Human Anatomy: Bone Structure and Functions

Skeletal System Overview

• The skeletal system comprises bones, cartilages, and ligaments, forming a strong framework for the body
• Bones and teeth are the most enduring reminders of a once-living body, symbolizing death in art and history
• Bones are living organs, permeated with nerves and blood vessels, demonstrating sensitivity and metabolic activity

Bone and Osseous Tissue

• Bone is a connective tissue whose matrix is hardened by minerals (calcium phosphate and others)
• This hardening process is called mineralization or calcification
• Osteology is the study of bone (and osseous tissue)
• Bone is composed of osseous tissue, blood, bone marrow, cartilage, adipose tissue, nervous tissue, and fibrous connective tissue

Functions of the Skeletal System

• Support: Bones of the legs, pelvis, and vertebral column hold up the body
• Movement: Skeletal muscles rely on bones for attachment and function in movement
• Protection: Bones encase and protect delicate organs like the brain and spinal cord
• Blood Formation: Red bone marrow is the primary site for blood cell production
• Electrolyte Balance: The skeleton regulates calcium and phosphate levels in the blood
• Acid-Base Balance: Bones aid in buffering the blood against excessive pH changes
• Detoxification: Bone tissue absorbs heavy metals and other foreign elements, mitigating their effects

Anatomical Structures in Bones

• Bones possess various structural elements, including protrusions, cavities, and holes
• Understanding these structures is important for medical diagnostics or procedures like injections, pulse checks, or X-rays

Bone Materials

• Bone tissue is about 1/3 organic and 2/3 inorganic material
• Organic components include collagen and large protein-carbohydrate complexes (glycosaminoglycans, proteoglycans, glycoproteins)
• Inorganic matter is primarily hydroxyapatite (a calcium phosphate crystal)

Types of Bones

• Flat bones: Thin, curved bones (like those in the skull, sternum, ribs, pelvis)
• Long bones: Important for movement (e.g., humerus, radius, ulna, femur, tibia, fibula)
• Short bones: Primarily in the wrist and ankle (carpals and tarsals)
• Irregular bones: Vertebrae, and certain skull bones (e.g. sphenoid and ethmoid bones).

Bones and Bone Tissues

• Bones are dynamic organs, consisting not only of osseous tissue but also of blood, bone marrow, cartilage, adipose tissue, nervous tissue, and fibrous connective tissue.

General Features of Bones

• Compact (dense) bone forms the outer shell, enclosing the medullary (marrow) cavity
• Spongy (cancellous) bone forms the inner layer.

Long Bones

• Diaphysis: Shaft of the bone
• Epiphysis: Expanded ends
• Epiphyseal plate (growth plate): Important for bone growth in children; it is absent in adults.

Periosteum

• A membrane that covers bone
• Provides continuity and support from muscles/tendons
• Essential role in bone growth and repair

Skeleton Divisions

• Appendicular Skeleton: Includes bones of the upper and lower limbs, pectoral girdle, and pelvic girdle
  • Upper Limb: Bones of the arm, forearm, and hand; includes humerus, radius, ulna, carpals, metacarpals, phalanges
  • Lower Limb: Bones of the thigh, leg, and foot; includes femur, tibia, fibula, tarsals, metatarsals, phalanges
  • Pectoral Girdle: Bones that attach the upper limb to the axial skeleton; includes clavicle and scapula
  • Pelvic Girdle: Bones that attach the lower limb to the axial skeleton; includes the coxal bones( ilium, ischium, pubis)
• Axial Skeleton: Includes skull, vertebral column, sternum, and ribs.

Specific Bones (Further Detail):

• This section breaks down the characteristics and features of each major bone type previously mentioned. (detailed descriptions of each bone from humerus to phalanges etc)
• This section includes the terms for each bone area or part, e.g., head, neck, and shaft, etc

Additional Notes (Supplemental Information)

• The skeleton's structure and components play a critical role in support, protection, movement, and other vital functions of the body.
• Knowledge of bones is essential for healthcare professionals for diagnostics and interventions.