Cyclobenzaprine (sold under the brand name Flexeril, among others) is a medication used for muscle spasms from musculoskeletal conditions of sudden onset. It is not useful in cerebral palsy. It is taken by mouth. Use is not recommended for more than a few weeks.Common side effects include headache, feeling tired, dizziness, and dry mouth. Serious side effects may include an irregular heartbeat. There is no evidence of harm in pregnancy, but it has not been well studied in this population. It should not be used with an MAO inhibitor. How it works is unclear.Cyclobenzaprine was approved for medical use in the United States in 1977. It is available as a generic medication. In 2020, it was the 39th most commonly prescribed medication in the United States, with more than 16 million prescriptions. It was not available in the United Kingdom as of 2012. Medical use
Cyclobenzaprine is used, in conjunction with physical therapy, to treat muscle spasms that occur because of acute musculoskeletal conditions. After sustaining an injury, muscle spasms to stabilize the affected body part occur, which may increase pain to prevent further damage. Cyclobenzaprine is used to treat such muscle spasms associated with acute, painful musculoskeletal conditions. It decreases pain in the first two weeks, peaking in the first few days, but has no proven benefit after two weeks. Since no benefit is proven beyond that, therapy should not be continued long-term. It is the best-studied muscle relaxer.
This kind of mixed germ cell tumor may be known simply as a teratoma with elements of embryonal carcinoma or choriocarcinoma, or simply by ignoring the teratoma component and referring only to its malignant component:  embryonal carcinoma and/or choriocarcinoma. They can present in the anterior mediastinum. Cause
Some investigators suggest that this distribution arises as a consequence of abnormal migration of germ cells during embryogenesis. Others hypothesize a widespread distribution of germ cells to multiple sites during normal embryogenesis, with these cells conveying genetic information or providing regulatory functions at somatic sites.Extragonadal GCTs were thought initially to be isolated metastases from an undetected primary tumor in a gonad, but many germ cell tumors are now known to be  congenital and originate outside the gonads. The most notable of these is sacrococcygeal teratoma, the single most common tumor diagnosed in babies at birth.Of all anterior mediastinal tumors, 15–20% are GCTs of which about 50% are benign teratomas. Ovarian teratomas may be associated with anti-NMDA receptor encephalitis. Location
Despite their name, GCTs occur both within and outside the ovary and testis. They are found in:}

head
inside the cranium — pineal and suprasellar locations are most commonly reported
inside the mouth — a fairly common location for teratoma
neck
mediastinum — account for 1% to 5% of all germ cell neoplasms 
pelvis, particularly sacrococcygeal teratomaIn females, GCTs account for 30% of ovarian tumors, but only 1 to 3% of ovarian cancers in North America.