front of the elbow, what joint action will it contribute
to?
Elbow flexion - With nearly twice the cross-sectional area of the biceps brachii, the
brachialis is the prime mover of elbow flexion
2. Bonus Question: Can this muscle supinate the forearm?
No - The radius is the “moving” bone of the forearm. The radius literally “revolves” or
“spins” around the stable ulna. A muscle can only contribute to supination or pronation if it
has an attachment to the radius.
3. Re-write your answers into one succinct table?
Brachialis
o Joint crossed: Elbow
o Actions: Flexion
Check your answers!
© 2014 Brent Brookbush