Muscles of the Back

Question 1

What muscles are in layer 1 (extrinsic)?

Answer 1

Trapezius and latissimus dorsi muscles

Question 2

What muscles are in layer 2 (extrinsic)?

Answer 2

Rhomboid major, rhomboid minor, and levator scapulae muscles

Question 3

What muscles are in layer 3 (extrinsic)?

Answer 3

Serratus posterior superior/inferior muscles

Question 4

What muscles are in layer 4 (intrinsic)?

Answer 4

Splenius capitis and splenius cervicis muscles

Question 5

What muscles are in layer 5 (intrinsic; largest layer)?

Answer 5

Iliocostalis (lumborum, thoracis, cervicis), longissimus (thoracis, cervicis, capitis), and spinalis (thoracis, cervicis, capitis) muscles

Question 6

What muscles are in layer 6 (intrinsic)?

Answer 6

Semispinalis (thoracis, cervicis, capitis), multifidus, rotatores longus/brevis muscles

Question 7

What muscles are in the suboccipital region?

Answer 7

Rectus capitis posterior major/minor and obliquus capitis superior/inferior muscles

Question 8

Trapezius Muscle

1) Origin
2) Insertion
3) Action
4) Innervation

Answer 8

1) Spinous processes of lower cervical and thoracic vertebrae
2) Lateral 1/3 of clavicle, acromion, and scapular spine
3) Rotate shoulder superiorly, retract scapula, elevate/depress scapula, extend/flex neck, and rotate face away when working unilaterally
4) Spinal accessory nerve (CNXI)

Question 9

Latissimus Dorsi Muscle

1) Origin
2) Insertion
3) Action
4) Innervation

Answer 9

1) Spinous processes of thoracic vertebrae, ribs, iliac crest
2) Floor of humeral intertubercular groove
3) Extend, adduct, medially rotate humerus; rotate shoulder inferiorly
4) Thoracodorsal nerve

Question 10

Rhomboid Major Muscle

1) Origin
2) Insertion
3) Action
4) Innervation

Answer 10

1) Thoracic spinous processes
2) Medial border of scapula (inferior to scapular spine)
3) Retract and elevate scapula, rotate shoulder inferiorly
4) Dorsal scapular nerve

Question 11

Rhomboid Minor Muscle

1) Origin
2) Insertion
3) Action
4) Innervation

Answer 11

1) Thoracic spinous processes, lower part of ligamentum nuchae
2) Medial border of scapula (at scapular spine)
3) Retract and elevate scapula, rotate shoulder inferiorly
4) Dorsal scapular nerve

Question 12

Levator Scapulae Muscle

1) Origin
2) Insertion
3) Action
4) Innervation

Answer 12

1) Posterior tubercles of transverse processes in cervical region
2) Medial border of scapula (superior to scapular spine)
3) Elevate scapula, rotate shoulder inferiorly; when the scapula is fixed, extend and laterally flex the neck
4) Dorsal scapular nerve

Question 13

Serratus Posterior Superior Muscle

1) Origin
2) Insertion
3) Action
4) Innervation

Answer 13

1) Nuchal line and lower cervical/upper thoracic spinous processes
2) Superior surfaces of upper ribs
3) Elevate ribs with forced inspiration
4) Intercostal nerve

Question 14

Serratus Posterior Inferior Muscle

1) Origin
2) Insertion
3) Action
4) Innervation

Answer 14

1) Spinous processes of lower thoracic/upper lumbar vertebrae
2) Inferior surface of lower ribs
3) Depress ribs with forced expiration
4) Anterior rami of lower thoracic vertebrae

Question 15

Splenius Capitis Muscle

1) Origin
2) Insertion
3) Action
4) Innervation

Answer 15

1) Lower 1/2 of nuchal line, spinous processes of lower cervical/upper thoracic vertebrae
2) Mastoid process of temporal bone, lateral 1/3 of superior nuchal line
3) Extend the neck, laterally flex the neck, and rotate the face toward when working bilaterally
4) Posterior rami of middle cervical vertebrae

Question 16

Splenius Cervicis Muscle

1) Origin
2) Insertion
3) Action
4) Innervation

Answer 16

1) Spinous processes of upper-middle thoracic vertebrae
2) Transverse processes of upper cervical vertebrae
3) Extend the neck, laterally flex the neck, and rotate the face toward when working unilaterally
4) Posterior rami of lower cervical vertebrae

Question 17

Iliocostalis Lumborum Muscle

1) Origin
2) Insertion
3) Action
4) Innervation

Answer 17

1) Posteromedial iliac crest, spinous processes of lower thoracic/lumbar vertebrae
2) Costal angles of middle to lower ribs
3) Maintain erect posture and extend/laterally flex vertebral column
4) Segmentally innervated by posterior rami of spinal nerves

Question 18

Iliocostalis Thoracis Muscle

1) Origin
2) Insertion
3) Action
4) Innervation

Answer 18

1) Costal angles of middle to lower ribs
2) Costal angles of upper to middle ribs and transverse process of C7
3) Maintain erect posture and extend/laterally flex vertebral column
4) Segmentally innervated by posterior rami of spinal nerves

Question 19

Iliocostalis Cervicis Muscle

1) Origin
2) Insertion
3) Action
4) Innervation

Answer 19

1) Costal angles of middle ribs
2) Posterior tubercles of transverse processes of lower cervical vertebrae
3) Maintain erect posture and extend/laterally flex vertebral column
4) Segmentally innervated by posterior rami of spinal nerves

Question 20

Longissimus Thoracis Muscle

1) Origin
2) Insertion
3) Action
4) Innervation

Answer 20

1) Transverse and accessory processes of lumbar vertebrae, posteromedial iliac crest
2) Transverse processes of thoracic/upper vertebrae
3) Maintain erect posture and extend/laterally flex vertebral column
4) Segmentally innervated by posterior rami of spinal nerves

Question 21

Longissimus Cervicis Muscle

1) Origin
2) Insertion
3) Action
4) Innervation

Answer 21

1) Transverse processes of upper thoracic vertebrae
2) Posterior tubercles of transverse and articular processes of cervical vertebrae
3) Maintain erect posture and extend/laterally flex vertebral column
4) Segmentally innervated by posterior rami of spinal nerves

Question 22

Longissimus Capitis Muscle

1) Origin
2) Insertion
3) Action
4) Innervation

Answer 22

1) Transverse processes of upper thoracic vertebrae, articular processes of middle to lower cervical vertebrae
2) Mastoid process of the temporal bone
3) Extend neck, laterally flex the neck, and rotate the face toward working unilaterally
4) Segmentally innervated by posterior rami of spinal nerves

Question 23

Spinalis Thoracis Muscle

1) Origin
2) Insertion
3) Action
4) Innervation

Answer 23

1) Spinous processes of lower thoracic/upper lumbar vertebrae
2) Spinous processes of upper thoracic vertebrae
3) Maintain erect posture and extend/laterally flex vertebral column
4) Segmentally innervated by posterior rami of spinal nerves

Question 24

Spinalis Cervicis Muscle

1) Origin
2) Insertion
3) Action
4) Innervation

Answer 24

1) Spinous processes of upper thoracic vertebrae
2) Spinous processes of upper cervical vertebrae
3) Maintain erect posture and extend/laterally flex vertebral column
4) Segmentally innervated by posterior rami of spinal nerves

Question 25

Semispinalis Thoracis Muscle

1) Origin
2) Insertion
3) Action
4) Innervation

Answer 25

1) Transverse processes of middle to lower thoracic vertebrae
2) Spinous processes of lower cervical/upper thoracic vertebrae
3) Extend spine and rotate spine away
4) Posterior rami

Question 26

Semispinalis Cervicis Muscle

1) Origin
2) Insertion
3) Action
4) Innervation

Answer 26

1) Transverse processes of upper thoracic vertebrae
2) Spinous processes of cervical vertebrae
3) Extend spine and rotate spine away
4) Posterior rami

Question 27

Semispinalis Capitis Muscle

1) Origin
2) Insertion
3) Action
4) Innervation

Answer 27

1) Transverse processes of lower cervical/upper thoracic vertebrae
2) Between superior and inferior nuchal lines of the occipital bone
3) Extend head, rotate face away
4) Posterior rami

Question 28

Multifidus Muscle

1) Origin
2) Insertion
3) Action
4) Innervation

Answer 28

1) Mamillary processes of lumbar vertebrae, transverse processes of thoracic vertebrae
2) Spinous processes 3 numeric segments superior, but does not insert onto atlas
3) Extend spine, rotate spine away
4) Posterior rami

Question 29

Rotatores Longus Muscle

1) Origin
2) Insertion
3) Action
4) Innervation

Answer 29

1) Transverse processes
2) Roots of spinous processes 2 numeric segments superior
3) Extend spine, rotate spine away
4) Posterior rami

Question 30

Rotatores Brevis Muscle

1) Origin
2) Insertion
3) Action
4) Innervation

Answer 30

1) Transverse processes
2) Roots of spinous processes 1 numeric segment superior
3) Extend spine, rotate spine away
4) Posterior rami

Question 31

Interspinalis Muscle

1) Origin
2) Insertion
3) Action
4) Innervation

Answer 31

1) Spinous process
2) Adjacent spinous process
3) Extend spine
4) Posterior rami

Question 32

Intertransversarii Muscle

1) Origin
2) Insertion
3) Action
4) Innervation

Answer 32

1) Transverse process
2) Adjacent transverse process
3) Laterally flex spine
4) Posterior/anterior rami

Question 33

Levator Costarum Longus Muscle

1) Origin
2) Insertion
3) Action
4) Innervation

Answer 33

1) Transverse processes of lower cervical/thoracic vertebrae
2) 2nd rib inferior to origin
3) Elevate ribs
4) Posterior rami

Question 34

Levator Costarum Brevis Muscle

1) Origin
2) Insertion
3) Action
4) Innervation

Answer 34

1) Transverse processes of lower cervical/thoracic vertebrae
2) Adjacent rib inferior to origin
3) Elevate ribs
4) Posterior rami

Question 35

Rectus Capitis Posterior Major Muscle

1) Origin
2) Insertion
3) Action
4) Innervation

Answer 35

1) Spinous process of C2
2) Lateral portion of inferior nuchal line
3) Extend head, rotate face forward
4) Suboccipital nerve

Question 36

Rectus Capitis Posterior Minor Muscle

1) Origin
2) Insertion
3) Action
4) Innervation

Answer 36

1) Posterior tubercle of C1
2) Below inferior nuchal line
3) Extend head
4) Suboccipital nerve

Question 37

Obliquus Capitis Inferior Muscle

1) Origin
2) Insertion
3) Action
4) Innervation

Answer 37

1) Spinous process of C2
2) Transverse process of C1
3) Rotate the face forward
4) Suboccipital nerve

Question 38

Obliquus Capitis Superior Muscle

1) Origin
2) Insertion
3) Action
4) Innervation

Answer 38

1) Transverse process of C1
2) Between superior and inferior nuchal lines
3) Extend and laterally flex the neck
4) Suboccipital nerve