Muscles of the Pectoral And Scapular Regions Flashcards
What is the innervation of the pectoralis major?
Lateral and medial pectoral nerves; Clavicular head (C5*, C6) sternocostal head (C7, C8, T1*)
What is the action of the pectoralis major?
Adducts and medially rotates humerus
Acting alone, clavicular head flexes humerus and sternocostal head extends it from the flexed position.
What is the origin and insertion for the pectoralis minor?
Origin
3rd-5th ribs near the costal cartilages (costochondral joints)
Insertion
coracoid process of scapula.
What is the innervation of the pectoralis minor?
Medial pectoral nerve (C8, T1)
What is the action of the pectoralis minor?
Stabilizes scapula against thoracic wall.
What is the origin and insertion of the subclavius?
Origin
Junction of 1st rib and it’s costal cartilage (1st costochondral joint)
Insertion
Inferior surface of middle third of clavicle
What is the innervation of the subclavius?
Nerve to subclavius (C5)
What is the action of the subclavius?
Anchors and depresses clavicle. Anchors sternoclavicular joint.
What is the origin and insertion of the serratus anterior?
Origin
lateral surface of ribs 1-8.
Insertion
Anterior surface of the medial border of scapula.
What is the innervation of the serratus anterior?
Long thoracic nerve (C6, C7)
What is the action of the serratus anterior?
Protracts scapula
What is the origin and insertion of the pectoralis major?
Origin
Clavicular head: anterior surface of the medial half of clavicle
Sternocostal head: anterior surface of the sternum, costal cartilages 1-6, aponeurosis of external oblique muscle.
Insertion
Lateral lip of the intertubercular sulcus of the humerus
What is the origin of the trapezius?
Medial one third of the superior nuchal line; external occipital protuberance; nuchal ligament; spinous processes C7-T12 vertebrae.
What is the insertion of the trapezius?
Lateral one third of clavicle; acromion in the spine of scapula.
What is the innervation of the trapezius?
Motor: spinal accessory nerve (CN XI)
Sensory: C3, C4
What is the action of the trapezius?
Descending part elevates; ascending part depresses; and middle part retracts scapula; descending and ascending parts act together to rotate the glenoid cavity superiorly.
What is the origin and insertion of the latissimus dorsi?
Origin
Spinous processes of T7-T12 vertebrae, the thoracolumbar fascia, iliac crest, and ribs 9-12.
Insertion
Floor of intertubercular sulcus of humerus
What is the innervation of the latissimus dorsi?
Thoracodorsal nerve (C6, C7, C8)
What is the action latissimus dorsi?
Extends, adducts, and medially rotates humerus; raises body toward arms during climbing.
(The handcuff muscle)
What is the origin and insertion of the levator scapulae?
Origin
Posterior tubercles of transverse processes of C1-C-4 vertebrae
Insertion
Medial border of scapula superior to root of scapular spine
What is the innervation of the Levator scapulae?
Dorsal scapular (C4, C5) and cervical nerves (C3, C4)
What is the action of the levator scapulae?
Elevates scapula and rotates glenoid cavity inferiorly by rotating scapula
What is the origin and insertion of the rhomboid minor?
Origin
Nuchal ligament; spinous processes of C7 and T1 vertebrae
Insertion
Smooth triangular area at medial and scapular spine
What is the innervation of the rhomboid major and minor?
Dorsal scapular nerve (C4*, C5)
What is the action of the rhomboid minor and major?
Retract scapula and rotate glenoid cavity inferiorly; fix scapula to thoracic wall.
What is the origin and insertion of the rhomboid major?
Origin
Spinous processes of T2-T5 vertebrae
Insertion
Medial border of scapula from spine to be inferior angle
