Bones of the Skeletal System: Pectoral Girdle and Upper Limb

Bones of the Skeletal System

Overview of the Human Skeleton

The human skeleton provides structural support, protects vital organs, and enables movement. It is divided into two main regions: the axial skeleton and the appendicular skeleton.

• Axial Skeleton: Includes the skull, vertebral column, and thoracic cage (ribs and sternum).

• Appendicular Skeleton: Includes the pectoral girdle, pelvic girdle, upper limbs, and lower limbs.

Key Functions:

• Support and shape for the body

• Protection of internal organs

• Facilitation of movement via muscle attachment

• Production of blood cells (hematopoiesis)

Major Bones and Regions (Anterior and Posterior Views)

The skeleton is composed of several major bones, each with specific anatomical and functional roles.

• Skull: Protects the brain and forms the structure of the face.

• Vertebral Column: Supports the body and protects the spinal cord.

• Pectoral Girdle: Consists of the clavicle and scapula; connects the upper limb to the trunk.

• Thoracic Cage: Includes the sternum and ribs; protects the heart and lungs.

• Pelvic Girdle: Formed by the hip bones; supports the lower limbs.

• Upper Limb: Humerus, radius, ulna, carpals, metacarpals, phalanges.

• Lower Limb: Femur, patella, tibia, fibula, tarsals, metatarsals, phalanges.

Pectoral Girdle and Upper Limb

Pectoral Girdle

The pectoral girdle anchors the upper limb to the axial skeleton and allows for a wide range of motion.

• Clavicle: Also known as the collarbone; connects the arm to the trunk at the sternum.

• Scapula: Also known as the shoulder blade; provides attachment points for muscles and articulates with the humerus.

Joints of the Pectoral Girdle:

• Acromioclavicular Joint: Connects the acromion of the scapula to the clavicle.

• Sternoclavicular Joint: Connects the clavicle to the manubrium of the sternum.

Manubrium: The upper part of the sternum, articulates with the clavicle.

Upper Limb Bones

The upper limb consists of several bones that enable complex movements and dexterity.

• Humerus: The bone of the upper arm; articulates with the scapula at the shoulder and with the radius and ulna at the elbow.

• Ulna: One of the two forearm bones; located on the medial side (pinky side) of the forearm.

• Radius: The other forearm bone; located on the lateral side (thumb side) of the forearm.

• Carpal Bones: Eight small bones forming the wrist.

• Metacarpal Bones: Five bones forming the palm of the hand.

• Phalanges: Fourteen bones forming the fingers (three per finger, two per thumb).

Anatomy of the Clavicle

The clavicle is a long bone with distinct anatomical features that facilitate its function and articulation.

• Acromial End: Lateral end that articulates with the acromion of the scapula.

• Sternal End: Medial end that articulates with the manubrium of the sternum.

• Conoid Tubercle: A small projection on the inferior surface near the acromial end, serving as a ligament attachment site.

Orientation: The clavicle is slightly S-shaped, with the acromial end being flatter and broader than the sternal end.

Summary Table: Major Bones of the Pectoral Girdle and Upper Limb

Region	Bone	Key Features	Articulations
Pectoral Girdle	Clavicle	Acromial end, sternal end, conoid tubercle	Acromion (scapula), manubrium (sternum)
Pectoral Girdle	Scapula	Spine, acromion, glenoid cavity	Clavicle, humerus
Upper Limb	Humerus	Head, shaft, distal condyles	Scapula (shoulder), radius & ulna (elbow)
Upper Limb	Ulna	Olecranon, trochlear notch	Humerus, radius
Upper Limb	Radius	Head, radial tuberosity	Humerus, ulna
Hand	Carpals	Eight small bones	Radius, metacarpals
Hand	Metacarpals	Five bones	Carpals, phalanges
Hand	Phalanges	Fourteen bones	Metacarpals

Key Terms and Definitions

• Girdle: A set of bones that attach the limbs to the axial skeleton.

• Articulation: The site where two bones meet (joint).

• Manubrium: The broad upper part of the sternum.

• Acromion: The bony process on the scapula.

Clinical Application Example

• Fracture of the Clavicle: Commonly occurs due to falls on the shoulder or outstretched hand. May affect the function of the pectoral girdle and upper limb mobility.

Additional info: The notes above expand on the anatomical features and functions of the bones shown in the provided images, including inferred context about the clinical relevance and definitions for clarity.