Appendicular Skeleton

Pectoral Girdle The pectoral girdle is made of the bones that attach the arms and hands to the axial skeleton The arms are attached by the clavicle (collarbone) and the scapula (shoulder blade) The bones of the arm are the humerus (upper arm) and the radius and ulna (lower arm)

Parts of the scapula The scapula has a protruding bone along the dorsal side called the “spine” Superior to it is the supraspinous fossa Inferior to the spine is the infraspinous fossa These are sites for large amounts of muscle attachment

Lower arm bones The radius and ulna connect the hand to the upper arm The radius runs along the thumb side and the ulna to the pinky side when the body is in anatomical position

Bones of the wrist and hand The wrist bones are carpals The bones of the hand are the metacarpals The digits are made of 3 bones each (except the thumb which only has 2) called phalanges

The Pelvic Girdle The pelvic girdle attaches the bones of the legs and feet to the axial skeleton The pelvis is actually 3 fused bones (os coxa) The ischium The ilieum The pubis These bones are separate in the fetus but fuse later

Pelvis continued The pubis bone is joined at the pubic symphysis—a cartilage pad This allows the pelvis to have some “give” and flexibility

Differences in male and female pelvis The male’s pelvic opening is heart shaped The female’s is more oval (allowing for baby’s head during birth) The male pubic arch is <90 degrees, the female pubic arch >90 degrees The male tailbone is tucked under, the female’s protrudes out more (again for childbirth)

Bones of the leg The femur (thigh bone) is the largest bone in the human body The patella (kneecap) helps connect the upper leg to the lower leg The lower leg is made of the tibia (which makes the shin bone) and the fibula—a non-weight bearing bone

Bones of the feet and ankles Ankle bones are tarsals Bones of the feet are metatarsals Digits—the toes—made of of 3 phalanges each except the big toe only has 2

Differences in cat and man The cat has one fewer carpal bone The cat only has 4 digits on the rear leg The cat’s pelvis is tilted at a different angle due to the fact they walk on all fours The clavicle of the cat is imbedded in muscle and not attached to any other bone (which bone in humans is not attached?)

Other random stuff to know The word “skeleton” comes from the Greek word for “dried up” or “mummy” The current form of the human skeleton has been around for about 3 million years