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?
4
Which indicator line points to Rhomboids Major and Minor?
5
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?
6
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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