LOCOMOTION AND MOVEMENT

 

• Appendicular skeleton: 126 bones
  • Fore limb – 60 ( 30 in each)
    • Humerus – 1 bone
    • Radius and ulna – 2 bones
    • Carpals (wrist bones) – 8 in numbers.
    • Metacarpals (palm bones) – 5 in numbers
    • Phalanges (digits) – 14 in number.
    
    
  • Hind limb – 60 (30 in each)
    • Femur (thigh bone- the longest and heaviest bone) – 1 number.
    • Tibia and fibula – 2 bones.
    • Tarsals (ankle bone) – 7 bones.
    • Metatarsals – 5 in numbers.
    • Phalanges (digits) – 14 in numbers.
    • Patella (knee cap) – 1 bone.
    
    
  • Pectoral girdles: consists of 2 bones each = 4 bones.
    • Helps in articulation of fore limb with the axial skeleton.
    • Each pectoral girdle made of two half.
    • Each half made of two bone the clavicle and scapula.
    • Scapula is a large triangular flat bone situated in the dorsal part of the thorax between the second and the seventh ribs.
    • Scapula is characterized by spine with acromion process.
    • Below acromion, is glenoid cavity to which head of humerus fits.
    • Clavicle is commonly called collar bone.
    
    
  • Pelvic girdle: 2 bones.
    • Pelvic girdle consists of two coxal bones.
    • Each coxal bone is formed of fusion of three bones
      • Ilium
      • Ischium
      • Pubis.
      
      
    • At the point of fusion of the three bones is a cavity called acetabulum to which the femur articulates.
    • Two halves of the pelvic girdle meets ventrally to form the pubic symphysis containing fibrous cartilage.

JOINTS :

• Joints are the points of contact between bones, or between bones and cartilages.
• Force generated by the muscles is used to carry out movement through joints, where joint acts as a fulcrum.
• Joints are classified into three types:
  • Fibrous joint
  • Cartilaginous joint
  • Synovial joint

Fibrous joints :

• Do not allow any movements.
• Found in flat bones which fuse end-to-end with the help of dense fibrous connective tissues in the form of sutures.
• These types of joints are found in the bones of cranium.

Cartilaginous joints :

• The bones involved are joined together with the help of cartilages.
• Permits very little movements.
• Joint between the vertebral column are the example of such joints.

Synovial joints :

• Characterized by the presence of a fluid filled synovial cavity between the articulating surfaces of the two bones.
• Allow free movement between two bones.
• The fluid inside it called synovial fluid covered by synovial membrane.
  • Ball and socket joint - between humerus and pectoral girdle
  • Hinge joint – knee joint
  • Pivot joint – between atlas and axis.
  • Gliding joint – between carpals.
  • Saddle joint – between carpals and metacarpals of thumb.

DISORDERS OF MUSCULAR AND SKELETAL SYSTEM :

Myasthenia gravis :

• It is an auto-immuno disorder.
• Affects the neuromuscular junction leads to fatigue.
• Caused weakening and paralysis of skeletal muscle.

Muscular dystrophy : Progressive degeneration of skeletal muscle mostly due to genetic disorder.

Tetany: rapid spasms (wild contractions) in muscle due to low Ca++ in body fluid.

Arthritis : inflammation of joints.

Osteoporosis : age related disorder characterized by decreased bone mass and increased chances of fractures. Decrease levels of oestrogen are a common cause.

Gout : inflammation of joints due to accumulation of uric acid crystals.

CBSE Biology (Chapter Wise) Class XI ( By Mr. Hare Krushna Giri ) 
Email Id : harekrushnagiri@yahoo.com