Unit 2: The Skeletal SystemLab 4: Bone Tissues and Articulation

Jessica Radke-Snead, MS, RDBio 241 Anatomy and Physiology

Review

• See assignment for Lecture 1 (faculty website) for review of labs 1-3

• Exams on Wednesday—be sure that you are familiar with lab materials (diagrams, models, slides, etc)

• Please see me if you need help with course material

Structures Observed in Slides of Bone Tissue

• Osteon: concentric rings (lamellae) of calcified matrix surrounding a vertically oriented blood vessel

• Lamellae– Concentric lamellae: layers of matrix concentrically arranged around a

central canal– Interstitial lamellae: older osteons that have been partially removed during

tissue remodeling• Central/Haversian canal: longitudinal channels in bone tissue

through which blood vessels, nerve fibers, and lymphatics pass• Lacuna: small cavity or depression in a tissue such as bone, cartilage

and the erectile tissues• Canaliculi: canals filled with ECF that connect osteons• Volkman’s canals: run perpendicular to central canal to convey blood

vessels to deeper osteons

Structures Observed in Slides of Bone Tissue

• Periosteum: CT that covers all bones– Outer fibrous layer and inner osteogenic layer

(stem cells lay matrix at surface)

• Dense irregular CT

Cells of Bone Tissue

• Osteoblast: bone-forming cell that arises from an osteogenic cell, deposits bone matrix and eventually becomes an osteocyte

• Osteocyte: mature bone cell formed when an osteoblast becomes surrounded by its own matrix and entrapped in a lacuna

• Osteoclast: macrophage of the bone surface that dissoves the matrix and returns minerals to the ECF

Lacuna with osteocyte

Concentric lamellae

Central canal

Interstitial lamellae

Compact Bone

Zones of Growth in Epiphyseal Plate

• Zone of resting cartilage – anchors growth plate to

bone• Zone of proliferating cartilage

– rapid cell division • Zone of hypertrophic cartilage

– cells enlarged & remain in columns

• Zone of calcified cartilage– thin zone, cells mostly dead

since matrix calcified– osteoclasts removing matrix– osteoblasts & capillaries

move in to create bone over calcified cartilage

Hyaline cartilage

Proliferating cartilage

Hypertrophic cartilage

Calcified cartilage

Spongy bone (trabeculae)

Compact bone

Periosteum

Growth at epiphyseal plates

Proliferative Cartilage

Calcified Cartilage

Functional Classification of Joints

• Synarthrosis (fibrous) joints– No joint cavity– Sutures: immovable; bind bones of skull together– Gomphoses: tooth to socket (periodontal ligament

allows movement to sense how hard we bite)– Syndesmoses: tibia and fibula or radius and ulna;

ROM differs greatly among each one but this is most mobile

• Amphiarthrosis (cartilaginous) joints– No joint cavity– Synchondrosis: bones bound by hyaline cartilage;

epiphysis and diaphysis (epiphyseal plate) or first rib to the sternum (costal cartilage)

– Symphyses: bones bound by fibrocartilage; pubic symphysis or intervertebral discs

Functional Classification of Joints

• Diarthrosis (synovial) joints– Have joint cavity– Bones separated by a film of synovial fluid– Most abundant and freely movable joints– Jaw, elbow, hip and knee joints

Functional Classification of Joints

Synovial Joints

Knee Joint

Exercise and Articular Cartilage• Exercise warms synovial fluid:

1. Becomes less viscous and more easily absorbed by the articular cartilage

2. Cartilage swells and provides a more effective cushion against compression

• Cartilage is non-vascular, so repetitive compression is important to its nutrition and waste removal– Compressed fluid and metabolic wastes squeezed out– Weight released cartilage absorbs synovial fluid (oxygen,

nutrients)• Weight-bearing exercise: builds bone mass and

strengthens the muscles that stabilize many joints

Lab Objectives

• Ensure that you complete each section of your lab guide:– Histology Use Unit 2 Lab 4 ppt (faculty website)– Articulations– Tibofemoral joint (including review for knee)– Movements at synovial joints– X Ray films– Anatomy of a long bone– Auditory ossicles

Please be careful with slides and bones. Ask for assistance if needed. Enjoy!