Lecture Notes: Skeletal System, Page 1 of 10

(Slide 1) Lecture Notes: Skeletal System I. (Slide 2) Tissues of the Skeletal System

A) Connective Tissue: tissues composed of extracellular matrix and specialized cells

1) bone (a) compact (b) spongy

2) cartilage (a) hyaline cartilage (b) fibrocartilage

3) fibrous (a) dense regular

B) (Slide 3) Compact Bone: Structural Organization

1) osteons: tubular/cylindrical units 2) osteocytes

3) lamella

(a) matrix: calcium salts and collagen (b) concentric rings (c) lacuna: spaces in matrix for cells

4) central canal: BV, nerves (heals quickly) 5) canaliculi

(a) channels between osteocytes (b) nutrient/waste exchange

C) (Slide 4) Spongy Bone: Structural organization

1) trabeculae (a) irregularly arranged plates (b) light but strong

2) red bone marrow (a) fills spaces (b) site of blood cell formation

D) (Slide 5) Cartilage: not as strong as bone but flexible due to jelly-like matrix of collagen and

elastin fibers

1) General Structure: (a) chondrocytes (cartilage cells) (b) lacuna (c) avascular: lacks blood supply so slow to heal

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2) (Slide 6) Hyaline Cartilage

(a) characteristics: firm, somewhat flexible (b) locations:

(1) – (2) –

(3) –

(4) –

3) Fibrocartilage

(a) characteristics: stronger than hyaline—wide rows of collagen

(b) locations:

E) (Slide 7) Fibrous Connective Tissue

1) structure: collagen and Fibroblasts 2) examples:

(a) ligaments: (b) tendons:

II. (Slide 8) Bones of the Skeleton

A) General Functions 1) support body (erect) 2) protect soft body parts (brain, heart, lungs) 3) produces blood cells (red bone marrow) 4) stores minerals and fats (calcium, phosphorus, adipose/yellow bone marrow) 5) permits flexible body movements

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B) (Slide 9) Categorized/Classified by Shape

1) long (a) mostly compact bone (b) most bones of limbs

2) short (a) ‘cube’ (b) mostly spongy bone (c) –

3) irregular 4) Flat

(a) thin/curved (b) _

C) (Slide 10) Long Bones

1) epiphysis (a) ends (b) covered with articular cartilage (c) spongy interior with red bone marrow

2) diaphysis (a) shaft (b) medullary cavity (space) (c) filled with yellow bone marrow

3) periosteum (membrane) (a) covers shaft

4) endosteum (membrane) (a) lines medullary cavity

D) (Slide 11) Skeleton (206) bones

1) Divisions

(a) Axial Skeleton (1) skull (2) hyoid (3) vertebral column (4) rib cage or bony thorax

(b) appendicular skeleton (1) pectoral girdle and arm (2) pelvic girdle and leg

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E) (Slide 12) Axial Skeleton 1) Skull: cranium and facial bones

(a) cranium: (1) function: protect brain and site of

muscle attachment (2) Structure/Bones:

(a) frontal (b) parietal (c) occipital (d) foramen magnum (e) temporal bone (f) sphenoid (g) ethmoid

(3) sinuses (spaces) (a) decrease weight (b) resonance in voice

(b) (Slide 13)Fetal Skull

(1) fontanels:

(a) allow skull bones to move slightly during birth (b) allow growth (c) replaced by bone/sutures

(2) ossification centers:

(a) conical projections (b) –

(c) (Slide 14) Facial Bones

(1) mandible-movable (2) maxillae (3) palatine (4) zygomatic (5) lacrimal (6) nasal

(d) Hyoid (1) anchors tongue (2) site muscle attachment

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2) (Slide 15) Vertebral Column (33 vertebrae)

(a) General functions: (1) supports head and trunk (2) protects spinal cord and roots of spinal nerves (3) site for muscle attachment (4) curves help prevent shock/flexible/center body weight on lower limbs

(b) types: (1) – (2) – (3) – (4) – (5) – (6)

(c) (Slide 16) Cervical Vertebrae (C1-C7)

(1) atlas C-1 ‘yes’ (2) Axis C-2 ‘no’ (3) small and light weight

(d) thoracic vertebrae (T1-T12) (1) costals (ribs) attach (2) bony thorax (3) protection (4) breathing movements

(e) Lumbar vertebrae (L1-L5) (1) lower/small of back (2) largest/block-like—receives most of body weight

(f) (Slide 17) Sacral vertebrae or sacrum (S1-S5) (1) fused (2) axial skeleton (3) contributes to bony pelvis (4) foramina allow passageways for spinal nerves

(g) coccyx (3-5) (1) fused (2) ‘tailbone’

(h) (Slide 18) intervertebral disks (1) structure (2) function:

(a) prevent vertical grinding (b) absorb shock (c) some movement/flexibility

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3) (Slide 19) Bony Thorax (a) components:

(1) – (2) – (3) – (4) –

(a) manubrium (b) body of sternum (c) xiphoid process

(b) function: (1) protection (2) –

(c) (Slide 20) Costals (1) male versus female (2) true ribs-7 pairs attached directly (3) false ribs-indirect/not attached (4) floating ribs

F) (Slide 21) Appendicular Skeleton

1) Pectoral Girdle and Arm

(a) Pectoral girdle

(1) components (a) – (b) –

(2) light weight (3) exceptional movement (4) disadvantage: easily dislocated

(b) (Slide 22) Arm (1) humerus (brachium) (2) radius

(a) lateral (b) antebrachium

(3) ulna (a) medial (b) antebrachium

(4) carpals 8 short bones (5) metacarpals 5 palma bones (6) phalanges

(a) digits (b) fingers: proximale, middle, distal (c) pollux: proximal, distal

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2) (Slide 23) Pelvic Girdle and Leg

(a) Pelvic Girdle (1) components:

(a) – (b) – (c) large and heavy

(2) function: (a) articulates with femur (b) protects reproductive/urinary organs (c) holds upper body weight

(3) (Slide 24) Coxal Bone (a) ileum (b) ischium (c) pubis (d) acetabulum (socket)

(4) leg

(a) femur 1. largest/strongest 2. ‘break hip’ femur neck

(b) tibia 1. medial malleolus

(c) fibula 1. lateral malleolus

(d) patella (e) (Slide 25) tarsals

1. 7 short bones 2. calcaneus

(f) metatarsals 1. instep 2. sole

(g) phalanges 1. digits 2. proximal, middle, distal 3. hallux: proximal, distal

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III. (Slide 26) Bone Growth & Repair

A) Bone Cells 1) osteoblasts

(a) bone cells—builders (b) secreting matrix (c) _

2) osteocytes: (a) mature bone cells (b) –

3) osteoclasts (a) bone cells—degraders/breakdown (b) contribute to bone growth/repair (c) hormonal controlled (d) _

B) (Slide 27) Ossification: bone formation

1) intramembranous ossification (a) bone that develops between sheets of fibrous connective tissue (b) example:

coronal, sagittal, lambdoid sutures

2) (Slide 28) Endochondral ossification (a) ‘within cartilage’ (b) – (c) embryonic skeleton

3) (Slide 29) Epiphyseal (growth) plates

(a) band of cartilage that continues to grow (b) cartilage replaced by bone (c) _ (d) subject to hormonal control

4) (Slide 30) Remodeling: adults—bone constantly being formed/broken down

(a) dynamic (b) increase/decrease blood calcium levels (c) osteoblasts/osteoclasts balanced activity important—osteoporosis (d) _ (e) _ (f) entire skeleton replaced 4X over lifetime

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C) (Slide 31) Steps in Bone Repair (Fracture)

1) hematoma formation (a) 6-8 hours (b) blood clot fills space (c) decreased blood supply/cells die

2) fibrocartilaginous callus (a) approximately 3 weeks (b) fibroblasts connect bone with fibrocartilage (c) new blood vessels form (d) phagocytes active

3) (Slide 32) bony callus (a) 3-4 months (b) osteoblasts build spongy bone (c) trabeculae connect bones

4) remodeling (a) osteoblasts build periphery/compact bone (b) osteoclasts form medullary cavity (c) reshape bone (dependent on stress)

IV. Articulations

A) Articulations: 1) – 2) hold bones together 3) give skeleton its rigid mobility

B) types: categorized by structure/movements 1) fibrous joints 2) cartilaginous joints 3) synovial joints

C) Fibrous Joints 1) structure: fibrous CT unite irregular edges (interlock) 2) function

(a) _ (b) _

3) example: hold cranial bones together (a) sutures formed from intramembranous ossification (b) coronal, sagittal, lambdoid sutures

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D) Cartilaginous Joints

1) structure: cartilage connects bones 2) function: 3) example:

(a) intervertebral discs: fibrocartilage (b) pubic symphysis: fibrocartilage (c) costal cartilages: hyaline cartilage (d) epiphyseal plate: hyaline

E) Synovial Joints

1) function: freely movable 2) structure:

(a) 2 bones separated by a cavity (b) hyaline protects epiphysis from grinding (c) fibrous CT and ligaments form capsule (d) lined with synovial membrane (e) synovial fluid lubricates/cushions during

movements