The Eustachian tube passes between -
GAPS BETWEEN PHARYNGEAL MUSCLES AND RELATED STRUCTURES
I. Between the base of the skull and superior constrictor i.e. above superior constrictor (Sinus of Morgagni) :

Levator veli palatini
Auditory tube(eustachian tube)
Ascending palatine artery

II. Between superior and middle constrictors :

Stylopharyngeus muscle
Glossopharyngeal nerve

III. Between Middle and Inferior constrictors :

Internal laryngeal nerve
Superior laryngeal vessels

These structures pierce the thyrohyoid membrane.
IV. Between lower border of inferior constrictor and esophagus :

Recurrent laryngeal nerve
Inferior laryngeal vessels
Superior and middle constrictors
Above superior constrictor
Middle and inferior constrictor
Below inferior constrictor