Anatomy of the Elbow
The elbow joint is an articulation of three bones that act as a lever for 100s of movements we do on a daily basis. It’s a very important joint, but in all honesty it doesn’t get a lot of love compared to other joints around the body. Again, like we have in previous articles, we will hit the basic anatomy of the elbow joint to give you more information, because I am sure you have had some type of injury involving your elbow. If you haven’t had a elbow specific injury, that’s alright, think about other things you may have struggled with in the past. Bicep tendinitis, lateral epicondylitis, (tennis elbow) triceps pain? Yep, they all still involve the elbow joint because those muscles, in addition to many others act on the elbow joint.
The elbow joint is a hinge synovial joint, that has three articulations. The first two include trochlea and capitulem of the humerus meeting with the trochlear notch of the ulna and head of the radius, thus creating the humero-ulnar and humero-radial joints. The overall joint capsule of the joint is weak in the anterior and posterior aspects of the elbow, and to sustain stabilization, it relies on the collateral ligaments on each side of the joint for structure. The collateral ligaments of the elbow are very similar to the collateral ligaments at the knee. The radial collateral ligament (RCL) and ulnar collateral ligament (UCL) help resist against varus and valgus forces respectively, just as the LCL and MCL do at the knee. The UCL may sound familiar to you because that is the ligament commonly injured during throwing or pitching where an athlete may need “Tommy John” surgery.
The third elbow joint articulation is held together by the annular ligament, which holds the radial head in the radial notch of the ulna. This is very important because this creates the proximal radio-ulnar joint, where pronation and supination occur. The proximal radio-ulnar joint is a pivot joint that allows that twisting movement of the head of the radius on the ulna. An example of pronation would be that twisting motion that you would perform when pouring coffee into a cup, whereas supination would be how you normally twist the hand to have the palm up when doing a standard bicep curl.
In addition to pronation and supination, the main two movements of the elbow are flexion and extension, which usually equate to about 170 degrees of motion from full extension to full flexion. You may notice that when you are carrying something that the forearm angles away from the body, this is called the carrying angle. This is aimed to “clear the hips” when walking, so historically, females tend to have a larger carrying angle because they usually carry wider hips for child bearing.
Proper elbow mechanics play a vital role in weightlifting, athletics and in everyday life. There are at least 16 muscles that act on the elbow in some fashion and it is important to remember that injuries to any of those muscles can affect the efficiency of our movement and cause it to become inadequate. We will dive in later on, into common elbow injuries after we continue to talk about the anatomy of the body. If you have had any elbow injuries, or would like to see specific structures, injuries or conditions discussed in future articles, please let us know and always remember to #HealByMoving.