Midterm- Shoulder Girdle Muscles

Question 1

Pectoralis Major

Answer 1

Origin: Medial 1/2 of clavicle anterior manubrium and body of sternum, costal cartilages of ribs 1-6, rectus sheath
Insertion: lateral lip of bicipital groove of humerus
Action: flexion of arm, extension of arm from position of full flexion, abduction of arm, medial rotation of arm
Innervation: Clavicular head: lateral pectoral C5, C6 Sternal head: medial pectoral C7, C8, T1

Question 2

Pectoralis minor

Answer 2

Origin: ventral aspect of ribs 3-5 near their costal cartilages
Insertion: coracoid process of scapula
Action: stabilization of scapula via depression, protraction toward thoracic wall
Innervation: Medial pectoral C8, T1

Question 3

Subclavius

Answer 3

Origin: 1st rib at costal cartilage
Insertion: inferior surface of middle 1/3 of clavicle
Action: anchors and depresses clavicle
Innervation: subclavian C5, C6

Question 4

Serratus anterior

Answer 4

Origin: anterolateral surface of ribs 1-8
Insertion: anterior surface of medial border of scapula
Action: protraction of scapula, stabilization of scapula, Lower fibers: assist upward rotation scapula, depression of scapula
Innervation: Long thoracic C5, C6, C7

Question 5

Trapezius

Answer 5

Origin: medial 1/3 of superior nuchal line, external occipital protuberance, nuchal ligament, spinous processes of C7-T12 vertebrae
Insertion: Lateral 1/3 of clavicle; acromion and spine of scapula
Action: Upper fibers: elevation and upward rotation of scapula; unilateral ipsilateral sidebend and contralateral rotation of neck; bilateral extension of neck; rotate contralaterally
∗ Middle fibers: retracts scapula
∗ Lower fibers: depress & upward rotation scapula
Innervation: CN XI, spinal accessory, C3, C4 spinal nerves

Question 6

Latissimus Dorsi

Answer 6

Origin: Spinous processes of T7-T12 vertebrae, thoracolumbar fascia, iliac crest, inferior 4 ribs
Insertion: Floor of intertubercular sulcus of humerus
Action: Extension of arm, adduction of arm, medial rotation of arm, depression and downward rotation of scapula
Innervation: Thoracodorsal C6, C7, C8

Question 7

Levator scapulae

Answer 7

Origin: transverse processes of C1-C4 vertebrae
Insertion: medial border of scapula between superior angle and base of spine
Action: elevation of scapula, downward rotation of scapula, Ipsilateral sidebend of neck
Innervation: Dorsal scapular C3, C4

Question 8

Rhomboid minor

Answer 8

Origin: Spinous processes of C7-T1 vertebrae
Insertion: medial border of scapula between spine and superior angle
Action: retract scapula, downward rotation of scapula; fix medial border of scapula to thoracic wall
Innervation: Dorsal scapular C4, C5

Question 9

Rhomboid major

Answer 9

Origin: Spinous processes of T2-5 vertebrae
Insertion: medial border of scapula between spine and inferior angle
Action: Retract scapula, downward rotation of scapula; fix medial border of scapula to thoracic wall
Innervation: Dorsal scapular C4, C5

Question 10

Deltoid

Answer 10

Origin: lateral 1/3 of clavicle, acromion, and spine of scapula
Insertion: Deltoid tuberosity of humerus
Action: Clavicular (anterior): flexion and medial rotation of the arm
Acromion (middle): abduction of arm
Spinal (posterior): extension, lateral rotation of arm
Innervation: Axillary C5, C6

Question 11

Supraspinatus

Answer 11

Origin: supraspinous fossa of scapula
Insertion: Superior facet of greater tubercle of humerus
Action:Initiates and assists deltoid in abduction of arm, stabilization of humerus in glenoid cavity
Innervation: Suprascapular C4, C5, C6

Question 12

Infraspinatus

Answer 12

Origin: infraspinous fossa of scapula
Insertion: middle facet of greater tubercle of humerus
Action:lateral rotation of arm, stabilization of humerus in glenoid cavity
Innervation: Suprascapular C5, C6

Question 13

Teres minor

Answer 13

Origin: middle part of lateral border of scapula
Insertion: inferior facet of greater tubercle of humerus
Action: lateral rotation of arm, stabilization of humerus in glenoid cavity
Innervation: Axillary C5,C6

Question 14

Teres major

Answer 14

Origin: posterior surface of inferior angle of scapula
Insertion: medial lip of intertubercular sulcus of humerus
Action: adduction of arm, medial rotation of arm
Innervation: Lower subscapular C5, C6

Question 15

subscapularis

Answer 15

Origin: subscapular fossa
Insertion: lesser tubercle of humerus
Action: medial rotation of arm, stabilization of humerus in glenoid cavity
Innervation: Upper and lower subscapular nerves C5, C6