Deep Muscles of the Back

Question 1

What are the intrinsic back muscles?

Answer 1

Intrinsic muscles are the deep back muscles a.k.a: the true back muscles (they originate and insert in the same region)

Function:

• They are primarily extensors and rotaters of the vertebral column also the head
• Help resist against gravity; maintain posture

Question 2

What are the extrinsic back muscles?

Answer 2

Extrinsic back muscles are the superficial muscles of the back and act as muscles of the upper limb

They originate in the back and insert in other regions

Question 3

What is the complex of deep muscles of the back called?

Answer 3

The Erector Spinae Muscles or the Erector Spinae Complex

-the largest muscles mass of the deep back muscles-

Question 4

What muscles make up the erector spinae complex?

Answer 4

From lateral to medial in vertical columns

• Iliocostalis
• Longissimus
• Spinalis

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Question 5

Where does the Iliocastalis orginate and insert/attach?

Answer 5

orginates at ilium and inserts on the ribs

- The most lateral

Question 6

Where does the Longissimus insert/attach?

Answer 6

attach to the transverese processes

Question 7

Where does the Spinalis insert/attach?

Answer 7

They attach to the spinous processes

- The most medial

Question 8

Where do the Erector Spinae Muscles orginate?

Answer 8

The scarum, the iliac crest, and the spinous process of the lumbar vertebra

Question 9

Where do the erector spinae muscles insert?

Answer 9

They travel laterally and anteriorly to insert on the thoracic and cervical vertebra, the ribs, and the skull

Question 10

What is the innervation of the Erector Spinae Muscles?

Answer 10

Dorsal rami of the spinal nerves

Question 11

What are the actions of the erector spiane muscles?

Answer 11

• Acting on both sides; they extend the vertebral column and extend the head
• Acting on one side; Contracting the muscles on one side will cause lateral flexion on the same side