The arm is one of the most used part of the body. Almost all activity that we do has the involvement of the arm. Its parts start from the shoulder extension to the hands. The arm is divided into three major sections; the bones, muscles, nerves. It is also composed of arteries and veins for normal blood flow and so it can function well. In this article, we will be looking at the vital parts of the arm.
1. Bones of the Arm
Arm bone is divided into parts. The upper arm, forearm, wrist, and the hand. For this article, we will focus on the upper arm and the forearm. Wrist and hand have separate anatomical characteristics that can be discussed separately.
The upper arm starts from the shoulder extension to the elbow. The bones that comprise that upper arm are the following:
This part of the arm is also called the shoulder blade. This is the one responsible in the attachment of the arm to the trunk of the body or the torso. This part is filled with muscle that serves as adhesive to the torso.
Next is this what we call collarbone. It is also attached to the torso. What it does is it helps the upper part of the arm to connect with the rest of the bones in the body.
The humerus is the long bone of the upper arm. This connects the scapula and the elbow joint. Like the scapula, muscles and ligaments are surrounding the humerus.
Joints are parts of the arm that connect each bone in the upper arm. The sternoclavicular joint connects the clavicle and breastbone or sternum. The glenohumeral joint connects the scapula and the humerus. Acromioclavicular joint connects the scapula and the clavicle. There is also an elbow joint. This part is the one connecting the humerus with the radius and ulna. It has three sub-joints. The proximal radioulnar joint which is why we can rotate our hands. Ulnohumeral joint is just a joint that connects the humerus to ulna. And lastly is the radiocapitellar joint that connects the humerus and the radius through the capitellum.
The forearm is from the elbow to the wrist. It is composed of 2 minor bones that are connected to the fingers. These bones are positioned side to side. The only difference is Radius can move depending on the activity of the hands; while Ulna is stationary. Radius aids in the movement of the elbow, wrist, and hands with the help of the muscles around.
This bone is the one connected to the thumb.
This bone is the one connected to the pinky finger.
2. Muscles of the Arm
Upper Arm Muscles
The muscles of the arm are divided into Anterior and Posterior compartment. Each compartment houses different muscles.
- Biceps Brachii
This is also called the two-headed muscles that are located at the front of the upper arm. This part of the arm is responsible in the lifting and pulling movements of the arm as well as the movement of the palm. This also helps in flexing the arm at the shoulder and the elbow.
Responsible in the flexing movement of the forearm. This muscle is situated beneath the biceps that acts as a bridge between ulna and humerus.
This tiny muscle near the shoulder helps in the flexing towards the body midline. This also stabilizes the humerus to the shoulder joint.
- Triceps Brachii
This one is responsible for the flexing of the forearm as it stabilizes the shoulder joint. This is also called triceps.
A tiny muscle that is the extension of the triceps. It helps the elbow as it extends and also helps the forearm to rotate.
Muscles in this area help in the movement of the wrist and fingers.
- Anterior Compartment
The superficial layer is composed of Flexor carpi ulnaris, Palmaris longus, Flexor carpi radialis, and Pronator teres. All of these are responsible for the movement of the wrist.
The intermediate layer is just composed of Flexor digitorum superficialis that is responsible in the movement of the fingers.
Deep compartment meanwhile is composed of Flexor digitorum profundus, Flexor pollicis longus, and Pronator quadrature. These also help in flexes and rotational movements.
- Posterior Compartment
This is the compartment that is atop of the forearm. This part of the arm doesn’t have an intermediate layer but is also responsible in the movement of wrist and fingers.
The superficial layer is composed of Brachioradialis, Extensor carpi radialis longus, Extensor carpi radialis brevis. This muscle is the shorter, wider counterpart to your extensor carpi radialis longus, Extensor digitorum, and Extensor carpi ulnari. These muscles are responsible in the adduction, abduction, and extension of the wrist and fingers.
The deep layer is composed of Supinator, Abductor pollicis longus, Extensor pollicis brevis, Extensor pollicis longus, and Extensor indices. Also responsible in the adduction, abduction, and extension of the wrist and fingers.
3. Nerves of the Arm
The arm is composed of three major nerves.
This nerve circulates from underneath the arm to the front of the elbow. It extends to the wrist via the carpal tunnel. This helps the wrist and the fingers to bend.
This nerve passes behind the back and inner side of the elbow. Aprat from flexing, this helps the fingers to move side to side.
This never can be seen at the back and the outer part of the upper arm. This helps the elbow, wrist, and fingers to straighten.
I hope that this article on the parts of the arm was helpful. If you are interested, visit the health facts page!