1. Ch. 6/7/8 – The Skeletal System

2. Introduction Bones are ALIVE and have many functions
There are a total of 206 bones in the human body

3. Functions of Skeletal System
Provide a surface for muscles to attach
Protect and support softer tissues and organs
Produce blood (hematopoeisis)
Store salts
Contain passageways for blood vessels and nerves

4. 5 Tissues found in Bone Bone (osseous) tissue Cartilage
Dense connective tissue
Blood
Nervous tissue

5. 2 Bone (Osseous) Tissues
1. Compact Bone – wall of the bone (along diaphysis); solid and strong
2. Spongy Bone – softer, porous bone; found in ends of bones (epiphyses)

6. Bone Structure
EPIPHYSIS - ends of bone; forms a joint with another bone.
2. DIAPHYSIS - shaft of the bone
3. ARTICULAR CARTILAGE - hyaline cartilage covering ends of bones
4. PERIOSTEUM - tough membrane-like covering over entire bone
5. MEDULLARY CAVITY - hollow chamber within the diaphysis, contains bone marrow
- Red Marrow - mainly in spongy bone in adults, produces blood cells
- Yellow Marrow - fat storage

8. Microscopic Structure
- MATRIX – where all of the bone cells live
- OSTEOCYTES - mature bone cells are enclosed in tiny chambers called LACUNAE
OSTEOCYTES form concentric rings called LAMELLA which surround HAVERSIAN CANALS that houses blood vessels
Volkmann’s Canals run horizontally connecting the vessels between OSTEONS

9. Bone Development
Bones first form as hyaline cartilage, then gradually change into bone tissue - a process called OSSIFICATION.
OSTEOBLASTS produce bone cells called OSTEOCYTES
OSTEOCLASTS - dissolve bone tissue to release minerals - a process called RESORPTION

11. Bone Structures Long bones (Humerus, Femur)
Longer than they are wide
Short bones (Carpals, Tarsals)
Approximately as wide as they are long
Flat bones (Scapula, Cranium)
Irregular bones (Mandible, Vertebra)

12. The skeleton is divided into two portions:
1. AXIAL SKELETON
2. APPENDICULAR SKELETON

13. Axial skeleton
Supports and protects organs of the head, neck, and trunk
Skull
Hyoid supports tongue for speaking and swallowing
Vertebral column
Thoracic cage (sternum and ribs)

14. Appendicular skeleton
Upper and lower limbs AND bones that hold those limbs to the axial skeleton
Upper limbs (arms) – Humerus, radius, ulna, carpals, metacarpals, phalanges
Pectoral girdle - scapula, clavicle
Lower limbs (legs) – Femur, fibula, tibia, patella, tarsals, metatarsals, phalanges
Pelvic girdle (hip bones) – 2 coxa

15. Vertebral column Cervical (7) – neck curvature
Thoracic (12) – attached to rib cage
Lumbar (5) – lower back curvature
Sacrum and Coccyx (fused)
**The ATLAS vertebrae is the 1st vertebrae (C1)
** The AXIS vertebrae is the 2nd (C2)

16. Abnormal spine curvature
Lordosis – “Swayback”; the spine curves significantly inward at the lower back

17. Abnormal Spine Curvature
2. Kyphosis - “Humpback”; abnormally rounded upper back

18. Abnormal Spine Curvature
3. Scoliosis – sideways or “S-shaped” curve to the spine

19. Types of Fractures
1. Simple/Closed – bone breaks, but does not damage surrounding tissue
2. Compound/Open – bone breaks and breaks through the skin
3. Greenstick – incomplete break and the bone bends
4. Comminuted – fragmented and shattered break
5. Stress/hairline – small crack caused by repeated impact

25. Unions between two or more bones A.k.a.— articulations
Joints
Unions between two or more bones
A.k.a.— articulations

26. 3 Types of Joints
Fibrous joint – found between bones that closely contact one another; connected with dense, fibrous tissue
Ex: sutures between bones in the skull
Least movable joint

27. 3 Types of Joints
2. Cartilagenous joint – connected by hyaline cartilage
Ex: vertebral column and pubic symphysis
Limited movement

28. 3 Types of Joints 3. Synovial Joint
Complex joints that allow free movement

29. 6 Synovial Joints Ball-and-socket—ex: shoulder
Condyloid—ex: metacarpals and phalanges
Gliding—ex: carpals
Hinge—ex: elbow
Pivot—ex: atlas and axis vertebra (head movement)
Saddle—ex: thumb