Definitions [1]
Define muscle.
Muscles are long bundles of contractile tissue, which has a fixed end (Origin) and a movable end which pulls some other part.
Key Points
Key Points: Joints and Its Classification
- Joints connect bones and help in body movement.
- They act as points of contact between bones or between bone and cartilage.
- Muscles act on joints like a fulcrum to produce movement.
- Joints are of three types: fibrous, cartilaginous and synovial.
- Fibrous joints → no movement (e.g., skull sutures).
- Cartilaginous joints → limited movement (e.g., between vertebrae).
- Synovial joints → free movement (e.g., ball & socket, hinge, pivot).
Key Points: Axial Skeleton
- The axial skeleton has 80 bones and forms the main axis of the body (head and trunk).
- It includes the skull, vertebral column, ribs and sternum.
- Skull has 22 bones → 8 cranial (protect the brain) and 14 facial (form the face); also includes the hyoid bone and ear ossicles (malleus, incus, stapes).
- The vertebral column has 26 vertebrae and protects the spinal cord; the first vertebra is the atlas.
- The vertebral column is divided into cervical (7), thoracic (12), lumbar (5), sacral (1 fused) and coccygeal (1 fused) regions.
- Ribs are 12 pairs → 7 true ribs, 3 false ribs, and 2 floating ribs.
- The rib cage (ribs + sternum + thoracic vertebrae) protects vital organs like the heart and lungs.
Key Points: Appendicular Skeleton
- The appendicular skeleton includes bones of the limbs and their girdles. Each limb has 30 bones.
- Upper limb - Humerus, Radius, Ulna, 8 Carpals, 5 Metacarpals, 14 Phalanges.
- Lower limb - Femur, Patella (kneecap), Tibia, Fibula, 7 Tarsals, 5 Metatarsals, 14 Phalanges.
- Pectoral girdle - Clavicle + Scapula; glenoid cavity of scapula articulates with humerus → shoulder joint.
- Pelvic girdle - two coxal bones, each formed by fusion of ilium + ischium + pubis; the acetabulum articulates with the femur.
- The two pelvic halves are joined by the pubic symphysis (fibrous cartilage).
