Asthi Dhatu (अस्थी धातु)

The term 'Asthi' (अस्थिः) in samskrit refers to a 'Bone'. Thus Asthi dhatu (अस्थि धातुः) mentioned in Ayurveda is similar to bony tissue in human body. In human beings Asthi dhatu performs the vital function of forming the skeleton, providing stability and shape. 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 of human bodies, the remnant tissue which one can find is bone. Thus bone or asthi is that body component which is not easily destroyed naturally very rapidly. In human beings Asthi dhatu performs the vital function of forming the skeleton, providing stability and shape.

अस्थिधातु विशिष्टलक्षणानि ॥ Characteristic feature of Asthi dhatu

Asthi dhatu is identified by Ayurveda acharyas by its peculiar feature of strength. Acharya Sushruta has beautifully explained the properties, role and importance of Asthi dhatu with example as follows,

अभ्यन्तरगतैः सारैर्यथा तिष्ठन्ति भूरुहाः | अस्थिसारैस्तथा देहा ध्रियन्ते देहिनां ध्रुवम् ॥

तस्माच्चिरविनष्टेषु त्वङ्मांसेषु शरीरिणाम् | अस्थीनि न विनश्यन्ति साराण्येतानि देहिनाम् ॥

मांसान्यत्र निबद्धानि सिराभिः स्नायुभिस्तथा | अस्थीन्यालम्बनं कृत्वा न शीर्यन्ते पतन्ति वा ॥ (Sush. Samh. 5/21-23)

abhyantaragataiḥ sārairyathā tiṣṭhanti bhūruhāḥ | asthisāraistathā dehā dhriyante dehināṁ dhruvam ॥

tasmācciravinaṣṭeṣu tvaṅmāṁseṣu śarīriṇām | asthīni na vinaśyanti sārāṇyetāni dehinām ॥

māṁsānyatra nibaddhāni sirābhiḥ snāyubhistathā | asthīnyālambanaṁ kr̥tvā na śīryante patanti vā ॥ (Sush. Samh. 5/21-23)

Meaning: Physical bodies of the humans are held stable by the strong asthi like the trees are held strong rooted to the ground due to their strong stem (heartwood). Since asthi are like the essence of the body those never decay and get destroyed long after decaying of mansa and twak (Muscular tissue and skin). Various sira (vessels, nerves) and snayu (tendons, ligaments) are attached to asthi and those are held in place because of asthi which themselves never decay or fall.

Thus Asthi dhatu is also termed as the extract (सारः | sara) of the body.

पांचभौतिकत्वम् ॥ Panchabhautika constitution

Asthi dhatu is that tissue which is called as essence or extract of body. It is strong, hard and stable. Therefore it is clear that it has Prithvi mahabhuta (पृथ्वी महाभूतम्) dominance in it. At the same time it is also khara (खरः | dry and rough) in texture. This property of Asthi is developed during its generation from meda dhatu by the action of Teja (तेजः) and Vayu (वायुः) along with Pruthvi (पृथ्वी). Also Asthi is one of the chief sites of vata residence. Thus Along with Pruthvi, Asthi dhatu has dominant vayu and teja mahabhuta as well.

अस्थिधातु उत्पत्तिः॥ Utpatti of Asthi dhatu

The asthi dhatu is formed from its predecessor meda dhatu. When meda dhatu is subjected to the process of micro-transformation (सूक्ष्मपचनम्), one processed part of it is specifically utilized to provide nourishment to the next dhatu in order i.e. Asthi Dhatu (अस्थि धातु). This part is responsible for development and nourishment of asthi dhatu in body. Transformation of this fluid and unctuous form of meda dhatu into solid and tough form of asthi dhatu happens due to action of Pruthvi, Teja and Vayu mahabhutas. In this process, there happens generation of excess dryness in the processed part. Such excess dryness and hardness are the distinguishing features of asthi dhatu from all other dhatus.

Saushiryam (सौषिर्यम् | Porosity) in bones are due to actions of vayu (वायु) and akasha (आकाश) mahabhuta.

अस्थि उपधातु॥ Upadhatu of Asthi

Nakha (नखाः | nails) and Danta (दंताः | teeth) are considered to be the Upadhatus (उपधातु | metabolic byproducts) of Asthi Dhatu. Those develop during the process of metabolism and development of asthi dhatu. Therefore it is observed that those suffering from diseases affecting Asthi dhatu may present with symptoms related to teeth and nails. Changes in the levels of asthi dhatu in body can be easily observed from the overall health of nails and teeth.

अस्थि मलाः॥ Malas of Asthi

During the micro-transformation of asthi dhatu inside body and formation of upadhatus, some entities are generated as waste byproducts and those are called Kesha (Scalp hair) and Loma (body hair). Thus hair on scalp and all over body are believed to be the waste products of metabolism of asthi dhatu and called as malas of asthi.

अस्थिसारता लक्षणानि॥ Characteristics of best quality or essence (asthisara)

Those who have supreme quality of asthi dhatu in a body are identified by some characteristic features. These features are called as asthi-sarata features (अस्थिसारता लक्षणानि). Most of these features are manifested on joints, nails and teeth. Thus one can identify the quality of asthi dhatu by assessing presence or absence of following signs in skin.

पार्ष्णिगुल्फजान्वरत्निजत्रुचिबुकशिरःपर्वस्थूलाः स्थूलास्थिनखदन्ताश्चास्थिसाराः|

ते महोत्साहाः क्रियावन्तः क्लेशसहाः सारस्थिरशरीरा भवन्त्यायुष्मन्तश्च॥ (Char. Samh. 8.107)

pārṣṇigulphajānvaratnijatrucibukaśiraḥparvasthūlāḥ sthūlāsthinakhadantāścāsthisārāḥ|

te mahotsāhāḥ kriyāvantaḥ kleśasahāḥ sārasthiraśarīrā bhavantyāyuṣmantaśca॥ (Char. Samh. 8.107)

Meaning: 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.

अस्थिधातु स्थानानि तथा भेदाः॥ Location and types of asthi dhatu

Asthi dhatu is present everywhere in the body mainly forming the skeleton of the bones. There are five types of Asthi in human body. These 5 types are as below,

Asthi bheda (अस्थिभेदाः Types of Asthi)

	Type	Site
1.	Kapala (कपाल Flat bones)	Knee (Janu), jaghana(pelvic), shoulder(amsa), Cheek(ganda),palate(talu),temples(shankha),skull(shiras)
2.	Ruchaka (रुचक Teeth) ruchaka	Teeth
3.	Taruna (तरुण Cartilages )	Nose(Ghrana), Ear(karna), Neck(griva),orbit of the eye(akshikosha)
4.	Valaya (वलय curved/Annular bones)	Ribs(Parshuka), vertebrae (prushthakasheruka)
5.	Nalaka (नलक Tubular bones)	All other long bones

अस्थिवहस्रोतसम् ॥ Asthivaha Srotas

Channels for transportation and transformation of asthi dhatu are known as asthivaha srotas. Acharya Charaka has mentioned meda dhatu and buttocks (jaghana) as the chief sites of this system.

॥ Other anatomical structures related to Asthi dhatu mentioned in Ayurveda

There are various other anatomical structures related to asthi dhatu. These can be included in the system.

अस्थिजालानि ॥ Asthi Jala

There are four types of network-like structures (जाल | jala) in body including, bone network (अस्थिजालानि | asthijala). There are four such networks formed from each of these types. They are present in wrist and ankle joints and interlinked together.

अस्थिसंघातानि ॥ Asthi sanghata

The places where many bones are present is called confluences. The confluences of bones are fourteen in number. They include ankle (गुल्फ़ | gulpha), knee (जानु | janu), and groin (वंक्षणम् | vankshana) in lower limbs and their counter parts wrist (मणिबंधम् | anibandha), elbow (कूर्परम् | kurpara) and axilla (कक्षा | kaksha) in upper limbs on each side. One is in the lower back (त्रिकम् | trika) and the other on the skull (शिरः | shira).

अस्थिमर्माणि ॥ Asthi Marmas

There are eight vital points formed from bones (अस्थि मर्माणि | asthi marma). Katikataruna (कटिकतरुणम्), Nitamba (नितंब), Ansaphalaka (अंसफलकम्) and Shankha (शंख) are those 4 marmas.

कार्यम्॥ Functions

Asthi dhatu performs the major function of dharana (धारणम् | providing support to the body). The skeleton formed by asthi gives shape, stability and protection to the vital soft organs. The locomotor function of a person is dependent on the health and state of Asthi dhatu. Apart from this it provides nourishment to the succeeding Majja dhatu and indirectly supports its function.

अस्थिधातुदुष्टिहेतवाः॥ Causes of vitiation

Various diet and lifestyle related factors that adversely affect asthi dhatu have been listed by Ayurveda acharyas. They cause imbalance in the levels as well as quality of the asthi dhatu, cause disturbance in the channels of its transport across the body and thus affect its function.

आहारहेतवाः ॥ Dietary causes

• Food items that aggravate Vata dosha (वातल आहारसेवनम्) in body lead to asthi dhatu imbalance in the body. This includes the dietary items which possess properties like laghu (लघु), ruksha (रुक्ष), sheeta (शीत), khara (खर), chala (चल) etc.

विहारहेतवाः ॥ Lifestyle causes

• Excessive physical exercise (अतिव्यायाम)
• Excessive jerks to the body or jerky movements (अतिसंक्षोभात)
• Excessive pressure on bones. (अतिविघट्टनात्)

अस्थिधातु॥ Importance in preservation of health and prevention

Asthi is that dhatu of body which provides framework in the form of skeleton which is responsible for providing shape to body and protection to inner organs. Thus the human body is held and sustained due to asthi. The locomotor activities or voluntary movements of body are possible due to presence of strong and firm asthi. Along with this asthi dhatu is also responsible for overall strength, endurance, firmness and in general for enthusiasm and longevity of body.