Lecture 10: Intrinsic Back Muscles

Question 0

What rami supply the deep muscles of the back?

Answer 0

Posterior rami of C1, C7, C8, L4 & L5 supply deep muscles of the back but DO NOT supply the skin of the back.

Question 1

The intrinsic back muscles are concerned with?

Answer 1

Movement of the spine and maintenance of posture

Question 2

Name the intrinsic back muscles in each of these layers:
Superficial layer
Intermediate layer
Deep layer

Answer 2

• Superficial layer: splenius capitis, splenius cervicis.
• Intermediate layer: erector spinae (iliocostalis, longissimus, spinalis)
• Deep layer: transversospinalis (semispinalis, multifidus, rotatores)

Question 3

What is the function of the superficial layer?

Answer 3

Cover and gold deep neck muscles in position

Question 4

Superficial layer

Splenius cervicis

Answer 4

Proximal attachment (origin)
Spinous processes of
T3-T6 vertebrae
Distal attachment (insertion)
Transverse processes
of C1-C3 vertebrae
Innervation
Posterior rami of lower cervical spinal nerves
Main action
Unilaterally: laterally flexes and rotates neck to same side
Bilaterally: extends neck

Question 5

Superficial layer

Splenius capitis

Answer 5

Proximal attachment (origin)
Nuchal ligament and spinous processes of C7-T3 vertebrae

Distal attachment (insertion)
Mastoid process of temporal bone and lateral third of superior nuchal line

Innervation
Posterior rami of middle cervical spinal nerves
Main action
Unilaterally: laterally flexes neck and rotates head to same side
Bilaterally: extends head

Question 6

Intermediate muscle layer:

Iliocostalis

Answer 6

Proximal attachment
Posterior sacrum, iliac crest, sacrospinous ligament, supraspinous ligament and spinous processes of lower lumbar & sacral vertebrae
Distal attachment
Angles of lower ribs and cervical transverse processes

Innervation
Posterior rami of spinal nerves
Main action
Unilaterally: Laterally flex vertebral column

Bilaterally: extends vertebral column and head

Most lateral and attachement to ribs and cervical TP

Question 7

Longissimus

Answer 7

Proximal attachment
Posterior sacrum, iliac crest, sacrospinous ligament, supraspinous ligament and spinous processes of lower lumbar & sacral vertebrae

Distal attachment
Between tubercles and angles of ribs, tranverse processes of thoracic and cervical vertebrae, mastoid process
Innervation
Posterior rami of spinal nerves
Main action
Unilaterally: Laterally flex vertebral column

Bilaterally: extends vertebral column and head

Question 8

Label the slide of the cadaver on pg 16

Answer 8

Yep do it it’s in learning objectives

Question 9

Spinalis

Answer 9

Proximal attachment
Posterior sacrum, iliac crest, sacrospinous ligament, supraspinous ligament and spinous processes of lower lumbar & sacral vertebrae

Distal attachment
Spinous processes of upper thoracic and midcervical vertebrae, and cranium
Innervation
Posterior rami of spinal nerves
Main action
Unilaterally: Laterally flex vertebral column

Bilaterally: extends vertebral column and head

Question 10

Name the muscles in the deep layer:

And label the shit out of slides 19, 20 and 21

Answer 10

Transversospinalis

• semispinalis
• multifidus
• rotators

Question 11

Semispinalis

Answer 11

Proximal attachement (origin):
Transverse processes of C4-T12 vertebrae
Distal attachment: spinous process of cervical and thoracic vertebrae
Innervation: posterior rami of spinal nerves
Main action: extends head, neck and thorax and rotates them to the opposite side.

Question 12

Multifundus

Answer 12

Origin: Posterior sacrum, PSIS, aponeurosis of erector spinae, SI ligaments, Mammillary processes of lumbar vertebrae, transverse processes of T1-T12 and articular processes of C4-C7
Distal attachment
Spinous processes of vertebrae above, spanning 2-4 segments
Innervation
Posterior rami of spinal nerves

Main action
Stabilises spine during local movements.
Pain/proprioception.

Question 13

Rotatores

Answer 13

Proximal attachment
Transverse processes
(best developed in thoracic)
Distal attachment
Lamina and transverse processes or spine above, spanning 1 or 2 segments
Innervation
Posterior rami of spinal nerves
Main action
Stabilise, extend and rotate spine.
Proprioception.

Question 14

Learn the slides on pages 25, 26, 27, 28

Answer 14

You

Question 15

The back muscles have _____actvity during the first stages of anterior flexion but decreases as extreme flexed position approached.
Extreme flexed position, the back muscles are relaxed and ligaments take over the stabilising role true or false.
This explains the danger of heavy lifting while the trunk is in extreme flexed position

Answer 15

Increased

Question 16

1. What muscles comprise the superficial layer of intrinsic back muscles?
2. 2. What region of the spine are rotatores best developed?
3. What regions of the spine does semispinalis traverse?
4. What is the largest muscle crossing the sacroiliac joint?
5. Do posterior rami of L1, L2 & L3 innervate muscle and skin of the back?

Answer 16

1. What muscles comprise the superficial layer of intrinsic back muscles? Splenius capitis, splenius cervicis.
2. 2. What region of the spine are rotatores best developed? Thoracic
3. What regions of the spine does semispinalis traverse? Cervical and thoracic
4. What is the largest muscle crossing the sacroiliac joint? Multifidus
5. Do posterior rami of L1, L2 & L3 innervate muscle and skin of the back? YES