Ischium jumping hurdles, basketball, and martial arts. These fractures occur at tubercles (bony projections that lack secondary ossification centers). Avulsion fractures occur where muscles are attached: anterior superior and inferior iliac spines, ischial tuberosities, and ischiopubic rami. A small part of bone with a piece of a tendon or ligament attached is avulsed (torn away). Ischial bursitis (also known as "weaver's bottom") is inflammation of the synovial bursa located between the gluteus maximus muscle and the ischial tuberosity, and is usually caused by prolonged sitting on a hard surface. Adoption of "ischium" into English-language medical literature dates back to c. 1640;
Petrous part of the temporal bone highly degraded, and contaminated by DNA from soil microbes. In 2015 it was found, surprisingly, that the petrous bone has remarkably high preservation of DNA. A 2017 study comparing DNA from different skeletal sites concluded that "The inner part of petrous bones and the cementum layer in teeth roots are currently recognized as the best substrates for (ancient DNA) research...Both substrates display significantly higher endogenous DNA content (average of 16.4% and 40.0% for teeth and petrous bones, respectively) than parietal skull bone (average of 2.2%)." Consequently, petrous bones are now the most widely-used skeletal site for the study of ancient