Twacha is one of the Indriyadhisthana which completely covers Meda, Shonita and all other Dhatu of the body and spreads all over the body. It is considered as the seat of Sparshanendriya as well as one among the main seat of Vata.
Formation of Tvacha:
According to Acharya Charaka, Tvacha is the Upadhatu of Mamsa, so ultimately Tvacha is formed by Mamsa and also it is a Matrujabhava because it is coming through ovum.
According to Acharya Sushruta, Tvacha has developed after the fertilization of the ovum. At the time of fertilization, Shukra, Shonita and Jeeva become united for the formation of Garbha. Its growth is rapid and nourished by Tridosha. Seven layers of the Tvacha are formed and deposited on this rapid transforming product in the same manner as the layers of cream are formed and precipitated on the surface of the boiling milk.
According to Acharya Vagbhata, Tvacha is formed by the Paka of Rakta Dhatu by its Dhatvagni. After the Paka of Rakta by its Dhatvagni, Rakta become dry in the form of skin like the deposition of cream on the surface of the boiling milk. Thus, Tvacha is also called as “Rakta Santanika”.
Panchabhautikatva of Tvacha:
All the organs are made of Panchamahabhuta. So Tvacha should have a Panchabhautika constitution.
Tvacha has been considered as the Upadhatu of Mamsa Dhatu that shows it is stable which is an innate quality of Prithvi.
Due to the presence of Jala Mahabhuta, Tvacha is Snigdha.
Tvacha has the specific Varna and lusture.
Tvacha is the Adhisthana of Sparshanendirya.
Presence of some micro channels of Sweda forming organs.
Layers of Tvacha:
There are some different opinions regarding the number of the layers of the Tvacha among the ancient Acharya.
Acharya Charaka has mentioned six layers of skin but only first two layers are named and rest of the four layers are counted as producing diseases.
Udakadhara: Udaka means watery substance or lymph
Ashrukadhara: Blood capillaries
3rd: anifestation of Sidhma and Kilasa
4th: Manifestation of Dadru and Kushta
5th: Manifestation of Alaji and Vidradhi
6th: Manifestation of Arunshi. If this layer is injured then the individual gets trembled and enters in to the darkness.
Acharya Sushruta has mentioned seven layers of Tvacha along with their specific name, thickness and prone origination of the disease.
1 Avabhasini: Sidhma, Padmini, Kantaka
2 Lohita: Tilkalaka, Vyanga, Nyachha
3 Shweta: Charmadala, Ajagallika, Mashaka
4 Tamra: Kilasa, Kushta
5 Vedini: Kushta, Visarpa
6 Rohini: Granthi, Apachi, Arbuda, Sleepada, Galaganda.
7 Mamsadhara: Bhagandara, Vidradhi, Arsha
Acharya Vagbhata has also described seven layers of skin but names are not mentioned. Commenting on Acharya Vagbhata, commentator Arundatta and Hemadri have named them according to nomenclature given by Sushruta.
Sharngadhara has also mentioned seven layers of the skin along with the probable onset of disease. The name of first six layers is as same as Sushruta but 7th layer is called Sthula, which is the site of Vidradhi.
Gangadhara has clarified the difference in opinion between Charaka and Sushruta on the basis of the different opinions regarding the layers of Tvacha. He explains that the third layer of Charaka is to be counted as two parts – superficial and deep. The superficial part is considered as third layer (Shweta) while the deep part as a fourth layer (Tamra) as mentioned by Sushruta.
TVACHA KRIYA SHAREERA
Tvacha and Dosha:
Skin has been considered as Sparshanendriya Adhishtana64 which is function of Vata.
Bhrajaka Pitta is located on the Tvacha for giving luster and colour.
Snigdhata, Slakshnata, Mruduta, Sthirata, Sheetata, Prasannata, Snigdha Varnata are the attributed to Kapha. For Ropana Karma (self-healing process), Kapha is responsible factor.
Tvacha and Dhatu:
Rasa: In the context of Twak Sara Purusha Lakshana it has been also said as
Rasa Sara. 1st layer of Tvacha, the Udakadhara also contains Rasa (lymph). So, it can be easily understood that there is a relation between Tvacha and Rasa.
Rakta: Among its functions of Rakta, Varna Prasadhana (impart colour to the skin) and Mamsa Pushti have been mentioned.
Mamsa: Twak is Upadhatu of Mamsa.
Tvacha and Mala:
Sweda: It is Mala of Meda which is excreted by Tvacha. Sweda maintains the
lustre and humidity of skin.
Nakha and Loma are Mala of Asthi Dhatu and Twakgata Sneha is the Mala
of Majja Dhatu.