Overview of the Appendicular Skeleton: Pectoral & Pelvic Girdles, Limbs, and Major Joints

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The pectoral girdle connects the upper limb to the axial skeleton and provides attachment points for muscles that move the shoulder and arm.

Bones: The clavicle (collarbone) and scapula (shoulder blade) form the pectoral girdle.
Joints: The main joint is the glenohumeral joint (shoulder joint), where the humerus articulates with the scapula.

The pectoral girdle is designed for maximum mobility to allow a wide range of arm movements.
This mobility comes at the expense of stability, making the shoulder joint more prone to dislocation.

The humerus is the single bone of the upper arm, articulating proximally with the scapula and distally with the radius and ulna.

The radius and ulna are the two bones of the forearm.
Radius: Located on the lateral (thumb) side.
Ulna: Located on the medial (pinky) side.
They articulate with each other at the proximal and distal radioulnar joints, allowing pronation and supination of the forearm.

Carpals: Eight small bones forming the wrist.
Metacarpals: Five bones forming the palm.
Phalanges: Fourteen bones forming the fingers (three per finger, two in the thumb).

Key features include the olecranon of the ulna (elbow), capitulum and trochlea of the humerus, and styloid processes of the radius and ulna.

The pelvic girdle is formed by two hip bones (coxal bones), each composed of three fused bones: the ilium, ischium, and pubis.

The acetabulum is the deep socket that receives the head of the femur, forming the hip joint.
Pelvic differences exist between sexes: female pelvis is wider and shallower for childbirth; male pelvis is narrower and deeper.

The femur is the longest and strongest bone in the body, articulating proximally with the pelvis and distally with the tibia and patella.

Tarsals: Seven bones forming the ankle and proximal foot (including the calcaneus and talus).
Metatarsals: Five bones forming the midfoot.
Phalanges: Fourteen bones forming the toes.
Arches: The foot has longitudinal and transverse arches for weight distribution and shock absorption.

Key features include the medial malleolus (tibia), lateral malleolus (fibula), and patellar surface (femur).

The femur and tibia are the primary weight-bearing bones of the lower limb.

Major joints of the appendicular skeleton allow for movement and support of the body.

Shoulder (Glenohumeral Joint): Ball-and-socket joint for wide range of motion.
Elbow: Hinge joint between humerus, radius, and ulna.
Wrist: Complex joint involving the radius, ulna, and carpal bones.
Hip: Ball-and-socket joint between femur and acetabulum.
Knee: Hinge joint between femur, tibia, and patella.
Ankle: Hinge joint between tibia, fibula, and talus.

Upper limb = mobility: The structure of the upper limb prioritizes movement and dexterity.
Lower limb = strength & weight-bearing: The lower limb is adapted for supporting body weight and locomotion.
Key landmarks & common fracture sites: Notable bony landmarks (e.g., greater trochanter, medial malleolus) are important for clinical assessment; common fracture sites include the clavicle, scaphoid, and femoral neck.
Bones used for sex and body size determination: The pelvis is the most reliable bone for sex determination; long bone measurements can estimate stature.

Girdle: A set of bones that attach the limbs to the axial skeleton.
Articulation: A joint; the point where two bones meet.
Phalanges: Bones of the fingers and toes.
Acetabulum: The socket in the pelvis that receives the femoral head.
Landmark: A prominent feature on a bone used for identification or attachment.

Sex determination from bones is most accurate using the pelvis due to differences in shape and size between males and females.
Body size estimation uses formulas based on long bone length, such as:

Additional info: Formula is an example; actual coefficients vary by population.