Elbow Anatomy

To understand the anatomy of the elbow it is important to understand a few medical terms

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Flexion - Bending your elbow, as in bringing your hand to your mouth

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Extension - Straightening your elbow

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Supination - Twisting your forearm and hand so your palm faces the ceiling (asking for change)

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Pronation - Twisting your forearm and hand so the back of your hand faces the ceiling

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Lateral - Outside of your arm/ elbow (furthest from the midline of the body)

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Medial - Inside of your arm/ elbow (nearest the midline of the body)

The elbow is more than a hinge joint, allowing for bending the arm/ elbow, flexion and extension. It also allows for rotation of the forearm wrist and

hand, supination and pronation. It is made up of:

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Muscles and tendons

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Ligaments

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Bones

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Nerves

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Blood vessels

Muscles and tendons

Tendons connect muscles to bone and transfer all the force generated by the muscles. All the muscles that extend your

wrist and fingers attach to a small bony area on the outer side (lateral side) of your elbow, otherwise called the

common extensor origin. It is pain here that is called tennis elbow (lateral epicondylitis).

 All the muscles that flex your wrist and fingers attach to a small area of bone the medial epicondyle on the inner side

of your elbow. It is pain here that suggests golfers elbow (medial epicondylitis).

Several muscles work to flex the elbow, most people think the biceps muscle is the main flexor of the elbow, in fact

Brachialis a muscle beneath biceps is the main elbow flexor. Biceps is very important for supination (asking for change).

Triceps is the main muscle straightening the elbow (extension).

Ligaments

Ligaments connect bones to bones, they help stabilise the elbow, stopping it from dislocating. There are essentially three ligament complexes around

the elbow.

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Medial collateral ligaments

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Lateral collateral ligaments

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Annular ligament

Bones

 The elbow joint is made up 3 bones:

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Humerus

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Radius (Radial head)

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Ulna (Olecranon)

The bone making up your upper arm is the

humerus, the humerus connects to the forearm bones at the elbow joint. The forearm contains two bones, the radius and the ulna.

The radius runs from the outer side of your elbow down the thumb side of your forearm. The ulna is on the inner side.

 The elbow joint has essentially two joints within it - one a hinge joint that allows bending and straightening of the elbow, the other allows for rotation

or twisting. It allows the forearm to twist (pronate and supinate) so you can show the back of your hand and twist your forearm to ask for change. 

The place where the ulna joins the humerus is called the ulna humeral joint and this is essentially the hinge joint that allow for bending and

straightening of the arm.

The radius ends in the radial head at the elbow, it joins onto the humerus at the elbow. The small part of the joint on the humerus side where the

radius attaches to it is called the capitellum and as such this half of the elbow joint is called the radiocapitellar joint. The radiocapitellar joint allows

for rotation of the forearm, wrist and hand (pronation and supination).

 In the elbow joint the ends of the bones are covered in articular cartilage, this is a very smooth slick material that allows the joint surfaces to slide

over each other.

Subchondral bone is a layer of hard bone that lies below the articular cartilage and supports the joint and anchors the cartilage onto the bone.

Nerves

There are three main nerves that cross the elbow and several small nerves that cross the elbow providing sensation to the skin on the forearm.

 The three main nerves are:

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Ulna nerve

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Median nerve

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Radial nerve (the PIN, posterior interosseous nerve is a branch)

Blood vessels