Muscles of the Back (Thorax and Deep Back Region)

Question 1

Trapezius

Answer 1

Origin:
Occipital bone, nuchal line, spinal processes of C7-T12

Insertion:
Lateral third of the clavicle, acromion, spine of scapula

Innervation:
CN XI - Accessory Nerve, Anterior rami of spinal nerve

Action:
Superior fibers - elevation and upward rotation of scapula, lateral flexion of the neck
Middle fibers - adduction of the scapula
Inferior fibers - depression and upward rotation of the scapula

Question 2

Latissimus Dorsi

Answer 2

Origin:
Spinous process of T7 - L5, thoracolumbar fascia, iliac crest, last 3 ribs

Insertion:
Humerus

Innervation:
Thoracodorsal nerve, Anterior rami of spinal nerve

Action:
Extends, adducts, and medially rotates humerus

Question 3

Rhomboid Major

Answer 3

Origin:
Spinous process of T2-T5

Insertion:
Medial border of scapula below base of spine of scapula

Innervation:
Dorsal scapular nerve, Anterior rami of spinal nerve

Action:
Fixes scapula to thoracic wall and retracts and rotates it to depress glenoid cavity

Question 4

Rhomboid Minor

Answer 4

Origin: Nuchal ligament, spines of C7 and T1

Insertion:
Medial border of scapula at spine of scapula

Innervation:
Dorsal scapular nerve, Anterior rami of spinal nerve

Action: Fixes scapula to thoracic wall and retracts and rotates it to depress glenoid cavity

Question 5

Levator Scapulae

Answer 5

Origin: Posterior tubercles of transverse processes of C1-C4

Insertion:
Medial border of scapula from superior angle

Innervation: Anterior rami of C3-C4 and dorsal scapular nerve

Question 6

Serratus Posterior Superior

Answer 6

Origin:
Nuchal ligament, spinous process of C7-T3

Insertion:
Superior aspect of ribs 2-4

Innervation:
Anterior rami of upper thoracic nerves

Action: Elevates ribs

Question 7

Serratus Posterior Inferior

Answer 7

Origin:
Spinous process of T11-L2

Insertion:
Inferior aspect of ribs 9-12

Innervation:
Anterior rami of lower thoracic nerves

Action:
Depresses ribs

Question 8

Erector spinae

• Spinalis: Medial
• Longissimus: Intermediate
• Iliocostalis: Lateral

Answer 8

Innervation: Posterior rami of spinal nerves

Question 9

Splenius Capitis

Answer 9

Origin:
Nuchal ligament, spinous process of C7-T3

Insertion:
Mastoid process of temporal bone, lateral third of superior nuchal line

Innervation:
Posterior rami of spinal nerve

Action:
Bilaterally - extend head
Unilaterally - laterally bends and rotates face to same side

Question 10

Splenius Cervicis

Answer 10

Origin:
Spinous process of T3-T6

Insertion:
Transverse process C1-C3

Innervation:
Posterior rami of spinal nerve

Action:
Bilaterally - extend head
Unilaterally - laterally bends and rotates face to same side

Question 11

Semispinalis

Answer 11

Origin:
Transverse process of C4-T12

Insertion:
Spinous processes of cervical and thoracic regions

Innervation:
Posterior rami of spinal nerve

Action:
Extends head, neck, and thorax and rotates them to opposite side

Question 12

Multifidus

Answer 12

Origin:
Sacrum, Ilium, transverse processes of T1-T12, and articular processes of C4-C7

Insertion:
Spinous processes of vertebrae above, spanning two to four segments

Innervation:
Posterior rami of spinal nerve

Action:
Stabilizes spine

Question 13

Rotatores

Answer 13

Origin:
Transverse processes of cervical, thoracic, and lumbar regions

Insertion:
Lamina and transverse process of spine above, spanning one or two segments

Innervation:
Posterior rami of spinal nerves

Action:
Stabilizes, extends, and rotates spine

Question 14

Rectus Capitis Posterior Major

Answer 14

Origin:
Spine of axis

Insertion:
Inferior nuchal line

Innervation:
Suboccipital nerve

Action:
Extends and rotates head to the same side

Question 15

Obliquus capitis superior

Answer 15

Origin:
Transverse process of atlas

Insertion:
Occipital bone

Innervation:
Suboccipital nerve

Action:
Extends and bends head laterally

Question 16

Obliquus capitis inferior

Answer 16

Origin:
Spine of axis

Insertion:
Transverse process of atlas

Innervation:
Suboccipital nerve

Action:
Rotates atlas to turn face to the same side

Question 17

Rectus capitis posterior minor

Answer 17

Origin:
Tubercle of posterior arch of atlas

Insertion:
Median inferior nuchal line

Innervation:
Suboccipital nerve

Action:
Extends head

Question 18

Intertransversii

Answer 18

Origin:
Extend between adjacent transverse processes of vertebrae

Insertion:
Extend between adjacent transverse processes of vertebrae

Innervation:
Posterior rami of spinal nerve

Action:
Lateral flexion of vertebral column

Question 19

Interspinales

Answer 19

Origin:
Spinous process

Insertion:
Adjacent spinous process

Innervation:
Posterior rami of spinal nerves

Action:
Extension of vertebral column

Question 20

Superficial Muscles

Answer 20

• Trapezius
• Latissimus dorsi
• Rhomboid Major
• Rhomboid Minor
• Levator Scapulae

Question 21

Intermediate Group

Answer 21

• Serratus posterior inferior

- Serratus posterior superior

Question 22

Deep Group (Superficial)

Answer 22

Erector Spinae

• Spinalis (M)
• Longissimus (I)
• Iliocostalis (L)

Question 23

Deep Group (Intermediate)

Answer 23

• Splenius Capitis

- Splenius Cervicis

Question 24

Deep group (Deep)

Answer 24

• Suboccipital muscles
• Intertransversarii
• Interspinales

Question 25

Suboccipital muscle borders

Answer 25

• Rectus capitis posterior major
• Obliquus capitis superior
• Obliquus capitis inferior