Muscles of the Back

Question 1

What is the organizational hierarchy of the back muscles?

Answer 1

1: superficial layer of the back
2: intermediate layer of the back
3: deep layer of the back
*deep layer also has 3 layers:
-superficial layer of the deep back muscles
-intermediate layer of the deep back muscles
-deep layer of the deep back muscles

Question 2

What muscles are located in the superficial layer of the back?

Answer 2

-trapezius
-latissimus dorsi
-rhomboid major/minor
-levator scapula

Question 3

What is the trapezius muscle (superficial layer of the back)?

Answer 3

-triangular muscle of the back
3 regions:
-upper trap
-mid trap
-lower trap

Question 4

What are the attachements for the trapezius?

Answer 4

-starts in the occiput and runs down the nuchal ligament and spinous processes of C7-C12
-comes of the spine of the scapula, acromion, and clavicle

Question 5

What is the innervation of the trapezius?

Answer 5

CN11

Question 6

What are the attachments for the latissimus dorsi (superficial layer of the back)?

Answer 6

Run along the spinous processes of the lower thoracic spine and continues down to the sacrum

-attach to the thoracolumbar fascia (fascia from lower thoracic spine to sacrum) and iliac creat

Question 7

What are the attachments for the rhomboids (superficial layer of the back)?

Answer 7

Runs doe the nuchal ligament and spinous processes of C7-T5 and connects to the medial border of the scapula

Major: larger set of muscle bands of fibers below minor

Minor: small muscle band of fibers above major

Question 8

What are the attachments for the levator scapula?

Answer 8

Runs down the cervical spine (C1-C4) and attaches down to the very top part of the medial border of the scapula

Question 9

What muscles are contained in the intermediate layer of the of the back?

Answer 9

-serratus posterior superior
-serratus posterior inferior

Question 10

What are the attachment points for the serratus posterior superior (intermediate layer of the back)?

Answer 10

Runs down the spinous processes of C7-T3 and attaches to the UPPER ribs
(located deep to rhomboid)

Question 11

What are the attachment points for the serratus posterior inferior (intermediate layer of the back)?

Answer 11

Runs down the spinous processes of T11-L1 and attaches to the LOWER ribs
(located deep to lats)

Question 12

Which muscles are located in the deep layer of the back?

Answer 12

3 portions/layers of deep layer of back:
Superficial layer of deep back muscles: Splenius capitis/cervicus
Intermediate layer of deep back muscles: Erector spinae
Deep layer of deep back muscles: Semispinalis, Multifidi, Rotators

Question 13

What are the attachments for the Splenius capitis/cervicus (superficial layer of deep back muscles)?

Answer 13

Runs down the spinous processes of C7-T8 (midline) and anchors onto the transverse processes of C1-4 and eventually connects to the occiput
*“V” shaped muscle that aids in lateral flexion on opposite sides and rotation to the same side

Question 14

What are the Erector spinae (intermediate layer of deep back muscles)? What is their action?

Answer 14

3 vertical columns of the erector spinae: ilicostalis, longissimus, spinalis

Action: extend the back (lean back) and assist with the flexion of the back (muscles contract to create tension to lean forward in a controlled manner against gravity)

Question 15

What are the attachments for the Semispinalis (deep layer of deep back muscles)?

Answer 15

Start at the transverse processes of T12-C4 and “jump way up” to anchor onto the spinous processes 4-6 vertebrae above them

Question 16

What are the attachments for the Multifidi (deep layer of deep back muscles)?

Answer 16

Start at the sacrum, lumbar, and thoracic vertebrae and “jump up” to anchor onto the spinous processes 2-4 vertebrae above them

Question 17

Run What are the attachments for the Rotators (deep layer of deep back muscles)?

Answer 17

Tiny muscles that start at the transverse processes of the entire spine and “jump up” to anchor 1-2 segments above them

Question 18

What are the actions of the semispinalis, multifidi, and rotators?

Answer 18

Contralateral rotation of the spine