Layer 1 Back Muscles

Question 1

Which two muscles are in layer one of the back?

Answer 1

Trapezius and latissimus dorsi

Question 2

What is the trapezius origin?

Answer 2

Spinous process of C7-T12, Ligamentum nuchae, external occipital protuberance and medial 1/2 of superior nuchal line of occipital bone

Question 3

What is the trapezius insertion?

Answer 3

Lateral 1/3 of the clavicle, acromion and scapular spine

Question 4

Whole muscle action of the trapezius?

Answer 4

Rotate part of the glenoid cavity superiorly and retract the scapula

Question 5

Upper fibers of trapezius action?

Answer 5

Elevate scapula

Question 6

Lower fibers of trapezius action?

Answer 6

Depress scapula

Question 7

With the scapula fixed, the upper fibers of the trapezius will do what?

Answer 7

Extend the neck working bilaterally, laterally flex the neck and rotate the face away when working unilaterally

Question 8

What is the trapezius innervated by?

Answer 8

Spinal accessory nerve (CN XI)

Question 9

What is the latissimus dorsi origin?

Answer 9

Spinous processes of T6-12, ribs 9-12, iliac crest and spinous processes of L1-5 and median sacral crest via thoracolumbar fascia

Question 10

What is the insertion for latissimus dorsi?

Answer 10

Floor of the humeral intertubercular groove

Question 11

What is the latissimus dorsi’s action?

Answer 11

Extend, adduct and medially rotate the humerus, rotate the glenoid cavity inferiorly

Question 12

What innervates the latissimus dorsi?

Answer 12

Thoracodorsal nerve