The Appendicular Skeleton

The Appendicular Skeleton 2 pairs of limbs & 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 medially Acromial end articulates with the scapula laterally Scapula – posterior: shoulder blade

Pectoral Girdle Attach the bones of the upper limbs to the axial skeleton The joints are freely movable in many directions

Scapulae: triangular, paired, but don’t connect in back (adds thoracic flexibility)

Scapula Also known as the shoulder blade Large, flat triangular bone situated in the posterior part of the thorax The glenoid cavity is a depression inferior to the acromion. It articulates with the humerus head to form the shoulder joint. The coracoid process is where muscles attach.

Scapula Glenoid cavity articulates with the humerus Acromium articulates with clavicle Coracoid process projects anteriorly

Clavicle Also known as the collarbone Long, slender S-shaped bone that is horizontally above the first rib

Upper Limb

Upper extremity Arm = upper arm Forearm - Radius & ulna Hand includes: Between shoulder and elbow (humerus) Forearm - Radius & ulna Hand includes: Wrist (carpus) Palm (metacarpus) Fingers (phalanges)

Humerus Longest and largest bone of the upper limb Articulates with the scapula at the shoulder & both the ulna and radius at the elbow

Upper arm Humerus is the only bone Head of humerus fits into glenoid cavity of scapula Articulates with the ulna& with the radius Medial & lateral epicondyles

Right humerus, anterior view

Forearm 2 bones: Ulna Radius Radius is thinner proximally & wide distally Ulna is slightly longer

Ulna Located on the medial side of the forearm (pinky side) Longer than the radius

Radius Located on the lateral side of the forearm (thumb side)

Right forearm bones, anterior view

In the anatomical position, the radius is lateral (thumb side)  with pronation the palm faces posteriorly and the bones cross Left forearm Anatomical position prone

Proximal and distal joints of the forearm proximal ulna

Carpus (Wrist) 8 carpals Held together by ligaments with four bones in each row Named for their shapes Short bones

The carpals in the top row are the: Scaphoid, Lunate, Triquetrum, and Pisiform The carpals in the bottom row are the: Trapezium, Trapezoid, Capitate, and Hamate

Hand Proximal is “wrist” – 8 carpal bones Palm of hand - 5 metacarpals Fingers (or digits) consist of long bones called phalanges Thumb (“pollex”) 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 & the sacrum & coccyx

Hip bone: 3 separate bones in childhood which fuse Ilium Ischium Pubis

Ilium Iliac crest Anterior superior iliac spine Greater sciatic notch Forms part of “acetabulum” (hip socket) which receives ball-shaped head of femur ilium ilium

Hip bones

Pelvis and childbearing Male/female differences: Large & heavy vs light & delicate Heart shaped pelvic inlet vs oval Narrow deep true pelvis vs wide & shallow Narrow outlet vs wide Less than 90 degree pubic arch vs more than 90 degree

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 & epicondyles Patella: sesmoid bone

Right femur, anterior view

Leg Tibia: shin bone Fibula Medial and lateral condyles Tibial tuberosity Distal medial malleolus (medial ankle) Fibula Distal lateral malleolus (lateral ankle)

Right lower leg, anterior view

Foot Tarsus: 7 tarsal bones 5 metatarsals 14 phalanges 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 Big toe = hallux

Right foot, superior (dorsal) view and inferior (plantar) view

Right foot, lateral and medial views