Anatomy of the Bone – Types and Structure of bone tissue
Bone tissue is a type of connective tissue.
- SUPPORT and PROTECTION
- BODY MOVEMENT – muscles “pull” on bones
- BLOOD CELL FORMATION – hemopoiesis occurs in red bone marrow
- STORAGE of inorganic salts – especially calcium phosphate, but also magnesium, sodium, potassium, carbonates and others.
Normally 206 bones present in our human skeleton
– 2 Main Divisions: AXIAL & APPENDICULAR
1. AXIAL: head, neck, trunk
SKULL, HYOID BONE (upper neck, under jaw, mandible)
VERTEBRAL COLUMN (spine/backbone)
THORACIC CAGE (rib cage-12 pairs)
2. APPENDICULAR: limbs and bones connecting the limbs to the:
PECTORAL GIRDLE (scapula & clavicle),
UPPER LIMBS (arms)
PELVIC GIRDLE (coxal bones),
LOWER LIMBS (legs)
EPIPHYSIS – expanded ends of bone. ARTICULATES (forms a joint) with another bone.
DIAPHYSIS – shaft of the bone
ARTICULAR CARTILAGE – hyaline cartilage covering the ends of bones
PERIOSTEUM – tough membrane-like covering over entire bone, except for articular cartilage. Connects with tendons and ligaments. Forms bone tissue.
MEDULLARY CAVITY – hollow chamber within the diaphysis connects to spaces in spongy bone. Filled with soft specialized tissue called bone marrow.
• Red Marrow – mainly in spongy bone in adults. Produces blood cells
• Yellow Marrow – fat storage. Replaces much of the red marrow in diaphysis through childhood
ENDOSTEUM – lining of the medullary cavity
Two Types of Bone Tissue
1. COMPACT (cortical) BONE – wall of the diaphysis, solid, strong
2. SPONGY (cancellous) BONE – epiphysis. Covered with a thin layer of compact bone. Many branching, bony “plates”
- MATRIX composed of collagen and inorganic salts.
- OSTEOCYTES (mature bone cells) are enclosed in tiny chambers called LACUNAE and form concentric “ring” (layers) around a passageway called the HAVERSIAN CANAL.
- The osteocytes are connected by minute passages called CANALICULI (canaliculus) through which tiny “branches” or processes pass.
- The circular layers of matrix material and osteocytes, along with the haversian canal, forms a unit called a HAVERSIAN SYSTEM. Compact bone tissue is formed in this way.
- The haversian canals are interconnected by passages called VOLKMANN’S CANALS. All of these canals contain blood vessels and nerve fibers.