Muscular Anatomy of the Shoulder

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Learning muscular anatomy takes time and memorization. This module will assist you in the process.

Study each of the following slides to familiarize yourself with the muscles of the shoulder. There are review exercises to complete throughout the module so you can test yourself.

Use the arrows below to navigate between pages. Visit each slide as often as needed, and take your time. To revisit a particular page, click the menu button and select that page from the menu.

Welcome!

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Group 3

Levator Scapula, Rhomboids, Deltoids Overview

Levator Scapula

Rhomboids Major and Minor

Deltoids

Review 3

Group 2

Trapezius, Latissimus Dorsi, Teres Major Overview

Trapezius

Latissimus Dorsi

Teres Major

Review 2

Group 4

Supraspinatus, Infraspinatus, Teres Minor, Subscapularis Overview

Supraspinatus

Infraspinatus

Teres Minor

Subscapularis

Review 4

Apply

Your turn

Welcome

About Origins, Insertions, and Actions

Group 1

Pectoralis Major and Minor Overview

Pectoralis Major

Pectoralis Minor

Review 1

This is an overview of what you will be studying, and will appear when you click the Menu button. To proceed, click the next arrow button.

About Origins, Insertions, and Actions:The origin of each muscle is the first place where that muscle attaches to bone. The second place the muscle attaches to bone is called the insertion. When a muscle is working, it pulls its insertion toward its origin, making an action.

Origins and insertions are described as bony landmarks within the skeletal system. To review these landmarks, click here.

Actions are described using medical terminology. To review these terms, click here.

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Pectoralis Major and Minor Overview

Pectoralis Major and Minor are the two main muscles in the chest. Pectoralis Major lies on top of Pectoralis Minor and is much larger.

Pectoralis Major moves the upper arm in almost all directions aside from abducting it away from the body.

Pectoralis Minor rotates, depresses, and protracts the scapula.

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Pectoralis MajorOrigin• medial half of clavicle• sternum• cartilages of upper 6 ribs

Insertion• lateral lip of bicipital grove of

humerus

Action• adduction• horizontal adduction of humerus• medial rotation of humerus• flexion of humerus• extension of humerus from a flexed position

Clavicle

Clavicular head of pectoralis major

Bicipital groove

Sternum

Pectoralis Major

Sternal head of pectoralis major

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Rib 1

Clavicle

Subclavius

Coracoid process

Pectoralis Minor

Pectoralis Minor

Origin• anterior 3, 4, 5 ribs (near costal

cartilages)

Insertion• coracoid process of

scapula

Action• protraction, depression,

downward rotation of scapula

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Which indicator line points to Pectoralis Major on this chart?

Review 1: Type in your response to the questions below in the box provided. When you are finished, click on the anatomy chart to reveal the correct answers.

Which indicator line points to Pectoralis Minor?

Which chest muscle protracts the scapula?

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Pectoralis Minor

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Trapezius, Latissimus Dorsi, Teres Major Overview

Trapezius and Latissimus Dorsi are the two largest muscles in the back.

Trapezius moves only the scapula.

All three of these muscles are superficial, meaning that they lie on top of other deeper muscles.

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Both Latissimus Dorsi and Teres Major insert into the bicipital groove, and perform the same actions on the humerus.

Skull

Trapezius

Acromion

Scapula

Vertebrae

TrapeziusOrigin• external occipital protuberance• ligamentum nuchae • spinous processes C7 – T12

(Upper, Middle, Lower)

Insertion• Upper: lateral clavicle

acromion• Middle: spine of scapula• Lower: root of spine of scapula

Action• Upper: elevation of scapula

upward rotation of scapula• Middle: retraction of scapula• Lower: depression of scapula

upward rotation of scapula

Trapezius

Clavicle

Acromion

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Latissimus DorsiHumerus

Latissimus Dorsi

Vertebrae

Iliac crest of hip bone

Sacrum

Humerus

Latissimus Dorsi

Vertebrae

Iliac crest of hip bone

Origin• thoracolumbar aponeurosis• lower 6 thoracic spinous processes• sacrum and iliac crest• lower 3 to 4 ribs• inferior angle of scapula

Insertion• bicipital groove of humerus

Action• extension• medial rotation of humerus• adduction of humerus

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Teres Major

Origin• inferior angle of scapula

Insertion• bicipital groove of humerus

Action• extension• medial rotation of humerus• adduction of humerus

Supraspinatus

Spine of scapula

Infraspinatus

Teres minor

Teres MajorHumerus

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Review 2: Type in your response to the questions below in the box provided. When you are finished, click on the anatomy chart to reveal the correct answers.

Which indicator line points to Trapezius?

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Which indicator line points to Latissimus Dorsi?

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Which indicator line points to Teres Major?

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Which two of these three muscles perform the same actions?

Latissimus Dorsi & Teres Major

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Levator Scapula, Rhomboids, Deltoids Overview Both Levator Scapula and the

Rhomboids act on the scapula (along with Trapezius).

The Deltoids are in charge of moving and supporting the arm any time it is away from the body. They are divided into three sections - anterior, middle, and posterior. Each section performs a different action.

Both Rhomboids, along with Levator Scapula are deep muscles, meaning that other muscles, in this case Trapezius, lie on top of them.

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Levator Scapula

Origin• C1 – C4 (transverse processes)

Insertion• vertebral border of scapula

from superior angle to root of spine

Action• elevation• downward rotation of

scapula

Cervical vertebrae I

Levator Scapula

Rhomboid minor

Rhomboid major

Scapula

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Rhomboids: Major and Minor

Origin• Minor: C7 and T1 (spinous processes)• Major: T2 – T5 (spinous processes)

Insertion• Minor: root of spine of scapula• Major: vertebral border of scapula from

root of spine to inferior angle

Action• retraction• downward rotation of scapula

Cervical vertebrae I

Levator scapula

Rhomboid Minor

Rhomboid Major

Scapula

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Deltoids

Origin• Anterior: lateral third of clavicle• Middle: lateral acromion• Posterior: spine of scapula

Insertion• deltoid tuberosity of humerus

Action• Anterior: flexion, horizontal adduction, medial

rotation of humerus• Middle: abduction of humerus to 90 degrees• Posterior: extension, horizontal adduction,

lateral rotation of humerus

Clavicle

Deltoid

Humerus

Acromion

Spine of scapula

Deltoid

Scapula

Deltoid tuberosity

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Review 3: Type in your response to the questions below in the box provided. When you are finished, click on the anatomy chart to reveal the correct answers.

Which indicator line points to Levator Scapula?

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Which indicator line points to Rhomboids Major and Minor?

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Which indicator line points to the Deltoids?

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Where do the Deltoids insert?

Deltoid tuberosity of humerus

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Supraspinatus, Infraspinatus, Teres Minor, Subcapularis Overview

These four muscles make up what is commonly known as the Rotator Cuff. The acronym SITS helps to remember them.

Supraspinatus, Teres Minor, and Infraspinatus share the same insertion point: the greater tubercle of the humerus.

Subscapularis is located on the anterior side of the scapula and lies between it and the ribs. Due to its location, it is sometimes not labeled on anatomical charts.

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Teres Minor and Infraspinatus share the same action: lateral rotation and extension of humerus.

Supraspinatus

Origin• supraspinous fossa of scapula

Insertion• greater tubercle of humerus

Action• abduction of humerus• stabilization of head of humerus

Spine of scapula

Infraspinatus

Teres minor

Humerus

Teres major

Supraspinatus

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Infraspinatus

Origin• infraspinous fossa of scapula

Insertion• greater tubercle of humerus

Action• lateral rotation of humerus• extension of humerus

Spine of scapula

Supraspinatus

Teres minor

Teres major

Humerus

Infraspinatus

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Teres Minor

Origin• upper axillary border of scapula

Insertion• greater tubercle of humerus

Action• lateral rotation of humerus• extension of humerus

Supraspinatus

Spine of scapula

Infraspinatus

Teres major

Humerus

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Subscapularis

Origin• subscapular fossa of scapula

Insertion• lesser tubercle of humerus

Action• medial rotation of humerus

Lesser tubercle of humerus

Humerus

Subscapularis

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Review 4: Type in your response to the questions below in the box provided. When you are finished, click on the anatomy chart to reveal the correct answers.

Which indicator line points to Supraspinatus?

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Which indicator line points to Infraspinatus?

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Which two muscles are not indicated on this chart?

Teres Minor & Subscapularis

What are the SITS muscles commonly known as?

The Rotator Cuff

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Apply: Contemplate the following scenario, and provide your answers in the space provided. When finished, click anywhere and a possible answer will appear.

Your friend Nicole calls you because she is having pain in her shoulder and would like to know which muscle is causing it. She is having difficulty lifting her arm parallel to, and above her shoulder, and gets a sharp pain when she both lifts her arm and turns it inward. While there may be many muscles involved, what muscle(s) are likely to be the main contributors to this pain?

Because it hurts when Nicole both medially rotates and lifts her arm, Anterior Deltoid is probably the main contributor to her pain. Pectoralis Major is also likely to be involved; it both moves the upper arm, and medially rotates the humerus. The Rotator Cuff muscles, particularly Subscapularis which also medially rotates the humerus, could be indicated as well.

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Your Turn: Write your own scenario similar to the one you just contemplated; think of an action, or combination of actions, and determine which muscles are involved in performing it.

Write the action in this box:Determine the muscles that perform it, and put them in this box:

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