He underwent surgery due to an injury to his extensor digitorum communis.

He is doing a special exercise to strengthen his extensor indicis.

He stretches his extensors every day.

He underwent surgery due to an injury to his extensor pollicis brevis.

He injured his extensor pollicis longus.

I strained a muscle at the gym yesterday.

He is doing a special exercise to strengthen his extensor digiti minimi.

He works in the general affairs department of that company.

What is the overall population?

He stretches every day to lengthen his legs.