अमूर्धमस्तकात् स्वाङ्गादकामे

Operational rule vidhi

is not elided after a word denoting a part of the body (with the exception of मूर्धन् and मस्तक) before every word other than काम.

Word by word (padaccheda)

Left context अमूर्धमस्तकात् pañcamī · ekavacanaLeft context स्वाङ्गात् pañcamī · ekavacanaRight context अकामे saptamī · ekavacana

Left context Pañcamī (5th case): "after X", the operation applies to what follows (1.1.67 तस्मादित्युत्तरस्य). Also used for limits and sources.
Right context Saptamī (7th case): "when X follows", the operation applies to what precedes (1.1.66 तस्मिन्निति निर्दिष्टे पूर्वस्य). Also a condition or domain ("in the sense of").

Full reading

अमूर्धमस्तकात् स्वाङ्गात् अकामे

Pāṇini leaves out words that carry over from earlier sūtras. Expand to see the rule as a reader actually understands it.

Commentary

is not elided after a word denoting a part of the body (with the exception of मूर्धन् and मस्तक) before every word other than काम।
Thus कण्ठे कालोऽस्य = कण्ठेकालः, उरसिलोमा, उदरेमणिः ॥ But मूर्धशिखः, मस्तकशिखः, मुखे कामोऽस्य = मुखकामः ॥ When the first member does not denote the name of a part of the body, the rule does not apply: as अक्षशौण्डः, nor does it apply when the first member does not end in a consonant or अ, as अंगुलित्राणः, जङ्घावलिः ॥

Śrīśa Chandra Vasu, The Ashtadhyayi of Panini (1897), via ashtadhyayi.com.