1. The Skeletal System

2. The Skeletal System
Parts of the skeletal system: bones, joints, cartilages, and ligaments
Function of bones:
Support body, protects organs, allows movement, storage of minerals & fats, blood cell formation
Divided into two divisions
Axial skeleton (skull, vertebrae, thorax)
Appendicular skeleton (limbs, pectoral and pelvic girdles)

3. Bones of the Human Body The adult skeleton has 206 bones
Two basic types of bone tissue
Compact bone: hard, solid
Homogeneous
Spongy bone
Small needle-like pieces of bone
Many open spaces
Figure 5.2b

4. Classification of Bones on the Basis of Shape
Figure 5.1

5. Gross Anatomy of a Long Bone
Diaphysis
Shaft, compact bone
Compact bone
Epiphysis
Ends of the bone
Mostly spongy bone
Articular Cartilage
Covers surface of ends
Hyaline cartilage
Reduces friction
Figure 5.2a

6. Structures of a Long Bone
Periosteum: Outside covering of diaphysis
Fibrous connective tissue
Sharpey’s fibers: Secure periosteum to underlying bone
Arteries: Supply bone cells with nutrients
Medullary cavity: Contains yellow marrow (mostly fat) in adults, red marrow (blood cell formation) in infants
Figure 5.2c

7. Bone Markings Bone Markings
Sites of attachments for muscles, tendons, and ligaments
Passages for nerves and blood vessels
Bone markings:
Projections and processes – grow out from the bone surface, bumps, mounds
Depressions or cavities – indentations

8. Microscopic Anatomy of Bone
Lacunae
Cavities containing bone cells (osteocytes)
Arranged in rings
Lamellae
Rings around central canal
Sites of lacunae
Canaliculi
Tiny canals
Form a transport system
Detail of Figure 5.3

9. Changes in the Human Skeleton
Embryo: skeleton is mostly hyaline cartilage
This cartilage is eventually replaced by bone
Cartilage remains in:
Bridge of the nose
Parts of ribs
Joints

10. Long Bone Formation and Growth
Figure 5.4a

11. Types of Bone Cells Osteocytes Mature bone cells Osteoblasts
Bone-forming cells
Osteoclasts
Bone-destroying cells
Break down bone matrix for remodeling and release of calcium
Bone remodeling is a process by both osteoblasts and osteoclasts

12. Bone Fractures Types of bone fractures
Closed (simple) fracture – broken bone does not penetrate the skin
Open (compound) fracture – penetrates through the skin

13. The Axial Skeleton Axial Skeleton
Forms the longitudinal part of the body
Divided into three parts
Skull
Vertebral column
Bony thorax

14. The Axial Skeleton
Figure 5.6

15. The Skull
Figure 5.7

16. Bones of the Skull
Figure 5.11

17. Paranasal Sinuses Paranasal Sinuses
Hollow portions of bones around nasal cavity
Lightens skull, voice resonates
Figure 5.10

18. The Fetal Skull The fetal skull is large compared to body
Fontanelles – fibrous membranes connecting the cranial bones (“soft spots” of baby’s head)
Allows brain to grow
Converts to bone within 24 months
Figure 5.13

19. The Vertebral Column Vertebrae separated by intervertebral discs
The spine has a normal curvature
Each vertebrae is given a name according to its location
Figure 5.14

20. The Bony Thorax Bony Thorax Protects major organs Three parts Sternum
Ribs
Thoracic vertebrae
Figure 5.19a

21. The Appendicular Skeleton
Limbs (appendages) – bones of arms, legs
Pectoral girdle – bones of chest
Clavicle – collarbone
Scapula – shoulder blade
Pelvic girdle – bones of pelvis

22. Bones of the Shoulder Girdle
Figure 5.20a–b

23. Bones of the Upper Limb The arm is formed by Humerus The forearm Ulna
Radius
Figure 5.21a–b

24. Bones of the Upper Limb The hand Carpals – wrist Metacarpals – palm
Phalanges – fingers
Figure 5.22

25. Bones of the Pelvic Girdle
Hip bones, protect several organs
Three pair of fused bones: Ilium, Ischium, Pubic bone

26. Bones of the Lower Limbs
Thigh bone: Femur
Lower leg:
Tibia
Fibula
Figure 5.24a–b

27. Bones of the Lower Limbs
The foot
Tarsus – ankle
Metatarsals – sole
Phalanges – toes
Figure 5.25

28. Structural Classification of Joints
Joints – hold bones together, allow mobility
Fibrous joints
Generally immovable
Sutures of scull, holds tibia fibula together
Cartilaginous joints
Immovable or slightly moveable
Pubic symphysis; between vertebra
Synovial joints
Freely moveable
Shoulder, elbow, wrists

29. Inflammatory Conditions Associated with Joints
Bursitis – inflammation of a bursa usually caused by a blow or friction
Tendonitis – inflammation of tendon sheaths
Arthritis – inflammatory or degenerative diseases of joints
Over 100 different types
The most widespread crippling disease in the US