Lower arm

Lower Arm

The lower arm refers to the region of the arm between the elbow and the wrist. It comprises two main bones, the radius and the ulna, which are pivotal in facilitating arm movement and function. This area is crucial for various motions, including rotation, flexion, and extension, allowing for a wide range of activities from lifting objects to performing delicate tasks.

Anatomy

The anatomy of the lower arm is complex, consisting of bones, muscles, nerves, and blood vessels. The two primary bones are:

• Radius: Located on the lateral side of the forearm, it is involved in the supination and pronation of the hand.
• Ulna: Situated on the medial side, it forms the elbow joint with the humerus above and the wrist joint with the carpal bones below.

These bones are connected by the interosseous membrane of the forearm, which provides additional surface area for muscle attachment and force transmission between the bones.

Muscles

Several muscles span the lower arm, categorized into two compartments: the anterior (flexor) and the posterior (extensor). The anterior compartment includes muscles such as the flexor carpi radialis, flexor carpi ulnaris, and palmaris longus, which are primarily involved in flexing the wrist and fingers. The posterior compartment contains the extensor carpi radialis longus, extensor carpi ulnaris, and extensor digitorum, which extend the wrist and fingers.

Nerves

The main nerves running through the lower arm include the median nerve, ulnar nerve, and radial nerve. These nerves are responsible for sensory and motor innervation to the forearm and hand, playing a critical role in hand movement and sensation.

Blood Supply

Blood supply to the lower arm is primarily through the radial artery and ulnar artery, which are branches of the brachial artery. These arteries, along with their corresponding veins, ensure adequate blood flow to the muscles and bones of the forearm.

Function

The lower arm plays a vital role in the movement and dexterity of the hand and wrist. It allows for a range of motions, including:

• Pronation and supination: The rotation of the hand and forearm, allowing the palm to face up or down.
• Flexion and extension: The movement of bending and straightening the wrist and fingers.
• Wrist abduction and adduction: The movement of the wrist side to side.

These movements are essential for daily activities, such as writing, typing, and gripping objects.

Common Conditions

Several conditions can affect the lower arm, including:

• Fractures of the radius or ulna, often resulting from falls or direct impacts.
• Tendonitis, inflammation of the tendons, commonly affecting those who perform repetitive motions.
• Carpal tunnel syndrome, a condition caused by pressure on the median nerve, leading to pain and numbness in the hand.