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© 2012 Pearson Education, Inc.
Concepts and Current Issues
Human BiologyS
ixth
Edi
tion
Michael D. Johnson
Lecture PresentationSuzanne Long
Monroe Community College
Chapter 5
The Skeletal System
© 2012 Pearson Education, Inc.
Skeletal System: Made of Connective Tissue
• The skeletal system is made up of three types of connective tissue– Bone– Ligaments– Cartilage
© 2012 Pearson Education, Inc.
Bones – Functions
• Bones: hard elements of the skeleton
• Five important functions1. Support
2. Protection
3. Movement
4. Blood cell formation
5. Mineral storage• Calcium• Phosphate
© 2012 Pearson Education, Inc.
Bone – Structure
• Bone: hard inorganic matrix of calcium salts & collagen fibers)– Compact bone: forms shaft and ends– Spongy bone: red marrow is found here– Cells: osteoblast (makes new bone matrix),
osteocytes (maintains the bone matrix), osteoclasts (breaks down bone matrix)
– Bone shapes: long, short, flat, irregular
• Periosteum: connective tissue covering the outside of the bone
© 2012 Pearson Education, Inc.
Epiphysis
Diaphysis
Epiphysis
a) A partial cut through a long bone. b) A closer view of a section of bone. Compact bone is a nearly solid structure with central canals for the blood vessels and nerves.
Blood vessels andnerve in central canal
Compact bone
Spongy bone
Spongy bone (spaces contain red bone marrow)
Compact bone
Yellow bone marrow
Blood vessel
Central cavity (contains yellow bone marrow)
Periosteum
d) A single osteocyte in a lacuna. Osteocytes remain in contact with each other by cytoplasmic extensions into the canaliculi between cells.
Osteocyte
Lacuna
Canalicula
Central canal
Osteon
Osteocytes
c) A photograph of an osteon of compact bone showing osteocytes embeded within the solid structure.
Osteon
Osteoblasts
Figure 5.1
© 2012 Pearson Education, Inc. Figure 5.1a
Epiphysis
Diaphysis
Spongy bone (spaces contain red bone marrow)
Compact bone
Yellow bonemarrow
Blood vessel
Periosteum
Central cavity(contains yellow bone marrow)
Epiphysis
a) A partial cut through a long bone.
© 2012 Pearson Education, Inc. Figure 5.1b
Osteon
Spongy bone
Compact bone
Osteoblasts
Blood vessels and nerve in central canal
b) A closer view of a section of bone. Compact bone is a nearly solid structure with central canals for the blood vessels and nerves.
© 2012 Pearson Education, Inc.
Cartilage and Ligaments
• Cartilage– Function: support– Types
• Fibrocartilage (menisci of knee, intervertebral discs)
• Hyaline (most cartilage is of this type)• Elastic cartilage (ears, epiglottis)
• Ligaments– Function: attach bone to bone– Dense fibrous connective tissue
© 2012 Pearson Education, Inc.
Bone Development
• Early fetal development: cartilage model– Formed by chondroblasts (cartilage-forming
cells)
• Later fetal development: osteoblasts replace cartilage with bone
• Childhood: primary and secondary ossification sites formed
• Adolescence: elongation at growth plates
© 2012 Pearson Education, Inc. Figure 5.2
Fetus: First2 months Developing
periosteum
Blood vessel
Fetus: At 2–3 months
Childhood
Adolescence
Cartilage growth plate
Compact bone containing osteocytes
Cartilage growth plate
a) Chondroblasts form hyaline cartilage, creating a rudimentary model of future bone.
b) The periosteum begins to develop and cartilage starts to dissolve. Newly developing blood vessels transport osteoblasts into the area from the periosteum.
c) Osteoblasts secrete osteoid and enzymes, facilitating the deposition of hard hydroxyapatite crystals.
d) The growth plates in long bones move farther apart and osteoblast activity continues just below the periosteum. The bone lengthens and widens.
© 2012 Pearson Education, Inc.
© 2012 Pearson Education, Inc. Figure 5.3
Growth plate
Jointcartilage
Chondroblasts deposit newcartilage at the outer surface
Osteoblastsconvert cartilageto bone at theinner surface
© 2012 Pearson Education, Inc.
© 2012 Pearson Education, Inc.
Bone Growth
© 2012 Pearson Education, Inc.
Hormonal Control of Bone Growth
• Preadolescence – Growth hormone stimulates bone
lengthening
• Early Adolescence– Estrogen and testosterone stimulate bone
lengthening
• Late Adolescence – Estrogen and testosterone cause
replacement of cartilage growth plates with bone
© 2012 Pearson Education, Inc.
Cells Involved in the Development and Maintenance of Bone
• Chondroblasts: cartilage-forming cells
• Osteoblasts: young bone-forming cells
• Osteocytes: mature bone cells
• Osteoclasts: bone-dissolving cells
© 2012 Pearson Education, Inc.
Mature Bone Remodeling and Repair
• Changes in shape, size, strength– Dependent on diet, exercise, age
• Bone cells regulated by hormones– Parathyroid hormone (PTH): removes calcium
from bone– Calcitonin: adds calcium to bone
• Repair: hematoma and callus formation
© 2012 Pearson Education, Inc. Figure 5.4
Bone removed here
New boneadded here
Compressive force
a) The application of force to a slightly bent bone produces a greater compressive force on the inside curvature. Compressive force produces weak electrical currents which stimulate osteoblasts.
(b) Over time, bone is deposited on the inside curvature and removed from the outside curvature.
c) The final result is a bone matched to the compressive force to which it is exposed.
© 2012 Pearson Education, Inc.
Bone Repair
© 2012 Pearson Education, Inc.
Human Skeleton
• 206 bones
• Axial skeleton– Skull, vertebral column, sternum, ribs
• Appendicular skeleton– Pectoral girdle, pelvic girdle, limbs
© 2012 Pearson Education, Inc. Figure 5.5
Axial skeleton
Cranium (skull)MaxillaMandible
Sternum
Vertebrae
Sacrum
Appendicular skeleton
Clavicle
Humerus
UlnaRadiusCarpals
Metacarpals
Phalanges
Coxal bone
PatellaTibiaFibula
TarsalsMetatarsalsPhalanges
Ribs
Scapula
Femur
© 2012 Pearson Education, Inc. Figure 5.6
Temporal bone
Frontal bone
Sphenoid bone
Ethmoid bone
Lacrimal bone
Nasal bone
Zygomatic bone
Maxilla
Mandible
Maxilla
Zygomatic bonePalatine bone
Sphenoid bone
Foramen magnum
Occipital bone
Parietal bone
Occipitalbone
External auditorymeatus
Vomer bone
© 2012 Pearson Education, Inc. Figure 5.7
Cervical vertebrae (7)
Thoracicvertebrae (12)
Lumbar vertebrae(5)
Sacrum(5 fused)
Coccyx (4 fused)
12
34567
123
45
6
7
8
9
10
11
12
1
2
3
4
5
© 2012 Pearson Education, Inc.
Axial Skeleton: Vertebral Column (cont.)
• Vertebral column– Regions: cervical, thoracic, lumbar, sacral,
coccygeal– Intervertebral disks: cushion vertebrae; assist
in movement and flexibility
• Ribs– Twelve pairs– Bottom two pair floating
• Sternum: breastbone– Three bones fused together
© 2012 Pearson Education, Inc. Figure 5.8
Spinal cord
Intervertebraldisk
Main bodiesof vertebrae
b) A herniated disk.
Articulations with another vertebra
Spinal nerve
Articulation with ribs
a) Healthy disks.
Herniated areapressing againsta nerve
© 2012 Pearson Education, Inc. Figure 5.8a
Spinal cord
Articulationswith anothervertebra
Spinal nerve
Articulation with ribs
a) Healthy disks.
Main bodies of vertebrae
Intervertebral disk
© 2012 Pearson Education, Inc. Figure 5.8b
Herniated areapressing againsta nerve
b) A herniated disk.
© 2012 Pearson Education, Inc. Figure 5.9
Sternum (breastbone)
Ribs
Cartilage
Vertebral column
Floating ribs
T11
T12
L1
L2
12
11
C7
T1 1
2
3
4
5
6
7
8910
© 2012 Pearson Education, Inc.
Appendicular Skeleton
• Pectoral girdle: shoulder– Clavicle and scapulas
• Pelvic girdles: hip– Coxal bones, sacrum, pubic symphysis
• Limbs– Arms: humerus, radius, ulna, wrist and hand
bones– Legs: femur, tibia, fibula, ankle and foot bones
© 2012 Pearson Education, Inc. Figure 5.10
Pectoral girdle
Clavicle(collar bone)
Scapula (shoulder blade)
Humerus(upper arm)
Ulna
Forearm
Radius
8 Carpals (wrist)
5 Metacarpals (hand)
14 Phalanges (finger bones)
© 2012 Pearson Education, Inc. Figure 5.11
Coxal bones and sacrum (pelvis)
Femur (upper leg)
Patella (knee cap)
Lower legTibia
Fibula
7 Tarsals (ankle)5 Metatarsals (foot)
14 Phalanges (toe bones)
Pubic symphysis
sacrum
© 2012 Pearson Education, Inc.
Joints (Articulations)
• Classified by degree of movement– Fibrous joint: immovable (e.g., sutures of
the skull)
– Cartilaginous joint: slightly movable, cartilage connection (e.g., pubic symphysis)
– Synovial joint: freely movable
© 2012 Pearson Education, Inc. Figure 5.12
b) A view of the knee with muscles, tendons, and ligaments in their normal position surrounding the intact joint capsule. The combination of ligaments, tendons, and muscles holds the knee tightly together.
Ligaments
Joint capsule
Tendon
Thigh muscles
Patella
Ligaments
a) A cutaway anterior view of the right knee with muscles, tendons, and the joint capsule removed and the bones pulled slightly apart so that the two menisci are visible.
Tendon
Patella
LigamentTibia
Fibula
Femur
Ligament
Meniscus
Hyaline cartilage
Posterior cruciate ligament
Anterior cruciate ligament
Meniscus
© 2012 Pearson Education, Inc. Figure 5.12a
Femur
Ligament
Meniscus
Fibula
Tibia
Tendon
Patella
Ligament
Hyaline cartilage
Posterior cruciate ligamentAnterior cruciate ligamentMeniscus
a) A cutaway anterior view of the right knee with muscles, tendons, and the joint capsule removed and the bones pulled slightly apart so that the two menisci are visible.
© 2012 Pearson Education, Inc. Figure 5.12b
Thighmuscles
Tendon
Joint capsule
Ligaments
Patella
Ligaments
b) A view of the knee with muscles, tendons, and ligaments in their normal position surrounding the intact joint capsule. The combination of ligaments, tendons, and muscles holds the knee tightly together.
© 2012 Pearson Education, Inc.
Synovial Joints
• Joint capsule: synovial membrane
• Synovial membrane secretes synovial fluid as a lubricant
• Hyaline cartilage acts as a cushion
• Types of synovial joints– Hinge joint– Ball and socket joint
• Tendons – join bone to muscle
• Ligaments-join bones to each other
© 2012 Pearson Education, Inc. Figure 5.13
Supination: Rotation of theforearm so palmfaces anteriorly.
d) Supination and pronation.
Pronation:Rotation of theforearm so palmfaces posteriorly
Humerus
Ulna
Radius Radius
Abduction:Movement of a limb away from a body’s midline
Adduction:Movement of a limbtoward the body’smidline
Abduction
AdductionAbduction
Adduction
a) Abduction and adduction.
Adduction
Abduction
Rotation:Movement of a body part around its own axis
Circumduction:Movement of a limbso that it describesa cone
b) Rotation and circumduction.
Flexion:Decreases the angle of a joint
Flexion
Extension
Hyperextension
Flexion Hyperextension:Extension beyondthe anatomicalposition
Extension
Flexion
ExtensionExtension:Increases the angle of a joint
c) Flexion, extension, and hyperextension.
Hyperextension
Imaginary cone off movement
Ulna
© 2012 Pearson Education, Inc. Figure 5.13a
Abduction: Movement of alimb away from a body’s midline
Adduction:Movement of a limbtoward the body’smidline
Abduction
Adduction
Abduction
Abduction
Adduction
Adduction
a) Abduction and adduction.
© 2012 Pearson Education, Inc. Figure 5.13b
Circumduction:Movement of a limbso that it describesa cone
Rotation:Movement of a body part around its own axis
Imaginary cone of movement
b) Rotation and circumduction.
© 2012 Pearson Education, Inc. Figure 5.13c
Flexion:Decreases the angle of a joint
Flexion
Extension
Hyperextension
Flexion
Flexion
Extension
Hyperextension
ExtensionExtension:Increases the angle of a joint
Hyperextension:Extension beyondthe anatomicalposition
c) Flexion, extension, and hyperextension.
© 2012 Pearson Education, Inc. Figure 5.13d
Supination:Rotation of theforearm so palmfaces anteriorly
Pronation:Rotation of theforearm so palmfaces posteriorly
Ulna
Radius
Humerus
Ulna
Radius
d) Supination and pronation.
© 2012 Pearson Education, Inc.
Diseases and Disorders of the Skeletal System
• Sprains: stretched or torn ligaments
• Bursitis and tendinitis: inflammations
• Arthritis: inflammation of joints– Osteoarthritis– Rheumatoid arthritis
• Osteoporosis: excessive bone loss