Dr. Sama ul Haque

ObjectivesDefine Skeleton.Differentiate between Axial and Appendicular

skeleton.Define bones with their constituents.Enumerate their functions. Define Cartilage.Discuss different types of cartilage with examples.Classify the bones on the following basis.

1. Histological or Microscopically2. Gross Appearance or Macroscopically

Objectives Define Ossification and its types. Describe developing parts of a typical long bone. Give the arterial supply of a Mature long Bone. What are different types of bone break. Define terms used for describing Bony features.

Axial SkeletonThese bones lie around the longitudinal axis of the body. Skull (cranium and facial bones) Vertebral column (vertebrae and discs)Thoracic cage (ribs and sternum)Function: Axial skeleton supports and protects organs of head, neck and thorax.

Appendicular skeletonPectoral or Shoulder girdle (clavicles and scapulae)Upper limbs (arms)Pelvic girdle (Hip bones, sacrum, coccyx)Lower limbs (legs)Function: 1.Voluntary movements2.Protection of delicate Structures

Composition of BonesCollagen: chief organic constituent (protein)Inorganic Calcium Salts: Vitamin D essential for

absorption

A Chemical Analysis of Bone

Cells Osteoblasts: bone building, bone repairing cells in the

periosteum and synthesize new matrix (Osteogenesis)

Osteocytes: osteoblast embedded within the bone matrix (mature bone cells)

Osteoclasts: cells that cause absorption of bone or dissolve bone matrix (Osteolysis)

PeriosteumDense, fibrous membrane covering bone

Contains blood vessels

Essential for bone cell survival and bone formation

Endosteum

Functions of BonesShape Support

Protection=> Skull=> Thoracic cage=> Vertebral Column

Functions of BonesMovement

=> Muscles => Tendons

=> Ligaments

Locomotion:

To provide a lever system against which muscles can pull.

Weight Transmission

Functions of Bones Mineral Storage

=> Calcium => Phosphate

=> Results in maintaining Electrolyte balance

Helps in Respiration

Functions of BonesBlood cell formation

Red Bone Marrow Red gelatinous mass consisting of Haemopoietic tissue

> Ends of long bones > Bodies of vertebrae

> Sternum > Flat bones of skull

CartilageType of Dense connective tissue ( Cells and fibers)

Perichondrium ( Fibro-vasculo-cellular membrane)

Cells = Characterized by Rigid with flexibility and Resilience. Avascular

Nerves and lymphatics are absent

Cells (Chondroblasts and chondrocytes)

Matrix => Connective tissue fibers (Collagen, Elastin)

Types of cartilage: 31.1. Hyaline cartilageHyaline cartilage: flexible and resilient

2.2. Elastic cartilageElastic cartilage: highly bendable

3.3. FibrocartilageFibrocartilage: resists compression and tension

Hyaline Cartilage Hyaline (Glass) Commonest form Bluish white, translucent and homogenous in

appearance with collagen fibers=> Articular cartilage=> Costal cartilage=> Tracheal cartilage

Ossifies to form bone in young age

Elastic Cartilage

Yellow; Elastin fibers More elastic than hyaline Sites

=> Pinna of the ear=> Epiglottis

Never ossifies

Fibro-cartilage White, Opaque with collagen fibers Sites

=> Intervertebral disc=> Intra articular disc

=> Menisci

Ossifies in old age

Classification of bones

Histological or Microscopically

Gross Appearance or Macroscopically

Compact and Spongy Bone

Histological or Microscopically

Compact and Spongy Bone

Classification of Bones According to Shape

Long Bones Short Bones Flat Bones Irregular Bones Sesamoid Bones

Developing parts of a typical long bone

Long Bones

Epiphysis (Spongy): Covered with Hyaline cartilage.

Diaphysis (Compact): Covered with Periosteum. Medullary cavity with yellow and red marrow. Examples:Femur, Tibia, Fibula, Humerus, Ulna, Radius, Clavicle.

Miniature Long Bones

Only one Epiphysis: Examples: Metacarpals Metatarsals Phalanges

Short Bones Cube-shaped Allows flexible movement Spongy bone covered by Compact bone Examples: Carpals & Tarsals,

Flat Bones Flat Plates Protect Vital Organs Examples: Bones of Vault of Skull Ribs Scapula Sternum

Flat bones

Irregular Bones Peculiarly Shaped to provide Support and Protection with Flexibility. Examples: Vertebrae Hip bone Bones of base of Skull.

Sesamoid Bones Periosteum absent. Ossify after birth. Functions:Resist pressureReduce friction Examples: Patella Pisiform Fabella

Ossification OR

Osteogenesis

CLASSIFICATION of BONESAccording to development:According to development:

1. MembranousMembranous = = starts as fibrous membrane,starts as fibrous membrane,calcium gradually deposited until structure calcium gradually deposited until structure becomes ossified becomes ossified intramembranous ossification intramembranous ossification

e.g.: bones of the skull, mandiblee.g.: bones of the skull, mandible

2. Cartilagenous2. Cartilagenous = starts as cartilage, gradually ossified = starts as cartilage, gradually ossifiedenchondral or intracartilagenous ossification.enchondral or intracartilagenous ossification.

e.g.: long bonese.g.: long bones

Developing parts of a typical long bone

The arterial supply of a Mature long Bone

Types of bone breaks

Simple: Skin is not pierced.Compound: Skin is pierced.Complete: Bone is broken in halfGreenstick: Incomplete break on outer arc.Comminuted: Broken into several pieces

Thank you