The adult human vertebral column has 4 natural curvatures: Cervical curve (convex forward/lordosis - neck region), Thoracic curve (concave forward/kyphosis - chest region), Lumbar curve (convex forward/lordosis - lower back region), and Sacral curve (concave forward/kyphosis - pelvic region). These curves provide strength, balance, and shock absorption. Abnormal curvatures: Scoliosis (lateral curve), Kyphosis (hunchback), Lordosis (swayback).

The Carpals are the 8 small bones of the wrist, arranged in two rows of four. Mnemonic: Some Lovers Try Positions That They Can't Handle. Proximal row: Scaphoid, Lunate, Triquetrum, Pisiform. Distal row: Trapezium, Trapezoid, Capitate, Hamate. The Scaphoid is the most commonly fractured carpal bone. Tarsals = ankle bones, Phalanges = finger/toe bones, Metatarsals = foot bones.

The Humerus (upper arm bone) is commonly called the funny bone - though the sensation comes from the ulnar nerve that passes over the medial epicondyle of the humerus. When bumped, it causes a tingling, electric shock-like sensation in the arm and fingers (ring and little finger). The name funny bone is a pun on the word humorous (resembling humerus). The humerus articulates with the scapula above and radius/ulna below.

Yellow Bone Marrow is found in the medullary cavity (shaft/diaphysis) of long bones in adults. Its primary function is fat storage - it contains mainly adipocytes (fat cells). Yellow marrow normally does NOT produce blood cells. However, during severe blood loss or anaemia, yellow marrow can convert back to red marrow and resume blood cell production. In children, most bone marrow is red; as we age, red marrow is gradually replaced by yellow marrow.

A Fracture is the medical term for a broken or cracked bone. Types: Simple (Closed) = bone breaks but doesn't pierce skin. Compound (Open) = broken bone pierces through skin. Greenstick = incomplete fracture (common in children). Stress fracture = tiny crack from repetitive stress. Comminuted = bone shatters into multiple fragments. Sprain = stretched/torn ligament, Dislocation = bone displaced from joint, Strain = stretched/torn muscle/tendon.

Bones are classified by shape: Long bones (Femur, Humerus, Tibia, Fibula, Radius, Ulna, Phalanges) = longer than wide, have shaft (diaphysis) and two ends (epiphyses). Short bones (Carpals, Tarsals) = roughly cube-shaped. Flat bones (Skull bones, Sternum, Scapula, Ribs) = thin and flat, protect organs. Irregular bones (Vertebrae, facial bones) = complex shapes. Sesamoid bones (Patella) = develop within tendons. Long bones act as levers for movement.

Each human foot contains 26 bones: Tarsals (ankle/heel bones) = 7 bones (including Calcaneus/largest tarsal/heel bone and Talus). Metatarsals = 5 bones (form the arch of the foot). Phalanges (toe bones) = 14 bones (3 per toe x 4 toes + 2 for big toe). Total = 7 + 5 + 14 = 26 bones per foot. Both feet together = 52 bones - about 25% of all bones in the body are in the feet.

The Epiphyseal Plate (Growth Plate/Physis) is a layer of hyaline cartilage located between the epiphysis (end) and diaphysis (shaft) of a growing long bone. It is the site where new bone is produced, allowing bones to grow in length during childhood and adolescence. When growth stops (around age 18-25), the plate ossifies and becomes the epiphyseal line. Injuries to the growth plate in children can disrupt bone growth.

The Cranium (braincase) is the part of the skull that encloses and protects the brain. It is composed of 8 cranial bones: Frontal (1 - forehead), Parietal (2 - top and sides of head), Temporal (2 - sides and base), Occipital (1 - back of head, contains foramen magnum), Sphenoid (1 - base of skull), Ethmoid (1 - between nasal cavity and brain). Together they form a rigid protective case for the brain.

The Periosteum is a dense, tough fibrous connective tissue membrane that covers the outer surface of bones (except at joint surfaces where articular cartilage is present). Functions: Bone growth (appositional/widthwise growth), Bone repair after fractures, Attachment of tendons and ligaments, and Nerve and blood supply to bone. The Endosteum is the thin membrane lining the inner surface of the bone marrow cavity.