Bone Development and Growth

Cellular Molecules and Signaling

• Exocytosis is a process involved in the signaling of neural molecules.

Appendicular Skeleton

• Consists of the bones of the upper limbs, lower limbs, and two girdles (pectoral and pelvic)
• Total bones: 126
• Four categories of bones based on shape:
  • Long bones (e.g., most bones in upper and lower limbs)
  • Short bones (e.g., bones in the wrist and ankle)
  • Flat bones (e.g., certain skull bones, ribs, scapulae, and sternum)
  • Irregular bones (e.g., vertebrae and facial bones)

Bone Development and Growth

• Osteoblasts produce compact bone on the surface of cartilage model, forming a bone collar
• Primary Ossification Center: forms as osteoblasts produce bone on the surface of calcified cartilage
• Secondary Ossification Center: created in the epiphyses by osteoblasts that migrate into epiphysis
• Endosteum: a single-cell layer of connective tissue that lines the internal surfaces of all cavities within bones
• Bone formation in the fetus follows two processes: intramembranous ossification and endochondral ossification

Bone Remodeling and Repair

• Bone Remodeling: a process where old bone is replaced with new bone
• Four Major Steps in Bone Repair:
  • Hematoma Formation
  • Callus Formation
  • Callus Ossification
  • Bone Remodeling
• Calcium Homeostasis: calcium is a critical physiological regulator of many processes required to achieve and maintain homeostasis

Pectoral Girdle and Upper Limb

• Pectoral Girdle: consists of two pairs of bones that attach each of the upper limbs to the body
• Scapula: a flat, triangular bone that can easily be seen and felt in a living person
• Clavicle: commonly known as the collarbone
• Forearm: consists of two bones, the ulna and radius
• Hand: consists of metacarpal bones and phalanges

Pelvic Girdle and Lower Limb

• Pelvic Girdle: consists of two hip bones and the sacrum
• Hip Bone: forms the pelvic girdle
• Sacrum: part of the pelvic girdle
• Lower Limb: consists of femur, patella, tibia, fibula, and phalanges

Skeletal Anatomy Overview

• Foramen: a hole in a bone
• Canal or Meatus: an elongated hole that forms a tunnel-like passage through the bone
• Fossa: a depression in a bone
• Tubercle or Tuberosity: a rounded projection on a bone
• Process: a sharp projection from a bone
• Condyle: a smooth, rounded end of a bone, where it forms a joint with another bone

Axial Skeleton

• Axial Skeleton: forms the central axis of the body
• Skull: consists of 8 cranial bones and 14 facial bones, a total of 22 bones
• Cranial Bones:
  • Frontal bone
  • 2 Parietal bones
  • 2 Temporal bones
  • Occipital bone
  • Sphenoid bone
  • Ethmoid bone