What to know about the humerus bone: anatomy, function, and fractures

The humerus is the bone in your upper arm that’s located between your elbow and your shoulder. Its main function is to provide support for your shoulder and a wide variety of movements for your arm. Fractures are the most common injury to the humerus, and often occur because of a direct blow to the bone.

Keep reading to learn more about your humerus, its different parts, why it’s important, and what types of injuries it can sustain.

  • Your humerus is classified as a long bone. Other types of long bones include the radius and ulna in your forearm and the femur in your upper leg.
  • Speaking of long, the humerus is the longest bone in your arm.
  • Despite its name, when you hit your “funny bone,” you’re not hitting your humerus. You’re actually hitting your ulnar nerve, which is located behind your elbow joint.
  • Bones in your arms or hands are more likely to be broken. This is because we commonly use these parts of our body to break a fall or reduce the impact of some kind of trauma or blow.

Your humerus is the only bone in your upper arm. It can be found between your elbow and your shoulder.

There are some important terms to know with regard to the anatomy of your humerus:

  • Proximal: This is the upper part of your humerus closest to your shoulder.
  • Body or shaft: This is the long, middle portion of your humerus.
  • Distal: This is the lower area of your humerus that’s closest to your elbow.

In addition to the areas mentioned above, the humerus is made up of other parts, too. Let’s explore some of these.

Parts of the humerus

  • Head: This rounded area of the proximal humerus interacts with your shoulder blade (scapula) to form your shoulder joint.
  • Tubercles: These bony areas of the proximal humerus serve as attachment points for the muscles of your shoulder joint. You have two tubercles — the greater and lesser tubercle.
  • Surgical neck: This part is located at the base of the proximal humerus and is a common site for fractures.
  • Epicondyles: These are bony protrusions at the distal (lower end) of your humerus. You have two — the medial and lateral epicondyle. They serve as attachment points for the muscles of your lower arm, wrist, and hand.
  • Trochlea: This part of your distal humerus interacts with the ulna bone in your lower arm.
  • Capitulum: The capitulum is the part of the humerus that interacts with the radius bone of your lower arm.
  • Fossae: You have three fossae, which are depressions that help to accommodate the bones of your lower arm when your elbow joint is moved.

Fractures are one of the most common injuries to the humerus. Humerus fractures are classified by their location:

  • Proximal: A break that occurs at the end of your humerus closest to your shoulder.
  • Mid-shaft or middle: A break that occurs in the shaft or body of your humerus.
  • Distal: A break that happens at the end of your humerus that’s closest to your elbow.

Humerus fracture causes

A humerus fracture most often occurs due to a direct blow. This type of injury often happens in contact sports or car accidents. You can also break your humerus if you fall with your arm outstretched.

Sometimes a humerus fracture can happen due to an underlying health condition. This is called a pathologic fracture and can be caused by conditions such as osteoporosis or cancer.

Humerus fracture symptoms

Some of the most common signs that you may have fractured your humerus include:

  • arm pain, which can be severe and often gets worse with movement
  • a cracking or snapping sound that happens at the time of the injury
  • swelling
  • bruising
  • a visible lump or bump in your upper arm
  • decreased range of motion

Treatment for proximal humerus fractures

Fractures to the proximal humerus occur near the shoulder joint. Most fractures to the proximal humerus can be treated without surgery, as long as the bones haven’t shifted out of their original position. In cases where the bones have moved, surgery may be recommended. The most common surgery in these cases involves realigning the bone fragments using plates, pins, or screws.

In cases where surgery is not required, your doctor may recommend going through physical therapy to help you regain strength and flexibility in the area.

Treatment for mid-shaft humerus fractures

A mid-shaft humerus fracture occurs when there is a direct blow to the upper arm. In most cases, there is a high likelihood that bones can be realigned by using a splint or sling in order to keep the bone in place and reduce movement. Your doctor will likely prescribe medication to relieve any initial pain or swelling, and they will follow up with you in a week order to evaluate whether it’s healing correctly.

These fractures may take up to 4 months to fully heal.

Treatment for distal humerus fractures

A distal fracture refers to when you break the lower part of the humerus, and is most commonly caused by directly hitting or falling on the bone. Although a fracture in this area can be painful, there are ways to successfully treat it and relieve any pain or swelling.

The type of treatment will depend on the severity of the fracture. Some treatment options may include one or a combination of the following:

  • applying ice to reduce pain and swelling
  • medications to help ease pain and swelling
  • immobilization using a sling or splint to prevent movement of your upper arm and help with healing
  • surgery for severe fractures, which can include plates and screws to help the bone to mend
  • physical therapy to help you maintain or regain strength, flexibility, and movement in the affected arm

The most common surgical procedures to treat a distal fracture are determined by the severity of your fracture. For more severe breaks, your doctor may recommend external fixation, where the surgeon will apply a frame to hold the bone in place during the operation.

The most common surgical treatment for distal fractures is open reduction and internal fixation. During the operation, your surgeon will reposition bone fragments into their original alignment and then hold them in place using plates and screws that are attached to the outside of the bones.

Recovery time can also depend on the severity of your injury as well as your overall health.

Depending on the type and severity of the fracture, it could take up to a year for the fracture to fully heal. Keep in mind that you may need to do physical therapy for several months afterward.

Your humerus has two important functions. These are movement and support. Let’s explore them in a little more detail.

The connections that the humerus makes at your shoulder and elbow allow for a wide variety of arm movements, such as:

  • rotation at the shoulder joint
  • raising your arms away from your body (abduction)
  • lowering your arms back toward your body (adduction)
  • moving your arm behind your torso (extension)
  • moving your arm in front of your torso (flexion)
  • straightening your elbow (extension)
  • bending your elbow (flexion)

In addition to being crucial for various arm movements, your humerus is also important for support. For example, parts of the humerus serve as a connection point for muscles in your shoulder and arm.

Other potential issues associated with the humerus include:

  • Radial nerve injury: The radial nerve runs through your arm. Radial nerve injury can be a complication of a humerus fracture, particularly middle or distal fractures.
  • Metastatic bone disease: Metastatic bone disease is when cancer that developed in one area of the body, such as the lungs or breast, spreads to the bones. According to the American Academy of Orthopaedic Surgeons, the humerus is commonly impacted.
  • Osteochondroses: This is a group of disorders in which bone growth is affected. One type, called Panner’s disease, can impact the distal area of the humerus, leading to pain in the elbow.

Your humerus is the long bone in your upper arm. The connections it makes at the shoulder and elbow enable you to make many different arm movements. The humerus is also a connection point for arm and shoulder muscles.

Humerus fractures are a common injury that are often caused by falls, car accidents, or contact sports. These fractures are typically treated with medications, immobilization, and physical therapy. Surgery may be needed in more severe cases.

See a doctor if you have upper arm pain that is severe, unexplained by another health condition, or affects your range of motion. Your doctor can help diagnose what may be causing your pain and develop a treatment plan.