Muscles of the Pectoral And Scapular Regions

Question 1

What is the innervation of the pectoralis major?

Answer 1

Lateral and medial pectoral nerves; 
Clavicular head (C5*, C6) 
sternocostal head (C7, C8, T1*)

Question 2

What is the action of the pectoralis major?

Answer 2

Adducts and medially rotates humerus

Acting alone, clavicular head flexes humerus and sternocostal head extends it from the flexed position.

Question 3

What is the origin and insertion for the pectoralis minor?

Answer 3

Origin
3rd-5th ribs near the costal cartilages (costochondral joints)

Insertion
coracoid process of scapula.

Question 4

What is the innervation of the pectoralis minor?

Answer 4

Medial pectoral nerve (C8, T1)

Question 5

What is the action of the pectoralis minor?

Answer 5

Stabilizes scapula against thoracic wall.

Question 6

What is the origin and insertion of the subclavius?

Answer 6

Origin
Junction of 1st rib and it’s costal cartilage (1st costochondral joint)

Insertion
Inferior surface of middle third of clavicle

Question 7

What is the innervation of the subclavius?

Answer 7

Nerve to subclavius (C5)

Question 8

What is the action of the subclavius?

Answer 8

Anchors and depresses clavicle. Anchors sternoclavicular joint.

Question 9

What is the origin and insertion of the serratus anterior?

Answer 9

Origin
lateral surface of ribs 1-8.

Insertion
Anterior surface of the medial border of scapula.

Question 10

What is the innervation of the serratus anterior?

Answer 10

Long thoracic nerve (C6, C7)

Question 11

What is the action of the serratus anterior?

Answer 11

Protracts scapula

Question 12

What is the origin and insertion of the pectoralis major?

Answer 12

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

Question 13

What is the origin of the trapezius?

Answer 13

Medial one third of the superior nuchal line; external occipital protuberance; nuchal ligament; spinous processes C7-T12 vertebrae.

Question 14

What is the insertion of the trapezius?

Answer 14

Lateral one third of clavicle; acromion in the spine of scapula.

Question 15

What is the innervation of the trapezius?

Answer 15

Motor: spinal accessory nerve (CN XI)

Sensory: C3, C4

Question 16

What is the action of the trapezius?

Answer 16

Descending part elevates; ascending part depresses; and middle part retracts scapula; descending and ascending parts act together to rotate the glenoid cavity superiorly.

Question 17

What is the origin and insertion of the latissimus dorsi?

Answer 17

Origin
Spinous processes of T7-T12 vertebrae, the thoracolumbar fascia, iliac crest, and ribs 9-12.

Insertion
Floor of intertubercular sulcus of humerus

Question 18

What is the innervation of the latissimus dorsi?

Answer 18

Thoracodorsal nerve (C6, C7, C8)

Question 19

What is the action latissimus dorsi?

Answer 19

Extends, adducts, and medially rotates humerus; raises body toward arms during climbing.

(The handcuff muscle)

Question 20

What is the origin and insertion of the levator scapulae?

Answer 20

Origin
Posterior tubercles of transverse processes of C1-C-4 vertebrae

Insertion
Medial border of scapula superior to root of scapular spine

Question 21

What is the innervation of the Levator scapulae?

Answer 21

Dorsal scapular (C4, C5) and cervical nerves (C3, C4)

Question 22

What is the action of the levator scapulae?

Answer 22

Elevates scapula and rotates glenoid cavity inferiorly by rotating scapula

Question 23

What is the origin and insertion of the rhomboid minor?

Answer 23

Origin
Nuchal ligament; spinous processes of C7 and T1 vertebrae

Insertion
Smooth triangular area at medial and scapular spine

Question 24

What is the innervation of the rhomboid major and minor?

Answer 24

Dorsal scapular nerve (C4*, C5)

Question 25

What is the action of the rhomboid minor and major?

Answer 25

Retract scapula and rotate glenoid cavity inferiorly; fix scapula to thoracic wall.

Question 26

What is the origin and insertion of the rhomboid major?

Answer 26

Origin
Spinous processes of T2-T5 vertebrae

Insertion
Medial border of scapula from spine to be inferior angle