Elbow Anatomy

The elbow is a complex joint formed by the articulation of three bones –the humerus, radius and ulna. The elbow joint helps in bending or straightening of the arm to 180 degrees and assists in lifting or moving objects.

The bones of the elbow are supported by:

• Ligaments and tendons
• Muscles
• Nerves
• Blood vessels

Bones and Joints of the elbow joint

The elbow joint is formed at the junction of three bones:

• The Humerus (upper arm bone) forms the upper portion of the joint. The lower end of the humerus divides in to two bony protrusions known as the medial and lateral epicondyles which can be felt on either side of the elbow joint.
• The Ulna is the larger bone of the forearm located on the inner surface of the joint. The curved shape of the ulna articulates with the humerus.
• The Radius is the smaller bone of the forearm situated on the outer surface of the joint. The head of the radius is circular and hollow which allows movement with the humerus. The connection between the ulna and radius helps the forearm to rotate.

The elbow consists of three joints because of articulation of the three bones namely:

• Humero-ulnar joint is formed between the humerus and ulna and allows flexion and extension of the arm.
• Humero-radial joint is formed between the radius and humerus, and allows movements like flexion, extension, supination and pronation.
• Radio-ulnar joint is formed between the ulna and radius bones, and allows rotation of the lower arm.

Articular cartilage lines the articulating regions of the humerus, radius and ulna. It is a thin, tough, flexible, and slippery surface that acts as a shock absorber and cushion to reduce friction between the bones. The cartilage is lubricated by synovial fluid, which further enables the smooth movement of the bones.

Muscles of the Elbow Joint

There are several muscles extending across the elbow joint that help in various movements. These include the following:

• Biceps brachii: upper arm muscle enabling flexion of the arm
• Triceps brachii: muscle in the back of the upper arm that extends the arm and fixes the elbow during fine movements
• Brachialis: upper arm muscle beneath the biceps which flexes the elbow towards the body
• Brachioradialis: forearm muscle that flexes, straightens and pulls the arm at the elbow
• Pronator teres: this muscle extends from the humeral head, across the elbow, and towards the ulna, and helps to turn the palm facing backward
• Extensor carpi radialis brevis: forearm muscle that helps in movement of the hand
• Extensor digitorum: forearm muscle that helps in movement of the fingers

Elbow joint ligaments and tendons

The elbow joint is supported by ligaments and tendons, which provide stability to the joint.

Ligaments are a group of firm tissues that connect bones to other bones. The most important ligaments of the elbow joint are the:

• Medial or ulnar collateral ligament: comprised of triangular bands of tissue on the inner side of the elbow joint.
• Lateral or radial collateral ligament: a thin band of tissue on the outer side of the elbow joint.

Together, the medial and lateral ligaments are the main source of stability and hold the humerus and ulna tightly in place during movement of the arm.

• Annular ligament: It is a group of fibers that surrounds the radial head, and holds the ulna and radius tightly in place during movement of the arm.

The ligaments around a joint combine to form a joint capsule that contains synovial fluid.

Any injury to these ligaments can lead to instability of the elbow joint.

Tendons are bands of connective tissue fibers that connect muscle to bone. The various tendons which surround the elbow joint include:

• Biceps tendon: attaches the biceps muscle to the radius, allowing the elbow to bend
• Triceps tendon: attaches the triceps muscle to the ulna, allowing the elbow to straighten

Nerves of the elbow joint

The main nerves of the elbow joint are the ulnar, radial and median nerves. These nerves transfer signals from the brain to the muscles that aid in elbow movements. They also carry the sensory signals like touch, pain, and temperature back to the brain.

Any injury or damage to these nerves causes pain, weakness or joint instability.

Blood vessels

Arteries are blood vessels that carry oxygen-pure blood from the heart to the hand. The main artery of the elbow is the brachial artery that travels across the inside of the elbow and divides into two small branches below the elbow to form the ulnar and the radial artery.

• Cubital Tunnel Syndrome
  

  Cubital Tunnel Syndrome is a condition characterized by compression of the ulnar nerve in an area of the elbow called the cubital tunnel.

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• Elbow Bursitis
  

  The elbow contains a large, curved, pointy bone at the back called the olecranon, which is covered by the olecranon bursa, a small fluid-filled sac that allows smooth movement between the bone and overlying skin. Inflammation of this bursa leads to a condition called olecranon bursitis.

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• Elbow Fractures
  

  Three bones, the humerus, radius and ulna, make up the elbow joint. Elbow fractures may occur from trauma, resulting from various reasons; a fall on an outstretched arm, a direct blow to the elbow, or an abnormal twist to the joint beyond its functional limit.

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• Tennis Elbow (Lateral Epicondylitis)
  

  Tennis elbow is the common name used for the elbow condition called lateral epicondylitis. It is an overuse injury that causes inflammation of the tendons that attach to the bony prominence on the outside of the elbow (lateral epicondyle).

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• Golfer’s Elbow (Medial Epicondylitis)
  

  Golfer’s elbow, also called medial epicondylitis, is a painful condition occurring from repeated muscle contractions in the forearm that leads to inflammation and microtears in the tendons that attach to the medial epicondyle.

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• Throwing Injuries
  

  An athlete uses an overhand throw to achieve greater speed and distance. Repeated throwing in sports such as baseball and basketball can place a lot of stress on the joints of the arm, and lead to weakening and ultimately, injury to the structures in the elbow.

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• Tricep’s Tendonitis
  

  Tendonitis refers to the inflammation of a tendon, which is a band of fibrous connective tissue that attaches a muscle to a bone.

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• Elbow Pain
  

  The bones in the elbow joint are held together by ligaments. The muscles and tendons move the bones around each other and help in performing various activities. Nerves pass through the joint. Damage to any of these structures can cause elbow pain.

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• Elbow Contracture
  

  Elbow contracture refers to a stiff elbow with limited range of motion. It is a common complication following elbow surgery, fractures, dislocations and burns.

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• Bicep Tendon Tear
  

  The biceps muscle, located in the front of the upper arm allows you to bend the elbow and rotate the arm. Biceps tendons attach the biceps muscle to the bones in the shoulder and in the elbow.

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• Elbow Dislocation
  

  The elbow is a hinge joint made up of 3 bones – humerus, radius and ulna. The bones are held together by ligaments to provide stability to the joint. Muscles and tendons move the bones around each other and help in performing various activities. Elbow dislocation occurs when the bones that make up the joint are forced out of alignment.

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• Compression Neuropathy
  

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• Elbow Joint Replacement
  

  Elbow Joint Replacement, also referred to as Total Elbow Arthroplasty, is an operative procedure to treat the symptoms of arthritis that have not responded to non-surgical treatments.

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• Fracture Care
  

  A bone fracture is a medical condition in which a bone is cracked or broken. It is a break in the continuity of the bone. While many fractures are the result of high force impact or stress, bone fracture can also occur because of certain medical conditions that weaken the bones, such as osteoporosis.

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• Distal Biceps Repair
  

  The distal biceps is usually repaired through a single incision (front of the elbow) or a double incision (front and back of the elbow) technique.

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• UCL Reconstruction
  

  UCL reconstruction surgery repairs the UCL by reconstructing it with a tendon from the patient’s own body (autograft) or from a cadaver (allograft). The most frequently used tissue is the palmaris longus tendon in the forearm.

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• Ulnar Nerve Transposition
  

  The ulnar nerve is one of the 3 main nerves in the arm that travels down from the neck through a bony protuberance inside the elbow (medial epicondyle), under the muscles of the forearm and down the hand on the side of the palm, towards the little finger.

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• Tennis Elbow Surgery
  

  Tennis elbow, also called lateral epicondylitis, is a painful condition occurring from repeated muscle contractions in the forearm that leads to inflammation and micro-tears in the tendons that attach to the lateral epicondyle. The lateral epicondyle is the bony prominence that is felt on the outside of the elbow.

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• Elbow Ligament Reconstruction
  

  The elbow is a complex joint of the upper limb formed by the articulation of the long bone of the upper arm or humerus and the two bones of the forearm, namely, radius and ulna.

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