Calcific bursitis refers to calcium deposits within the bursae. The species name refers to the presence of a sac of the corpus bursae. Inflammation of the bursae is called bursitis. Males possess small spicules and small bursae or alae. "Bursae" or "bursas" is its plural form. Muscle, cartilage, nerves, bursae, ligaments and tendons may be damaged from overuse. Some patients have intra-articular bodies resting in stable positions within joint recesses or bursae. The ostium bursae, or genital opening, of the female is angled to the left. There are more than 150 bursae in the human body. Quite often they are associated with synovial pockets or bursae. Phrynophiurida have bursae for gas exchange and excretion. Four considerably smaller bursae are located on the back of the knee. Water flows through the bursae by means of cilia or muscular contraction. Bursae that are infected require further investigation and antibiotic therapy. Many species brood developing larvae in the bursae, effectively giving birth to live young.