INTRODUCTION TO THE SKELETAL SYSTEM

Bone Function and Structure

OVERVIEW

Histology of Bone Tissue Bone Function and Structure Bone Growth & Development Joints The Axial Skeleton The Pectoral Girdle The Upper Limbs The Pelvic Girdle The Lower Limbs

BONE FUNCTIONS

FUNCTIONS Support- framework that supports body and

cradles its soft organs

Protection- for delicate organs, heart, lungs, brain

Movement- bones act as levers for muscles

Mineral storage- calcium & phosphate

Blood cell formation- hematopoiesis

BONE CLASSIFICATION

Bones classified by shape: Long - metacarpals, metatarsals, phalanges,

humerus, ulna, radius, tibia, fibula

Short - carpals, tarsals

Flat - rib, scapula, skull, sternum

Irregular - vertebrae, some facial bones

Round (Sesamoid) - patella

BONE STRUCTURE

LONG BONE STRUCTURE Diaphysis- middle

compact bone medullary cavity- contains yellow marrow (fat) lined with endosteum (squamous epithelium

Metaphysis: regions between diaphysis and epiphysis Epiphyseal growth plate: layer of hyaline cartilage that allow

diaphysis to grow in length; ceases to grow between ages 18-21; replaced by bone then becomes epiphyseal line

Epiphysis- ends spongy bone contains red marrow compact bone, articular cartilage

BONE STRUCTURE (CONT.)

LONG BONE STRUCTURE (CONT.) Articular cartilage: thin layer of hyaline cartilage where bone articulates

(joint) with another; reduces friction and absorbs shock

Bone enclosed in periosteum, composed of outer fibrous layer of dense irregular connective tissue and inner osteogenic layer; allows bone growth in thickness; protects bone, assists in fracture repair, bone nourishment and attachment point for ligaments and tendons

Perforating fibers: Sharpey’s fibers, attachment to underlying bone, c/o thick bundles of collagen extend into extracellular matrix of bone

Blood vessels in periosteum

Medullary cavity: hollow cylindrical space with diaphysis that contains fatty yellow marrow in adults

Endosteum: thin membrane that lines the internal surface facing the medullary cavity; made of single layers of cells and connective tissue

BONE STRUCTURE

BONE STRUCTURE

Copyright 2009, John Wiley & Sons, Inc.

BLOOD AND NERVE SUPPLY OF BONE

Bone supplied with blood Periosteal arteries:

with nerves supply periosteum and compact bone

Epiphyseal veins: carry blood away from long bones

Nerves accompany blood vessels that supply bones Periosteum has many

sensory nerves sensitive to tearing or tension

SUMMARY

Histology of Bone Tissue Bone Function and Structure Bone Growth & Development Joints The Axial Skeleton The Pectoral Girdle The Upper Limbs The Pelvic Girdle The Lower Limbs