OSSEOUS
SYSTEM
PREPARED BY MR. ABHIJIT DAS
HUMAN SKELETON
The human skeleton is divided into two main parts: the axial
skeleton and the appendicular skeleton.
AXIAL SKELETON (80)
The axial skeleton forms the central
axis of the body and includes the following:
1.
Skull:29
o Cranial
Bones (8): Protect the brain.
o Facial
Bones (14): Form the structure of the face.
o
Ear Bones (6): Malleus
(2), Incus (2), Stapes (2)
o Hyoid
bone (1): Supports the tongue.
2.
Vertebral Column:26
o Cervical
Vertebrae: Neck region (7 vertebrae).
o Thoracic
Vertebrae: Upper back, where ribs attach (12 vertebrae).
o Lumbar
Vertebrae: Lower back (5 vertebrae).
o Sacrum:
Five fused vertebrae forming the back part
of the pelvis.
o Coccyx:
Tailbone, usually four fused vertebrae.
3.
Thoracic Cage:25
o Ribs
(24):
Twelve pairs that protect the heart and lungs.
o Sternum
(1):
Breastbone, consisting of the manubrium, body, and xiphoid process.
APPENDICULAR SKELETON (126)
The appendicular skeleton is associated with the limbs and girdles.
1.
Pectoral (Shoulder) Girdle:4
o Clavicle
(2):
Collarbone.
o Scapula
(2):
Shoulder blade.
2.
Upper Limbs:30X2=60
o Humerus
(1):
Upper arm bone.
o Radius
and Ulna (2): Forearm bones.
o Carpals
(8):
Wrist bones.
o Metacarpals
(5):
Palm bones.
o Phalanges
(14):
Finger bones.
3.
Pelvic (Hip) Girdle:2
o Hip
Bones (2): Form the pelvis.
4.
Lower Limbs:30X2=60
o Femur (1):
Thigh bone.
o Patella (1):
Kneecap.
o Tibia
and Fibula (2): Lower leg bones.
o Tarsals (7):
Ankle bones.
o Metatarsals (5):
Foot bones.
o Phalanges (14):
Toe bones.
- Axial
Skeleton: Comprises the skull, vertebral
column, and thoracic cage. It supports and protects the brain, spinal
cord, and thoracic organs.
- Appendicular Skeleton: Includes the pectoral and pelvic girdles and the limbs. It facilitates movement.
JOINTS
Joints are
structures in the body where two or more bones meet,
allowing for movement and providing mechanical support.
Joints are classified into three
types: Fibrous (synarthrosis)
with no movement, Cartilaginous (amphiarthrosis)
with slight movement, and Synovial (diarthrosis)
with free movement.
FIBROUS JOINTS
Ø No movement between the bones.
Ø A
dense fibrous connective tissue is present
within two bones.
Ø Example:
Sutures in the cranium.
CARTILAGINOUS JOINTS
Ø Slight movement between the bones.
Ø A
cartilage is present within two bones.
Ø Example:
Joint between vertebrae.
SYNOVIAL JOINTS
Ø Free movement between the bones.
Ø Synovial fluid is present within the joint,
providing lubrication.
Ø These
joints are classified into six types:
1. Gliding
joint
2. Ball
and socket joint
3. Hinge
joint
4. Pivot
joint
5. Condyloid
joint
6. Saddle
joint
GLIDING
JOINT
· The
joining surfaces are flat.
· No angular movement is allowed.
· Examples:
Intercarpal and intertarsal
joints.
BALL
AND SUCKET JOINT
· The
most movable type of joint in the body.
· Examples:
Shoulder joint, hip
joint.
HINGE
JOINT
· Bones
fit together like a hinge on a door.
· Examples:
Elbow joint, knee
joint, phalanges.
PIVOT
JOINT
· One
bone is inside another bone.
· These
joints allow for rotation.
· Example:
Joint between the atlas and axis (C1 and C2
vertebrae).
CONDYLOID
JOINT
· A
condyle is a rounded projection on a bone.
· In
this joint, a condyle is fitted into a cup-shaped
depression of another bone.
· Example:
Joint between the occipital bone and atlas.
SADDLE
JOINT
· Bones
fit together like a person sitting on a horse.
· Example:
Joint at the base of the thumb (between the carpal and metacarpal of the
thumb).
· [Saddle=A seat attached on the back of a horse]
DISORDERS OF JOINTS
1. Osteoarthritis:
The most common form of arthritis, characterized by the breakdown of cartilage in joints, leading to pain, stiffness,
and reduced mobility.
2. Rheumatoid
Arthritis: An autoimmune disorder
where the immune system attacks the synovium (the
lining of the membranes that surround the joints), causing inflammation, pain,
and joint damage.
3. Gout:
A form of inflammatory arthritis caused by the accumulation
of uric acid crystals in the joint, leading to sudden, severe pain,
redness, and swelling.