"In situ" means at the site.
Origin.originOriginorigin
The medical term for something of cardiac origin is "cardiac." This refers to any condition or symptom that originates from the heart.
Psychogenic means of mental origin or causation
Proximal means nearer the point of origin.
The insertion is the end of the muscle. The origin is the beginning.
My favorite is "idiopathic", but "cryptogenic" is also correct.
Etomology
Epidemiology
"Primary" is often used to describe a primary tumor site.
Alopecia areata.
Syncope is the medical term meaning fainting.