Anatomy of the Clavicle and Scapula

Clavicle (Collarbone)

• S-shaped bone, connecting the sternum (breastbone) to the scapula (shoulder blade).
• Acts as a strut, supporting the arm and transmitting forces from the upper limb to the axial skeleton.
• Medial end articulates with the manubrium of the sternum.
• Lateral end articulates with the acromion of the scapula.
• Provides stability and allows for a wide range of arm movement.
• Susceptible to fractures, particularly in the middle third.

Scapula (Shoulder Blade)

• Large, flat, triangular bone, located posteriorly in the upper back.
• Doesn't directly articulate with the axial skeleton; it is connected to the clavicle and humerus.
• Glenoid cavity: shallow socket that articulates with the head of the humerus, forming the glenohumeral joint.
• Acromion: prominent extension of the scapula that articulates with the clavicle at the acromioclavicular joint.
• Coracoid process: projection that provides attachment points for muscles involved in moving the arm and shoulder.
• Scapular spine: a prominent ridge that divides the posterior surface of the scapula into supraspinous and infraspinous fossae.
• Subscapular fossa: a large medial depression on the anterior surface of the scapula.

Humerus

• Long bone of the upper arm.
• Proximal end: head (articulates with the glenoid cavity), anatomical neck, greater tubercle, lesser tubercle.
• Distal end: medial and lateral epicondyles (projections for muscle attachments), trochlea (articulates with ulna), capitulum (articulates with radius).
• Deltoid tuberosity: rough area on the lateral side of the shaft, where the deltoid muscle attaches.
• Surgical neck: a constricted area near the juncture of the head and the shaft, a frequent fracture site.
• Crucial for upper limb movement, acting as the major connecting bone to the forearm.

Radius

• Lateral bone of the forearm.
• Proximal end: head (articulates with the capitulum of the humerus), radial tuberosity (attachment for biceps).
• Distal end: articulates with the scaphoid and lunate bones of the wrist.
• Crucial for pronation and supination of the forearm.

Ulna

• Medial bone of the forearm.
• Proximal end: olecranon process (point of the elbow), coronoid process.
• Distal end: styloid process (serves as an attachment point).
• Trochlear notch: articulates with the trochlea of the humerus.
• Crucial for pronation and supination of the forearm and for elbow stability.

Articulations/Joints

• Glenohumeral joint (shoulder): Ball-and-socket joint, enables a wide range of motion.
• Acromioclavicular joint: Plane joint between the acromion of the scapula and the clavicle.
• Sternoclavicular joint: Saddle joint between the clavicle and sternum.
• Elbow joint: Combination of hinge joints (humeroulnar and humeroradial) that enables flexion and extension.
• Radiocarpal joint (wrist): Condyloid joint where radius and ulna articulate with the carpal bones, allowing flexion, extension, and circumduction.

Muscle Attachments

• Numerous muscles are attached throughout the bones of the shoulder and arm, making them crucial for movement, stability, and support.
• These attachments are vital for understanding and maintaining proper function.