Slide 0 Copyright © 2005. Elsevier, Inc. All Rights Reserved. Chapter 6 The Skeletal System.

Copyright © 2005. Elsevier, Inc. All Rights Reserved.

Chapter 6Chapter 6

The Skeletal System


Chapter 6Lesson 6.1Chapter 6Lesson 6.1


Functions of BoneFunctions of Bone

• Supports and gives shape to the body• Protects internal organs

• The skull protects the brain; the breastbone and ribs protect the heart and lungs.

• Helps make movements possible• Stores calcium• Hemopoiesis

• the process of blood cell formation is carried on in the red bone marrow.


Types of BonesTypes of Bones

• Long example: humerus (upper arm)

• Short example: carpals (wrist)

• Flat example: frontal (skull)

• Irregular example: vertebrae (spinal cord)


• Structural components Diaphysis or shaft Medullary cavity—hollow area inside

diaphysis containing yellow marrow Epiphyses or ends of the bone—spongy

bone contains red bone marrow

Structure of Long BonesStructure of Long Bones


Longitudinal section of a long bone

Structure of Long Bones (cont’d.)Structure of Long Bones (cont’d.)


Microscopic Structure of Bone and CartilageMicroscopic Structure of Bone and Cartilage

• Bone types Spongy

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

Compact (Dense) Structural units are called osteons or Haversian

systems


Microscopic Structure of Bone and Cartilage (cont’d.)


• Cartilage Cell type called chondrocyte Has the flexibility of firm plastic Matrix is gel-like and lacks blood vessels Has no blood vessels, so nutrients must diffuse

through the matrix to reach cells




• Microscopic structure of bone


Bone Formation and GrowthBone Formation and Growth

• The process of “remodeling” A newborn’s skeleton has many bones that have not

completely ossified Cartilage models replaced by calcified bone matrix

• Osteoblasts form new bone• Osteoclasts resorb bone• As long as the epiphyseal plate remains

between epiphyses and diaphysis, growth continues

• Epiphyseal line marks where two centers of ossification have fused together


Bone Formation and Growth (cont’d.)Bone Formation and Growth (cont’d.)

Endochondral ossification


Chapter 6Lesson 6.2Chapter 6Lesson 6.2


Divisions of SkeletonDivisions of Skeleton

Skeleton: two divisions and their subdivisions• Axial skeleton

Skull Spine Thorax Hyoid bone

• Appendicular skeleton Upper extremities, including shoulder girdle Lower extremities, including hip girdle


Divisions of Skeleton (cont’d.)Divisions of Skeleton (cont’d.)

Axial Skeleton Skull Spine (Vertebral Column)

Consists of a series of separate bones called vertebrae

Sections called: cervical, thoracic, lumbar, sacrum, coccyx

Curves of the spine give strength to support body


Divisions of Skeleton (cont’d.)

• The skull


Divisions of Skeleton (cont’d.)

• The spinal column



Axial Skeleton• Thorax

Formed by: 12 pairs of ribs The sternum (breastbone) Thoracic vertebrae



Bones of the thorax



Appendicular Skeleton• Upper Extremity

Formed by: Scapula (shoulder blade) Clavicle (collarbone)

o Attached by sternoclavicular joint Humerus Radius and ulna Wrist and hands—27 bones in all


Bones of the arm, elbow joint, and forearmDivisions of Skeleton (cont’d.)



Appendicular Skeleton• Lower Extremity

Two coxal (pelvic) bones Femur; longest bone in the body

o Articulates proximally with coxal bone in socket called the acetabulum

Patella (kneecap) Tibia (shinbone) Fibula (slender bone in the lower leg) Phalanges, composed of metatarsals and

tarsals


Bones of the thigh, knee joint, and legDivisions of Skeleton (cont’d.)



Bones of the right foot


Differences Between a Man’s and a Woman’s SkeletonDifferences Between a Man’s and a Woman’s Skeleton

• Size—male skeleton generally larger• Shape of pelvis—male pelvis deep and narrow,

female pelvis broad and shallow• Size of pelvic inlet—female pelvic inlet

generally wider, normally large enough for baby’s head to pass through it

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


Differences Between a Man’s and a Woman’s Skeleton (cont’d.)

• Comparison of the male and female pelvis


Joints (Articulations)Joints (Articulations)

• Kinds of joints Synarthrosis (no movement)

Fibrous connective tissue grows between articulating bones

Example: sutures of skull Amphiarthrosis (slight movement)

Cartilage connects articulating bones Example: symphysis pubis


Joints (Articulations) (cont’d.)Joints (Articulations) (cont’d.)

Diarthrosis (free movement)—most joints belong to this class Structures of freely movable joints—joint capsule

and ligaments hold adjoining bones together but permit movement at joint

Articular cartilage—covers joint ends of bones and absorbs jolts

Synovial membrane—lines joint capsule and secretes lubricating fluid

Joint cavity—space between joint ends of bones


Joints (Articulations) (cont’d.)

• Joints of the Skeleton


Joints (Articulations) (cont’d.)

Types of diarthrotic joints

Slide 0 Copyright © 2005. Elsevier, Inc. All Rights Reserved. Chapter 6 The Skeletal System.

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