Skeletal System. Chapter 5

Transcription

1 Skeletal System Chapter 5

2 Components of the Skeletal System Skeleton subdivided Axial Skeleton-longitudinal axis of body Appendicular Skeletonlimbs and girdles Skeletal System includes Joints 3 types Cartilages 3 types Hyaline, Fibrocartilage, Elastic Ligaments bone to bone

3 Functions of Bones Support: framework Protection: protect soft body organs examples? Movement: skeletal muscles attached to bones via tendons Storage: fats in the internal cavities of bones and minerals such as Ca++ and Phosphorus. Blood cell formation: hematopoiesis (blood cell formation) marrow cavities of some bones.

4 Classification of Bones Two types of osseous tissue Compact bone-dense, smooth, homogeneous Spongy boneneedlelike pieces of bone and lots of open space.

5 Classification based on Shape Four groups 1) Long bones longer than wide, shaft with heads at both ends, mostly compact bone, all bones of limbs except patella, wrist, ankle 2) Short bones cube shaped, mostly spongy, wrist, ankle, sesamoid bones 3) Flat bones thin, flattened, usually curved, outer layers of compact bone sandwich spongy, skull, ribs, sternum 4) Irregular bones don t fit previous categories, hip bones, vertebrae

6 Structure of a Long Bone Diaphysis - shaft Periosteum - fibrous connective tissue membrane Endosteum Sharpey s fibers - perforating fibers connect periosteum to bone Epiphyses - ends, compact bone enclosing spongy Articular cartilage - covers epiphyses, glassy hyaline cartilagedecreases friction Epiphyseal line - adult bones, epiphyseal plate in growing bones, hyaline cartilage, growth, replaced by bone in puberty

7 Structure of a Long Bone Medullary cavity 1) adults - yellow marrow 2) infants red marrow - in adults red marrow confined to spongy bone of flat bones and epiphyses of some long bones Bone Markings Table 5.1 projections vs depressions ex. Trochanter, Foramen

8 Microscopic Anatomy of Long Bone Osteocytes mature bone cells Lacunae cavities where osteocytes found Lamellae circles lacunae found Haversian canals center of lamellae Osteon lamellae + Haversian canal Canaliculi Volkmann s canals

9 Microscopic Anatomy of Long Bone Osteocytes mature bone cells Lacunae cavities where osteocytes found Lamellae circles lacunae found Haversian canals center of lamellae Osteon lamellae + Haversian canal Canaliculi Volkmann s canals

10 Bone Formation, Growth, and Remodeling Skeleton formed from bone and cartilage Embryos vs young children Cartilage remains in nose, parts of ribs, joints Ossification bone formation

11 Ossification Ossification 2 phases 1) Hyaline cartilage model covered w/ bone matrix by Osteoblasts 2) Cartilage digested opening Medullary cavity -By birth hyaline cartilage models coverted to bone except articular cartilages and epiphyseal plates

12 Bone Growth - Lengthening New cartilage added 2 places external articular cartilage and ephiphyseal plate What do each of these do? Old cartilage digested replaced by bony matrix

13 Bone Growth - Widening Appositional Growth diameter increase Osteoblasts in periosteum add bone tissues to diaphysis Osteoclasts in endosteum remove bone from inner diaphysis Occurs at about same rate Controlled by hormones Ends in puberty epiphyseal plates converted to bone

14 Bone Remodeling 2 Factors 1) Ca++ in blood bones as storage a) below homeostatic levels parathyroid glands release PTH into blood. - PTH activates osteoclasts b) above homeostatic levels - Ca++ deposited as calcium salts

15 Bone Remodeling 2) pull of gravity and muscles on bone Necessary to retain proportions and strength during growth Bones become thicker and form projections where bulky muscles attached No stress bones weaken and atrophy Ca++ uptake/release and remodeling work together PTH determines WHEN bone broken down or deposited based on [Ca++] in blood Muscle pull and gravity determine WHERE bone broken down or deposited

16 Bone Fractures Occur less often in youth, requires exceptional trauma twists or smashes Two types simple or compound Comminuted many fragments Compression crushed Depressed broken bone portion pressed inward (skull) Impacted broken ends forced into each other Spiral ragged break due to twisting Greenstick incomplete break

17 Bone Repair 1) 2) 3) 4) Reduction closed or open, immobilization to all healing Hematoma forms blood vessels broken, blood filled swelling Fibrocartilage callus formation mass of repair tissue cartilage matrix, bony matrix, and collagen fibers, act as splint Bony Callus forms osteoblasts and osteoclasts migrate to break, spongy bone callus forms Bone Remodeling permanent patch due to stresses

18 Axial Skeleton Bones of Skull Cranium + facial Cranium encloses brain tissue Facial hold eyes, facial expressions Joined by sutures immovable joints 1 exception what is it?

19 Cranium Bones Frontal forehead Parietal most of cranium, sagittal suture Temporal around ear, squamous suture Occipital floor and back, lambdoid suture Sphenoid butterfly shaped

20 Facial Bones and Damage Cleft Palate incomplete Maxillae formation

21 Infant vs Adult Skull Infant Face small to cranium Cranium ¼ body length Fibrous regions fontanels allow compression, brain growth Adult Completely ossified Fused at sutures 1/8 body length ms2/diagrams2.html

22 Vertebral Column Axial Support of body Skull to pelvis 26 vertebrae (which type?) connected and reinforced by ligaments Protects spinal cord Before birth 33 vertebrae Separated by fibrocartilage intervertebral discs

23 Vertebral Column Discs and S-shape prevent shock to head and make trunk flexible Primary curvatures thoracic and sacral regions Make C-shape of newborn Secondary curvatures cervical and lumbar Develop after birth Allow to center weight

24 Herniated Discs Drying of discs, weakening of ligaments predisposes older to problem Also caused due to exceptional twisting Pressure from disc on spinal cord or nerves numbness and/or pain

25 Abnormal Spine Curvatures Scoliosis, Kyphosis, Lordosis All are either congenital, result of disease, due to poor posture, or unequal pull of muscles on spine

26 Thoracic Cage Also known as bony thorax Protects organs in thoracic cavity Made up of sternum, ribs, and thoracic vertebrae What kind of bones are these?

27 Ribs 12 pair True Ribs 1st 7 pair Attach to sternum via costal cartilages False Ribs last 5 pair Indirectly or not attached to sternum Floating Ribs last 2 pair Lack sternal attachment Intercostal space filled with intercostal muscle

28 Appendicular Skeleton Shoulder Girdle Consist of 2 bones Clavicle collar bone Scapula shoulder blades

29 Upper Limbs 30 bones Arm Humerus Which type of bone? Forearm Radius, Ulna Hand Carpal (8) wrist Metacarpals (1->5) Phalanges (14)

30 Pelvic Girdle Large and heavy bones Attached to axial skeleton Bearing weight most important function Houses reproductive organs, urinary bladder, part of large intestines

31 Lower Limbs Thigh Femur heaviest, strongest bone in body Leg Tibia, Fibula Foot Tarsals (7) Metatarsals (5) Phalanges (14) Supports weight, level to propel bodies

32 Joints All bones form joint except 1 2 functions hold bone together, mobility Classified 2 ways Functionally amount of movement Synarthroses - immovable Amphiarthroses - slightly Diarthroses freely Where would you find each? Structurally separation of body regions at joint Fibrous - immovable Cartilaginous - both Synovial - freely

33 Joints Cartilaginous bone ends connected by cartilage Intervertebral joints of spine (amphiarthrotic) Epiphyseal plate of growing long bone (synarthrotic) Fibrous boned united by fibrous tissue Sutures of cranium, connective tissue

34 Joints Types of Synovial Joints based on shape Shape determines movement Plane, hinge, pivot, condyloid, saddle, balland-socket Synovial bones joined by cavity filled with synovial fluid All joints of limbs

35 Diseases of the Joints Sprains ligaments, tendons damaged, heal slowly and painful due to low blood supply Arthritis joint inflammation, 100+ diseases, most widespread degenerative disease. Acute bacterial infection, Antibiotics Chronic Osteoarthritis, Rheumatoid, gouty

36 Osteoarthritis % elderly wear and tear Articular cartilage Bone spurs restricted movement

37 Rheumatoid Arthritis (RA) Chronic inflam. Disease 3x women Joints of fingers, wrists, ankles and feet Symmetrical Auto-immune Cartilage destroyed, scar tissue connect bones, ossifies

38 Gouty Arthritis Uric acid accumulates in blood, deposits crystals in joints, Normally affects single joint Mostly men, rarely before

39 The End