Chapter 6,7 & 8Chapter 6,7 & 8

Bones and Skeletal Tissue

Bones and Cartilages of the Bones and Cartilages of the Human BodyHuman Body

Figure 6.1

How are bones classified?How are bones classified?

Axial skeleton – bones of the skull, vertebral column, and rib cage

Appendicular skeleton – bones of the upper and lower limbs, shoulder, and hip

Long bonesLong bones

Long bones – longer than they are wide (e.g., humerus)

Figure 6.2a

Short bonesShort bones

Short bones– Cube-shaped

bones of the wrist and ankle

– Bones that form within tendons (e.g., patella)

Figure 6.2b

Flat bonesFlat bones

Flat bones – thin, flattened, and a bit curved (e.g., sternum, and most skull bones)

Figure 6.2c

Irregular bonesIrregular bones

Irregular bones – bones with complicated shapes (e.g., vertebrae and hip bones)

Figure 6.2d

What are the functions of bones?What are the functions of bones?

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

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

Movement – provide levers for muscles Mineral storage – reservoir for minerals, especially

calcium and phosphorus Blood cell formation – hematopoiesis occurs within

the marrow cavities of bones

What is the Gross Anatomy of What is the Gross Anatomy of Bones?Bones?

Compact bone – dense outer layerSpongy bone – honeycomb of trabeculae

(little beams) filled with red bone marrow

What is the structure of a long What is the structure of a long bone?bone?

Diaphysis– Tubular shaft that forms the axis of long bones– Composed of compact bone that surrounds the

medullary cavity– Yellow bone marrow (fat) is contained in the

medullary cavity

Structure of Long BoneStructure of Long Bone

Epiphyses– Expanded ends of long bones– Exterior is compact bone, and the interior is spongy

bone– Joint surface is covered with articular (hyaline)

cartilage– Epiphyseal line separates the diaphysis from the

epiphyses

Structure of Long BoneStructure of Long Bone

Figure 6.3a,b

What are the bone membranes?What are the bone membranes? Periosteum – double-layered protective membrane

– Outer fibrous layer is dense regular CT– Inner osteogenic layer is composed of osteoblasts and

osteoclasts– Richly supplied with nerve fibers, blood, and lymphatic

vessels, which enter the bone via nutrient foramina– Sharpey’s fibers: secures the underlying bone to the

periosteum. They are tufts of collagen fibers.

Endosteum – delicate membrane covering internal surfaces of bone

Structure of Long BoneStructure of Long Bone

Figure 6.3a, c

What is the structure of short, What is the structure of short, irregular, and flat bones?irregular, and flat bones?

Thin plates of periosteum-covered compact bone on the outside with endosteum-covered spongy bone on the inside

Have no diaphysis or epiphyses

Contain bone marrow between the trabeculae

Figure 6.4

Where is the location of Where is the location of hematopoietic tissue (Red Marrow)?hematopoietic tissue (Red Marrow)?

In infants– Found in the medullary cavity and all areas of

spongy bone In adults

– Found in the middle of flat bones, and the head of the femur and humerus

What is microscopic structure of What is microscopic structure of bone: compact bone?bone: compact bone?

Haversian system, or osteon – the structural unit of compact bone– Lamella – weight-bearing, column-like matrix tubes

composed mainly of collagen– Haversian, or central canal – central channel

containing blood vessels and nerves– Volkmann’s canals – channels lying at right angles

to the central canal, connecting blood and nerve supply of the periosteum to that of the Haversian canal

Microscopic Structure of Bone: Microscopic Structure of Bone: Compact BoneCompact Bone

– Osteocytes – mature bone cells– Lacunae – small cavities in bone that contain

osteocytes– Canaliculi – hairlike canals that connect

lacunae to each other and the central canal

Microscopic Structure of Bone: Microscopic Structure of Bone: Compact BoneCompact Bone

Figure 6.5a, b

What is the chemical What is the chemical composition of bone? (Organic)composition of bone? (Organic)

Osteoblasts – bone-forming cellsOsteocytes – mature bone cellsOsteoclasts – large cells that reabsorb or break

down bone matrix

Chemical Composition of Bone: Chemical Composition of Bone: InorganicInorganic

Hydroxyapatites, or mineral salts– Sixty-five percent of bone by mass– Mainly calcium phosphates– Responsible for bone hardness and its

resistance to compression

What are the types of markings What are the types of markings found on bones?found on bones?

Bulges, depressions, and holes that serve as: – Sites of attachment for muscles, ligaments,

and tendons– Joint surfaces– Conduits for blood vessels and nerves

Tuberosity – rounded projectionCrest – narrow, prominent ridge of boneTrochanter – large, blunt, irregular

surfaceLine – narrow ridge of bone

Bone Markings: Projections – Sites of Bone Markings: Projections – Sites of Muscle and Ligament AttachmentMuscle and Ligament Attachment

Tubercle – small rounded projectionEpicondyle – raised area above a condyleSpine – sharp, slender projectionProcess – any bony prominence

Bone Markings: Projections – Sites of Bone Markings: Projections – Sites of Muscle and Ligament AttachmentMuscle and Ligament Attachment

Head – bony expansion carried on a narrow neck

Facet – smooth, nearly flat articular surface

Condyle – rounded articular projectionRamus – armlike bar of bone

Bone Markings: Projections That Bone Markings: Projections That Help to Form JointsHelp to Form Joints

Bone Markings: Depressions and Bone Markings: Depressions and OpeningsOpenings

Meatus – canal-like passageway Sinus – cavity within a bone Fossa – shallow, basinlike depression Groove – furrow Fissure – narrow, slitlike opening Foramen – round or oval opening through a bone

How do bones develop?How do bones develop?

Osteogenesis and ossification – the process of bone tissue formation, which leads to:– The formation of the bony skeleton in embryos– Bone growth until early adulthood– Bone thickness, remodeling, and repair

Formation of the Bony SkeletonFormation of the Bony Skeleton

Begins at week 8 of embryo developmentIntramembranous ossification – bone

develops from a fibrous membraneEndochondral ossification – bone forms by

replacing hyaline cartilage

Intramembranous ossification

Functional Zones in Long Bone Functional Zones in Long Bone GrowthGrowth

Growth zone – cartilage cells undergo mitosis, pushing the epiphysis away from the diaphysis

Transformation zone – older cells enlarge, the matrix becomes calcified, cartilage cells die, and the matrix begins to deteriorate

Osteogenic zone – new bone formation occurs

Long Bone Growth and Long Bone Growth and RemodelingRemodeling

Growth in length – cartilage continually grows and is replaced by bone as shown

Remodeling – bone is reabsorbed and added by appositional growth as shown

Figure 6.10

Fracture Repair