Bones

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Bones
Dr. Sama ul Haque
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Objectives

• Define 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 Microscopically
• 2. Gross Appearance or Macroscopically

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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.
  

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Axial Skeleton

• These 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.

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Appendicular skeleton

• Pectoral or Shoulder girdle
• (clavicles and scapulae)
• Upper limbs (arms)
• Pelvic girdle
• (Hip bones, sacrum, coccyx)
• Lower limbs (legs)
• Function
• Voluntary movements
• Protection of delicate Structures

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Composition of Bones

• Collagen chief organic constituent (protein)
• Inorganic Calcium Salts Vitamin D essential for
  absorption

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A Chemical Analysis of Bone
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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)

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Periosteum

• Dense, fibrous membrane covering bone
• Contains blood vessels
• Essential for bone cell survival and bone
  formation
• Endosteum

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Functions of Bones

• Shape
• Support
• Protection
• gt Skull
• gt Thoracic cage
• gt Vertebral Column

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Functions of Bones

• Movement
• gt Muscles
• gt Tendons
• gt Ligaments
• Locomotion
• To provide a lever system against which muscles
  can pull.
• Weight Transmission

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Functions of Bones

• Mineral Storage
• gt Calcium
• gt Phosphate
• gt Results in maintaining Electrolyte balance
• Helps in Respiration

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Functions of Bones

• Blood cell formation
• Red Bone Marrow
• ? Red gelatinous mass consisting of
• Haemopoietic tissue
• gt Ends of long bones
• gt Bodies of vertebrae
• gt Sternum
• gt Flat bones of skull

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Cartilage

• Type 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 gt Connective tissue fibers (Collagen,
  Elastin)

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Types of cartilage 3

• Hyaline cartilage flexible and resilient
• Elastic cartilage highly bendable
• Fibrocartilage resists compression and tension

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Hyaline Cartilage

• Hyaline (Glass)
• Commonest form
• Bluish white, translucent and homogenous in
  
  appearance with collagen
  fibers
• gt Articular cartilage
• gt Costal cartilage
• gt Tracheal cartilage
• ? Ossifies to form bone in young age

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Elastic Cartilage

• Yellow Elastin fibers
• More elastic than hyaline
• Sites
• gt Pinna of the ear
• gt Epiglottis
• ? Never ossifies

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Fibro-cartilage

• White, Opaque with collagen fibers
• Sites
• gt Intervertebral disc
• gt Intra articular disc
• gt Menisci
• ? Ossifies in old age

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Classification of bones

• Histological or Microscopically
• Gross Appearance or Macroscopically

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Compact and Spongy Bone
Histological or Microscopically
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Compact and Spongy Bone
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Classification of Bones According to Shape

• Long Bones
• Short Bones
• Flat Bones
• Irregular Bones
• Sesamoid Bones

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Developing parts of a typical long bone
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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.

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Miniature Long Bones

• Only one
• Epiphysis
• Examples
• Metacarpals
• Metatarsals
• Phalanges

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Short Bones

• Cube-shaped
• Allows flexible
• movement
• Spongy bone
• covered by
• Compact bone
• Examples
• Carpals Tarsals,

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Flat Bones

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

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Flat bones
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Irregular Bones

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

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Sesamoid Bones

• Periosteum absent.
• Ossify after birth.
• Functions
• Resist pressure
• Reduce friction
• Examples
• Patella
• Pisiform
• Fabella

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• Ossification
• OR
• Osteogenesis

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CLASSIFICATION of BONESAccording to
development

• 1. Membranous starts as fibrous membrane,
• calcium gradually deposited until structure
  
• becomes ossified ? intramembranous
  ossification
• e.g. bones of the skull, mandible
• 2. Cartilagenous starts as cartilage,
  gradually ossified
• enchondral or intracartilagenous
  ossification.
• e.g. long bones

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Developing parts of a typical long bone
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The arterial supply of a Mature long Bone
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Types of bone breaks Simple
Skin is not pierced. Compound Skin is
pierced. Complete Bone is broken in
half Greenstick Incomplete break on outer
arc. Comminuted Broken into several pieces
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• Thank you