Ectatic is the state of dilation, of any part of the body.

I believe this hasn't been answered as it is a typo; they probably meant to write sciatic nerve, or ischiatic nerve is composed of L4-S3 spinal and anterior and posterior divisions of the lumbosacral plexus.

If its dilated up to 3 cm, seems to be a precursor condition to distended (swollen) condition which is a precursor to a ruptured aorta

Usually occurs in the descending (or abdominal) aorta.

According to SOWPODS (the combination of Scrabble dictionaries used around the world) there are 8 words with the pattern EC---I-. That is, seven letter words with 1st letter E and 2nd letter C and 6th letter I. In alphabetical order, they are:

ecbolic

ecdemic

ecdysis

ectasia

ectasis

ectatic

ectopia

ectopic

According to SOWPODS (the combination of Scrabble dictionaries used around the world) there are 7 words with the pattern -C--TI-. That is, seven letter words with 2nd letter C and 5th letter T and 6th letter I. In alphabetical order, they are:

acmatic

acratic

acrotic

ectatic

sceptic

sciatic

scottie