The fundamental medical treatise, the rGyud-bZhi, is comprised of four sections, usually known as the Four Tantras: The Root Tantra, The Explanatory Tantra, The Oral Instruction Tantra & The Last/Subsequent Tantra.
The complete text encompasses 5900 verses which are grouped into 156 chapters.
The following is a short description of the contents of this treatise, which lists the different topics discussed in Tibetan medicine and illustrates the lucid and systematic presentation of the instructions.
The first Tantra, the Root Tantra, is comprised of six chapters giving a brief outline of the whole text and comparing the medical system with a tree. There are 3 roots sprout into 9 stems, 47 branches and bearing 224 leaves. The nine stems represent the nine sections of medical science, the branches stand for general information and the leaves illustrate the details.
The second Tantra, the Explanatory Tantra, encompasses 31 chapters and is teaches about the life cycle (conception, childbirth, functioning of the three humours and signs of death), causes, conditions and classification of the diseases. It specifies the properties of medicinal ingredients and explains in detail of diet, behaviour and the rules for maintaining health, etc. It also contains a code which the physicians should up-hold in conducting his profession.
The third Tantra, the Oral Tradition Tantra, consists of 92 chapters which mainly teach the 101 disorders of the three humours indicating their causes, conditions, symptoms and methods of treatments and therapies.
The fourth tantra, the Last Tantra, is comprised of 27 chapters, which deal with diagnosis (such as urine analysis and pulse reading), pacifying medicinal ingredients and their preparations (pills, powders, syrups, medicinal butters, etc.), evacuative medications (purgatives and emetics) and treatments such as (moxibustion, golden-needle therapy, cupping, massage etc).