Asthi Dhatu (अस्थी धातु)

The term 'Asthi' in samskrit refers to a 'Bone'. Thus Asthi dhatu mentioned in Ayurveda is similar to bony tissue in human body. In a literal sense, the word Asthi means that entity which doesn't get destroyed easily and stays longer as compared to all other counterparts. It is well known that even after years of burial is human bodies, the remnant tissue which one can find is bone. Thus bone or asthi is that component which is not easily destroyed naturally. In human beings Asthi dhatu performs the vital function of forming the skeleton, providing stability and shape.

Etymology and derivation

The word Asthi is a combination of two Sanskrit words "as” and “kthin”. They together give the meaning “stability”. It denotes a bone or the kernel of a fruit.

Definition

Asthi is a body component which stays for a longer time (asyate) and which takes part in movements (kshipyate) with muscles. It is also termed as the extract (sara) of the body which remains even after the destruction of all other body components. [Su.Sa.Sharira Sthana 5/21-22]

Fundamental constitution (panchabhautika sanghatana) and properties

Fundamental constitution of asthi dhatu shows predominance of Prithvi mahabhuta.

• The physical properties of "asthi dhatu" are heaviness (guru), roughness (khara), hardness (kathina), bulkiness (sthula), static (sthira), with a definite physical form (murtimanta).

Metabolism and Development

The asthi dhatu is formed from its predecessor adipose tissue (meda dhatu). The nourishing portion of adipose tissue (meda dhatu) and constituents of nutrient fluid (ahara rasa) are transformed into asthi dhatu by action of factors responsible for its metabolism (asthi dhatvagni). Agni mahabhuta and vayu mahabhuta play a major role in the solidification and roughness of asthi by acting upon prithvi mahabhuta components of adipose tissue (meda dhatu).[Cha. Sa. Chikitsa Sthana 15/30]

Porosity in bones are due to actions of vayu and akasha mahabhuta. [Cha. Sa. Chikitsa Sthana 15/30]

Metabolic byproducts and waste products (Upadhatu and mala)

During the process of metabolism and development of asthi dhatu, nails (nakha) are formed as the metabolic byproducts (upadhatu). [Su. Sa. Sutra Sthana 46/529] Sharangadhara considered teeth (danta) only as metabolic byproduct.[Sha. Sa. Purva khanda chapter 5]

Scalp hair (kesha) and body hair(loma) are waste products of metabolism of asthi dhatu. [Cha.Sa. Sutra Sthana 15/18]

Characteristics of best quality or essence (asthisara)

The persons with essence of asthi dhatu have prominent heels (parshni), ankles (gulpha), knee joint (janu), elbows (aratni), collarbones (jatru), chin (chibuka), head (shira), flanks (parshva) and joints and also bones and teeth. Such persons are highly enthusiastic, active, enduring, having strong and firm body as well as longevity.[Cha.Sa. Vimana Sthana 8/107]

Anatomical and physiological structures

The asthi dhatu is present in various forms as below.

Channels for transportation and transformation of asthi dhatu (asthivaha srotas)

The channels originate from predecessor meda dhatu and buttocks (jaghana). [Cha. Sa. Vimana Sthana 5/8] There are various other anatomical structures related to asthi dhatu. These can be included in the system. The structures are as described below.

Functions

The important function of asthi dhatu is providing structure and support to the body. It also nourishes the successor bone marrow tissue (majja dhatu).[Su. Sa. Sutra Sthana 15/5]

Causes of vitiation

The following are causative factors for the vitiation of channels for transport and transformation of asthi dhatu (asthivahasrotasa). [Cha. Sa. Vimana Sthana 5/17]

Dietary causes

• Excessive consumption of food that aggravates vatadosha in body. This includes the dietary items which possess properties like light to digest (laghu), dry(ruksha), cold(sheeta), rough(khara), highly penetrating or subtle (sukshma), mobile(chala).

Lifestyle causes

• Excessive physical exercise
• Excessive jerks to the body or jerky movements
• Excessive pressure on bones.

Signs of decrease

• loss of scalp and body-hair, beard, nails and teeth
• fatigue
• loose joints
• pain in bones
• dryness
• breaking of teeth and nails

[Cha. Sa. Sutra Sthana 17/67], [Su. Sa. Sutra Sthana 15/9]

Signs of increase

• extra tooth and bony growth [Su. Sa. Sutra Sthana 15/14]

Importance in preservation of health and prevention

Bone tissue (asthi dhatu) is considered as the essence of body tissue which remains even after destruction of all other tissues. [Su. Sa. Sharira Sthana 5/21-22]

The enthusiasm, endurance, strength, body structure, firmness, and longevity depend upon quality of asthi dhatu. [Cha. Sa. Vimana Sthana 8/107]