Functional Anatomy of the Skeletal System Flashcards

1
Q

Cartilage

A
  • The fetal precursor tissue in the development of many bones
  • Supports non-skeletal structures (e.g. ear, larynx, tracheobronchial tree)
  • Chondrocytes aggregate in lacunae (openings), forming isogenous groups
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2
Q

Properties of Cartilage

A
  1. Avascular
  2. Permeable (conducts nutrients/water)
  3. Flexible, but weight bearing (resistance to compression)
  4. Elasticity & resiliency
  5. Resistance to shear forces
  6. Slippery (low friction at articular joints)
  7. Poor regenerative capacity
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3
Q

Types of Cartilage

A
  • Differ only in the fiber types*
    1. Hyaline cartilages
    • Provide support, flexibility, & resilience
    • Most abundant type
      1. Elastic cartilages
    • Similar to hyaline, but have elastic fibers
      1. Fibrocartilages
    • Collagen fibers-good tensile strength
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4
Q

Hyaline Cartilages

A
Matrix (amorphous & glassy)
  - hyaluronic acid
  - chondroitin sulfate
  - keratin sulfate
  - H20 (60-70%)
Fibers (*collagenous*)
  - Invisible d/t refractive matrix index

NOTE: May become calcified

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5
Q

Hyaline Cartilage Locations

A
  • Intercostals (connect ribs to the sternum)
  • Wall of trachea & bronchi
  • Articular cartilage of bone
  • Epiphyseal plate
  • Fetal axial skeleton
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6
Q

Fibrocartilage

A
Matrix
  - Hyaluronic acid
  - Chondroitin sulfate
  - Keratin sulfate
  - Water
Fibers
  - *Dense collagenous* bundles
Properties
  - Resistance to compression & shear forces
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7
Q

Fibrocartilage Locations

A
  • Partially moveable joints*
  • Intervertebral discs
  • Pubic symphysis
  • Meniscus of knee joint
  • Attach tendons to bone
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8
Q

Elastic Cartilage

A
Matrix
  - hyaluronic acid
  - chondroitin sulfate
  - keratin sulfate
  - water
Fibers
  - elastic (*elastin*)
Properties
  - resiliency
  - pliability
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9
Q

Elastic Cartilage Locations

A
  • External ear
  • Walls of external auditory canal & eustachian tubes
  • Epiglottis & larynx
  • Bridge of the nose
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10
Q

Growth of Cartilage

A

Appositional Growth:

  • Peripheral* mitosis & differentiation of fibroblasts (upward growth towards the perichondrium)
    • Multiplication & growth
    • Occurs in mature cartilage

Interstitial Growth:
Mitosis of chondrocytes & deposition of new matrix (upward & inward growth)
- Occurs in the stroma
- Occurs in young cartilages

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11
Q

Bone

A

Living, vascular form of connective tissue
- 206 bones in the human skeleton

Functions:

  • support/shape
  • protection
  • movement
  • mineral (Ca, fat, marrow) & growth factor storage
  • blood cell formation
  • triglyceride (fat) storage
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12
Q

Bone Classification: Location

A
2 groups, based on location
- Axial skeleton (brown)
  `skull, vertebral column, ribcage
- Appendicular skeleton (yellow)
  `upper & lower limbs
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13
Q

Bone Classification: Shapes

A
- Long bone--longer than wide
  ` ex. humerus
- Short bones--
  ` cube-shaped (wrist/ankle-talus)
  ` sesamoid bones (in tendons, e.g. patella)
- Flat bones--thin, flat, slightly curved
  ` ex. sternum, skull
- Irregular bones--complicated shapes
  ` ex. vertebra
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14
Q

Bone Classification: Texture

A

Compact bone:

  • Dense
  • Usually limited to the cortices of mature bones (outer surfaces of bone)

Cancellous:

  • Lattice of bone spicules
  • Occurs in the ends of long bones
  • Fills flat & irregular bones
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15
Q

Periosteum

A
  • Outer fibrous layer
  • Inner osteogenic layer
    ` osteoblasts (bone-forming cells)
    ` osteoclasts (bone-destroying cells)
    ` osteogenic cells (stem cells)
  • Nerve fibers, nutrient blood vessels, & lymphatic vessels enter bone via the nutrient foramina
  • Secured to underlying bone by Sharpey’s fibers (perforating fibers)
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16
Q

Endosteum

A
  • Delicate membrane on internal surfaces of bone

- Contains osteoblasts & osteoclasts

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17
Q

Location of Hematopoietic Tissue

A

Hematopoietic Tissue = Red Marrow

  • Trabecular cavities of the heads of the femur & humerus
  • Trabecular cavities of the dipole of flat bones

Red bone marrow of newborn infants:
- Medullary cavities & all spaces in spongy bone

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18
Q

Blood Supply of a Long Bone

A

Diaphysial artery (1 or 2)

  • Enter shaft obliquely through nutrient foramina -> lead to nutrient canals
  • Entrance is characteristically away form the dominant growing epiphysis (e.g. growing end in leg is at knee, enter & point toward hip)

Metaphysial artery

Epiphysial artery

NOTE: epiphyseal & metaphysial arteries join the diaphysial arteries near the epiphysis

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19
Q

Nerve Supply of Bones

A
  • Autonomic & sensory supply
  • Most numerous in the articular extremities
  • Osteoblast possess receptors for neuropeptides found in nerves
    neuropeptide Y calcitonin gene-related peptide
    vasoactive intestinal peptide substance P
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20
Q

Microstructure of Bones

A

Components:

  1. mineralized extracellular matrix
  2. specialized cells
  3. components of the periosteum, endosteum, & marrow
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21
Q

Bone Matrix

A
  • Consists of ground substance w/ numerous collagen fibers
  • 10-20% of mass = water
  • 60-70% of mass = inorganic salts & mineral salts (microcrystalline calcium & phosphate hydroxides -> hydroxyapatite)
  • Proportions vary w/ age, location & metabolic status
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22
Q

Bone Cells

A

Osteogenic (osteoprogenitor) cells
= Stem cells in periosteum & endosteum that give rise to osteoblasts

Osteoblasts
= matrix synthesizing cell responsible for bone growth

Osteocytes
= mature bone cells

Osteoclasts
= cells that break down (resorb) bone matrix

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23
Q

Microstructure of Bone: Compact Bone

A

Haversian system, or osteon = structural unit
- Lamellae
weight-bearing column-like matrix tubes
- Central (Haversian) canal–contains blood vessels & nerves
- Perforating (Volkmann’s) canals
at right angles to the central canal connects blood vessels & nerves of the periosteum & central canal
- Lacunae–small cavities that contain osteocytes
- Canaliculi–hairlike canals connecting lacunae to each other & the central canal

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24
Q

Microstructure: Spongy Bone

A

Trabeculae

  • Align along lines of stress
  • No osteons
  • Contain irregularly arranged lamellae, osteocytes, & canaliculi
  • Capillaries in endosteum supply nutrients
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25
Q

Types of Ossification

A

(1) Intramembranous
- membrane bone develops from fibrous membrane
- forms flat bones (e.g. clavicles & cranial bones)

(2) Endochondral
- cartilage (endochondral) bone forms by replacing hyaline cartilage
- forms most of the rest of the skeleton

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26
Q

Intramembranous Ossification Process

A
  1. Mesenchymal cells cluster & differentiate into osteoblasts -> form ossification center in fibrous connective tissue membranes
  2. Osteoblasts begin secreting osteoid -> calcification within days -> trapped osteoblasts become osteocytes
  3. Accumulating osteoid deposited b/t embryonic blood vessels randomly -> network of trabeculae (= woven bone); vascular mesenchyme condenses on external woven bone -> periosteum
  4. Trabeculae below periosteum thicken & are replaced w/ mature lamellar bone -> compact bone plates; spongy bone (dipole), become red marrow
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27
Q

Endochondral Ossification

A
  • Uses hyaline cartilage models

- Requires breakdown of hyaline cartilage prior to ossification

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28
Q

Endochondral Ossification Process

A
  1. Bone collar forms around hyaline cartilage model
  2. Cartilage in the center of the diaphysis calcifies & develops cavities
  3. Periosteal bud inavades the internal cavities & spongy bone begins forming
  4. Diaphysis elongates & a medullary cavity forms; secondary ossification centers appear in the epiphyses
  5. Epiphyses ossify, then hyaline cartilage remains only in the epiphyseal plates & articular cartilages
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29
Q

Post-natal Bone Growth

A

Interstitial Growth:
- increases length of long bones

Appositional Growth:
- increases thickness & remodeling of all bones by osteoblasts & osteoclasts on bone surfaces

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30
Q

Epiphyseal Functional Zones

A
  1. Proliferation (growth)
    • cartilage cells undergo mitosis
  2. Hypertrophic
    • older cartilage cells enlarge
  3. Calcification
    • matrix becomes calcified
    • cartilage cells die
    • matrix begins deteriorating
  4. Ossification (osteogenic)
    • new bone forms
31
Q

Control of Bone Remodeling

A
  • Hormonal mechanisms that maintain calcium homeostasis in the blood
  • Mechanical & gravitational forces
32
Q

Parathyroid Hormone Control of Blood Ca2+

A

Primarily control of blood Ca2+ levels

Decreased blood Ca2+ levels -> parathyroid glands release of PTH -> PTH stimulates osteoclasts to degrade bone matrix & release Ca2+ -> increased blood Ca2+ levels

33
Q

Calcitonin Control of Blood Ca2+

A

Less control than PTH

Increased blood Ca2+ -> parafollicular cells of thyroid release calcitonin -> osteoblasts deposit calcium salts -> decrease blood Ca2+ levels

34
Q

Leptin Control of Bone Density

A

Influences bone density by inhibiting osteoblasts

35
Q

Blood Supply of a Long Bone

A

Diaphysial artery (1 or 2)

  • Enter shaft obliquely through nutrient foramina -> lead to nutrient canals
  • Entrance is characteristically away form the dominant growing epiphysis

Metaphysial artery

Epiphysial artery

NOTE: epiphyseal & metaphysial arteries join the diaphysial arteries near the epiphysis

36
Q

Blood Supply of a Long Bone

A

Diaphysial artery (1 or 2)

  • Enter shaft obliquely through nutrient foramina -> lead to nutrient canals
  • Entrance is characteristically away form the dominant growing epiphysis

Metaphysial artery

Epiphysial artery

NOTE: epiphyseal & metaphysial arteries join the diaphysial arteries near the epiphysis

37
Q

Nerve Supply of Bones

A
  • Autonomic & sensory supply
  • Most numerous in the articular extremities
  • Osteoblast possess receptors for neuropeptides found in nerves
    neuropeptide Y calcitonin gene-related peptide
    vasoactive intestinal peptide substance P
38
Q

Nerve Supply of Bones

A
  • Autonomic & sensory supply
  • Most numerous in the articular extremities
  • Osteoblast possess receptors for neuropeptides found in nerves
    neuropeptide Y calcitonin gene-related peptide
    vasoactive intestinal peptide substance P
39
Q

Microstructure of Bones

A

Components:

  1. mineralized extracellular matrix
  2. specialized cells
  3. components of the periosteum, endosteum, & marrow
40
Q

Microstructure of Bones

A

Components:

  1. mineralized extracellular matrix
  2. specialized cells
  3. components of the periosteum, endosteum, & marrow
41
Q

Bone Matrix

A
  • Consists of ground substance w/ numerous collagen fibers
  • 10-20% of mass = water
  • 60-70% of mass = inorganic salts & mineral salts (microcrystalline calcium & phosphate hydroxides -> hydroxyapatite)
  • Proportions vary w/ age, location & metabolic status
42
Q

Bone Matrix

A
  • Consists of ground substance w/ numerous collagen fibers
  • 10-20% of mass = water
  • 60-70% of mass = inorganic salts & mineral salts (microcrystalline calcium & phosphate hydroxides -> hydroxyapatite)
  • Proportions vary w/ age, location & metabolic status
43
Q

Bone Cells

A

Osteogenic (osteoprogenitor) cells
= Stem cells in periosteum & endosteum that give rise to osteoblasts

Osteoblasts
= bone forming cells

44
Q

Bone Cells

A

Osteogenic (osteoprogenitor) cells
= Stem cells in periosteum & endosteum that give rise to osteoblasts

Osteoblasts
= matrix synthesizing cell responsible for bone growth

Osteocytes
= mature bone cells

Osteoclasts
= cells that break down (resorb) bone matrix

45
Q

Microstructure of Bone: Compact Bone

A

Haversian system, or osteon = structural unit
- Lamellae
weight-bearing column-like matrix tubes
- Central (Haversian) canal–contains blood vessels & nerves
- Perforating (Volkmann’s) canals
at right angles to the central canal connects blood vessels & nerves of the periosteum & central canal
- Lacunae–small cavities that contain osteocytes
- Canaliculi–hairlike canals connecting lacunae to each other & the central canal

46
Q

Microstructure: Spongy Bone

A

Trabeculae

  • Align along lines of stress
  • No osteons
  • Contain irregularly arranged lamellae, osteocytes, & canaliculi
  • Capillaries in endosteum supply nutrients
47
Q

Types of Ossification

A

(1) Intramembranous
- membrane bone develops from fibrous membrane
- forms flat bones (e.g. clavicles & cranial bones)

(2) Endochondral
- cartilage (endochondral) bone forms by replacing hyaline cartilage
- forms most of the rest of the skeleton

48
Q

Ossification Process

A
  1. Mesenchymal cells cluster & differentiate into osteoblasts -> form ossification center in fibrous connective tissue membranes
  2. Osteoblasts begin secreting osteoid -> calcification within days -> trapped osteoblasts become osteocytes
  3. Accumulating osteoid deposited b/t embryonic blood vessels randomly -> network of trabeculae (= woven bone); vascular mesenchyme condenses on external woven bone -> periosteum
  4. Trabeculae below periosteum thicken & are replaced w/ mature lamellar bone -> compact bone plates; spongy bone (dipole), become red marrow
49
Q

Endochondral Ossification

A
  • Uses hyaline cartilage models

- Requires breakdown of hyaline cartilage prior to ossification

50
Q

Endochondral Ossification Process

A
  1. Bone collar forms around hyaline cartilage model
  2. Cartilage in the center of the diaphysis calcifies & develops cavities
  3. Periosteal bud inavades the internal cavities & spongy bone begins forming
  4. Diaphysis elongates & a medullary cavity forms; secondary ossification centers appear in the epiphyses
  5. Epiphyses ossify, then hyaline cartilage remains only in the epiphyseal plates & articular cartilages
51
Q

Post-natal Bone Growth

A

Interstitial Growth:
- increases length of long bones

Appositional Growth:
- increases thickness & remodeling of all bones by osteoblasts & osteoclasts on bone surfaces

52
Q

Epiphyseal Functional Zones

A
  1. Proliferation (growth)
    • cartilage cells undergo mitosis
  2. Hypertrophic
    • older cartilage cells enlarge
  3. Calcification
    • matrix becomes calcified
    • cartilage cells die
    • matrix begins deteriorating
  4. Ossification (osteogenic)
    • new bone forms
53
Q

Control of Bone Remodeling

A
  • Hormonal mechanisms that maintain calcium homeostasis in the blood
  • Mechanical & gravitational forces
54
Q

Parathyroid Hormone Control of Blood Ca2+

A

Primarily control of blood Ca2+ levels

Decreased blood Ca2+ levels -> parathyroid glands release of PTH -> PTH stimulates osteoclasts to degrade bone matrix & release Ca2+ -> increased blood Ca2+ levels

55
Q

Calcitonin Control of Blood Ca2+

A

Less control than PTH

Increased blood Ca2+ -> parafollicular cells of thyroid release calcitonin -> osteoblasts deposit calcium salts -> decrease blood Ca2+ levels

56
Q

Leptin Control of Bone Density

A

Influences bone density by inhibiting osteoblasts

57
Q

Bone Response to Mechanical Stress

A

Wolff’s Law–bone grows or remodels in response to forces or demands placed upon it

Supporting observations:

  1. R or L handedness -> thicker/stronger bones in one upper limb
  2. Curved bones are thickest where they are most likely to buckle
  3. Trabeculae form along lines of stress
  4. Large, bony projection occur where heavy, active muscles attach
58
Q

Bone Response to Mechanical Stress

A

Wolff’s Law–bone grows or remodels in response to forces or demands placed upon it

Supporting observations:

  1. R or L handedness -> thicker/stronger bones in one upper limb
  2. Curved bones are thickest where they are most likely to buckle
  3. Trabeculae form along lines of stress
  4. Large, bony projection occur where heavy, active muscles attach
59
Q

Joints

A

Region of the skeleton where 2 or more bones meet & articulate

60
Q

Functional Classification of Joints

A

Based on the amount of movement allowed by the joint

  1. Synarthroses–immovable
  2. Amphiarthroses–slightly movable
  3. Diarthroses–freely movable
61
Q

Structural Classification of Joints

A

Based on material binding bones together & whether or not a joint cavity is present

  1. Fibrous
  2. Cartilaginous
  3. Synovial
62
Q

Fibrous Joints

A
  • bones joined by dense fibrous connective tissue
  • no joint cavity
  • most are synarthrotic (immovable)

Types:

  1. Sutures
  2. Syndesmoses
  3. Gomphoses
63
Q

Fibrous Joints: Sutures

A

Joint held together w/ very short, interconnecting fibers, & bone edges interlock

found only in the skull

64
Q

Fibrous Joints: Syndesmosis

A

Joint held together by a ligament
- fibrous tissue can vary in length, but is longer than sutures

*Ex. fibula & tibia connection

65
Q

Fibrous Joints: Gomphosis

A

“Peg in socket”

- *Ex. periodontal ligament

66
Q

Cartilaginous Joint

A
  • bones united by cartilage
  • no joint cavity

Types:

  1. Synchondroses
  2. Symphyses
67
Q

Cartilaginous Joint: Synchondroses

A

A bar or plate of hyaline cartilage that unites the bones

  • Epiphyseal plate (temporary hyaline cartilage joint)
  • Joints b/t sternum (manubrium) & 1st rib
68
Q

Cartilaginous Joint: Symphyses

A

Hyaline cartilage covers the articulating surfaces & is fused to an intervening pad of fibrocartilage
- ex. intervertebral discs & pubic symphysis

69
Q

Synovial Joints

A

Joints w/ maximum amount of movement

  • all ar diarthrotic
  • includes all limb joints & most joints of the body
70
Q

Synovial Joints: Distinguishing Features

A
  1. Articular cartilage–hyaline cartilage
  2. Joint (synovial) cavity–small potential space
  3. Articular (joint) capsule
    Outer fibrous capsule = dense irregular CT Inner synovial membrane = loose CT
  4. Synovial fluid
    Viscous filtrate (plasma + hyaluronic acid) Lubricates & nourishes articular cartilage
71
Q

Types of Synovial Joints

A
  1. Plane (ex. joint b/t intercarpal bones)
  2. Hinge (ex. elbow joint)
  3. Pivot (ex. b/t atlas & axis–C1-2)
  4. Bicondylar (ex. knee)
  5. Ellipsoid (ex. radiocarpal joint)
  6. Saddle (ex. 1st carpometacarpal joint-thumb)
  7. Ball & Socket (ex. shoulder, hip)
72
Q

Bursae

A

= Synovial joint

  • friction-reducing structure
  • flattened, fibrous sacs lined w/ synovial membranes (extension outside joint cavity)
  • contain synovial fluid
  • commonly act as “ball bearings” where ligaments, muscles, skin, tendons, or bones rub together (ex. b/t scapula & humerus)
73
Q

Tendon Sheath

A

= Synovial joint (extension of a synovial membrane outside the joint cavity

  • friction-reducing structure
  • elongated bursa that wraps completely around a tendon