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Objectives for Musculoskeletal System
1. List the functions of the skeletal system.
2. Name the 3 types of cartilage and given examples of each type of cartilage.
3. Describe the different shapes of bone.
4. Differentiate the bone cell types.
5. Describe the internal bone structures.
6. Compare compact and spongy bone.
7. State the stages of bone growth.
8. Describe the hormonal control effects on bone development.
9. Name the 2 divisions of the skeletal system and list their parts.
10. State the 3 classifications of joint movements.
11. List the 3 different types of joints.
12. Discuss the various skeletal injuries.
13. List 4 different types of fractures.
14. Review the stages of bone healing.
15. Compare compartment syndrome, crush syndrome, and fat embolism.
16. Compare the 3 types of muscles.
17. Discuss the principles of muscle contractions with myosin/actin.
Note: spacing is now 1.5 – don’t add to outline just for you
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Musculoskeletal System- Lecture 2
I. Skeletal System
A. Function
1. Support
2. Leverage
3. Protection
4. Storage
B. Macroscopic
1. Shapes
a. Long
b. Short
c. Irregular
d. Flat
2. Types bone
a. Compact – solid
b. Spongy – network with spaces
3. Periosteium
a. Fibrous outer
b. Cellular inner
4. Endosteum
C. Microscopic Bone
1. Cells
a. Osteogenic
b. Osteoblasts
c. Osteocytes
1) Lacuna – small pockets that contain bone cells
2) Lamellae – narrow sheets of calcified matrix where
lacunae lie circular & parallel to long axis of central
canal
3) Canaliculi – small channels radiate through matrix
4) Arranged in layers
d. Osteoclasts
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2. Microscopic Compact
a. Haversian canal – osteon arranged around canal that has
blood vessels
b. Perforating canals – passageways for linking blood vessels to
central canals
D. Parts
1. Diaphysis
2. Epiphyses
3. Marrow
4. Periosteum
5. Endosteum
E. Compact vs Spongy Bone
1. Spongy Bone (no osteons)
a. Trabeculae
b. Not heavy stress areas
3) Lighter weight
c. Canaliculi communicate with spongy
2. Compact
a. Osteon (Haversian system) = basic functioning unit
b. Perforating canals (canals of Volkmann)
c. Found in high stress areas
d. Heavier weight
F. Bone Growth and Development
1. Ossification
a. Intramembranous ossification
b. Endochondral ossification
1) Stages ossification
a) chondrocytes disintegrate
b) Blood vessels grow edges & convert to
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osteoblasts
c) Shaft encloses bone sheath
d) Blood vessels penetrate at shaft & branch to
epiphyseal ends
e) Blood vessels invade epiphyseal & secondary
ossification
f) Epiphyseal coated in compact bone & internal
spongy
g) Articular surface cartilaginous
h) Epiphyseal plate separates spongy bone ends
from marrow
2) Appositional growth
2. Hormonal control
a. Parathyroid Hormone
b. Calcitonin
c. Vitamin D
d. Vitamin A & C
e. Hormones (growth, thyroid, sex)
f. Calcium
3. Blood supply & innervations
a. Blood supply
b. Nerve supply
4. Bursae
E. Cartilage
1. Characteristics
2. Types
a. Elastic – flexibility (ear)
b. Hyaline – most abundant type; epiphyseal plates; ribs;
respiratory airways, articulating surface moving joint
c. Fibrocartilage – between vertebra discs
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3. Chondrocytes = cartilage cells
E. Skeletal Overview
1. Terminology – bone markings
a. Divisions
1) Axial – supports and protects organs, attachments
a) Skull (differences in child & infant) - 29
(1) Frontal
(2) Parietal
(3) Occipital
(4) Temporal
(5) Sphenoid
(6) Ethmoid
(7) Facial (maxillary, palatine, vomer,
zygomatic, nasal, lacrimal,
inferior nasal conchae, nasal complex,
mandible)
(8) Hyoid
b) Neck
(1) Curves
(a) Primary
(b) Secondary
(2) Anatomy
(a) Body
(b) Pedicles
(c) Transverse processes
(d) Spinous process
(e) Articular Facet
(f) Vertebral arch
(g) Vertebral foramen
(h) Vertebral canal
(i) Intervertebral foramina
(j) Intervertebral disc
(3) Regions
(a) Cervical (7)
[1] Atlas (C1)
[2] Axis (C2)
[3] Odontoid process
(b) Thoracic (12)
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(c) Lumbar (5) – thicker & oval
(d) Sacrum (5 fused into 1)
(e) Coccyx (1)
c) Thorax
(1) Ribs & Sternum
(a) Floating ribs
(b) False & true ribs
(c) Manubrium
(d) Xiphoid process
2) Appendicular Division (limbs, pelvis, pectoral – 126 )
(31 lower limbs & 32 upper)
a) Pectoral – scapulae, clavicles
c) Upper limb
(1) Humerus
(2) Radius & Ulna
(3) Wrist & Hand
d) Pelvic Girdle
(1) Ilium
(2) Pubis
(3) Ischium
(4) Sacroliac joint
(5) Acetabulum
(6) Coccyx
e) Lower Limb
(1) Femur
(2) Tibia ( shinbone – medial larger)
(3) Fibia ( lateral – smaller)
(4) Ankle (tarsus = 7)
(a) Talus
(b) Calcaneus
(c) Navicular
(d) Cuboid
(e) Cuneiform bones (1,2,3)
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(4) Metatarsal & phalanges
2. Articulations/Movement
a. Joints
1) Classification
a) Synarthroses (Immovable)
b) Amphiarthroses (Slightly movable)
c) Diarthroses (Freely movable)
2) Types of Joints
a) Gliding – movement flat surfaces clavicle &
manubrium, adjacent vertebrae,
b) Hinge – angular movement single plane
elbow, ankle, interphalangeal joint
c) Pivot – rotations only - C1 C2
d) Ellipsoidal – movement bones with depression
opposing surface - wrist & radius
e) Saddle – movement where axis & opposing
faces nest together/angular motion,
circumduction not rotation – thumb base
f) Ball & Socket – round head in cup depression
of another bone – hip & shoulder
b. Tendons & Ligaments
1) Tendons
2) Ligaments
c. Form & Function
1) Types
a) Gliding - clavicles
b) Hinge – elbow, knee, ankle, phalageal
c) Pivot – rotation head (axis & atlas)
d) Ellipsoidal - phalanges
e) Saddle – thumb
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f) Ball-and-socket – shoulder & hip
F. Injuries/Trauma
1. Sprains – stretches or tears one or more ligaments in a joint
acute pain at site with inflammation & bruising
2. Strains – overstretch muscle
3. Subluxation
4. Dislocation
5. Fractures (type, location, direction line/position)
a. Types
1)Greenstick
2) Torus
3) Transverse
4) Oblique
5) Spiral
6) Comminuted
7) Segmental
8) Impacted
9) Closed
10) Open
11) Compression
12) Epiphyseal fracture
b. Manifestations
1) Basic bone fracture
2) Hip fractures
3) Facial
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c. Bone Healing (reduction = restoration/fix open/closed)
1) Stages
a) Hematoma (1-2 days)
b) External callus & internal callus
c) Spongy bone bridge
f) Remodeling (reabsorption)
2) Healing time
a) Children (4-6 weeks)
b) Adolescent (6-8 weeks)
c) Adults (8-10 weeks)
3) Impaired healing
a) Age
b) Diseases
c) Medications
d) Circulatory problems
e) Coagulation problems
f) Poor nutrition
4) Complications
a) Fracture blisters
b) Compartment syndrome (6 P’s)
PAIN, PARESTHESIA, PARALYSIS,
Pallor, Presure, Progression
(1) Causes
(2) Treatment
(a) Primary survey
(b) Measure pressures
(c) Fasciotomies
(d) Fluid resusciatation
c) Crush Syndrome
(1) Entrapment
(2) Rhabdomyolysis
potassium, lactic acid, phosphate,
(3) Reperfusion
(a) Superoxide radicals
(4) Post extrication = problems
(5) Complications
(a) Hyperkalemia
(b) Hypocalcemia
(c) Hyperphosphatemia
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(d) Metabolic acidosis
(e) Hypothermia
(f) Acute renal failure
(6) Treatment
(a) Aggressive fluid resuscitation
(b) Pain control
(c) Treat metabolic disorders
hyperkalemia/hypocalcemia
c) Fat Embolism (long bone)
(1) Hallmark signs = Respiratory Distress,
Decreasing LOC, Petechiae
d) Osteomyelitis – almost impossible to heal
usually remove bone
G. Other Bone Complications
1. Osteopenia
2. Osteoporosis
3. Rickets
4. Paget Disease
5. Rheumatic (Arthritis, Lupus, Sclerosis)
6. Arthritis
7. Gout
8. Scoliosis
II. Muscles (Skeletal, Cardiac, Smooth) = excitability, contractility, extensibility,
elasticity – (700 muscles)
A. Striated vs Smooth
1. Cardiac & Skeletal= striated
2. Actin & myosin filaments give striped appearance
3. Skeletal
a. Most abundant (40-45% body weight)
b. Voluntary- somatic innervation
c. Works with tendons
d. Moves bones
e. Multinucleated
f. Myosin & Actin filaments arranged in groups
4. Cardiac a. Found only in heart
b. Smaller in size
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c. Single nucleus
d. Interconnected at intercalated discs (special gaps)
e. Involuntary control (autonomic)
5. Smooth – can undergo mitotic activity (involuntary muscles)
a. Found hollow tubes (ureters), iris, wall of blood vessels, wall
hollow organs (stomach)
b. Structure
1) Spindle shaped & smaller
2) Central located Z band
3) Bundles of filaments are parallel not crisscrossed
4) Actin attached to dense bodies
5) Arranged in sheets/bundles
c. Contraction
1) Sarcoplasmic reticulum less developed
2) No transverse tubules
3) Relies on Ca entrance across membrane
4) Does not have troponin but calmodulin
5) Calcium-calmodulin complex acts with myosin/actin
B. Functions
1. Produce movement
2. Maintain posture and position
3. Support soft tissue
4. Guard entrances and exits
5. Attaches to bones
C. Muscle structure (Striated muscles)
1. Macroanatomy
a. Epimysium – covering
b. Fascicles – smaller bundles
c. Perimysium – cover fascicles
d. Muscle Fibers
e. Endomysium – connective tissue surrounding fibers
2. Microanatomy
a. Cytoplasm (sarcoplasms)
1) Sarcolemma – cell membrane
2) Myofibrils (parallel bundles actin & myosin)
a) Thin – actin
b) Thick- myosin
3) Sarcomere – structural & functional units
(inside myofibril and repeating units)
a) Z lines
b) M lines
c) A bands
d) I bands
4)Sarcoplasmic Reticulum (like smooth ER)
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5) Terminal Cisternae- high Ca ions – transport Ca
into cisternae by muscle= contractions
a) Sacs to store Ca
b) Contraction occur with release Ca
6) Transverse tubules (T tubules) – opening across
Surface sarcolemma; run perpendicular to fiber
b. Myofibrils & myofilaments (Sarcomere = whole unit)
1) Myofibril – cylinder
a) Contraction of muscles due shortening
(1) Mitochondria & glycogen granules- ATP
2) Myofilaments – protein = myosin & actin
a) Actin= thin
b) Myosin= thick
c) Tropomyosin
d) Troponin
e) Calcium
3. Muscle Contraction (All or None factor)
a. Contraction= sliding of myosin over actin (shortening fiber)
1) Crossbridges of myosin head with actin filaments
2) Must have ATP for energy
3) Swivel in fixed arc
4) Each unit does own movement then sends it on to next
b. Myosin structure
1) Thin tail and globular head (binding site for actin)
2) Active site for ATP breakdown
3) Binds also ATP breaks link with actin
4) Structure head one end; tails other end opposite
c. Thin filament = actin
1) Globular protein lined in 2 rows coil around long helical
strand
2) Tropomyosin = provides site attachment for globular
heads of myosin
3) Troponin – noncontractile covers tropomyosin binding
site to prevent cross-bridging of myosin & actin
d. Event
1) Action potential leads to Ca release from sarcoplasmic
reticulum
2) Ca binds to troponin & uncovers tropomyosin binding
site
3) Uncovered tropomyosin head allows myosin attached
4) Myosin attached allows cross-bridging with actin =
Contraction
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5) Energy from ATP breaks cross-bridging = stop
6) Ca pumped back into sarcoplasmic reticulum
7) Prolonged immobility leads to muscle breakdown
releases myoglobin, muscle enzymes, electrolytes
myoglobin concentrates in urine = kidney failure
8) Rigor Mortis – inability of myosin to release from actin
no ATP available
NOTE: Creatine kinase (CK)- enzyme in muscle and brain; CK-MB specific for
cardiac muscle & increases= myocardial damage; Troponin protein not normally
present and if is indicates heart muscle damage (seen in labs 3-6 hours)
D. Control of Contraction
1. Communication
a. Neuromuscular junction- site of communication nervous &
muscle system
1) Synaptic knob- bulb with cytoplasm filled with
Mitochondria and molecules of acetylcholine (Ach)
a) Acetylcholine = neurotransmitter
2) Synaptic cleft
3) Motor end plate- receptor for Ach
4) Acetylcholinesterase- enzyme breaks down Ach
b. Action Potential (electrical stimuli)
1) Stimuli released down axon leads to Ach release
2) Ach crosses synaptic cleft binds with Ach receptor
3) Sudden rush of Na ions-produces action potential
4) Action potential spreads over muscle fiber leads to Ca
release
E. Muscle Mechanics
1. Periods
a. Latent period
b. Contraction phase (tension)
c. Relaxation
2. Neuron Control
a. Motor Unit (finer movement motor neuron only operate 2-3
muscles)
b. Tone
1) Muscle tone- resting tension
2) Atrophy no motor neuron stimulation= small & weak
c. Isotonic vs Isometric contraction
1) Isotonic- tension rises until relaxation occurs
2) Isometric- tension rises but no change in length
3. Anaerobic contractions= lactic acid build up- recovery conversion
back to pyruvic acid which is used for ATP
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4. White meat vs Dark meat
a. White= more fat around = breast
b. Dark = more blood vessels = leg
5. Terminology
a. Tension
b. Resistance
c. Compression
d. Frequency
1) Twitch
6. Energy
a. ATP
b. Creatine phosphokinase (CPK)
c. Aerobic metabolism
d. Anaerobic
e. Muscle fatigue
7. Muscle performance
a. Fast fibers
b. Slow fibers
F. Names of Muscles (axial & appendicular) - review on own
G. Aging Factors
1. Smaller in size
2. Less elastic
3. Less tolerant
4. Less able to recover
H. Disorders
1. Fibromyalgia – inflammation
2. Myasthenia – autoimmune disease weakness & fatigue
3. Hernia
4. Strain
5. Spasms
6. Neuromuscular blockade (drugs)
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