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Overview of the Skeleton
Exercise 8 Overview of the Skeleton
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Two Skeletal Divisions
Axial skeleton Bones around the body’s “axis” or center of gravity Skull, vertebrae, thoracic cage Appendicular skeleton Bones of the limbs or “appendages” & how they attach to the axis (scapulae and coxal bones)
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Figure 8.1 The human skeleton.
Cranium Skull Facial bones Bones of pectoral girdle Clavicle Thoracic cage Scapula (ribs and sternum) Sternum Upper limb Rib Humerus Vertebra Vertebral column Radius Ilium Ulna Bones of pelvic girdle Carpals Ischium Pubis Phalanges Metacarpals Femur Patella Lower limb Tibia Fibula Talus Tarsals Metatarsals Phalanges Calcaneus Anterior view Posterior view
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CARTILAGE LOCATIONS Hyaline cartilage Elastic cartilage Fibrocartilage
Most skeletal cartilages Sturdy support with some “give” Costal cartilage (ribs), nose, articular cartilage, larynx, trachea, branches into lungs (bronchi) Elastic cartilage More flexible Tolerates repeated bending External ear, epiglottis Fibrocartilage Very strong Handles heavy compression Intervertebral discs, pubic symphysis, meniscus (knee)
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Figure 8.2 Cartilages in the adult skeleton and body.
Epiglottis Thyroid cartilage Larynx Cartilage in external ear Cartilages in nose Cricoid cartilage Trachea Lung Articular cartilage of a joint Costal cartilage Cartilage in intervertebral disc Respiratory tube cartilages in neck and thorax Bones of skeleton Cartilages Axial skeleton Hyaline cartilages Pubic symphysis Appendicular skeleton Elastic cartilages Fibrocartilages Meniscus (padlike cartilage in knee joint) Articular cartilage of a joint 6
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Types of bones: Texture
Compact bone Looks smooth & homogenous Hard, dense Protective exterior of ALL bones Fig. 6-2
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Types of bones: Texture
Cancellous/ Spongy bone Deep to the compact bone Porous: bars of bone and open spaces Most bones have both types Fig. 6-2
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Figure 8.3b The structure of a long bone (humerus of the arm).
Articular cartilage Compact bone Spongy bone 9
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Types of bones: Shape Long bones Longer than wide
Femur, humerus, radius, ulna, fibula, tibia, … Most of upper & lower extremity bones Fig. 6-1
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Types of bones: Shape Short bones ~cube-shaped
Carpals, tarsals (wrist, ankle bones) Fig. 6-1
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Types of bones: Shape Flat bones
Broad surface for muscle attachment or protection of underlying organs Many cranial bones, ribs, pectoral girdle (shoulders) Fig. 6-1
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Types of bones: Shape Irregular bones Other bones Varied shapes
Vertebrae, some skull bones Fig. 6-1
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Long Bone Anatomy Epiphysis Diaphysis Medullary cavity ends
Shaft (middle) Medullary cavity Marrow cavity, interior of the shaft Fig. 6-2
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Long Bone Anatomy Red bone marrow In adults:
found in porous chambers of spongy bone, in epiphyses In infants: found in medullary cavity Production of WBCs, RBCs, platelets
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Long Bone Anatomy Yellow bone marrow
Contains large amounts of yellow fat In medullary cavity of adults
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Long Bone Anatomy Articular cartilage Fibrous periosteum
Thin hyaline cartilage cap to each epiphysis Facilitates joint movement Fibrous periosteum Dense regular connective tissue (fibrous membrane) Covers surface of bone EXCEPT where there’s articular cartilage Tendon/muscle attachment Periosteum
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Microscopic Bone Structure
Osteon Central canal and all the concentric rings (lamellae) surrounding it Compact bone Spongy bone Osteon (Haversian system) Periosteum
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Central Canal Parallel to long axis of bone Center of osteon
Blood vessels, nerves, lymph vessels Central (Haversian) canal
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Lamella (plural, lamellae)
Rings of matrix of the osteon Around the central canal Circumferential lamellae Lamellae
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Lacuna (plural, lacunae)
Spaces within the matrix, between the lamellae Contain osteocytes Vein Nerve Artery Lamellae Canaliculus Central canal Osteocyte in a lacuna Lacunae
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Osteocytes Mature bone cells Within the lacunae Osteocyte in a lacuna
Vein Nerve Artery Lamellae Canaliculus Osteocyte in a lacuna Central canal Lacunae
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Canaliculus (pl, canaliculi)
Tiny channels connecting lacunae Nutrient diffusion Vein Nerve Artery Lamellae Canaliculus Central canal Osteocyte in a lacuna Lacunae
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Figure 8.4c Microscopic structure of compact bone.
Interstitial lamellae Lacuna (with osteocyte) 25
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Osteocyte vs Chondrocyte
Osteocyte = “bone” “cell” Chondrocyte = “cartilage” “cell” Each type is “housed” in the lacunae of the respective tissue (bone, cartilage)
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Cartilage cells undergo mitosis. 1
Figure 8.5 Growth in length of a long bone occurs at the epiphyseal plate. Resting zone Proliferation zone Cartilage cells undergo mitosis. 1 Hypertrophic zone Older cartilage cells enlarge. 2 Calcified cartilage spicule Calcification zone Matrix calcifies; cartilage cells die; matrix begins deteriorating; blood vessels invade cavity. 3 Osteoblast depositing bone matrix Ossification zone New bone forms. 4 Osseous tissue (bone) covering cartilage spicules 27
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Table 8.1 Bone Markings
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Review Figure 8.1 29
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Review Figure 8.1a 30
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Review Figure 8.1b 31
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Review Figure 8.1c 32
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Review Figure 8.2 33
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