Arm Bones

The bones of the arm consist of the humerus in the upper arm and the radius and ulna in the forearm. The arm’s bones enable movement in the shoulder, elbow, wrist, and fingers, which are essential for daily activities.

Forelimbs and Hindlimbs

• The human body has two pairs of limbs, forelimbs, and hindlimbs. Each pair comprises 30 bones.
• These limbs are bilateral pairs found in vertebrate animals, including humans.
• Forelimbs are adapted for functions such as grasping, manipulation, and support.
• Hindlimbs are specialized for locomotion, providing propulsion and support during movement.

Parts of the Arm

The arm is divided into several parts, including the upper arm, lower arm, forearm, and hand.

• Upper Arm: Also known as the brachium, it extends from the shoulder to the elbow joint.
• Lower Arm: It consists of the region between the elbow and the wrist and is commonly divided into the forearm and the hand.
• Forearm: This section includes the radius and ulna bones, extending from the elbow to the wrist.
• Hand: The terminal part of the upper limb, facilitates complex movements and fine motor skills.

Also Read: Difference Between Locomotion And Movement

Bones in the Arm

The human arm has three bones: the humerus, the radius, and the ulna. The humerus is the upper arm bone, and the radius and ulna are the forearm bones. The humerus connects the shoulder to the elbow, and the radius and ulna connect the elbow to the wrist. The three bones form a hinge joint called the elbow.

Humerus

• The humerus is the longest bone in the body, aside from the bones in the legs, and is located in the upper arm between the shoulder and elbow. 
• The head articulates with the scapula, forming the shoulder joint, while the distal end articulates with the radius and ulna.
• It’s responsible for supporting the shoulder and enabling a variety of arm movements. 
• The humerus also supports ligaments, tendons, muscles, and parts of the circulatory system.

Radius and Ulna

• The radius and ulna are the two bones in the forearm that work together to support the wrist and forearm, and allow the hand and wrist to rotate smoothly.
• The ulna is slightly longer and larger than the radius. 
• The radius pivots around the ulna to allow movement at the proximal and distal radio-ulnar joints.

Anatomy of Hand

The anatomy of the hand consists of 27 bones (including the carpals, metacarpals, and phalanges), muscle, tendons, ligaments, and nerves that allow complex movements and fine motor skills.

Wrist (Carpal Bones)

• Made up of 8 carpal bones (Trapezium, Trapezoid, Scaphoid, Lunate, Hamate, Capitate, Pisiform, Triquetrum).
• These eight small bones are arranged in two rows and articulate with the radius and ulna proximally and the metacarpal bones distally.
• They provide stability and flexibility to the wrist joint.

Palm (Metacarpal Bones)

• It contains 5 metacarpal bones.
• The metacarpals form the framework of the palm, connecting the wrist to the fingers.
• Each metacarpal bone corresponds to one of the five digits and provides support for grasping and manipulation.

Fingers (Phalanges)

• It comprises 14 phalanges bones.
• Each finger consists of three phalangeal bones (proximal, middle, and distal), except for the thumb, which has two.
• The phalanges allow for precise movements and gripping actions, essential for various tasks and activities.

Also Read: Arm Muscles Diagram and Anatomy

The arm body part is the upper limb of vertebrates. Anatomy of the arm involves the detailed study of its bones, muscles, nerves, blood vessels, and connective tissues. Learning about the arm muscles and arm bones helps in understanding how movements are coordinated and how injuries can be prevented or treated.

In this article, we will cover the anatomy of the arm and read about the nerve supply and blood supply in the arm along with arm muscles and bones, in detail.