Chapter 6 The Skeletal System. Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 2 FUNCTIONS OF THE SKELETAL

Chapter 6Chapter 6The Skeletal SystemThe Skeletal System

Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 2

FUNCTIONS OF THE SKELETAL FUNCTIONS OF THE SKELETAL SYSTEMSYSTEM

Supports and gives shape to the bodySupports and gives shape to the body Protects internal organsProtects internal organs Helps make movements possibleHelps make movements possible Stores calciumStores calcium Hemopoiesis, or blood cell formationHemopoiesis, or blood cell formation


TYPES OF BONESTYPES OF BONES

Four major types, according to overall Four major types, according to overall shape of the boneshape of the bone Long—Example: humerus (upper arm)Long—Example: humerus (upper arm) Short—Example: carpals (wrist)Short—Example: carpals (wrist) Flat—Example: frontal (skull)Flat—Example: frontal (skull) Irregular—Example: vertebrae (spinal cord)Irregular—Example: vertebrae (spinal cord)

Some also recognize a sesamoid (round) Some also recognize a sesamoid (round) bone categorybone category Example: patella (kneecap)Example: patella (kneecap)


STRUCTURE OF LONG BONESSTRUCTURE OF LONG BONES

Structural components (Figure 6-1)Structural components (Figure 6-1) Diaphysis or shaft—hollow tube of hard Diaphysis or shaft—hollow tube of hard

compact bonecompact bone Medullary cavity—hollow area inside diaphysis Medullary cavity—hollow area inside diaphysis

bone that contains yellow marrowbone that contains yellow marrow Epiphyses, or ends of the bone—spongy bone Epiphyses, or ends of the bone—spongy bone

that contains red bone marrowthat contains red bone marrow Articular cartilage—covers epiphyses and Articular cartilage—covers epiphyses and

functions as a cushionfunctions as a cushion Periosteum—strong membrane covering bone Periosteum—strong membrane covering bone

everywhere except at joint surfaceseverywhere except at joint surfaces Endosteum—lining of medullary cavityEndosteum—lining of medullary cavity



MICROSCOPIC STRUCTURE OF BONE MICROSCOPIC STRUCTURE OF BONE AND CARTILAGEAND CARTILAGE

Bone types (Figure 6-2)Bone types (Figure 6-2) SpongySpongy

• Texture results from needlelike threads of bone called Texture results from needlelike threads of bone called trabeculaetrabeculae surrounded by a network of open spaces surrounded by a network of open spaces

• Found in epiphyses of bonesFound in epiphyses of bones

• Spaces contain red bone marrowSpaces contain red bone marrow CompactCompact

• Structural unit is an osteon—calcified matrix arranged in Structural unit is an osteon—calcified matrix arranged in multiple layers or rings called multiple layers or rings called concentric lamellaconcentric lamella

• Composed of osteocytes, lacunae, and canaliculiComposed of osteocytes, lacunae, and canaliculi

• Covered by periosteumCovered by periosteum



MICROSCOPIC STRUCTURE OF BONE MICROSCOPIC STRUCTURE OF BONE AND CARTILAGEAND CARTILAGE

Cartilage (Figure 6-4)Cartilage (Figure 6-4) Cell type called Cell type called chondrocytechondrocyte Matrix is gel-like and lacks blood vesselsMatrix is gel-like and lacks blood vessels


BONE FORMATION AND GROWTH BONE FORMATION AND GROWTH (Figures 6-5 and 6-6)(Figures 6-5 and 6-6)

Early bone development (before birth) Early bone development (before birth) consists of cartilage and fibrous structuresconsists of cartilage and fibrous structures

Cartilage models gradually replaced by Cartilage models gradually replaced by calcified bone matrix—process called calcified bone matrix—process called endochondral ossificationendochondral ossification

Osteoblasts form new bone, and Osteoblasts form new bone, and osteoclasts resorb boneosteoclasts resorb bone



DIVISIONS OF SKELETONDIVISIONS OF SKELETON

Skeleton composed of the following divisions Skeleton composed of the following divisions and their subdivisions:and their subdivisions: Axial skeletonAxial skeleton

SkullSkull Spine (vertebral column)Spine (vertebral column) ThoraxThorax

Appendicular skeletonAppendicular skeleton Upper extremities, including shoulder (pectoral) Upper extremities, including shoulder (pectoral)

girdlegirdle Lower extremities, including hip (pelvic) girdleLower extremities, including hip (pelvic) girdle

Location and description of bones—see Location and description of bones—see Figures 6-7 to 6-17 and Tables 6-2 to 6-6Figures 6-7 to 6-17 and Tables 6-2 to 6-6

















DIFFERENCES BETWEEN A MAN’S AND A DIFFERENCES BETWEEN A MAN’S AND A WOMAN’S SKELETONWOMAN’S SKELETON

Size—male skeleton generally largerSize—male skeleton generally larger Shape of pelvis—male pelvis deep and Shape of pelvis—male pelvis deep and

narrow; female pelvis broad and shallownarrow; female pelvis broad and shallow Size of pelvic inlet—female pelvic inlet Size of pelvic inlet—female pelvic inlet

generally wider, normally large enough for generally wider, normally large enough for baby’s head to pass through it (Figure 6-baby’s head to pass through it (Figure 6-18)18)

Pubic angle—angle between pubic bones Pubic angle—angle between pubic bones of female generally widerof female generally wider


JOINT (ARTICULATIONS)JOINT (ARTICULATIONS)

Every bone except the hyoid (which anchors the tongue) connects to Every bone except the hyoid (which anchors the tongue) connects to at least one other boneat least one other bone Kinds of joints (Figures 6-19 to 6-21)Kinds of joints (Figures 6-19 to 6-21)

Synarthroses (no movement)—fibrous connective tissue grows Synarthroses (no movement)—fibrous connective tissue grows between articulating bones; example: sutures of skullbetween articulating bones; example: sutures of skull

Amphiarthroses (slight movement)—cartilage connects articulating Amphiarthroses (slight movement)—cartilage connects articulating bones; example: symphysis pubisbones; example: symphysis pubis

Diarthroses (free movement)—most joints belong to this classDiarthroses (free movement)—most joints belong to this class• Structures of freely movable joints—joint capsule and ligaments hold Structures of freely movable joints—joint capsule and ligaments hold

adjoining bones together but permit movement at jointadjoining bones together but permit movement at joint

• Articular cartilage—covers joint ends of bones and absorbs jointsArticular cartilage—covers joint ends of bones and absorbs joints

• Synovial membrane—lines joint capsule and secretes lubricating fluidSynovial membrane—lines joint capsule and secretes lubricating fluid

• Joint cavity—space between joint ends of bonesJoint cavity—space between joint ends of bones

Types of freely movable joints—ball-and-socket, hinge, pivot, Types of freely movable joints—ball-and-socket, hinge, pivot, saddle, gliding, and condyloidsaddle, gliding, and condyloid





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Chapter 6 The Skeletal System. Elsevier items and derived items © 2008, 2004 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 2 FUNCTIONS OF THE SKELETAL