ShoulderSource-checked
Infraspinatus
Infraspinatus
Pronunciation: in-fra-spy-NAY-tus
For beginners
A rotator cuff muscle that turns your arm outward and keeps the shoulder stable during many movements.
Show the advanced explanation
With teres minor, it provides most of the shoulder's external rotation torque and posteriorly stabilizes the glenohumeral joint, resisting anterior translation of the humeral head.
Structure & function
- Location
- A deep muscle on the shoulder blade, below its spine.
- Origin
- Infraspinous fossa of the scapula.
- Insertion
- Greater tubercle of the humerus.
- Main action(s)
- Externally (laterally) rotates the arm and stabilizes the humeral head.
- Joint(s) crossed
- Glenohumeral joint
- Movement plane
- transverse
- Innervation
- Suprascapular nerve (C5–C6)
- In daily movement
- Rotates the arm outward — like reaching for a seatbelt or opening a door outward.
- In exercise
- Prime mover in external-rotation exercises; stabilizer in pulling and pressing.
- Commonly confused with
- Confused with teres minor, which shares its external-rotation role.
- Common misconceptions
- External rotators are often under-trained relative to internal rotators used in pressing.
Exercises that use this muscle
As a primary mover
As a secondary / stabilizer
- Face Pull (secondary)
- Dumbbell Overhead Press (stabilizer)
⚠ Safety note
Progress rotator cuff work with light loads and high control.
Sources
“The infraspinatus is a rotator cuff muscle that laterally (externally) rotates the arm.”
Anatomy and Physiology 2e — OpenStax, Rice University · Ch. 11.5 Muscles of the Pectoral Girdle and Upper Limbs
Peer-reviewed textbook · License: CC BY-NC-SA 4.0 · Last checked 2026-07-19
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