Hadayaṃ
Heart
Hadayaṃ — the heart, eleventh item of the canonical list. Visuddhimagga VIII.111 describes it as 'inside the chest, in the centre between the two lungs, leaning a little toward the left side'; the heart is given the form of a closed lotus-bud with its mouth turned downward, holding 'a half-handful of blood' that nourishes the entire mind-faculty. Theravāda Abhidhamma additionally treats the hadaya-vatthu (heart-base) as the physical support for the mind-consciousness element — a doctrine elaborated chiefly in the commentaries. The contemplation here is on the heart as a meat-organ, not as the seat of feeling: a fist-sized piece of muscle, full of blood, gripped by sinews. The same visual locus reappears as a positive seat of awareness in the parallel Hesychast and TCM systems — the Theravāda intent is opposite, dispassion rather than communion.
Point 6 of 8 in Theravāda 32 Parts of the Body (Dvattiṃsākāra)
Cross-tradition overlaps
No overlapping points are registered for this point.
Sources
Majjhima Nikāya 10.10 (primary_canonical)
“In this body there are head hairs, body hairs, nails, teeth, skin, flesh, sinews, bones, bone marrow, kidneys, heart, liver, diaphragm, spleen, lungs, large intestines, small intestines, contents of the stomach, feces, bile, phlegm, pus, blood, sweat, fat, tears, grease, saliva, mucus, oil of the joints, and urine.”
MN 10.10 names the heart (hadaya) eleventh in the body-parts enumeration. It is listed as one constituent of the body to be contemplated without the ordinary sentimental or aesthetic projection onto it.
Visuddhimagga VIII.111 (primary_canonical)
“The heart is in the inside of the chest, between the two breasts, in shape resembling a lotus-bud with its mouth turned downward, holding about a half-handful of blood.”