He underwent surgery on his extraocular muscle.

He is doing special exercises to strengthen his external obturator muscle.

The external intercostal muscle plays an important role in respiration.

The external anal sphincter plays a crucial role in helping us control defecation.

The external urethral sphincter is an important muscle for controlling the excretion of urine.

I went to see the beautiful scenery of Sotogahama.

I have been to Outer Mongolia.

There are many introduced species of plants living in this park.

He engaged in an extravehicular activity from the spaceship.

He is undergoing training for extravehicular activity.