Bones and Key Landmarks of the Upper and Lower Extremities

Upper Extremity Bones and Landmarks

Clavicle

The clavicle is a long bone that serves as a strut between the shoulder blade and the sternum. It is important for shoulder mobility and stability.

• Acromial end: The lateral end, articulates with the acromion of the scapula.

• Sternal end: The medial end, articulates with the manubrium of the sternum.

Scapula

The scapula (shoulder blade) is a flat, triangular bone that provides attachment for several muscles and forms the socket of the shoulder joint.

• Acromion process: Extension of the scapular spine; articulates with the clavicle.

• Spine: Prominent ridge on the posterior surface.

• Supraspinous fossa: Depression above the spine; origin for supraspinatus muscle.

• Infraspinous fossa: Depression below the spine; origin for infraspinatus muscle.

• Coracoid process: Hook-like projection; attachment for muscles and ligaments.

• Glenoid fossa: Shallow cavity; articulates with the head of the humerus.

• Suprascapular notch: Passage for the suprascapular nerve.

• Medial, lateral, and superior angles: Corners of the scapula.

• Medial, lateral, and superior borders: Edges of the scapula.

Humerus

The humerus is the long bone of the upper arm, articulating with the scapula at the shoulder and the radius and ulna at the elbow.

• Greater tubercle: Lateral projection; muscle attachment.

• Lesser tubercle: Anterior projection; muscle attachment.

• Intertubercular sulcus (groove): Between tubercles; passage for biceps tendon.

• Deltoid tuberosity: Lateral surface; attachment for deltoid muscle.

• Head: Proximal, rounded end; articulates with glenoid fossa.

• Anatomical neck: Just below the head; site of joint capsule attachment.

• Radial fossa: Receives the head of the radius during elbow flexion.

• Coronoid fossa: Receives the coronoid process of the ulna during elbow flexion.

• Capitulum: Lateral condyle; articulates with the radius.

• Trochlea: Medial condyle; articulates with the ulna.

• Medial epicondyle: Medial projection; muscle attachment.

• Lateral epicondyle: Lateral projection; muscle attachment.

Radius

The radius is one of the two forearm bones, located on the lateral (thumb) side.

• Head: Proximal end; articulates with the capitulum of the humerus.

• Neck: Narrow area below the head.

• Radial styloid process: Distal projection; ligament attachment.

• Radial tuberosity: Proximal, medial projection; attachment for biceps brachii.

Ulna

The ulna is the medial bone of the forearm, forming the elbow joint with the humerus.

• Olecranon: Proximal, posterior projection; forms the elbow tip.

• Coronoid process: Proximal, anterior projection; fits into the coronoid fossa of the humerus.

• Ulnar styloid process: Distal projection; ligament attachment.

• Trochlear notch: Articulates with the trochlea of the humerus.

Lower Extremity Bones and Landmarks

Pelvis

The pelvis is a bony ring formed by the hip bones, sacrum, and coccyx, supporting the spinal column and protecting pelvic organs.

• Iliac crest: Superior border of the ilium; muscle attachment.

• Sacroiliac joint: Articulation between sacrum and ilium.

• Ischial tuberosity: Posterior projection; supports body weight when sitting.

• Pubic symphysis: Cartilaginous joint between pubic bones.

• Acetabulum: Cup-shaped cavity; articulates with femoral head.

• Obturator foramen: Large opening; passage for nerves and vessels.

• Greater sciatic notch: Passage for sciatic nerve.

• Pelvic brim: Edge of the pelvic inlet.

Femur

The femur is the longest and strongest bone in the body, forming the thigh.

• Head: Proximal, rounded end; fits into acetabulum.

• Surgical neck: Below the head; common fracture site.

• Greater trochanter: Lateral projection; muscle attachment.

• Lesser trochanter: Medial projection; muscle attachment.

• Lateral epicondyle: Distal, lateral projection; ligament attachment.

• Medial epicondyle: Distal, medial projection; ligament attachment.

• Lateral condyle: Distal, lateral articular surface.

• Medial condyle: Distal, medial articular surface.

• Intercondylar fossa: Depression between condyles.

• Patellar surface: Anterior surface; articulates with patella.

Tibia

The tibia is the larger, medial bone of the lower leg, bearing most of the body's weight.

• Lateral condyle: Proximal, lateral articular surface.

• Medial condyle: Proximal, medial articular surface.

• Intercondylar eminence: Ridge between condyles.

• Tibial tuberosity: Anterior projection; attachment for patellar ligament.

• Medial malleolus: Distal, medial projection; forms ankle.

Fibula

The fibula is the slender, lateral bone of the lower leg, providing muscle attachment and stability to the ankle.

• Head: Proximal end; articulates with tibia.

• Lateral malleolus: Distal, lateral projection; forms outer ankle.

Summary Table: Major Bones and Key Landmarks of the Extremities

Bone	Key Landmarks
Clavicle	Acromial end, Sternal end
Scapula	Acromion process, Spine, Supraspinous fossa, Infraspinous fossa, Coracoid process, Glenoid fossa, Suprascapular notch, Angles, Borders
Humerus	Greater/Lesser tubercle, Intertubercular sulcus, Deltoid tuberosity, Head, Anatomical neck, Radial/Coronoid fossa, Capitulum, Trochlea, Epicondyles
Radius	Head, Neck, Radial styloid process, Radial tuberosity
Ulna	Olecranon, Coronoid process, Ulnar styloid process, Trochlear notch
Pelvis	Iliac crest, Sacroiliac joint, Ischial tuberosity, Pubic symphysis, Acetabulum, Obturator foramen, Greater sciatic notch, Pelvic brim
Femur	Head, Surgical neck, Greater/Lesser trochanter, Epicondyles, Condyles, Intercondylar fossa, Patellar surface
Tibia	Lateral/Medial condyle, Intercondylar eminence, Tibial tuberosity, Medial malleolus
Fibula	Head, Lateral malleolus

Example: Clinical Application

• Fractures of the surgical neck of the humerus are common in elderly patients and may affect the axillary nerve.

• The olecranon is the bony prominence of the elbow, often fractured in falls.

• Medial malleolus and lateral malleolus are common sites for ankle sprains and fractures.