Muscles of Back (Pages 117-129)

Questions and Answers

What is the primary role of extrinsic back muscles?

Facilitate spinal movements

Maintain posture

Support the vertebral column

Produce and control limb movements (correct)

Which muscle receives motor fibers from the spinal accessory nerve (CN XI)?

Rhomboids

Latissimus dorsi

Trapezius (correct)

Levator scapulae

Which group of muscles is described as being responsible for producing posture and spinal movements?

Posterior axio-appendicular muscles

Superficial respiratory muscles

Intrinsic (deep) back muscles (correct)

Extrinsic back muscles

Which of the following muscles is classified as an intermediate extrinsic back muscle?

Serratus posterior superior Signup and view all the answers

What is the primary function of the serratus posterior muscles?

Proprioception rather than motor Signup and view all the answers

Which nerve innervates the serratus posterior superior muscle?

Intercostal nerves Signup and view all the answers

Where are the intrinsic back muscles primarily located?

Alongside the spine Signup and view all the answers

What muscle connects the axial skeleton to the superior appendicular skeleton?

Trapezius Signup and view all the answers

What is the primary function of the intrinsic back muscles?

To maintain posture and control movements of the vertebral column Signup and view all the answers

Which layer of intrinsic back muscles covers the deep neck muscles?

Superficial layer Signup and view all the answers

What is the role of the thoracolumbar fascia?

To serve as a covering for the intrinsic back muscles in the thoracic and lumbar regions Signup and view all the answers

Which muscle group is considered the chief extensor of the vertebral column?

Erector spinae muscles Signup and view all the answers

How are the erector spinae muscles organized?

Into three columns: iliocostalis, longissimus, and spinalis Signup and view all the answers

Which structure does the deep fascia of the intrinsic back muscles attach to laterally?

Cervical and lumbar transverse processes and the angles of the ribs Signup and view all the answers

What does the term 'splenion' refer to in the context of intrinsic back muscles?

A muscle that covers the neck like a bandage Signup and view all the answers

What type of innervation do intrinsic back muscles receive?

Dorsal rami of spinal nerves Signup and view all the answers

Study Notes

Overview of Back Muscles

Body weight distribution is anterior to the vertebral column, necessitating strong back muscles for support and movement.
Back muscles are categorized into two main groups: extrinsic and intrinsic.

Extrinsic Back Muscles

Comprises superficial and intermediate muscles responsible for limb and respiratory movements.
Superficial extrinsic muscles include:
- Trapezius: Receives motor fibers from the spinal accessory nerve (CN XI).
- Latissimus Dorsi: Attaches to the humerus, facilitating arm movements.
- Levator Scapulae: Elevates the scapulae.
- Rhomboids: Retracts the scapulae.
Intermediate muscles, mainly serratus posterior (superior and inferior), act as proprioceptors rather than motors, innervated by intercostal nerves:
- Serratus posterior superior: Located deep to rhomboids and innervated by the first four intercostal nerves.
- Serratus posterior inferior: Located deep to latissimus dorsi and innervated by the last four intercostal nerves.

Intrinsic Back Muscles

These muscles maintain posture and control vertebral column movements, innervated by the posterior rami of spinal nerves.
Enclosed by deep fascia that connects to the nuchal ligament, spinous processes, and various vertebral landmarks.
The thoracolumbar fascia provides structural support to the lumbar intrinsic back muscles.

Muscle Layers

Superficial Layer:
- Splenius Muscles: Thick and flat, covering deeper neck muscles. Includes:
  - Splenius Cervicis: Extends to cervical vertebrae.
  - Splenius Capitis: Extends to the cranium.
Intermediate Layer:
- Erector Spinae Muscles: Chief extensors of the vertebral column, positioned in a groove alongside the spine.
  - Iliocostalis: Lateral column of the erector spinae.
  - Longissimus: Intermediate column.
  - Spinalis: Medial column.

Function and Structure

Superficial muscles are primarily involved in limb movement, while intrinsic muscles focus on spine stability and movement.
Proper function of these muscles is essential for maintaining posture and enabling complex movements of the upper body.

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Description

This quiz focuses on the back muscles discussed from pages 117 to 129. Learn about the major groups of muscles, including extrinsic and intrinsic back muscles, their functions, and their importance in supporting the vertebral column. Test your knowledge on the anatomical details and mechanics of these essential muscles.