Shoulder Muscles Quiz – Rotator Cuff, Back and Front

All 13 muscles on the diagram

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Back, surface 5

Deltoid (shoulder muscle) Shaped like a triangle standing on its point. It starts on the collarbone and on the tip and ridge of the shoulder blade and ends halfway down the humerus. Its middle fibers are the main lifters of the arm out to the side.
Trapezius (traps) A broad, flat muscle from the skull and spine. It runs out to the collarbone and the ridge of the shoulder blade. Its upper fibers lift the shoulder blade, its middle fibers pull it back and its lower fibers pull it down.
Infraspinatus Fills the hollow of the shoulder blade below its ridge. It ends on the head of the humerus. It turns the arm outward. One of the four rotator cuff muscles.
Teres minor A narrow muscle along the outer edge of the shoulder blade. It ends on the head of the humerus. It turns the arm outward and is part of the rotator cuff.
Teres major Pulls the arm in and back and turns it inward. It runs from the bottom corner of the shoulder blade to the front of the humerus. It is not part of the rotator cuff.

Back, deep 4

Supraspinatus Starts the lift of the arm out to the side. It fills the hollow above the ridge, passes under the bony roof of the shoulder and ends on the head of the humerus. A rotator cuff muscle.
Levator scapulae Lifts the shoulder blade. A strap from the top four neck vertebrae to the upper corner of the shoulder blade.
Rhomboid minor Sits just above the rhomboid major. From the spines of C7 and T1 to the inner edge of the shoulder blade, level with its ridge.
Rhomboid major Both rhomboids pull the shoulder blade back toward the spine. From the spines of T2 to T5 to the inner edge of the shoulder blade, below its ridge.

Front, deep 4

Subclavius A small muscle along the underside of the collarbone. It runs from the first rib. It anchors the collarbone and pulls it down.
Pectoralis minor It lies under the pectoralis major. It runs from ribs 3 to 5 up to the coracoid process, a knob on the shoulder blade, and holds the shoulder blade against the chest wall.
Serratus anterior Holds the shoulder blade against the ribs. It turns the blade so the arm can be raised above the shoulder. Strips from the sides of ribs 1 to 8 run back to the inner edge of the shoulder blade.
Subscapularis Covers the face of the shoulder blade that lies against the ribs. It ends on the front of the head of the humerus. It turns the arm inward. The fourth rotator cuff muscle.

How this list was compiled: Every name and detail line was checked on 2026-09-30 against Gray, Anatomy of the Human Body, 20th edition, 1918 (public domain), the chapters on the muscles connecting the upper limb to the trunk and the muscles of the shoulder, https://archive.org/details/anatomyofhumanbo00grayrich; TeachMeAnatomy, The Intrinsic Muscles of the Shoulder, https://teachmeanatomy.info/upper-limb/muscles/shoulder/intrinsic/, The Extrinsic Muscles of the Shoulder, https://teachmeanatomy.info/upper-limb/muscles/shoulder/extrinsic/, and Muscles of the Pectoral Region, https://teachmeanatomy.info/upper-limb/muscles/pectoral-region/; and Kenhub, Shoulder muscles, https://www.kenhub.com/en/library/anatomy/shoulder-muscles. The wording is in our own words. Licence: own work

The drawing: Drawn for this site on 2026-09-30 from plain geometry; nothing traced. Licence: own work

How it works

A right shoulder drawn three times: from behind, from behind again with the two big surface muscles lifted off, and from the front with the chest muscle removed. Name all thirteen and you have the muscles of the shoulder labeled.

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From behind: surface, then deep

First the trapezius and the deltoid, with the infraspinatus, teres minor and teres major showing between them. The second drawing takes the two big muscles away: the levator scapulae and both rhomboids run to the shoulder blade, and the supraspinatus lies in the hollow above its ridge.

From the front: under the chest muscle

A lab sheet that says correctly label the muscles of the shoulder often means this view, the deep anterior muscles of the chest labeled one by one: subclavius under the collarbone, pectoralis minor in three strips, serratus anterior like saw teeth on the ribs, and subscapularis in the armpit.

Rotator cuff: supraspinatus, infraspinatus, teres minor, subscapularis. Teres major is not one of them.
Supraspinatus starts the lift of the arm out to the side; the deltoid then takes over.
Pectoralis minor ends on the shoulder blade, not on the arm.

Questions and answers

What are the four rotator cuff muscles?

Supraspinatus, infraspinatus, teres minor and subscapularis. All four start on the shoulder blade and end on the head of the humerus, and together they hold the ball of the joint in its socket.

What are the muscles of the shoulder?

Six run from the shoulder blade or collarbone to the humerus: the deltoid, teres major and the four rotator cuff muscles. Others run from the trunk: trapezius, latissimus dorsi, levator scapulae and the rhomboids behind; the pectorals, serratus anterior and subclavius in front.

Which muscle lifts the arm out to the side?

Two share the job. The supraspinatus does the first part of the lift, about the first 15 degrees, and the middle fibers of the deltoid do most of the rest.

What does the serratus anterior do?

It holds the shoulder blade flat against the rib cage and turns it, which lets the arm be raised above shoulder height. Its name comes from its saw-toothed edge on the ribs.