1. Muscular Anatomy of the Shoulder
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2. Welcome!
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.
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3. Menu
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.
Welcome
About Origins, Insertions, and Actions
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
Group 1
Pectoralis Major and Minor Overview
Pectoralis Major
Pectoralis Minor
Review 1
Group 3
Levator Scapula, Rhomboids, Deltoids Overview
Levator Scapula
Rhomboids Major and Minor
Deltoids
Review 3
Apply
Your turn

4. 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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5. 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 Minor rotates, depresses, and protracts the scapula.
Pectoralis Major moves the upper arm in almost all directions aside from abducting it away from the body.
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6. Pectoralis Major Menu Origin medial half of clavicle sternum
Clavicular head of pectoralis major
Origin
medial half of clavicle
sternum
cartilages of upper 6 ribs
Bicipital
groove
Sternum
Pectoralis Major
Insertion
lateral lip of bicipital grove of
humerus
Sternal head of pectoralis major
Action
adduction
horizontal adduction of humerus
medial rotation of humerus
flexion of humerus
extension of humerus from a flexed position
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7. Pectoralis Minor Menu Origin
Rib 1
Clavicle
Subclavius
Origin
anterior 3, 4, 5 ribs (near costal cartilages)
Coracoid
process
Pectoralis
Minor
Insertion
coracoid process of scapula
Action
protraction, depression, downward rotation of scapula
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8. 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 Major on this chart? 2
Which indicator line points to Pectoralis Minor? 35
Which chest muscle protracts the scapula?
Pectoralis Minor
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9. Trapezius, Latissimus Dorsi, Teres Major Overview
Trapezius and Latissimus Dorsi are the two largest muscles in the back.
All three of these muscles are superficial, meaning that they lie on top of other deeper muscles.
Trapezius moves only the scapula.
Both Latissimus Dorsi and Teres Major insert into the bicipital groove, and perform the same actions on the humerus.
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10. Trapezius Menu (Upper, Middle, Lower) Trapezius Origin
Skull
Trapezius
Origin
external occipital protuberance
ligamentum nuchae
spinous processes C7 – T12
Acromion
Scapula
Insertion
Upper: lateral clavicle
acromion
Middle: spine of scapula
Lower: root of spine of scapula
Vertebrae
Trapezius
Action
Upper: elevation of scapula
upward rotation of scapula
Middle: retraction of scapula
Lower: depression of scapula
Clavicle
Acromion
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11. Latissimus Dorsi Menu Latissimus Dorsi Origin
Humerus
Latissimus Dorsi
Origin
thoracolumbar aponeurosis
lower 6 thoracic spinous processes
sacrum and iliac crest
lower 3 to 4 ribs
inferior angle of scapula
Vertebrae
Iliac crest of hip bone
Sacrum
Insertion
bicipital groove of humerus
Humerus
Latissimus Dorsi
Action
extension
medial rotation of humerus
adduction of humerus
Vertebrae
Iliac crest of hip bone
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12. Teres Major Menu Origin inferior angle of scapula Teres Major
Supraspinatus
Spine of scapula
Origin
inferior angle of scapula
Infraspinatus
Teres minor
Teres Major
Humerus
Insertion
bicipital groove of humerus
Action
extension
medial rotation of humerus
adduction of humerus
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13. 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? 31
Which indicator line points to Latissimus Dorsi? 28
Which indicator line points to Teres Major? 29
Which two of these three muscles perform the same actions?
Latissimus Dorsi & Teres Major
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14. Levator Scapula, Rhomboids, Deltoids Overview
Both Levator Scapula and the Rhomboids act on the scapula (along with Trapezius).
Both Rhomboids, along with Levator Scapula are deep muscles, meaning that other muscles, in this case Trapezius, lie on top of them.
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.
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15. Levator Scapula Menu Origin C1 – C4 (transverse processes)
Cervical vertebrae I
Origin
C1 – C4 (transverse processes)
Levator Scapula
Rhomboid minor
Insertion
vertebral border of scapula from superior angle to root of spine
Rhomboid major
Scapula
Action
elevation
downward rotation of scapula
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16. Rhomboids: Major and Minor Menu Rhomboid Minor Origin
Cervical vertebrae I
Levator scapula
Rhomboid Minor
Origin
Minor: C7 and T1 (spinous processes)
Major: T2 – T5 (spinous processes)
Rhomboid Major
Scapula
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
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17. Deltoids Menu Origin Anterior: lateral third of clavicle
Middle: lateral acromion
Posterior: spine of scapula
Deltoid
Humerus
Insertion
deltoid tuberosity of humerus
Acromion
Spine of scapula
Action
Anterior: flexion, horizontal adduction, medial rotation of humerus
Middle: abduction of humerus to 90 degrees
Posterior: extension, horizontal adduction, lateral rotation of humerus
Deltoid
Scapula
Deltoid tuberosity
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18. 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? 4
Which indicator line points to Rhomboids Major and Minor? 5
Which indicator line points to the Deltoids? 30
Where do the Deltoids insert?
Deltoid tuberosity of humerus
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19. 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.
Teres Minor and Infraspinatus share the same action: lateral rotation and extension of humerus.
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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20. Supraspinatus Menu Supraspinatus Origin supraspinous fossa of scapula
Spine of scapula
Infraspinatus
Origin
supraspinous fossa of scapula
Teres minor
Teres major
Insertion
greater tubercle of humerus
Humerus
Action
abduction of humerus
stabilization of head of humerus
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21. Infraspinatus Menu Infraspinatus Origin infraspinous fossa of scapula
Supraspinatus
Spine of scapula
Infraspinatus
Origin
infraspinous fossa of scapula
Teres minor
Teres major
Insertion
greater tubercle of humerus
Humerus
Action
lateral rotation of humerus
extension of humerus
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22. Teres Minor Menu Origin upper axillary border of scapula Insertion
Supraspinatus
Spine of scapula
Infraspinatus
Origin
upper axillary border of scapula
Teres major
Insertion
greater tubercle of humerus
Humerus
Action
lateral rotation of humerus
extension of humerus
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23. Subscapularis Menu Origin subscapular fossa of scapula Subscapularis
Lesser
tubercle of humerus
Origin
subscapular fossa of scapula
Humerus
Subscapularis
Insertion
lesser tubercle of humerus
Action
medial rotation of humerus
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24. 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? 6
Which indicator line points to Infraspinatus? 7
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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25. 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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26. 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.
Determine the muscles that perform it, and put them in this box:
Write the action in this box:
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