VIDEO
CONTENT
QUIZ
MATERIALS
Quick Facts
Shoulder Girdle
Arm
Forearm
Wrist to Hand
The human upper limb is a structural masterpiece, comprising various bones that form its framework. These bones are essential for movement and stability, allowing us to perform a myriad of tasks. Let’s embark on a journey to explore the main bones that compose the symphony of our upper limb.
The Shoulder Girdle: The Starting Point Our journey begins with the shoulder girdle, which anchors the upper limb to the axial skeleton.
- Clavicle (Collarbone): This slender bone runs horizontally between the sternum (breastbone) and the scapula (shoulder blade). It serves as a strut, providing support and stability while allowing a range of movements for the shoulder.
- Scapula (Shoulder Blade): The scapula is a flat, triangular bone lying on the posterior aspect of the ribcage. Its complexity is hidden in its details – with the glenoid cavity articulating with the humerus, the acromion and coracoid processes serving as attachment points for muscles and ligaments, and the scapular spine dividing its surface into distinct regions.
The Arm: A Single, Solid Pillar The upper arm, known scientifically as the brachium, houses a lone, robust bone.
- Humerus: The humerus is the longest bone in the upper limb. It has a rounded head that fits into the glenoid cavity of the scapula to form the shoulder joint. Distally, it articulates with the two bones of the forearm at the elbow. The humerus is a common site for muscle attachment and is crucial for both gross and fine motor movements.
The Forearm: A Duo of Dynamics The forearm, or antebrachium, contains two parallel bones that enable a wide range of movements.
- Radius: The lateral bone of the forearm when in the anatomical position (thumb side). It is pivotal for the movement known as pronation and supination, which allows the palm to face up or down.
- Ulna: The medial bone of the forearm (pinky side). The ulna’s primary role is in forming the elbow joint where its olecranon process creates the point of the elbow, allowing for the bending and extension of the arm.
The Wrist to Hand: Complex yet Refined Translating the forearm’s movements into fine manipulations is the task of the wrist and hand.
- Carpal Bones: Eight small bones form the wrist, arranged in two rows. These carpal bones act like a conduit, transmitting forces from the arm to the hand while providing flexibility.
- Metacarpal Bones: The palm comprises five metacarpal bones, one for each finger. They act as the palm’s long support beams, giving structure to the hand.
- Phalanges: The fingers and thumb consist of 14 phalanges in total – small long bones that allow for the intricate dexterity of the hand. The thumb has two, while the fingers each have three phalanges, enabling bending and flexing motions.