Chapter 7 Skeletal System

Functions of Skeletal System: 1. Support 2. Protection Stores inorganic materials Functions of Skeletal System: 1. Support 2. Protection Stores inorganic materials

Classification – bones classified by shape: 1. Long 1. Long Flat 3. Flat Sesamoid 5. Sesamoid

Structure of Long Bone Epiphysis- Epiphyseal disk (line)-growth plate Diaphysis- Medullary cavity-hollow chamber in center Spongy bone- cancellous bone, found mainly in epiphysis Compact bone- Periosteum-tough, vascular covering Endosteum- membrance of bone forming cells Articular cartilage-

Structure of a Long Bone Red marrow- Yellow marrow- stores fats, no blood cell production.

Compact vs. Spongy Bone Perforating(Volkmann’s) canal- Connects central canals Trabeculae- Canaliculi- canals btwn osteocytes Osteocyte-Bone cells Lacunae-

Compact vs. Spongy Bone

Bone Development – 2 Types: 1. Intramembranous ossification (changing cartilage to bone) (ex. - skull) layers of undifferentiated connective tissue appear at sites of future bone osteoblasts become osteocytes (mature bone cells) when completely surrounded by a bony matrix Connective tissue on surface forms the periosteum

Intramembranous Ossification

Intramembranous Ossifiction

2. Endochondral ossification (remainder of skeleton) Hyaline cartilage models form at sites of future bone Cartilage cells degenerate over time osteoblasts become osteocytes when completely surrounded by a bony matrix

Endochondral Ossification

Bone Development In a long bone, hyaline cartilage is replaced by bony tissue in the center of the diaphysis first (primary ossification center) Bone develops from this point towards the end of the bone

Bone Development

Growth of Bones Epiphyseal disk – area of growth; separates epiphysis from diaphysis; 4 layers: 1. Resting cells – 2. Reproducing cells - as they reproduce, they lengthen the bone 1.

Growth of Bones 3. Mature cells – 4. Degenerating cells & osteoblasts depositing bony tissue

Epiphyseal disk Bones thicken through- out life as compact bone is added under peri- osteum Hyaline cartilage on ends remains

Epiphyseal disk 1. Radial growth plate→ 2. Fracture – distal end of radius → Digital growth plate (in fingers) (2 ½ yr. old)→

Fractures Greenstick- Fissuered- inc. longitudinal break Comminuted-complete, fragments bone Transverse- Oblique- complete at angle other than right angle Spiral-

Fracture Repair 4 stages –Blood escapes from blood vessels and from hematoma. –Spongy bone forms near blood vessels, fibrocartilage forms in distant regions (within days to weeks) –Bony callus forms from cartilaginous callus similar to bone formation –Osteoclasts remove excess bone to restore to original

Factors Affecting Bone Growth (Nutrients) DeficiencyEffect Vit D (for Ca absorption) Vit A (for osteoblast & osteoclast activity) Vit C (for collagen synthesis)

Rickets/Osteomalacia

Homeostasis of Bone Tissue

Factors Affecting Bone Growth (Hormones) DeficiencyEffect Pituitary growthPituitary dwarfism hormone(excess – pituitary (stimulates cell divisiongigantism/acro- in the epi. disks)megaly) Thyroid hormonepremature disk (stimulates cartilageossification-growth replacement in disk)stunted

Pituitary dwarfism

Acromegaly Yao Defen is 34 yrs. old & The world’s tallest female at 7ft. 8 in!!

Factors Affecting Bone Growth (Hormones & Exercise) DeficiencyEffect Sex hormonesstimulate ossifi- (cause growth ofcation of disks; long bones; estrogenstop bone length stronger than androgen) Physical stressbone thins & weak- (stimulates bone width;ens; atrophy hypertrophy)

2 divisions of skeleton: 1.Axial – 2. Appendicular – pectoral & pelvic girdles, upper & lower limbs Human Skeleton – composed of 206 bones (extra – sutural)

Axial vs. Appendicular Skeleton

Surface Markings on Bone Surface of bones have various structural features for specific functions Depressions & Openings: Foramen Meatus Sinus

Foramen Opening for b.v., nerves, ligaments (ex.- foramen magnum)

Meatus Tubelike passageway (ex.-external auditory meatus)

Sinus Cavity within a bone (ex.-frontal sinus)

Surface Markings on Bone Processes that Form Joints: Condyle Head Facet

Condyle Rounded process for articulation w/another bone (ex. – mandibular condyle)

Head An enlargement at the end of a bone (ex.- head of femur)

Facet Small, nearly flat surface where 2 bones articulate (ex.-vertebral facet)

Surface Markings on Bone Processes that Connective Tissue Attaches To: Tuberosity Spine Trochanter Crest Process

Tuberosity Knoblike process (ex.-ischial tuberosity)

Spine Thornlike ridge or projection (ex.-spine of scapula)

Trochanter Large process or projection (ex.-trochanter of femur)

Crest Ridgelike projection (ex.-iliac crest)

Process Prominent projection on a bone (ex.-spinous process)

Surface Markings – Misc. Suture - Interlocking lines where bones meet (ex.-coronal suture)