Elbow Anatomy: Understanding the Structure of Your Elbow

The elbow allows you to bend and straighten your arm, and to rotate your hand. Its bones, ligaments, tendons, and muscles all work together. Understanding their roles will help you follow your physical therapist’s explanations and understand your treatment.

What are the main structures of the elbow?

The elbow consists of three bones, ligaments, muscles, and tendons that support and guide its movements. The humerus is the bone in the upper arm. The radius and ulna, also known as the cubitus, form the forearm. These bones connect at three joints that work together.

The Bones of the Elbow

The humerus is the bone of the arm that ends in two bony protrusions called epicondyles (medial and lateral). These epicondyles serve as attachment points for the tendons of the flexor and extensor muscles of the wrist and fingers. It is at these attachment points thatlateral epicondylitis (tennis elbow) andmedial epicondylitis develop: tendon problems that can be associated with repetitive strain. Changes in the tendon, inflammation, and increased tenderness can contribute to the pain; the severity varies from person to person.¹

The radius is the bone on the thumb side of the forearm. Its rounded head connects with the humerus and allows for forearm rotation.

The ulna (or cubitus) is the medial bone of the forearm (toward the ear). Its end near the elbow forms the olecranon, the bony protrusion you can feel on the back of the elbow.

The Three Joints

The humeroulnar joint connects the humerus to the ulna and acts like a hinge, allowing the elbow to bend and straighten. It is the main joint for bending and straightening your arm.

The humeroradial joint connects the humerus to the radius. It helps with bending and straightening, and also facilitates rotational movements.

The proximal radioulnar joint allows the radius to pivot around the ulna, creating pronation (palm down) and supination (palm up) movements.

The Stabilizing Ligaments

The ulnar (or medial) collateral ligament stabilizes the inner side of the elbow. Composed of three bands of tissue, it prevents the elbow from flaring outward during throwing motions. Baseball pitchers place intense strain on this ligament.

The radial collateral ligament stabilizes the outer side of the elbow. It is part of a group of ligaments that also includes the lateral ulnar collateral ligament and the annular ligament. This group limits excessive inward movement and certain rotations. The anatomical description of the elbow distinguishes these ligaments².

The annular ligament encircles the head of the radius, holding it firmly against the ulna. This allows for rotation while ensuring the stability of the proximal radioulnar joint.

Tendons and Muscles

Tendons transmit the force from muscles to bones. The biceps tendon attaches to the radius and allows for elbow flexion (bending) and supination. The triceps tendon attaches to the olecranon and produces elbow extension (straightening).

The flexor muscles bend the elbow. The main ones are the brachialis, the biceps brachii, and the brachioradialis. Other muscles, including the pronator teres, can assist them.

Extensor muscles include the triceps brachii (the main muscle for extension) and the anconeus (an accessory muscle for extension).

How Does the Elbow Work?

The elbow combines two types of joints: a hinge joint for bending and straightening the arm, and a pivot joint for rotating the hand. This design allows for a wide range of motion while maintaining the stability needed for daily activities and sports.

Flexion and Extension

Bending the elbow brings the hand closer to the shoulder. In a study of 352 healthy adults, the average active range of motion of the dominant elbow was 146 degrees. This average varied notably by age, sex, and body mass index—a measure of weight relative to height—and does not, on its own, define a complete normal range.³ The brachialis muscle provides the main flexion force, assisted by the biceps and the brachioradialis. You use this movement to carry objects, eat, and brush your teeth.

Extension (straightening) brings your arm back to a straight position. The triceps brachii generates the force for extension, supported by the small anconeus muscle. Full extension allows you to lock your elbow to push or support your body weight.

Pronation and Supination

Pronation turns the palm of the hand downward (as if pouring water from a bottle). The radius pivots around the stationary ulna via the pronator teres and pronator quadratus muscles. In a study of 352 healthy adults, the average active pronation on the dominant side was 80 degrees. Range of motion varies from person to person; 80 degrees is not a mandatory target.³

Supination turns the palm upward (as if to receive change). The biceps brachii and the supinator muscle produce this movement. In a study of 352 healthy adults, the average active supination on the dominant side was 87 degrees. Range of motion varies from person to person; 87 degrees is not a mandatory target.³ These rotations are essential for using a screwdriver, opening a doorknob, or turning a key.

Force Transmission

The elbow transmits loads between the hand, forearm, and upper arm. When pushing or lifting an object, the muscles generate forces that counterbalance the external load. The load on the joint also depends on the position of the arm and the work done by the muscles. A study modeling the elbow describes this combination of forces⁴.

The cartilage that covers the bone surfaces and the synovial fluid, which lubricates the joint, reduce friction and absorb some of the forces transmitted through the joint.

Joint Stability

The elbow's stability relies on three complementary systems:

1. Bone stability: The interlocking of the articular surfaces, especially between the humerus and the ulna, contributes to stability
2. Ligamentous Stability: The medial and lateral collateral ligaments prevent excessive valgus (outward) and varus (inward) movements.
3. Muscular Stability: The muscles crossing the elbow constantly adjust their tension to maintain position and control movements.

What are common elbow injuries?

Common elbow injuries include epicondylitis, bursitis, sprains, and fractures. Tendons, ligaments, bones, or nerves may be affected. The examination helps determine which structures are causing your symptoms.

Lateral epicondylitis (tennis elbow)

Lateral epicondylitis affects the tendons of the muscles that extend the wrist and fingers, which attach to the lateral epicondyle of the humerus.

Repetitive or wrist-straining tasks, such as certain types of manual labor, can contribute to this pain. A painful movement does not mean that a new tear occurs with every movement. The pain is concentrated on the outer side of the elbow and often radiates down the forearm. The pain can also reduce the strength needed to grip an object.

Medial Epicondylitis (Golfer's Elbow)

Medial epicondylitis affects the tendons of the wrist flexor and pronator muscles that attach to the medial epicondyle. Medial epicondylitis is about three times less common than lateral epicondylitis.^{5, 6} In the population-based study, it was associated with repetitive movements and forceful exertion. The movements involved can occur at work or during sports: gripping a tool, squeezing an object, or repeating wrist movements. The name “golfer’s elbow” does not, therefore, limit this condition to people who play golf.

The pain is located on the inner side of the elbow and worsens with wrist flexion or forearm pronation. Activities like firmly gripping objects, lifting, or twisting become painful.

Elbow Bursitis

Elbow bursitis is characterized by inflammation of the bursa located at the tip of the elbow (olecranon). This small, fluid-filled sac normally reduces friction between the skin and the bone during movement.

Direct trauma (falling on the elbow), prolonged pressure (resting elbows on a table), or repetitive movements can irritate the bursa. Visible swelling at the back of the elbow is the most obvious sign, sometimes accompanied by redness and warmth.

Elbow Sprain

An elbow sprain damages the collateral ligaments (medial or lateral) following a forced movement or trauma. Causes include falling onto an outstretched arm, a sudden twisting motion, or a direct impact.

A medial sprain is more common among pitchers due to repeated stress on the ulnar collateral ligament. A lateral sprain often accompanies an elbow dislocation, when the bones of the joint shift out of their normal position. Symptoms include pain, swelling, bruising, and a feeling that the elbow lacks stability.

In a study of 64 people who had suffered an elbow dislocation following a low-impact injury, the average age was 44 years. All dislocations were posterior: 53% were also lateral, 41% were strictly posterior, and 6% were also medial. These proportions characterize this patient series.⁷

Other Common Injuries

Biceps tendinopathy affects the biceps tendon near the elbow, at its attachment to the radius. The pain is located in the crook of the elbow and worsens with flexion against resistance or supination.

Cubital Tunnel Syndrome compresses the ulnar nerve as it passes through the elbow, causing numbness and tingling in the little and ring fingers.

A Fracture of one of the three elbow bones requires immobilization followed by rehabilitation to regain range of motion and strength.

Elbow osteoarthritis can be primary or post-traumatic, with the latter resulting from an elbow injury.

How does physical therapy help with elbow pain?

Physical therapy helps reduce elbow pain and restore range of motion, strength, and functional movement. Our physical therapists specializing in elbow pain tailor exercises and manual techniques to your specific condition.

Precise Anatomical Assessment

The evaluation assesses your symptoms, your movements, and your strength. The physical therapist selects the appropriate tests based on your medical history and the results of the examination. The tests target specific structures to replicate your symptoms and help confirm or rule out a diagnosis.

This standardized evaluation helps distinguish epicondylitis from bursitis, or a ligament sprain from tendinopathy. The diagnosis then guides the selection of a treatment tailored to your condition.

Three-Phase Treatment

Phase 1: Pain Control and Protection

To relieve pain after an injury, we can use massage and gentle joint movements. Applying heat or cold can help manage symptoms in the short term; people react differently to heat and cold, so it’s worth trying both.

For persistent pain on the outer side of the elbow, progressive exercises strengthen the muscles that lift the wrist. Joint mobilization can also reduce pain in the short term and make it easier to grasp objects. Treatment is tailored to your tolerance¹.

For epicondylitis—pain on the outside of the elbow—cortisone injections provide short-term relief, but the pain often returns afterward. Therefore, they are not recommended as a first-line treatment.⁸

Phase 2: Progressive Mobilization

The resumption of movement is tailored to the injury and the instructions you’ve received. The physical therapist can help you move your elbow and then show you the movements to do on your own. The exercises progress based on your pain, stiffness, and how your elbow responds.

We’ll work on limited movements: bending and straightening the elbow, then turning the palm downward and upward. The goal is to regain the mobility you need for your daily activities. Many everyday movements are still possible without a full range of motion; however, some movements require more mobility than others. An analysis of daily movements illustrates this difference⁹.

Phase 3: Strengthening and Function

The final phase involves rehabilitation of the functional movements of your elbow and wrist. We strengthen the muscles that have lost strength, based on your specific condition and activities.

For epicondylitis, we focus on the wrist extensors. For instability, we strengthen the stabilizing muscles. The program may include movement control exercises: positioning the arm precisely, keeping the elbow stable, and adjusting force based on the task.

Self-Rehabilitation and Prevention

Your participation in the at-home exercises is part of your treatment. The physical therapist will go over how to do them with you and adapt them to fit into your daily routine.

We teach you exercises to do at home, movements you can perform on your own, and strategies for modifying the activities that caused your injury. To prepare for your return to activity and minimize the risk of recurrence, we adjust the repetitive tasks, loads, and movements that cause you problems at work or during sports.

A treatment backed by research

We’ll use the same measurements to track your pain, range of motion, and strength. The treatment plan is based on research findings relevant to your elbow condition.

Well-conducted rehabilitation helps restore elbow mobility, strength, and functionality, while minimizing the risk of stiffness and chronic pain.

Elbow Anatomy FAQ

Frequently asked questions about the elbow concern its anatomy, movements, pain, injury prevention, medical consultation, and recovery. The elbow connects three bones and allows the arm to bend and the hand to rotate. The following answers explain its movements, common pain, and reasons for seeking medical attention.

What are the three bones of the elbow?

The elbow connects the humerus (upper arm bone) to the radius and ulna (forearm bones). These three bones form three distinct joints, allowing for flexion, extension, and rotation.

What are pronation and supination?

Pronation turns the palm downwards, and supination turns it upwards. The radius pivots around the fixed ulna to produce these rotations, which are essential for daily activities.

Why does the outside of my elbow hurt?

Pain on the outer side of the elbow is often caused by tendinopathy, a problem affecting the tendons of the muscles that extend the wrist. Changes in the tendon tissue have long been recognized as one of the causes.¹⁰ Inflammation and increased sensitivity of the nervous system may also contribute to the symptoms. The pain is not always proportional to the changes observed in the tendon.¹

Which muscles bend and straighten the elbow?

The brachialis, biceps, and brachioradialis flex the elbow. The triceps and anconeus extend it. These muscles work together to control the movements of the elbow.

How can I prevent elbow injuries?

Vary your movements to avoid overuse, warm up before activity, strengthen your arm and forearm muscles, use proper technique during sports, and take breaks during repetitive tasks.

When should I see a physiotherapist for elbow pain?

See a physical therapist if the pain persists or limits your range of motion, strength, or activities. Go to the emergency room if you have a deformed elbow following an injury, severe pain accompanied by difficulty moving your arm, tingling or numbness in your arm, or a sudden loss of strength. A swollen arm accompanied by a fever or chills requires urgent medical attention on the same day. These signs require prompt care¹¹.

How long does elbow rehabilitation take?

The duration of rehabilitation depends on the injury, the degree of stiffness, and the range of motion that needs to be regained. After certain elbow injuries, regaining full range of motion can take about six to eight weeks; extension may return more slowly or remain limited. This guideline does not apply to all fractures, surgeries, or persistent pain. The physical therapist monitors your pain, range of motion, and strength to adjust the treatment plan accordingly. A hospital information sheet explains this recovery timeline¹².

Sources:

1. Lucado AM, Day JM, Vincent JI, MacDermid JC, Fedorczyk J, Grewal R, et al. Lateral Elbow Pain and Muscle Function Impairments. J Orthop Sports Phys Ther. 2022;52(12):CPG1-CPG111. ↩ Back to text: 1st, 2nd, 3rd citations
2. Card RK, Lowe JB, Launico MV. Anatomy, Shoulder and Upper Limb, Elbow Joint. [Updated December 9, 2025]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2026. ↩ Back to text
3. Zwerus EL, Willigenburg NW, Scholtes VA, Somford MP, Eygendaal D, van den Bekerom MP. Normative values and factors affecting elbow range of motion. Shoulder Elbow. 2019;11(3):215-224. ↩ Back to text: 1st, 2nd, 3rd citations
4. Chadwick EK, Nicol AC. Elbow and wrist joint contact forces during occupational pick-and-place activities. J Biomech. 2000;33(5):591-600. ↩ Back to text
5. Shiri R, Viikari-Juntura E, Varonen H, Heliövaara M. Prevalence and determinants of lateral and medial epicondylitis: a population study. Am J Epidemiol. 2006;164(11):1065-74. ↩ Back to text
6. Wolf JM, Mountcastle S, Burks R, Sturdivant RX, Owens BD. Epidemiology of lateral and medial epicondylitis in a military population. Mil Med. 2010;175(5):336-9. ↩ Back to text
7. Schnetzke M, Ellwein A, Maier D, Wagner FC, Grützner PA, Guehring T. Injury patterns following simple elbow dislocation: radiological analysis suggests the existence of a pure valgus dislocation mechanism. Arch Orthop Trauma Surg. 2021;141(10):1649-1657. ↩ Back to text
8. Coombes BK, Bisset L, Vicenzino B. Efficacy and safety of corticosteroid injections and other injections for the management of tendinopathy: a systematic review of randomized controlled trials. Lancet. 2010;376(9754):1751-67. ↩ Back to text
9. Morrey BF, Askew LJ, Chao EY. A biomechanical study of normal functional elbow motion. J Bone Joint Surg Am. 1981;63(6):872-7. ↩ Back to text
10. Ashe MC, McCauley T, Khan KM. Tendinopathies of the upper extremity: a paradigm shift. J Hand Ther. 2004;17(3):329-34. ↩ Back to text
11. National Health Service (NHS), United Kingdom. Elbow and arm pain. ↩ Back to text
12. North Bristol NHS Trust. How to Treat Your Injured Elbow. ↩ Back to text

Our physical therapists defined the research strategy, plan, and clinical content of this article. An AI tool assisted with the literature review and text editing to ensure consistency in content and writing style.