Answer

In Jain Dharma, 6 Saṃhanana (संहनन) means the six types of bone-joint structures of the body. They are mainly discussed in relation to the strength of the body and spiritual capacity.

Here is a simple “drawing-style” explanation:

Vajra-Rṣabha-Nārāca Saṃhanana
[Bone]===<>=== [Bone]
   Strongest and most perfect joint
Rṣabha-Nārāca Saṃhanana
[Bone] ==<>== [Bone]
   Very strong joint, but less than the first
Nārāca Saṃhanana
[Bone] --<>-- [Bone]
   Strong joint
Ardha-Nārāca Saṃhanana
[Bone] --<  -- [Bone]
   Half-locked joint
Kīlikā Saṃhanana
[Bone] --|-- [Bone]
   Joint held like by a peg
Sevārta / Asamprāpta-Sṛpāṭikā Saṃhanana
[Bone]   |   [Bone]
   Weakest joint structure

Explanation

The six Saṃhanana are:

• Vajra-Rṣabha-Nārāca Saṃhanana – the strongest body-joint structure.
• Rṣabha-Nārāca Saṃhanana – very strong, but slightly less perfect.
• Nārāca Saṃhanana – strong joint structure.
• Ardha-Nārāca Saṃhanana – half narāca type.
• Kīlikā Saṃhanana – peg-like joining.
• Sevārta / Asamprāpta-Sṛpāṭikā Saṃhanana – weakest type of joining.

Spiritual Understanding

In Jain teachings, Saṃhanana is important because a very strong body structure is traditionally connected with the ability to undertake the highest level of austerity and spiritual effort. The first type, Vajra-Rṣabha-Nārāca Saṃhanana, is considered the best.

Takeaway

The 6 Saṃhanana describe six levels of bodily joint strength, from the strongest and most perfect to the weakest.