「Buttocks」with「repeated worms in spread legs」refers to the many GENERIC varieties of intestinal parasites visible in sticky fluids of diarrheal discharge when egg sacs are released, but the parents are still FIRMLY ATTACHED, CONNECTED to the intestinal walls:
　「Almost everyone has parasites. It's simply a fact of life. …ninety percent of humans will have a problem with parasites in their lifetime. …The World Health Organization (WHO) classifies parasites as among the six most dangerous diseases that infect humans. Parasites outrank cancer as the number one global killer, and account for many of the digestive woes from which people suffer. The CDC (Center for Disease Control and Prevention) estimates that over sixty million people in the United States are likely infected with Toxoplasma gondii, a parasite associated with raw meat and contact with cat feces. …There are more than a hundred different types of parasites who enjoy living out their lives inside of human beings.」
　　[　now-dead link was http://www.puristat.com/parasites/default.aspx 2012-12-04　so instead see　[　https://mygoodgut.com/parasites/　2023-05-18　]
　And how much worse were these conditions several millennia ago? if one member of a tribe was infested with ANAL PARASITES, it was highly likely that all members were infested. It is also clearly possible that the sages were referring to the FAMILY MEMBERS themselves as anal parasites as burrowers into a sibling's night soil, parents with children, and so on. Note that such behavior often leads to the parasitic colonization of other orifices with mucous membranes other than just the anus. Parasites can generally feed off of any soft and wet tissue.
　「Buttocks, genitals」and「firmly attached inside spread legs.」For snakes that is the cloaca of the female, the single orifice used for reproduction, urination, defecation, and birth, attached to one hemipenis of the male, all「firmly attached.」A KIND, GENUS as related to biology, as one kind of animal normally「hooks up genitalia」and copulates only with another animal of the same kind, and normally of the opposite sex—although that is not an absolute rule, and obviously does not apply to zooerastiating humans, the species presumed to possess the highest degree of intelligence…
　Yet, as a「repeatedly bobbing head of snake in buttocks」or「repeatedly loose dripping stink in orifice within spread-legged buttocks」to mean CONCENTRATED ATTENTION, NAMELESS, ALL OF THE SAME KIND it is difficult to dismiss this glyph also as a reference to homosexual male humans, bonobos, or swine serving into rectums…especially in light of related glyphs.

Modern definitions (that generally disregard history) …excluding politically incorrect concepts and other meanings deemed offensive today; may list only pigeonholed definitions, euphemisms, or meaningless mnemonics)
Chinese: to join together; to fix one's attention on; to concentrate on; category; genus (taxonomy); family members; dependents; to belong to; subordinate to; affiliated with; be born in the year of (one of the 12 animals); to be; to prove to be; to constitute
Japanese: genus, generic, to entrust, to send, to belong to, to come under, to be affiliated with, to be subject to
Unihan extended: class, category, type; belong to
EDRDG: belong; genus; subordinate official; affiliated

Used within names (nanori)
さっか　･　つき