Extrinsic Back Muscles

Question 1

What are the extrinsic back muscles

Answer 1

Trapezius, latissumus dorsi, levator scapulae, rhomboids

Question 2

Trapezius origin

Answer 2

medial third of superior nuchal line
external occipital protuberance
nuchal ligament
spinous process of C7-T12 vertebrae

Question 3

Trapezius insertion

Answer 3

lateral third of clavicle; acromion and spine of scapula

Question 4

trapezius innervation

Answer 4

spinal accessory nerve (CNXI)

C3 and C4

Question 5

Latissimus Dorsi origin

Answer 5

spinous processes of inferior six thoracic vertebrae
thoracolumbar fascia
iliac crest
inferior three or four ribs

Question 6

latissimus dorsi insertion

Answer 6

floor of intertubercular sulcus of humerus

Question 7

latissimus dorsi innervation

Answer 7

thoracodorsal nerve

C6, C7, C8

Question 8

Levator scapulae origin

Answer 8

posterior tubercles of transverse processes of C1-C4 vertebrae

Question 9

Levator Scapulae insertion

Answer 9

medial border of scapula superior to root of spine

Question 10

levator scapilae innervation

Answer 10

dorsal scapular (C5) and cervical spinal nerves (C3, C4)

Question 11

rhomboid minor originate

Answer 11

nuchal ligament

spinous processes of C7 and T1 vertebrae

Question 12

rhomboid minor insertion

Answer 12

triangular area at medial end of scapular spine

Question 13

rhomboid minor innervation

Answer 13

dorsal scapular nerve

C4, C5

Question 14

rhomboid major origin

Answer 14

spinous processes of T2- T5 vertebrae

Question 15

rhomboid major insertion

Answer 15

medial border of scapula from level of spine to inferior angle

Question 16

rhomboid major innervation

Answer 16

dorsal scapular nerve

C4, C5

Question 17

trapezius main actions

Answer 17

descending (superior): elevation
ascending (inferior): depresses
middle part or all together: retracts scapula
descending and ascending act together to rotate glenoid cavity superiorly

Question 18

latissimus dorsi main actions

Answer 18

extends, adducts and medially rotates shoulder joint

raises body towards arms during climbing

Question 19

levator scapulae main actions

Answer 19

elevates scapula and tilts the glenoid cavity inferiorly by rotating scapula

Question 20

rhomboids main actions

Answer 20

retract scapula and rotate it to depress glenoid cavity

fix scapula to thoracic wall

Question 21

intermediate extrinsic back muscles

Answer 21

serratus posterior superior and inferior

Question 22

posterior serratus superior origin

Answer 22

nuchal ligament

spinous processes C7-T3

Question 23

posterior serratus superior insertion

Answer 23

superior border of ribs 2 to 4

Question 24

posterior serratus superior innervation

Answer 24

2nd to 5th intercostal nerves

Question 25

posterior serratus superior action

Answer 25

elevates ribs

Question 26

posterior serratus inferior origin

Answer 26

spinous processes of T11 to L2

Question 27

posterior serratus inferior insertion

Answer 27

inferior borders ribs 8 to 12

Question 28

posterior serratus inferior innervation

Answer 28

spinal nerves T9 to T12 (anterior rami)

Question 29

posterior serratus inferior action

Answer 29

depression of ribs