Muscular Anatomy of the Shoulder Start

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. Menu

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

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. Menu

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. Menu

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 Menu

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 Menu

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 Menu

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. Menu

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 Menu

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 Menu

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 Menu

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 Menu

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. Menu

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 Menu

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 Menu

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 Menu

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 Menu

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. Menu

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 Menu

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 Menu

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 Menu

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 Menu

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 Menu

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. Menu

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: Menu