Upper Extremity Muscles Flashcards
Pectoralis major origin
- clavicular head (ant. surface of sternal 1/2 of clavicle)
- sternocostal head (ant. surface of sternum and adjacent superior 6
- aponeurosis of external abdominal oblique
Pectoralis major insertion
Common tendon to the lateral lip of the intertubercular groove
Pectoralis major action
- adducts and medially rotates humerus
- acting alone: clavicular head flexes humerus, sternocostal head extends it
Pectoralis major innervation
- clavicular head: lateral pectoral nerve (C5-6)
- sternocostal head: medial pectoral nerve (C7-T1)
- C7 comes from communicating branch off lateral pectoral n.
Pectoralis minor origin
Ribs 3-5 near their costal cartilages
Pectoralis minor insertion
Medial border and superior surface of coracoid process of scapula
Pectoralis minor action
- stabilizes scapula by pulling it anteriorly and inferiorly against thoracic wall
- minor protractor by moving scapula laterally and anteriorly around thoracic cage
Pectoralis minor innervation
Medial pectoral n. (C8-T1)
Subclavius origgin
Junction of rib 1 and its costal cartilage
Subclavius insertion
Inferior surface of middle 1/3 of clavicle
Subclavius action
Draws clavicle medially
Subclavius innervation
Nerve to subclavius (C5-6)
Serratus anterior origin
- external surfaces of lateral parts of ribs 1-8
- fascia overlying external intercostal muscles
Serratus anterior insertion
Anterior surface of medial border of scapula
Serratus anterior action
- protracts scapula and holds it against thoracic wall (w/subclavius)
- rotates scapula (pulls on inferior angle of scapula, assists trapezius)
Serratus anterior innervation
Long thoracic nerve (C5-7)
What are the pectoral muscles?
- pectoralis major
- pectoralis minor
- subclavius
- serratus anterior
What are the extrinsic muscles of the back?
- trapezius
- latissimus dorsi
- levator scapulae
- rhomboids
Trapezius origin
- medial 1/3 of sup. nunchaku line
- external occipital protuberance
- ligamentum nuchae
- spinous processes C7-12
Trapezius insertion
- lateral 1/3 of clavicle, acromion and spine of scapula
- superior fibers extend more laterally
- inferior fibers insert on spine as an aponeurosis (w/out extending to acromion)
Trapezius action
- elevates, retracts, and rotates scapula
- superior fibers elevate
- middle fibers retract
- inferior fibers depress
- sup. and inferior fibers act together to superiorly rotate lateral angle
Trapezius innervation
Spinal accessory n. (CN XI) and ventral rami of cervical n. (C3-4)
Latissimus dorsi origin
- spinous processes of the inferior 6 thoracic vertebrae
- throacolumbar fascia
- iliac crest and ribs 9-12
Latissimus dorsi insertion
Floor of intertubercular groove of humerus
Latissimus dorsi action
- extends, adducts, and medially rotates the humerus
- raises body towards arms during climbing
Levator scapulae origin
Posterior tubercles of transverse processes of C1-4 vertebrae
Levator scapulae insertion
Superior part of medial border of scapula
Levator scapulae action
Elevates scapula and inferiorly rotates lateral angle of scapula
Levator scapulae innervation
- Dorsal scapular n. (C5)
- cervical n. (C3-4)
Rhomboid minor origin
- Ligamentum nuchae
- spinous processes of C7-T1
Rhomboid major origin
Spinous processes T2-5
Rhomboid insertion
Medial border of scapula from level of spine of scapula to inferior angle
Rhomboid action
- retracts scapula and inferiorly rotates lateral angle
- depresses glenoid cavity
- fixes scapula to thoracic wall
Rhomboid innervation
Dorsal scapular n. (C4-5)
What are the scapular muscles?
- deltoid
- supraspinatus
- infraspinatus
- teres minor
- teres major
- subscapularis
Deltoid origin
Lateral 1/3 of clavicle, acromion, and spine of scapula
Deltoid insertion
Deltoid tuberosity of humerus
Deltoid action
- ant. part-flexes and medially rotates arm
- middle part-abducts arm
- post. part-extends and laterally rotates arm
Deltoid innervation
Axillary n. (C5-6)
Supraspinatus origin
Supraspinous fossa of scapula
Supraspinatus insertion
Superior facet of greater tubercle of humerus
Supraspinatus action
- Abduct arm (assists deltoid)
- rotator cuff muscle
Supraspinatus innervation
Suprascapular n. (C4-6)
Infraspinatus origin
Infraspinous fossa of scapula
Infraspinatus insertion
Middle facet on reader tubercle of humerus
Infraspinatus action
- laterally rotate arm
- rotator cuff muscle helps hold head of humerus in glenoid cavity
Infraspinatus innervation
Suprascapular n. (C5-6)
Teres minor origin
Superior part of lateral border of scapula
Teres minor insertion
Inferior facet on greater tubercle of humerus
Teres minor action
- laterally rotate arm
- rotator cuff muscle helps hold head of humerus in glenoid cavity
Teres minor innervation
Axillary n. (C5-6)
Teres major origin
Dorsal surface of inferior angle of scapula
Teres major insertion
Medial lip of intertubercular groove of humerus
Teres major action
Adducts and medially rotates arm
Teres major innervation
Lower subscapular n. (C5-6)
Subscapularis origin
Subscapular fossa
Subscapularis insertion
Lesser tubercle of humerus
Subscapularis action
- medially rotates and adducts arm
- rotator cuff muscle helps hold head of humerus in glenoid cavity
Subscapularis innervation
Upper and lower subscapular n. (C5-7)
