The Skeletal System: Bones, Functions, and Structure

1. The Skeletal System

2. How many bones are in the body? 206

3. There are 5 main functions of bones • Framework- support muscles • Protection- surrounds vital organs, etc. • Levers- attach to muscles to provide movement • Produce blood cells- red, white, and platelets • Storage- calcium

4. Parts of long bones • Long bones are bones of extremities • Periosteum-tough membrane covering outside of bones • Contains osteoblasts which are special cells that form new bone tissue

5. Spongy Bone • Located at the ends of long bones • Has many small, open spaces that make bones lightweight • Filled with a substance called marrow • yellow composed of fat cells • red produces red blood cells

7. Cartilage • Smooth, slippery, thick layer of tissue • Covers the ends of bones • Does not contain blood vessels or minerals • Flexible and acts as a shock absorber • Makes movement easier by reducing friction

9. Two sections of a skeleton • Axial Skeleton 2. Appendicular Skeleton

10. Axial Skeleton • Forms main trunk of the body • Composed of the skull, spinal column, ribs, and sternum

11. Appendicular Skeleton • Forms extremities (arms and legs) • Composed of shoulder girdle, arm bones, pelvic girdle, and leg bones

12. Skull • Composed of cranial and facial bones

13. Cranium • Spherical structure that surrounds and protects the brain • At birth, the cranium is not solid bone • Spaces are called fontanels “soft spots” that allow for brain growth • Turns into solid bone by 18 months • Composed of 8 bones • Frontal • Two parietal • Two temporal • Occipital • Ethmoid • Sphenoid

14. Facial bones • Fourteen facial bones • Main bones of the face • Mandible: lower jaw • Maxilla: two bones forming upper jaw • Zygomatic: two cheek bones • Nasal: five bones in upper part of nose • Lacrimal: two bones at inner aspect of eyes • Palatine: two bones of hard palate or roof of mouth

15. Sutures • Areas where cranial bones have joined together

17. Sinuses • Air spaces in the bones of the skull • Act as a resonating chamber for the voice • Lined with mucous membranes

18. Foramina (Foramen) • Openings in the bones • Allow nerves and blood vessels to enter or leave bone

19. Vertebrae Spinal column is composed of 26 bones called vertebrae • Protects the spinal cord • Provides support for head and trunk

20. Main sections of vertebral column: • Cervical: 7 neck vertebrae • Thoracic: 12 vertebrae in back of chest, attached to ribs • Lumbar: 5 vertebrae by waist • Sacrum: 1 large vertebra on back of pelvic girdle • Coccyx: 1 fused vertebra called “tailbone”

21. Intervertebral disks • Pads of cartilage tissue that separate vertebrae • Act as shock absorbers • Permit bending and twisting movements of vertebral column

23. Ribs (costae) • 12 pairs of long, slender bones • Attach to thoracic vertebrae on dorsal surface of body

24. True ribs • First 7 pairs of ribs • Attach directly to sternum on front of body • False ribs • Next 5 pairs of ribs • First three pairs attach to cartilage of rib above • Floating ribs • Last 2 pairs of false ribs • No attachment on front of body

25. Sternum • “Breastbone” • Consists of three parts • Manubrium or upper region • Gladiolus: body or center area • Xiphoid process: small piece of cartilage at bottom (landmark for chest compressions) • Two clavicles attach to the manubrium by ligaments • Ribs attach to sternum with cartilage

26. Shoulder or pectoral girdle • Two clavicles or “collarbones” • Two scapulas or “shoulder bones” • Scapula provides for attachment of upper arm bone

27. Bones of the arm • Humerus: upper arm bone • Radius: lower arm bone on thumb side that rotates around ulna to allow the hand to turn freely • Ulna: larger bone of lower arm that contains a projection called the olecranon process at upper end, forming “elbow”

28. Wrist and hands • Carpals: 8 wrist bones on each hand • Metacarpals: 5 bones on each hand to form palm • Phalanges: • 14 bones on each hand to form a thumb and fingers • 3 on each finger • 2 on each thumb

29. Pelvic Girdle • Made of two os coxaeor “hip bones” • Join with sacrum on dorsal part of body • Join together at a joint called the symphysis pubis on ventral part of body

31. Each os coxae is made of three bones that are fused or joined • Ilium • Ischium • Pubis • Contains 2 recessed areas or sockets called acetabulum that provide for attachment of smooth rounded head of the femur • Obturator foramen • Opening between the ischium and pubis • Allows for passage of nerves and blood vessels to and from the legs

33. Bones of the legs • Femur: Thigh bone • Patella: Knee cap • Tibia: Larger weight bearing bone of lower leg. Commonly called the “shin bone” • Fibula: slender smaller bone of the lower leg that attaches to the proximal end of the tibia

34. Ankles and Feet • Tarsals: 7 bones of ankles • Calcaneous- Heel bone • Metatarsals: 5 bones forming instep of foot • Phalanges • 14 bones on each foot • Form the toes • 2 on each great toe • 3 on each of other toes

35. Joints

36. Joints • areas where 2 or more bones join together • Ligaments: • connective tissue bands that hold long bones together

37. 3 Main Types of Joints • Diarthrosis or synovial • Freely movable • Ex: “Ball-and-socket joints” of the shoulder and hip • Ex: Hinge joints of the elbow and knee

38. 2. Amphiarthrosis • Slightly movable • Ex: is the attachment of the ribs to the thoracic vertebrae • Ex: symphysis pubis or joint between two pelvic bones 3. Synarthrosis • Immovable • Examples are the suture joints of the cranium

39. Diseases and Abnormal Conditions

40. Arthritis Group of diseases involving an inflammation of the joints

41. Two main types: • Osteoarthritis • Chronic disease that occurs with aging • Symptoms: Joint pain, stiffness, aching, limited range of motion • Treatment: rest, heat/cold applications, ASA, anti-inflammatory medications, steroid injections, special exercises

42. 2. Rheumatoid • Chronic inflammatory disease of joints • Three times more common in women • Often begins between age 35-45 • Scar tissue forms and atrophy of bone and muscle occurs • Permanent deformity and immobility • Treatment: • Rest and prescribed exercise • Anti-inflammatory medications: ASA and steroids • Surgery, or arthroplasty to replace damaged joints such as hips or knees

44. Bursitis Inflammation of bursae, (small fluid-filled sacs surrounding joints)

45. Bursitis frequently affects shoulders, elbows, hips, or knees • Symptoms: • Severe pain, limited movement, accumulation of fluid in joint • Treatment: • Pain medications and rest • Injections of steroids and anesthetics into joint • Aspiration of joint • Physical therapy to preserve joint motion

48. Fractures A crack or break in a bone

49. Types of fractures: • Greenstick: bone is bent and splits, causing a crack or an incomplete break: common in children • Simple: complete break with no damage to skin • Compound: break in bone that ruptures through skin; increased chance of infection

50. Types of fractures, cont… • Impacted: broken fragments; or splinters into more than two pieces • Spiral: severe twisting of a bone causing one or more breaks: common in skiing and skating accidents • Depressed: broken piece of skull bone moves inward • Colles: breaking and dislocation of the distal radius that causes a characteristic bulge at the wrist, caused by falling with outstretched hand.