Main Components of the Human Arm
The arm is one of the most utilized parts of the human body, serving as an upper limb that comprises a variety of bones, muscles, and nerves. Each component plays a distinct role in movement and functionality. The arm can be divided into three primary sections, which will be elaborated on in the following sections.
Upper Arm
The upper arm is the longest and highest segment of the arm, making it particularly susceptible to injuries such as fractures compared to other parts. This segment extends from the shoulder and includes the armpit and the elbow. The upper arm primarily consists of the humerus bone along with a network of joints and muscles. Central to this section is the humerus, the longest bone in the arm, which connects the shoulder to the elbow and comprises several muscles and ligaments. The upper arm contains two key bones:
- Scapula: Also known as the shoulder blade, this triangular-shaped flat bone connects the arm to the torso.
- Clavicle: The clavicle plays a vital role in distributing the forces from the upper arm to the rest of the skeletal framework, alleviating stress on it.
The table below outlines the different types of joints in the upper arm and their locations:
| Joint Name | Joint Location |
| Acromioclavicular Joint | Connects the scapula and clavicle. |
| Sternoclavicular Joint | Links the clavicle and sternum. |
| Glenohumeral Joint | Connects the shoulder joint with the humerus. |
Forearm
The forearm is classified as the lower segment of the arm, stretching from the elbow to the wrist. It primarily consists of two bones that allow for rotation and is connected to the elbow joint, which links the humerus with the radius and ulna. These two bones are:
- Radius: The radius connects with the wrist bones at the wrist joint, facilitating movement in both the wrist and fingers.
- Ulna: This bone is linked to the humerus at the elbow joint and is considered stable; thus, fractures in this area can be challenging and painful.
Hand
The hand performs numerous simple motor functions, such as grasping and holding objects, as well as fine motor tasks like picking up tiny items with the fingers. Additionally, it plays a role in tactile interactions with various tools. The human hand consists of five fingers plus a total of 19 essential bones. It is divided into four main components:
- Fingers: Each hand comprises five fingers, including the thumb, index, middle, ring, and pinky. These fingers are essential for gripping both small and large objects and are responsible for manual dexterity tasks such as writing and drawing.
- Wrist: This area connects the arm and hand, facilitating smooth hand movements.
- Palmar Surface: Referring to the palm of the hand, this is the lower region of the hand.
- Dorsal Surface: The back of the hand, which is comprised of a network of veins located on the rear side of the hand.