CH 6 Skeletal System Part I

1. CH 6 Skeletal SystemPart I

2. Fun Bone Facts • When you were born you had over 300 bones. Now, you have 206 bones. • Over half the body's bones are in the hands and feet. • The only jointless bone in your body is the hyoid bone in your throat. • As your bones grow, you get taller (of course). Your growth in height is likely to stop by the time you are 16 if you're a girl and 18 if you're a boy. • Your bones are 50% water and 50% solid matter. • The smallest bone in the body is the stirrup (stapes) in the ear measuring about 3 mm in length. • The longest bone in the body is the femur.

3. Bone • Osteology- The study of bone structure and the treatment of bone disorders Bone Functions: • Support- Provides points of attachment for muscle and other soft tissues • Protection- Protects organs from injury • Body Movement- As muscles contract, they pull and move bones • Stores Minerals- Especially calcium and phosphorous- When minerals are in demand by the body, they are released from bones to the bloodstream for distribution • Stores Chemical Energy- Yellow bone marrow is found in certain bones and contains adipocytes. This stored fat can be used for energy • Newborns do not have yellow bone marrow- just red bone marrow

4. Produces blood cells- Red bone marrow in certain bones produces all red blood cells, white blood cells and platelets. This process is called hematopoiesis • Red bone marrow is found in adults at the pelvis, ribs, sternum, vertebrae, skull and the ends of arm and thigh bones Though once used in various preparations, bone marrow has fallen out of favor as a food in the United States; However many other countries still feast on it. Diners in the US in the 18th century used a marrow scoop (or marrow spoon), often of silver and with a long thin bowl, as a table implement for removing marrow from a bone.

5. “Bone” Appétit!!

6. Parts of a Long Bone • Bones are either long, short, flat or irregular. Their shape is relative to their function. • Examples of long bones include the femur, humerus, tibia, fibula, radius and ulna. • The parts of a long bone are: • Diaphysis – The shaft of the bone (longest section) • Epiphyses – The distal and proximal ends of bones • Metaphyses- The 2 regions in a bone where the diaphysis meets the epiphyses • Each includes an epiphyseal plate (growth plate) made up of hyaline cartilage. This is where bones elongate.

7. Articular cartilage- Thin layer of hyaline cartilage covering the epiphyses. This is where the bone forms a joint with another bone. • Medullary cavity- Space within the diaphysis that contains yellow bone marrow in adults. • Endosteum- Lining of the medullary cavity that contains bone forming cells • Periosteum- Tough outer membrane that surrounds the bone surface where cartilage is not present. • Compact bone- Layer of the diaphysis inside the periosteum that gives bone its strength • Spongy bone- A lattice work of bone material that has many air spaces. Stores red bone marrow. The thin columns of spongy bone are called trabeculae

8. Anatomy of a Long Bone

10. Pop Quiz • What is the tough outer layer of a long bone? • What are the ends of long bone covered with? • What is the shaft of the bone called? • What material is found in the medullary cavity? • What does hematopoesis mean?

11. Bone Cells • The formation of mature bone cells is as follows: Osteogenic cellsOsteoblastsOsteocytes • Osteogenic cells undergo cell division in the inner portion of the periosteum and endosteum • Osteoblasts are developed osteogenic cells that do not have the ability to divide. They secrete collagen- gives bone some flexibility. • Osteocytes are mature bone cells that are trapped in collagen (matrix) and perform the daily metabolic activities of the bone.

12. Microscopic Structure of Compact Bone • Perforating Canals (Volkmann’s Canals)- Tunnels that extend transversely across the width of bones. These canals carry blood vessels and nerves. • Haversian Canals- Tunnels that run lengthwise through bone and connect with Perforating Canals • Lamellae- Concentric circles of hard, mineralized matrix (collagen strengthened with calcium and phosphorus • Lacunnae- Spaces between lamellae which contain osteocytes

13. Structure of compact bone continued… • Canaliculi- Channels projecting outward from lacunnae. These channels connect lacunnae with each other. This allows many routes for nutrients and oxygen to reach bone cells. • Osteon- Each Haversian canal with its surrounding lamellae, lacunnae, osteocytes and canaliculi

18. ANOTHER POP QUIZ…. • What are the repeating circular units found in bone tissue called? • What is in the center of an osteon? • What two things are found that run through #2? • What are bone cells called? • Where are they found (the space)? • What is bone matrix composed of?

19. ANOTHER POP QUIZ…. • What are the repeating circular units found in bone tissue called? Osteon/Haversian system • What is in the center of an osteon? Haversian/central canal • What two things are found that run through #2? Blood vessel/nerve fibers • What are bone cells called? osteocytes • Where are they found (the space)? lacunae • What is bone matrix composed of? Collagen and minerals like calcium and phosphorus

23. Bone Formation • The process by which bone forms is called ossification. This begins during the 6th or 7th month of fetal development and continues throughout adulthood. • During ossification, hyaline cartilage becomes bone. This happens by the following steps: • A membrane develops around the cartilage called the perichondrium (This eventually become the periosteum). • Chondrocytes (cartilage cells) trigger the uptake of calcium.

24. Ossification continued… • 3. Chondrocytes die because they can’t receive nutrients through the calcified matrix. • 4. Osteogenic cells in the perichondrium develop into osteoblasts and ultimately osteocytes. • 5. This continues until the hyaline cartilage of the epiphyseal plate is completely replaced with bone. The new bone in this area is called the epiphyseal line.

27. Bone Surface Markings • The markings on bones serve as sites of attachment for muscles and/or ligaments. • Openings in bones serve as passageways for blood vessels and/or nerves. • Projections on bones take part in forming joints.

28. Trochanter A trochanter is a smooth, rounded projection Femur

29. Spine A spine is a sharp, slender, often pointed projection

30. Fossa - a surface depression or concavity

31. Facet A facet is a small, flat surface

32. Condyle Condyle – a large, convex projection that usually contacts another bone

33. Fissure A fissure is a deep cleft between adjacent parts of bone

34. Meatus A meatus is a canal within a bone

35. Foramen A foramen is a natural opening on a bone surface

36. Tubercle – rough, rounded projection

37. Suture A suture is a line at the junction of bones in the skull

38. Sinus - a hollow space within bone

39. Organization of the Skeleton • The adult human skeleton has 206 bones. • The skeleton can be divided into… • Axial skeleton – Includes the bones of the skull, ear, hyoid, vertebral column, ribs and sternum • Appendicular skeleton- Includes the bones of the upper and lower limbs, pectoral girdle and pelvic girdle • What is a girdle? Appendicular bone that connects to the axial skeleton

41. Appendicular Skeleton

43. Skull • The skull contains 22 bones • 8 cranial bones • 14 facial bones • Skull bones are held together by immovable joints called sutures: • Coronal suture- Unites the frontal bone with the 2 parietal bones • Sagittal suture- Unites the 2 parietal bones • Lamboid suture- Unites the parietal bones to the occipital bone • Squamous suture- Unites the parietal bones to the temporal bones

44. Cranial Bones • The 8 cranial bones are as follows: Frontal bone, 2 Parietal bones, 2 Temporal bones, Occipital bone, Sphenoid bone, Ethmoid bone * Color these on the picture and label the sutures

46. Facial bones • You need to be able to identify the following facial bones: Maxillae, Mandible, Nasal, Palatine, Zygomatic, Lacrimal, Vomer *Color these on the picture

48. Sinuses • A hollow in a bone • Function in producing mucus (trap infection) and acting as resonating chambers for our speaking and singing. • Sinuses are continuous with the nasal cavity; therefore, infection in the nasal cavity can travel to the sinuses and cause membranes of the sinuses to become inflammed. • The 4 paranasal sinuses are: Frontal sinus, Sphenoid sinus, Ethmoid sinus,andMaxillary sinus

50. Hyoid Bone • The hyoid bone does not attach to any other bone. It is suspended by ligaments and muscles. • The hyoid bone is in the neck between the mandible and larynx (voice box). • It is often fractured during strangulation. • It supports the tongue and provides attachment sites for tongue and neck muscles.