“in between the shoulders”, i.e. the chest Ja.v.173 = Ja.vi.171 (phrase lohitakkho vihat’ antaraṃso).

B.Sk. antarâṃsa; antara + aṃsa

whose back is flat (i.e. not hollow) between the shoulder-blades (one of the 32 characteristics of a mahapurisa)

…cp. Vin.ii.123.

• -antaraṃsa “one whose shoulder-hole is heaped up, one who has the shoulders well filled out…

…flat-headed); Ja.vi.171 (˚antaraṃsa flat-chested); Mil.121 (of a river); Vv-a.301 (˚gambhīra)
■ abl. puthulato (as adv.) across…