Elbow

Your elbow is a special joint.

It is between your upper arm and your forearm. It works like a hinge. This helps you move your hand. You can move your hand toward your body. You can also move it away. This happens because of three bones. The bones work together to let you bend. They also let you turn your hand. Your elbow is very important for moving.

It helps you do many things every day.

The elbow is the part between your upper arm and forearm.

It is a hinge joint. This means it works like a door hinge. It lets you move your hand toward or away from your body. The elbow uses three bones. The humerus is in your upper arm. The radius and the ulna are in your forearm. These bones meet in three different ways. One part acts like a hinge. Another part acts like a ball and socket. The third part lets the radius rotate. This rotation helps you turn your hand.

There are many parts that help the elbow work. Small bands of tissue called ligaments hold the bones together. Muscles also help you move. Three main muscles help you bend your arm. These are the brachialis, the brachioradialis, and the biceps brachii. To straighten your arm, you use the triceps brachii muscle.

Tiny fat pads and a fluid-filled sac help the joint move smoothly. Even as you grow, these bones change and fuse together.

The elbow is the area between your upper arm and your forearm. It is a special place where bones meet to let you move. Humans and other primates have elbows, but other animals are simply called forelimb joints. The elbow is made of three bones working together. The humerus is the bone in your upper arm. The radius and the ulna are the two bones in your forearm.

This joint acts like a hinge to help your hand move toward or away from your body.

This joint works in three different ways at once. First, the humerus and the ulna meet at the humeroulnar joint. This part is a simple hinge that lets you bend and straighten your arm. Second, the humerus and the radius meet at the humeroradial joint. This part acts like a ball-and-socket joint. Third, the radius and the ulna meet at the proximal radioulnar joint. This allows the radius to rotate, which helps you turn your hand.

Many parts help the elbow stay strong and move smoothly. A fibrous joint capsule encloses the whole area. Thick bands called ligaments are on the sides to hold everything in place. The ulnar collateral ligament is on the side closest to your body. The radial collateral ligament is on the side away from your body. Inside the capsule, a synovial membrane helps things glide. There are even small fat pads that move out of the way when you bend your arm.

Muscles are the engines that make the elbow move. Three main muscles help you bend your arm, which is called flexion. These are the brachialis, the brachioradialis, and the biceps brachii. The biceps brachii is very important for both bending and turning your hand. To straighten your arm, which is called extension, you use the triceps brachii. This muscle attaches to the olecranon, which is the bony part at the tip of your elbow. These muscles work together to control every movement.

Your elbow changes as you grow from a child into a teenager. Small centers of bone appear in a specific order. Doctors use the name CRITOE to remember this order. This stands for the capitellum, radial head, internal epicondyle, trochlea, olecranon, and external epicondyle. These parts appear at ages 1, 3, 5, 7, 9, and 11. Eventually, these pieces fuse together into solid bone. Knowing this order helps doctors see if a growing child has a broken bone.

The elbow is the complex region located between the upper arm and the forearm. It surrounds the elbow joint, which allows the forearm and hand to move toward or away from the body. While the term "elbow" is specifically used for humans and other primates, other vertebrates possess a similar structure called a forelimb joint. The anatomy of this area is vital for many daily movements. It includes several prominent landmarks like the olecranon and the cubital fossa, which is the elbow pit.

The elbow joint functions through the interaction of three distinct bones. The humerus is the bone of the upper arm. The radius and the ulna are the two bones of the forearm. These bones meet at three different points to create a complex system of movement. First, the humeroulnar joint connects the trochlea of the humerus to the trochlear notch of the ulna. This is a simple hinge joint that allows for flexion and extension. Second, the humeroradial joint connects the capitulum of the humerus to the head of the radius. This acts as a ball-and-socket joint. Third, the proximal radioulnar joint connects the head of the radius to the radial notch of the ulna. This allows the radius to rotate, enabling movements known as pronation and supination.

Several bony landmarks define the elbow's shape. At the bottom of the humerus are the medial and lateral epicondyles. The medial epicondyle is on the side closest to the body, while the lateral epicondyle is on the side away from it. The olecranon is found at the head of the ulna. When the elbow is flexed, these three points form a shape called the Hueter triangle. In most people, the humerus has a groove on the trochlea that spirals on the posterior side. This creates a carrying angle, where the forearm forms an angle to the upper arm during extension.

To keep the joint stable, a fibrous joint capsule encloses the entire area. This capsule is strengthened by ligaments on the sides. The ulnar collateral ligament is located on the medial side. It has an anterior band, a posterior band, and a thinner intermediate part. The ulnar nerve actually crosses this intermediate part. On the other side, the radial collateral ligament attaches to the lateral epicondyle. Inside the capsule, a synovial membrane provides lubrication. This membrane is very extensive and covers many parts of the bones. It even includes folds called plicae, which are remnants of embryonic development.

Muscles act as the engines for elbow movement. To perform flexion, or bending the arm, three main muscles work together. The brachialis acts exclusively as an elbow flexor. The brachioradialis helps with flexion and also aids in rotation. The biceps brachii is a major flexor that also helps stabilize the shoulder. For extension, or straightening the arm, the triceps brachii is the primary muscle. The triceps originates on the humerus and the scapula and inserts onto the olecranon. These muscles have different levels of efficiency depending on the angle of the joint. For example, the biceps is most efficient when the elbow is at 80 to 90 degrees.

Blood and nerves are essential for the elbow's health. The joint receives blood from an extensive circulatory anastomosis. This is a network where different arteries, like the brachial and ulnar arteries, connect to one another. Lymphatic drainage occurs through two sets of nodes located above the medial epicondyle. These are the deep and superficial cubital nodes. The nerves that provide sensation and movement control include the musculocutaneous, median, radial, and ulnar nerves. This complex network ensures the muscles and tissues receive necessary nutrients and signals.

The elbow undergoes a specific developmental process during childhood. Small centers of bone, called apophyseal growth centers, appear in a predictable order. Doctors use the mnemonic CRITOE to remember this sequence: capitellum, radial head, internal epicondyle, trochlea, olecranon, and external epicondyle. These centers appear at ages 1, 3, 5, 7, 9, and 11. Later, during adolescence, these centers fuse together into solid bone. Understanding this timeline is crucial for doctors. It helps them distinguish between normal growth and a traumatic fracture in pediatric patients.