We are continuing BeneFIT Physical Therapy’s Anatomy Blog Series this month with the Elbow Joint. Each month we will feature a different part of the body. BeneFIT PT’s staff is highly trained in knowing all about human anatomy so that we can effectively help our patients with their specific areas of concern, rehabilitation and strengthening.
Outside of when we bang our funny bone or develop tennis/golfers elbow we probably don’t think too much about our elbows and how they function. They kinda get lost in the shuffle of our shoulders and wrists/hands since they are not as mobile as those two joints. In the gym we might pay more attention as we bust out our bicep curls but even then based on the number of people who let these joints flop around into bad positioning I don’t know how much more attention they are getting. So in this post let’s dive into the elbow joint and give it some much needed love!
When we look at our elbows that bony end part is actually just the end of one of the bones in there. It is actually one of the two ends of the bones that are in our forearm while the third is in our upper arm. The joint is comprised of:
Humerus – the bone of our upper arm. The top part (called the humeral head) is part of the shoulder joint while the bottom part ends in a similar shape to our femurs (that thigh bone from our hip or knee post) and is the bone that we touch on both the inside and outside of our elbow.
- Ulna – One of the bones in our forearm, this is the bone that creates that bump on the back of the elbow. It also is the bone that creates a little bump at your wrist on the pinky finger side of your wrist.
- Radius – this is the other bone in our forearm. The top part of it you can’t really feel by your elbow but this is the bone that rolls over the ulna to make our palm go from facing the sky to facing the floor and back. It also is the bone that creates a little bump at your wrist on the thumb side of your wrist.
The joint itself is considered a “hinge” joint based on how the ulna meets the humerus. It can flex (bend) and extend (straighten). It also can slightly rotate (pronation/supination) based on how the radius can roll over the ulna just below the elbow.
The bones are stabilized with ligaments that form a capsule around the joint which is a fluid filled sac that provides lubrication to the joint. Remember ligaments are what connect bone to bone to keep joints stable. Baseball players and fans of baseball are very familiar with one of them as it can get damaged from pitching or throwing. However, the reality is there are 3 primary ligaments in the elbow:
Radial Collateral Ligament – located on the inside of the elbow, this ligament helps prevent separation of the joint on the medial, or inside, of the elbow.
- Lateral Ulnar Collateral Ligament – located on the outside of the elbow, this ligament helps prevent separation of the joint on the lateral, or outside, of the elbow.
- Annular Ligament – holds the top of the radius (called the radial head) tightly against the ulna. This ligament prevents the radius from rolling away from the ulna when we rotate the elbow.
Both the radial and lateral ulnar collateral ligaments provide the bulk of the elbows stability by holding the humerus and ulna tightly together. The Lateral Ulnar Collateral Ligament (UCL) is the ligament that commonly gets injured for pitchers in baseball. It is the ligament they are talking about when a pitcher suffers a UCL sprain/tear and is the ligament that gets repaired in the Tommy John Surgery.
Tendons are similar to ligaments except that they connect muscles to bones. In the elbow there are 2 primary tendons that attach the muscles of the upper arm to the bones of the elbow:
- Biceps Tendon – attaches the bicep muscle to the radius. The tendon itself actually extends from the bottom of the biceps and dives between the radius and ulna to attache on the medial side of the radius.
- Triceps Tendon – attaches the tricep muscle to the back of the top of the ulna, called the olecranon.
The elbow joint is different then other joints in that it is primarily a hinge joint between the ulna and humerus. What this means is that our elbow joint really just bends and extends. The rotation component of our forearm comes from the interaction of the radius rolling over the ulna. This lay out makes it hard to combine the two motions to create multi-directional movement patterns at the elbow. Really all that happens is that your elbow bends and extends and the only question is which way your palm faces while it does the bending or extending. Despite some of the simplicity of movement at this join compared to others there still are 8 muscles around the elbow:
Triceps Brachii – this is the muscle on the back of the upper arm. It has three muscle bellies which is where the Tri in triceps comes from. It is responsible for extending the elbow.
- Anconeus – this is a small muscle in the back of the arm just above the elbow joint itself. It assists the triceps in extending the elbow and provides support to the elbow.
- Biceps Brachii – this is the muscle on the front of the upper arm. It has two muscle bellies which is where the Bi in biceps comes from. It helps flex the elbow and is also the primary muscle for supination of our forearm. Additionally, it actually starts above the shoulder joint and can actually help flex the shoulder as well.
- Brachialis – this muscle is deep (or under) the biceps brachii muscle. It also helps to flex the elbow joint.
- Brachioradialis – this muscle is located along the posterior lateral aspect of the elbow. However, it primarily helps to flex the elbow joint when the forearm is in pronation (palm towards the floor).
- Supinator – this muscle starts on the top part of our ulnar bone and wraps around the radius bone. When we use this muscle we create forearm supination (we bring our palm up towards the sky).
- Pronator Teres – this muscle starts on the lateral epicondyle of our humerus and wraps over towards our ulnar. We use this muscle to create forearm pronation (we bring our palm down towards the floor).
- Pronator Quadratus – this muscle is located more in our forearm and assists our pronator treres muscle in pronating our arm.
To keep things simple:
- The muscles that straighten the elbow: Triceps Brachii and Anconeus.
- The muscles that bend the elbow: Biceps Brachii, Brachialis, Brachioradialis and Pronator Teres.
- The muscles that bring our palm towards the sky or facing to the front of us: Biceps Brachii and Supinator.
- The muscles that bring our palm towards the floor or facing behind us: Pronator Teres and Pronator Quadratus.
The muscles of our elbow joint really only have to focus on moving our elbow and forearm around to better position our wrist and hands. They often have to work in conjunction with each other to achieve the many different positions we can achieve. The stability of the joint comes from the three bones and how they fit together.
Bringing it all together
Our elbow joints are most similar to our knee joint in that both rely on the bones to provide the support while the muscles just move everything around. Just like the knee, elbow injuries tend to focus on muscle strains, ligament injuries, and overuse injuries. Although you might have to deal with some combination of bone, muscle, ligament, or nerves involved in any injury. Touching base with your Physical Therapist can speed up the process in figuring out what exactly is causing your pain…even without seeing an Orthopedist or getting an MRI!
If you’re having any issue with your elbow or forearm currently and want to get it checked out just contact either of our offices. Our Doctors of Physical Therapy can see you without a prescription, covered by your insurance, often times within 24 hours from your call!