The Spanish word 'membrana' (meaning 'membrane') comes directly from the Latin word 'membrana', which meant 'skin' or 'membrane'. This Latin word was derived from 'membrum', meaning 'limb' or 'member' - the connection being that membranes are like the covering or skin that wraps around bodily members or limbs.

A related Spanish word is 'miembro' (meaning 'member'), which also comes from the Latin 'membrum'. While 'membrana' refers to a thin tissue or layer that covers or connects parts of the body, 'miembro' retained the original meaning of a body part or limb, and also developed the extended meaning of a person belonging to a group, just like in English.

The English word 'membrane' is a direct cognate of Spanish 'membrana', as both come from Latin 'membrana'. Similarly, the English word 'member' is related, coming from Latin 'membrum'. This makes it easy to remember - a membrane is like a thin covering that wraps around various members (parts) of the body.