Shoulder Muscles Flashcards
Pectoralis Major
O:
Clavicular head–> anterior surface of sternal 1/2 clavicle
Sternocostal head–> anterior surface of sternum and adjacent superior 6 costal cartilages, aponeurosis of external oblique
I:
Common tendon to the lateral lip of the intertubercular groove
A: Adducts humerus Medially rotates humerus Clavicular head--flexes humerus Sternocostal head--extends humerus
N:
Lateral and medial perctoral nerves
Clavicular–lateral C5,C6
Sternocostal–medial C7, comes from communicating branch off lateral pectoral n
Pectoralis Minor
O:
Ribs 3-5 near their costal cartilages
I:
Medial border and superior surface of coracoid process of scapula
A:
Stabilizes scapula by pulling it anteriorly and inferiorly against thoracic wall
Minor protractor by moving scapula laterally and anteriorly around the thoracic cage
N:
Medial pectoral C8, T1
Subclavius
O:
Junction of rib 1 and its costal cartilage
I:
Inferior surface of middle 1/3 of clavicle
A:
Draws clavicle medially
N:
Nerve to subclavius (C5, C6)
Serratus Anterior
O:
External surfaces of lateral parts of ribs 1-8
Fascia overlying external intercostals
I:
Anterior surface of medial border of scapula
A:
Protracts scapula and holds it against thoracic wall (along with subclavius)
Rotates scapula by pulling on inferior angle to assist trapezius
N:
Long thoracic n (C5, C6, C7)
Trapezius
O: Medial 1/3 of superior nuchal line External occipital protuberance Ligamentum nuchae SP of C7-T12 Lumbar and sacral SP--pulls on the thoracolumbar fascia
I: Lateral 1/3 of clavicle Acromion and spine of scapula Superior fibers extend more laterally Inferior fibers insert on spine as aponeurosis w/o extending to acromion
A: Superior fibers--elevate scapula Middle fibers--retract scapula Inferior fibers--depress scapula Superior+Inferior fibers together superiorly rotate the lateral angle of the scapula
N: Spinal accessory (CN XI) and ventral rami of C3, C4
Latissimus Dorsi
O: SP of inferior 6 thoracic vertebrae Thoracolumbar fascia Iliac crest Ribs 9-12
I:
Floor of intertubercular groove of humerus
A:
Extends humerus
Adducts humerus
Raises body towards arms when climbing
N: Thoracodorsal n (C6, C7, C8)
Levator Scapulae
O:
Posterior tubercles of TP of C1-C4
I:
Superior part of medial border of scapula
A:
Elevates scapula and inferiorly rotates the lateral angle of scapula
N:
Dorsal scapular n C5
Cervical n C3, C4
Rhomboids
O:
Minor–Ligamentum nuchae and SP of C7, T1
Major–SP of T2-T5
I:
Medial border of scapula from level of spine of scapula to inferior angle
A:
Retracts scapula
Inferiorly rotates lateral angle, depressing glenoid cavity
Fixes scapula to thoracic wall
N:
Dorsal scapular n C4, C5
Deltoid
O:
Lateral 1/3 of clavicle
Acromion
Spine of scapula
I:
Deltoid tuberosity of humerus
A:
Anterior–flexes and medially rotates arm
Middle–Abducts arm
Posterior–Extends and laterally rotates
N: Axillary n (C5, C6)
Supraspinatus
O:
Supraspinous fossa of scapula
I:
Superior facet of greater tubercle of humerus
A:
Abduct arm (assist deltoid)
Rotator Cuff Muscle
N:
Suprascapular n C4, C5, C6
Infraspinatus
O:
Infraspinous fossa of scapula
I:
Middle facet on greater tubercle of humerus
A:
Laterally rotate arm
Rotator cuff–> helps hold head of humerus in glenoid cavity
N: Suprascapular n (C5, C6)
Teres Minor
O:
Superior part of lateral border of scapula
I:
Inferior facet on greater tubercle of humerus
A:
Laterally rotate arm
Rotator Cuff
N:
Axillary nerve C5, C6
Teres Major
O:
Dorsal surface of inferior angle of scapula
I:
Medial lip of intertubercular groove of humerus
A:
Adducts arm
Medially rotates arm
N:
Lower subscapular n C5, C6, C7
Subscapularis
O:
Subscapular fossa
I:
Lesser tubercle of humerus
A:
Medially rotates arm
Adducts arm
Rotator cuff
N:
Upper and lower subscapular n C5, C6, C7
