• (muscle, extraocular) A group of muscles in the orbit extending from the posterior orbit to the eye and upper eyelid; primary function is the movement of the eye and retraction of the upper eyelid.
  CDISC Terminology
  Clinical Data Interchange Standards Consortium (CDISC), 2021
• (extraocular muscle) A group of extrinsic muscles that are responsible for moving the eye and lifting the eyelid. These include: superior rectus, inferior rectus, medial rectus, inferior oblique, and levator palpebrae superioris, all innervated by CN III (oculomotor nerve), superior oblique, innervated by CN IV (trochlear nerve), lateral rectus, innervated by CN VI (abducens nerve).
  NCI Thesaurus
  U.S. National Cancer Institute, 2021
• (oculomotor muscles) The muscles that move the eye. Included in this group are the medial rectus, lateral rectus, superior rectus, inferior rectus, inferior oblique, superior oblique, musculus orbitalis, and levator palpebrae superioris.
  NLM Medical Subject Headings
  U.S. National Library of Medicine, 2021
• (extraocular muscle) Voluntary muscles which control eye movement.
  CRISP Thesaurus
  National Institutes of Health, 2006
• (extraocular muscles) Six paired muscles that direct the eyes' circular, side-to-side, and up-and-down movements.
  Harvard Dictionary of Health Terms
  Harvard Medical Publishing, 2011
• Extraocular muscles differ histologically from most other skeletal muscles in that they are made up of 2 different types of muscle cells. Each muscle cell is composed of groups of myofibrils called sarcomeres.
  Medscape
  WebMD, 2019