Chapter 6Bones and

Skeletal TissuesPart A

Skeletal Cartilages, Classification of Bones, and

Functions of Bones

Without BonesWe would look

like Slugs

Skeletal Cartilage

s

Skeletal Cartilages• Cartilage tissue consists

primarily of water–Accounts for its resilience (ability to spring back to its original shape after being compressed)

• Contains no blood vessels or nerves

• Surrounded by the perichondrium

Perichondrium• Surrounds skeletal cartilage • Made from dense irregular

connective tissue• Resists outward expansion

when cartilage is compressed• Contains blood vessels from

which nutrients diffuse through matrix to reach cartilage cells–This limits cartilage thickness

Skeletal Cartilages• Three types of Skeletal Cartilages–Hyaline–Elastic–Fibrocartilage

• All contain chondrocyte cells and an extracellular matrix of ground substance and fibers

Hyaline Cartilage

• Looks like frosted glass when freshly exposed

• Provides support, flexibility, and resilience

• Is the most abundant skeletal cartilage

• Contains fine collagen fibers

Hyaline Cartilage• Is present in these cartilages:

–Articular – covers the ends of long bones

–Costal – connects the ribs to the sternum

–Respiratory – makes up the larynx and reinforces air passages

–Nasal – supports the nose

Hyaline Cartilage in Blue

Figure 6.1

Elastic Cartilage• Similar to

hyaline cartilage but contains more elastic fibers–Better able to stand repeated bending

Elastic Cartilage• Found in the

external ear and the epiglottis –Epiglottis is the flap that covers the opening of the larynx when we swallow

Elastic Cartilage in Green

Figure 6.1

Fibrocartilage• Highly

compressible with great tensile strength

• Contains thick collagen fibers

Fibrocartilage• Found in sites

subjected to both heavy pressure and stretch–menisci of the knee

–intervertebral discs

Fibrocartilage in Red

Figure 6.1

Growth of Cartilage• Cartilage grows in two ways• 1. Appositional – Growth from

outside–cells in the perichondrium secrete matrix against the external face of existing cartilage

Growth of Cartilage• Cartilage grows in two ways• 2. Interstitial – Growth from

inside–lacunae-bound chondrocytes inside the cartilage divide and secrete new matrix, expanding the cartilage from within

Growth of Cartilage• Typically cartilage growth ends

during adolescence (same time as skeleton)

• Calcification of cartilage occurs under certain conditions–During normal bone growth in youth

–During old age

Growth of Cartilage

• Calcified cartilage is not bone• Calcification is when calcium

salts are deposited in the matrix and harden

Classification of

Bones

Classification of Bones• Two basic types

of bone tissue–Compact Bone

•Homogeneous

•Dense - looks smooth and solid to the naked eye

Classification of Bones• Two basic types

of bone tissue–Spongy Bone

•Honey comb of small needle-like pieces of bone

•Many open spaces

Classification of Bones• The 206 named bones of the

human skeleton are divided into two groups:–Axial skeleton–Appendicular skeleton

Axial Skeleton

• Includes bones of the skull, vertebral column, and rib cage

• Most involved in protecting, supporting, or carrying other body parts

Axial Skeleton in dark tan

Figure 6.1

Appendicular Skeleton• Includes bones of the upper and

lower limbs, shoulder, and hip

Appendicular Skeleton• Locomotion

–Helps us move–Helps us manipulate our environment

Appendicular Skeletons in yellow

Figure 6.1

Classification of Bonesby Shape

• Long Bones• Short bones• Flat bones• Irregular bones

Long Bones• Longer than

they are wide

• Has a shaft with heads at both ends

• Contains mostly compact bone

Figure 6.2a

Long Bones• Examples of

long bones–Humerus–Femur–The bones in your fingers

Figure 6.2a

Short Bones• Contains mostly

spongy bone • Cube shaped

–Wrist and ankles•Carpals – Tarsals

Short Bones• Sesamoid

bones–shaped like a sesame seed

–Special bones that form within tendons•Example: Patella

Flat Bones• Thin &

Flattened• Usually

curved• Thin layers

of compact bone around a layer of spongy bone Figure 6.2c

Flat Bones• Examples

–Sternum–Ribs–Scapulae–most skull bones

Figure 6.2c

Irregular Bones• Irregular

shape• Bones with

complicated shapes or ones that do not fit into other categories

Figure 6.2d

Irregular Bones• Examples

–vertebrae –hip bones

Figure 6.2d

Functions of

Bones

Function of Bones• Support• Protection • Movement • Mineral storage• Blood cell formation

Function of Bones• Support of the body

–form the framework that supports the body and cradles soft organs

• Protection of soft organs–provide a protective case for the brain, spinal cord, and vital organs

• Movement due to attached skeletal muscles–provide levers for muscles

Function of Bones

• Storage of minerals and fats–reservoir for minerals, especially calcium and phosphorus

• Blood cell formation–hematopoiesis occurs within the marrow cavities of bones

Study Guide

• You should be able to complete pages 120-122 of the study guide for the study guide check.

QuizNext time! If you

snooze, you lose.