SKELETAL SYSTEM

• Parts of the skeletal system include:

  – Bones (skeleton)

  – Joints

  – Cartilages

  – Ligaments
• The Skeletal System Divided into two divisions:

  1. Axial skeleton (skull, ribs and vertebra)

  2. Appendicular skeleton (pelvis, extremities)
• Functions of Bones

  • Support of the body

  • Protection of soft organs

  • Movement due to attached skeletal

  muscles

  • Storage of minerals and fats

  • Blood cell formation
• The Axial Skeleton is the Upper Part of the Skeleton.

  The Appendicular Skeleton is the Lower Part of the Skeleton.
• The adult human skeleton has 206 bones.
• The human skeleton of a baby has about 300 bones at birth.
• Two basic types of bone tissues are the Compact bone and Spongy bone.
• A type of bone tissue that is characterized as being homogeneous is the Compact bone.
• A type of bone tissue that is characterized as being homogeneous is the Compact bone.
• A type of bone tissue that is small, needle-like pieces of bone, and has many open spaces is the Spongy bone.
• The four classifications of bones are the Long bones, Short Bones, Flat Bones, and Irregular Bones.
• Long bones

  – Typically longer than it is wide

  – Have a shaft with heads at both ends

  – Contain mostly compact bone

  • Examples: Femur, humerus
• Short Bones:

  • Generally cube-shaped
  • Contain mostly spongy bone
  • Examples: Carpals and Tarsals
• Flat Bones

  • Thin and flattened, usually curved
  • Thin layers of compact bone around a layer of spongy bone
  • Examples: Skull, ribs, sternum
• Irregular Bones

  • Irregular in Shape
  • Do not fit into other bone classification categories
  • Examples: Vertebrae and hip
• Diaphysis

  • Shaft
  • Composed of compact bone
  • Located at the middle
• Epiphysis

  • Ends of the bone
  • Composed of mostly spongy bone
• Articular Cartilage

  • Covers the external surface of the epiphysis
  • Made of hyaline cartilage
  • Decreases friction at joint surfaces 
• Medullary cavity

  • Cavity of the shaft
  • Contains yellow marrow (mostly fat) in adults
  • Contains red marrow (for blood cell formation) in infants
• Bone Growth

  • Epiphyseal plates allow for the growth of long bone during childhood

  – New cartilage is continuously formed

  – Older cartilage becomes ossified

  • Cartilage is broken down

  • Bone replaces cartilage
• Bone Fractures

  • A break in a bone

  • Types of bone fractures

  – Closed (simple) fracture – break that does not

  penetrate the skin

  – Open (compound) fracture – broken bone

  penetrates through the skin

  • Bone fractures are treated by reduction

  and immobilization

  – Realignment of the bone
• The six common types of bone fractures are the:

  • Comminuted
  • Compression
  • Depressed
  • Impacted
  • Spiral
  • Greenstick
• Comminuted Fracture

  • Bone breaks into many fragments.
  • Common in the aged, whose bones are more brittle.
• Compression Fracture

  • Bone is crushed
  • Common in porous bones (i.e Osteoporotic Bones)
• Depressed Fracture

  • The broken bone portion is pushed inwards.
  • Typical of skull fracture.
• Impacted Fracture

  • Broken bone ends are forced into each other.
  • Commonly occurs when one attempts to break a fall with outstretched arms.
• Spiral Fracture

  • Ragged break occurs when excessive twisting forces are applied to a bone.
  • Common sports fracture.
• Greenstick Fracture

  • Bone breaks incompletely, much in the way a green twig breaks.
  • Common in children, whose bones are more flexible than those of adults.
• The heart, lungs, and liver are examples of internal organs that are being protected by our ribs.
• The Axial Skeleton

  • Forms the longitudinal part of the body

  • Divided into three parts

  – Skull

  – Vertebral column

  – Bony thorax
• The Skull

  • Two sets of bones

  – Cranium

  – Facial bones

  • Bones are joined by sutures

  • Only the mandible is attached by a freely

  movable joint
• The Hyoid Bone

  • The only bone that does not articulate with another bone

  • Serves as a moveable base for the tongue
• The Vertebral Column

  • vertebrae separated by intervertebral discs

  • The spine has a normal curvature

  • Each vertebrae is given a name according to its location
• Changes in the Human Skeleton

  • In embryos, the skeleton is primarily hyaline cartilage. Much of this cartilage is replaced by bones during development.

  • Cartilage remains in isolated areas

  – Bridge of the nose

  – Parts of ribs

  – Joints
• The Bony Thorax

  • Forms a cage to protect major organs

  • Made up of three parts

  – Sternum

  – Ribs

  – Thoracic vertebrae
• The Pectoral (Shoulder) Girdle

  • Composed of two bones in the shoulder

  – Clavicle – collarbone

  – Scapula – shoulder blade

  • These bones allow the upper limb to have

  exceptionally free movement
• Bones of the Upper Limb

  • The arm is formed by a single bone - Humerus

  • The forearm has two bones – Ulna, Radius

  • The hand

  – Carpals – wrist

  – Metacarpals – palm

  – Phalanges – fingers
• Bones of the Pelvic Girdle

  • Hip bones (Coxal bone)

  • Composed of three pairs of fused bones

  – Ilium

  – Ischium

  – Pubic bone

  • The total weight of the upper body rests on the pelvis

  • Protects several organs

  – Reproductive organs

  – Urinary bladder

  – Part of the large intestine
• Bones of the Lower Limbs

  • The thigh has one bone

  – Femur – thigh bone

  • The leg has two bones

  – Tibia

  – Fibula

  • The Tibia is larger than the Fibula

  • The foot

  – Tarsus – ankle

  – Metatarsals – sole

  – Phalanges – toes
• Arches of the Foot

  • Bones of the foot are arranged to form three strong arches

  – Two longitudinal (Medial Longitudinal Arch and Lateral Longitudinal Arch)

  – One transverse (Transverse Arch)