Arm

Your arm helps you reach and move.

The arm goes from your shoulder to your elbow. The part below the elbow is the forearm. Your hand is at the end of it.

Long bones stay inside your arm. Muscles move those bones. Nerves send messages to your muscles. Blood travels through tubes to help you. Your arm is very special!

Your arm is a busy part of your body.

Scientists call the part from your shoulder to your elbow the arm. The part from your elbow to your wrist is the forearm.

Long bones live inside your arm. The humerus is one big bone. It joins the shoulder and the elbow. Two other bones, the radius and ulna, are in your forearm.

Muscles help you move. A thin layer called fascia divides the arm into two parts. The front part has three muscles. The back part has one muscle called the triceps.

Nerves send signals to these muscles. The musculocutaneous nerve helps the front muscles. The radial nerve helps the back muscle.

Blood also moves through the arm. The brachial artery is the main tube for blood. It carries blood to the muscles. Veins carry blood back. Two main veins are the basilic and the cephalic veins.

These veins help move blood from your hand and arm.

The human arm is a very useful part of the body.

In science, the arm means the part between the shoulder and the elbow. The part from the elbow to the wrist is the forearm. The hand is the part at the very end. Many people use the word arm to mean the whole limb. This includes the shoulder and the muscles around it.

Inside the arm, there are several important parts working together. The humerus is a long bone in the upper arm. It connects to the scapula at the shoulder joint. At the elbow, the humerus joins the radius and the ulna. The elbow works like a hinge joint. This allows the arm to bend and move. Muscles are also split into two groups by a thin layer called fascia. The front group has three muscles: the biceps brachii, brachialis, and coracobrachialis. The back group has only one muscle called the triceps brachii.

Nerves act like wires to send signals through the arm. The musculocutaneous nerve helps the three muscles in the front. It starts from the C5, C6, and C7 spinal nerves. The radial nerve helps the triceps muscle in the back. This nerve travels near the deep artery of the arm. Other nerves, like the median and ulnar nerves, pass through the arm too. The median nerve travels between the biceps and triceps. The ulnar nerve passes behind a part of the humerus called the medial epicondyle.

Blood must flow through the arm to keep it healthy.

The brachial artery is the main tube for blood. It is a continuation of the axillary artery. This artery carries blood to the muscles in the front. It also gives off a branch called the deep artery of the arm. Veins carry blood back away from the hand. The basilic vein travels on the inner side of the arm. The cephalic vein travels on the outer side. A vein called the median cubital vein connects these two.

People have used the arm as a symbol for a long time. In Egypt, the arm was used in hieroglyphs.

In Hindu and Buddhist art, gods are often shown with many arms. This can show that they have great power. In West Africa, the Bambara people use the forearm to represent the spirit. Raising your hands is also a common sign for surrender. It can also be a sign for mercy or justice.

In human anatomy, the term "arm" has two different meanings. In common conversation, people use it to describe the entire upper limb. This includes the shoulder, the forearm, and the hand. However, in academic science, the arm refers specifically to the segment between the shoulder joint and the elbow joint.

The shoulder joint is known as the glenohumeral joint. The part between the elbow and the wrist is called the forearm. The end of the limb is the hand. Understanding these specific parts helps scientists study how the body moves and functions.

The structure of the arm relies on a central bone called the humerus. This long bone connects to the scapula at the shoulder joint. At the other end, the humerus meets the radius and the ulna at the elbow. The elbow acts as a complex hinge joint.

This hinge allows the limb to bend and straighten. Muscles are organized into two distinct groups called compartments. These compartments are separated by a layer of tissue called fascia. This fascia connects to the periosteum, which is the outer layer of the bone. The arm is divided into an anterior compartment in the front and a posterior compartment in the back.

The anterior compartment contains three specific muscles: the biceps brachii, the brachialis, and the coracobrachialis. These muscles are controlled by the musculocutaneous nerve. This nerve originates from the lateral cord of the brachial plexus. It specifically comes from the C5, C6, and C7 spinal nerves. The nerve pierces the coracobrachialis muscle to reach the others. In the posterior compartment, there is only one muscle: the triceps brachii. This muscle is supplied by the radial nerve. The radial nerve originates from the posterior cord of the brachial plexus. It travels through the lower triangular space of the arm. This space is bounded by the shaft of the humerus and the triceps.

Nerves also pass through the arm to reach the forearm, even if they do not supply the arm muscles directly. The median nerve travels in a plane between the biceps and the triceps. It reaches the cubital fossa, which is the shallow depression at the elbow. In this area, the median nerve is the most medial structure. The ulnar nerve also travels between the biceps and triceps. However, at the elbow, it passes behind the medial epicondyle of the humerus. This location is important because fractures in this area can damage the nerve.

Blood supply is managed by a system of arteries and veins. The brachial artery is the primary artery of the arm. It is a continuation of the axillary artery. This transition happens just below the lower border of the teres major muscle. The brachial artery travels through the anterior compartment. It sits between the median nerve and the biceps tendon in the cubital fossa.

It also gives off a branch called the deep artery of the arm. This deep artery travels with the radial nerve in the spiral groove of the humerus. This close relationship means a bone fracture could cause both nerve damage and a haematoma, which is a collection of blood.

Veins work to drain blood from the arm and the extremities. Two main veins serve this purpose: the basilic vein and the cephalic vein. The basilic vein runs along the medial side of the arm. It ends at the level of the seventh rib. The cephalic vein runs on the lateral side. It passes through the deltopectoral triangle, a space between the deltoid and pectoralis major muscles.

A third vein, the median cubital vein, connects these two. This connecting vein is very important for venepuncture, which is the process of withdrawing blood. The cubital fossa is also a key area for measuring blood pressure.

Humans have used the arm as a powerful symbol throughout history. In Egyptian culture, the arm was a component of hieroglyphs.

In Hindu, Buddhist, and Egyptian iconography, the arm represents the power of a ruler. In Hindu tradition, gods are often shown with many arms to represent omnipotence, or unlimited power. In West Africa, the Bambara people use the forearm to symbolize the spirit. This spirit acts as a link between God and humans. Even today, raising both hands is a universal gesture. It can signal surrender, a plea for mercy, or a call for justice.