The Appendicular Skeleton THE SKELETAL SYSTEM The Appendicular Skeleton 2 pairs of limbs and 2 girdles Pectoral shoulder girdle attaches upper limbs Pelvic hip girdle secures lower limbs 3 Segmented limbs Upper arm Arm Forearm Hand Lower leg Thigh Leg Foot Pectoral Girdle Shoulder Girdle Clavicle anterior collar bone Sternal end attaches to the manubrium Acromial end articulates with the scapula medially laterally Scapula posterior shoulder blade Scapulae triangular paired but don t connect in back adds thoracic flexibility Scapula Glenoid cavity articulates with the humerus Acromium articulates with clavicle Coracoid process projects anteriorly Upper extremity Arm or Brachium upper arm Between shoulder and elbow humerus Forearm or Antebrachium Radius ulna Hand includes Wrist carpus Palm metacarpus Fingers phalanges Arm Humerus is the only bone Head of humerus fits into glenoid cavity of scapula Distal medially trochlea articulates with the ulna Distal laterally capitulum articulates with the radius Medial lateral epicondyles Right humerus anterior view Right humerus posterior view Forearm Radius is thinner proximally like a spool of thread and wide distally ulna is slightly longer and looks like a monkey wrench supposedly 2 bones articulate with each other proximally and distally Interosseous membrane between them Ulna Olecranon hinges with the humerus forming elbow Styloid process distally Radius Contributes to wrist joint Styloid process anchors a ligament to wrist thumb side Right forearm bones anterior view Right forearm bones posterior view Left forearm In the anatomical position the radius is lateral thumb side with pronation the palm faces posteriorly and the bones cross prone Anatomical position Prone body lying face down Suppine body lying face up you can remember prone if you think about how you would fall forward onto your face if you passed out pronation moves the forearm into the prone position and supination moves it back to the anatomical position Proximal and distal joints of the forearm proximal ulna Hand Proximal is wrist 8 carpal bones Palm of hand 5 metacarpals Fingers or digits consist of miniature long bones called phalanges thumb pollex has 2 fingers have 3 proximal middle distal Right hand 2 views Pelvic Girdle Hip Girdle Strongly attached to axial skeleton sacrum Deep sockets More stable than pectoral shoulder girdle Less freedom of movement Made up of the paired hip bones Bony pelvis is basin like structure hip bones plus the axial sacrum and coccyx Hip bone os coxae 3 separate bones in childhood which fuse Ilium Ischium Pubis Ilium ilium Iliac crest Anterior superior iliac spine Greater sciatic notch Forms part of acetabulum hip socket which receives ball shaped head of femur ilium Ischium Body Ramus Ischial spine Ischial tuberosity Part of socket ischium ischium Pubis Joins medially in pubic symphysis Forms obturator foramen large hole with ischium Part of socket pubis pubis Hip bones with labels Pelvis and childbearing Male female differences Large heavy vs light Heart shaped pelvic inlet vs delicate oval Narrow deep true pelvis vs wide shallow Narrow outlet vs wide Less than 90 degree pubic arch vs more than 90 degree Birth canal changes shape as baby descends head turns Lower limb Thigh femur Leg lower leg Tibia Fibula Foot Thigh Femur is largest longest and strongest bone in the body Head fits in socket acetabulum of pelvis Neck is weakest Greater trochanter Distal lateral medial condyles and epicondyles Patella sesmoid bone Right femur anterior view Right femur posterior view Leg Tibia shin bone Medial and lateral condyles Tibial tuberosity Distal medial malleolus medial ankle Fibula Distal lateral malleolus lateral ankle Interosseous membrane Right lower leg anterior view Foot Tarsus 7 tarsal bones Talus articulates with tibia and fibula anteriorly and calcaneus posteriorly Calcaneus heel bone Smaller cuboid navicular and 3 cunieforms medial intermediate and lateral 5 metatarsals 14 phalanges Great toe is hallux Right foot superior dorsal view and inferior plantar view Right foot lateral and medial views