1. Chapter 5 Skeletal System

2. Organization
Bones is composed of osseous tissue. Bones comprise the skeleton.
The skeleton functions in:
Support
Protection
Movement
Storage

3. Organization
The skeleton is comprised of 206 bones divided into sections:
Axial: head, neck, and trunk TOTAL: approx. 80
Skull – two sets of bones: Cranium (8) & Facial bones (14)
Hyoid Bone
Vertebral Column (24 vertebrae, Sacrum (5 fused), Coccyx (4 fused)
Sternum, Ribs (12 pairs)
Appendicular: limbs and connecting bones TOTAL: 126
Pectoral Girdle: clavicle & scapula
Bones of the arm – 30 bones
Pelvic Girdle: 2 coxal bones
Bones of the leg – 29 bones

4. Bone Structure
Long bones are the most common in the skeletal system. Their major parts are:
Externally
Diaphysis – shaft – compact bone
Periosteum – covers shaft – connective tissue
Epiphysis – ends – spongy bone
Articular cartilage – covers ends - connective tissue
Internally
Medullary cavity
Yellow marrow – adipose tissue
Red marrow – red blood cells
Matrix
Osteocytes (mature bone cells)

5. Bone tissue
There are two types of bone tissue found within long bones:
Compact bone – dense & looks smooth
Spongy bone – small needlelike pieces of bone & lots of open space

6. Bone Tissue Microscopic structure of compact bone:
Compact bone contains a matrix where the bone cells live. It is composed of collagen, phosphorus, calcium, and magnesium.
There are tiny chambers within the matrix called lacunae where the mature bone cells live. These mature bone cells are called osteocytes. The osteocytes are connected to each other through tiny canals called the canaliculi.
The osteocytes form rings called the osteon (matrix) around canals that house blood vessels and nerves. These canals are called Haversian canals. Haversian canals are connected to each other by Volkmann’s canal.

8. Bone Development & Growth
The formation of bone is called ossification.
There are two types of bones in the skeleton as far as growth is connected:
Intramembranous (flat bones – form from flat connective tissue)
Endochondral (all other bones)

10. Bone Development & Growth
All bones start as hyaline cartilage. Within a long bone there are two areas of growth.
Appositional growth – increase in diameter
Interstitial growth – increase in length
The epiphyseal plate, also known as the growth plate, is found between the epiphysis and the diaphysis of a long bone. In this area bone cells ossify and growth in length occurs. These growing bone cells are called OSTEOBLASTS (bone forming cells).
CARTILAGE becomes OSTEOBLASTS which becomes OSTEOCYTES.
When minerals are needed by the body, osteoclasts dissolve bone tissue to release the minerals. This process is called mineral resorption.

11. Types of Joints There are three basic types of joints:
Fibrous joints (not movable)
Ex: Sutures of the Skull
Cartilaginous joints (slightly movable)
Ex: Pubic synthesis, Intervertebral joints
Synovial joints (freely movable)
Contain synovial fluid to lubricate the joint
Ex: Plane joints, hinge joint, pivot joint, condyloid joint, saddle joint, ball-and-socket joint

14. Fractures Complete fracture: the bone snaps into two or more parts
Greenstick: one side of the bone is broken and the other only bent.
Single: bone is broken in one place into two pieces
Comminuted: bone is broken or crushed into three or more pieces
Bowing: incomplete fractures of tubular long bones usually in pediatric patients
Open: broken bone that penetrates the skin

16. Abnormal Bone Conditions
Bone spurs: bony projections that develop along the edges of bones
Osteoporosis: bone-thinning disease in which the bones become fragile & easy to fracture
Disorders of the spine
Scoliosis: sideways curvature of the spine that occurs most often during the growth spurt just before puberty
Kyphosis: exaggerated rounding of the back
Lordosis: excessive curvature of the lower back inward
Ankylosis: abnormal stiffening and immobility of a joint due to fusion of the bones

17. Bone Spur

18. Osteoporosis

19. Scoliosis

20. Kyphosis

21. Lordosis

22. Ankylosis