Human Skeletal System

Study Notes

The skeletal system consists of 206 bones and a few cartilages, divided into axial and appendicular skeleton.
The axial skeleton includes 80 bones along the main axis of the body.

The skull is composed of 22 bones, including cranial and facial bones.
Cranial bones protect the brain, while facial bones form the front part of the skull.
The hyoid bone is present at the base of the buccal cavity.
The middle ear contains three tiny bones called ear ossicles.
The skull articulates with the vertebral column through occipital condyles.
The vertebral column is made up of 26 vertebrae, divided into cervical, thoracic, lumbar, sacral, and coccygeal regions.
The vertebral column protects the spinal cord, supports the head, and serves as the attachment point for the ribs and back muscles.

The sternum is a flat bone on the ventral midline of the thorax.
There are 12 pairs of ribs, with the first seven pairs being true ribs, attached to the thoracic vertebrae and sternum.

Each limb is made up of 30 bones.
The hand (forelimb) bones include the humerus, radius, ulna, carpals, metacarpals, and phalanges.
The leg (hind limb) bones include the femur, tibia, fibula, tarsals, metatarsals, and phalanges.
The knee is covered by the patella.
The pectoral girdle articulates the upper limbs with the axial skeleton and consists of the clavicle and scapula.
The pelvic girdle articulates the lower limbs and is formed by the fusion of the ilium, ischium, and pubis bones.

Joints are points of contact between bones or bones and cartilage.
Joints can be fibrous, cartilaginous, or synovial.
Fibrous joints do not allow movement, while cartilaginous joints permit limited movement.
Synovial joints have a fluid-filled cavity, allowing considerable movement.
Examples of synovial joints include ball and socket, hinge, pivot, gliding, and saddle joints.

Myasthenia gravis is an autoimmune disorder affecting the neuromuscular junction.
Muscular dystrophy is a degenerative disorder.
Tetany is rapid spasms in muscles due to low calcium levels.
Arthritis is inflammation of joints.
Osteoporosis is a disorder characterized by decreased bone mass.
Gout is inflammation of joints due to uric acid crystal accumulation.