- the bones of your skeleton. OSSEUS
- Bone tissue is a type of connective tissue. Your skeleton performs several important functions.
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 with 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)
"LONG BONE" = typical bone
1. EPIPHYSIS - expanded ends of bone. ARTICULATES (forms a joint) with another bone.
2. DIAPHYSIS - shaft of the bone
3. ARTICULAR CARTILAGE - hyaline cartilage covering the ends of bones
4. 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
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
- OSTEOCYTES (mature bone cells) are enclosed in tiny chambers called LACUNAE and form concentric "ring" (layers) around a passageway called the HAVERSION 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
There are two types of bone based on the way the bones form
1. Intramembranous bones = broad, flat bones of the skull. These bones form from membrane-like sheets of connective tissue
2. Endochondral bones = all other bones.
1. SYNARTHROTIC - immoveable joint, such as bones in the skull, these junctions are called SUTURES. - Fibrous Joints
2. AMPHIARTHROTIC - slightly moveable joint, vertebrae - Cartilaginous Joints
3. DIARTHROTIC - freely moveable joint, such as shoulders, hips, knees, elbows, wrists, fingers
--these joints are enclosed within a fibrous capsule which contains a lubricating fluid called SYNOVIAL fluid. These are called SYNOVIAL JOINTS.
Ball & Socket
1. Frontal - anterior portion above eyes
2. Parietal - one on each side of the skull, just behind frontal bone
3. Occipital - forms the back of the skull and base of the cranium
4. Temporal - forms parts of the sides and base of cranium
5. Sphenoid - wedged between several other bones in anterior portion of the cranium
6. Maxilla - forms upper jaws
7. Mandible - lower jaws, only moveable bone of the skull
Sutures - connection points between skull bones
1. Coronal - between frontal and parietal bones
2. Lambdoidal - between occipital and parietal bones
3. Squamosal - between temporal and parietal bones
4. Sagittal - between parietal bones
Fontanels - "soft spots"
of an infant's skull, these form sutures as you age
- anterior fontanel, posterior fontanel, sphenoid fontanel, mastoid fontanel
Foramen Magnum - Large opening through the underside of the skull, spinal cord enters skull
Ribs - Thoracic Cage, 12 pairs
- True Ribs - first seven pairs, attach directly to STERNUM by costal cartilage
- False Ribs - last five pairs (Vertebralchondral)
- Floating ribs - last two pairs (Vertebral)
Pectoral Girdle: Shoulder. Two clavicles (collar bones) and two scapula (shoulder blade)
Arms: Upper arm - humerus. Lower
arm - radius and ulna.
Wrist - 8 small bones called carpals
Fingers - Metacarpals, Phalanges
Pelvic Girdle: Hips. Two large bones called COXAL BONES
Legs: Upper leg (thigh) - FEMUR.
Lower leg - tibia & fibula.
Ankle and Upper foot - 7 bones called TARSALS,
Largest is the heel bone called the CALCANEOUS
Toes - Metatarsals, Phalanges