Explore the different sections using the drop down menu to learn about the different muscles of the upper extremity
Tips
Before beginning to learn about muscles, it is important to first be familiar with the bony landmarks
This is because muscles will originate and insert onto these bony landmarks and by having the landmarks memorized, learning the muscles becomes a lot easier
Another tip is to not blindly learn muscle actions, but rather think about the orientation of the muscle and which joint or joints it is crossing, and then deduce what its actions can be
For example, the flexor carpi radialis crosses the elbow and wrist joints and is on the anterior surface, so it can be deduced that it flexes the elbow and the wrist, along with radially deviating the wrist since it inserts onto the lateral/thumb side of the hand
Think of if a rope was attached at point A (the origin) to point B (the insertion). If the rope was shortened as if a muscle contraction was occurring, what direction would it pull and what movements would occur at the joints it crosses?
Recommended link for learning muscle origins, insertions, actions, and innervations:
https://www.kenhub.com/en/library/anatomy/upper-limb-muscles-and-movements
Origin:
Is the fixed attachment point of a muscle
Usually does not move much during a contraction
Is usually on the proximal end (closer to the trunk)
Insertion:
Is the moveable attachment point of a muscle
When the muscle contracts, the insertion is pulled toward the origin
Is usually on the distal end (further away from the trunk)
Action:
Is the movement a muscle does when it contracts
The action of a muscle depends on the joints it crosses and the direction of the muscle fibers
Innervation
Is the nerve that connects to a muscle to stimulate a contraction to occur
The nerve originates from the spinal cord (brachial plexus for the upper extremity)
During a voluntary contraction, motor neurons in the brain send a signal down to the spinal cord, where the message is then relayed through the brachial plexus to the specific nerve that innervates the muscles involved in the movement