Skeletal System

1. Skeletal System

2. Introduction • The framework of bones and cartilage that protects our organs and allows us to move is called the skeletal system. • The branch of medicine that deals with the preservation and restoration of the skeletal system, articulations (joints), and associated structures is called orthopaedics.

3. The skeletal system performs the following functions: • Support • Protection (for internal organs) • Movement • Mineral storage • Storage of blood cell-producing cells • Storage of energy

4. Bone Composition • Bone is very strong for its relatively light weight • The major components of bone are: • Calcium carbonate • Calcium phosphate • Collagen • Water Cortical Bone Spongy Bone Medullary (marrow) cavity

5. Bone Composition Cont’d • Calcium carbonate and calcium phosphate: • Make up 60-70% of bone weight • Provide much of the bone’s stiffness and resistance to pressing or squeezing forces • Collagen (a protein): • Gives bone its characteristic flexibility and contributes to its ability to resist pulling and stretching forces • With aging, collagen is lost progressively and bone becomes more brittle. • Water • Bone consists of much smaller proportion of water than other body parts

6. Bone Classification • According to the degree of porosity, bone can be classified into two general categories: • Cortical bone (low porosity) • Spongy or cancellous bone (high porosity)

8. Effect of Fitness on Bone • When bones are subjected to regular physical activity and habitual loads, they tend to become denser and more mineralized • e.g. Right forearm of the right-handed tennis player is more dense than her left one from using it more frequently • Inactivity works in the opposite direction, leading to a decrease in weight and strength. • e.g. Loss of bone mass has been noted in bed-ridden patients, inactive senior citizens, and astronauts

9. Types of Bones • There are five principal types of bones • All bones are classified based on shape

10. 1. Long bones (e.g. thighs, legs, toes, arms, forearms, and fingers) • greater length than width • consist of a shaft and extremities (ends) • slightly curved for strength • consist mostly of compact bone (dense bone with few spaces) but also contain considerable amounts of spongy bone (bone with large spaces)

11. 2. Short bones (e.g. wrist, ankle bones) • Somewhat cube-shaped and nearly equal in length and width • Spongy except at the surface where there is a thin layer of compact bone

12. 3.Flat bones (e.g. cranial bones, sternum, ribs, scapulas) • Generally thin and composed of two more or less parallel plates of compact bone enclosing a layer of spongy bone • Flat bones afford considerable protection and provide extensive areas for muscle attachment

13. Irregular bones (e.g. vertebrae, and certain facial bones) • Have complex shapes and cannot be grouped into any of the other three categories • They vary in the amount of spongy and compact bone

14. 5.Sesamoid bones • Are small bones in tendons where considerable pressure develops, for instance, the wrist • Their number varies greatly from person to person • All people have at least two sesamoid bones: the patella (kneecap)

15. Divisions of the Skeletal System • The adult human skeleton consists of 206 bones grouped as the axial skeleton and the appendicular skeleton. • The axial division consists of the bones of the skull, auditory ossicles, hyoid bone, ribs, breastbone, and the backbone. • The appendicular division consists of the bones of the upper and lower extremities (limbs), plus the bones called girdles, which connect the extremities to the axial skeleton. • There are 80 bones in the axial division and 126 in the appendicular. Listed below are the divisions of the skeletal system.

16. Axial Skeleton Skull Sternum Ribs Vertebral Column

17. Skull • Divided into two parts: a) Calvaria b) Face

18. a) Calvaria Parietal Bone Frontal Bone Occipital Bone Temporal Bone

19. Calvaria Cont. • May be fractured in blows to the skull (e.g., in hockey, being checked and hitting the skull on the ice) • Temporal bone: • more fragile of the calvaria bones • overlies one of the major blood vessels • if fractured and displaced internally = medical emergency (picture)

20. b) Facial Bones Lacrimal Bone Nasal Bone Zygomatic Bone Maxilla Bone Mandible Bone

21. Lumbar vertebra, lateral view 7 Cervical Vertebrae (of the neck) 12 Thoracic Vertebrae (of the chest) Lumbar vertebra, superior view 5 Lumbar Vertebrae (of the lower back) Sacrum (mid-line region of buttocks) Coccyx (4 or 5 fused vertebrae of the tail bone) Vertebral Column

22. Vertebral Column • Vertebrae are arranged in a cylindrical column interspersed with fibrocartilaginous (intervertebral) discs • Function: • provides a strong and flexible support for the body and the ability to keep the body erect • the point of attachment for the muscles of the back. • protect the spinal cord and nerves • absorbs shock through the intervertebral discs without causing damage to other vertebrae

23. Ribs • Twelve pairs • Made up of : • bone • cartilage which strengthen the chest cage and permit it to expand. • Curved and slightly twisted making it ideal to protect the chest area

24. Ribs Cont’d • All 12 pairs of ribs articulate with the twelve thoracic vertebrae posteriorly • Classified into three groups based on anterior attachment: (picture) • true ribs • 1-7 • attach to both the vertebrae and the sternum • false ribs • 8-10 • attach only to the sternum indirectly, through 7th rib • floating ribs • 11 and 12 • only attach to the vertebral column

25. True Ribs (1-7) False Ribs (8-10) Floating Ribs (11-12) The Ribs Manubrium Sternal Body Xiphoid Process Costal Cartilages

26. Sternum • Mid-line breast bone • The clavicles and ribs one to seven articulate with the sternum Sternum – comprised of the manubrium, sternal body and xiphoid process

27. Appendicular skeleton Consists of: • 1. The pectoral gridle (chest) • 2. Pelvic girdle (hip) • 3. The upper limbs • 4. The lower limbs

28. Clavicle Scapula 1.Pectoral Girdle Consists of: • Scapula (shoulder blade) • Clavicle (collar bone) • Allows the upper limb great mobility • The sternoclavicular joint is the only point of attachment between the axial skeleton and the pectoral girdle

29. 2. Pelvic Girdle • Formed by pair of os coxae (hip bones) • supports the bladder and abdominal contents • Attachment: • Posteriorly – join with the sacrum • Anteriorly - join to each other anteriorly • Laterally – join to the head of thigh bone through a cup-shaped acetabulum

30. Humerus Radius Ulna 3. Upper Limb • Humerus • The arm bone • shoulder to elbow • Radius and Ulna • The forearm bones • elbow to wrist • the radius being located on the thumb side of the hand • when you pronate the forearm, the radius is actually crossing over the ulna - try it yourself

31. Carpals Proximal Phalanx Metacarpals Phalanges Middle Phalanx Distal Phalanx Upper Limb Cont.

32. Femur Patella 4. Lower Limb • Femur • thigh bone • from hip to knee • Patella • knee cap • sesamoid bone in the tendon of the quadriceps muscles (thigh)

33. Fibula Tibia Lat. malleolus Med. malleolus Lower Limb Cont’d • Tibia and Fibula • leg bones • From knee to ankle • Tibia is medial and fibula is lateral • Medial malleolus and Lateral malleolus • The distal ends of the tibia and fibula, respectively • commonly referred to as the "ankle bones" • can be easily palpated

34. Talus Calcaneus Tarsals Metatarsals Phalanges Lower Limb Cont’d • Tarsals • ankle bones • calcaneus or the heel bone • talus • Metatarsals • 5 bones of the foot • unite with the toes • Phalanges • toe bones • three per toe except the big toe - proximal, middle and distal

35. Skeletal Surface Markings • The surfaces of bones have various structural features adapted to specific functions. These features are called surface markings. Long bones that bear a great deal of weight have large, rounded ends that can form sturdy joints, for example. Other bones have depressions that receive the rounded ends.