Tubercles are caused by a bacteria / germ called Mycobacterium tuberculosis, The bacteria is contaminated through air, water, liquid ( Unpasteurized milk). Once the bacteria has entered it most likely attaches to the aveoiles in the lung. Your body consists of Macrophages which are Macrophages are leukocytes (white blood cells) which are present in all tissues of the body [ Easy terms macrophage are white blood cells that fight bad things such as bacteria, viruses, pathogenic protozoan, anything foreign or not desirable to the human body. When a Macrophage comes and detects the Mycobacteriam Tuberculosis it eats it away like a pakman just gobbles it up. Unfortunately the Mycobacterium Tuberculosis avoids the Lysosomes which are a unit of you white blood cells that digest and destroy/ consume these unwanted macromolecules/ micromolecules. After replication the Mycobacterium Tuberculosis just breaks out of the Macrophage destroying it or in biological terms lysis the Macrophage which causes an immediate alert to other Macrophage that rush up and all gather up around the Mycobacterium tuberculosis causing TUBERCLES.
It may help if you search for tubercle bacillus, which is what it is more commonly known as. It is the aerobic, non-endospore-forming rod shaped bacterium (Mycobacterium tuberculosis) that causes tuberculosis.
Between the bones you have the Parietal Tubercles (eminences) which is the widest portion of the entire skull. Also........ The Greater Tubercle of the humerus.
A basal tubercle is a fleshy mass of tissue located at the junction of a mushroom and its substrate.