Podcast
Questions and Answers
What is the primary role of extrinsic back muscles?
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)?
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?
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?
Which of the following muscles is classified as an intermediate extrinsic back muscle?
What is the primary function of the serratus posterior muscles?
What is the primary function of the serratus posterior muscles?
Which nerve innervates the serratus posterior superior muscle?
Which nerve innervates the serratus posterior superior muscle?
Where are the intrinsic back muscles primarily located?
Where are the intrinsic back muscles primarily located?
What muscle connects the axial skeleton to the superior appendicular skeleton?
What muscle connects the axial skeleton to the superior appendicular skeleton?
What is the primary function of the intrinsic back muscles?
What is the primary function of the intrinsic back muscles?
Which layer of intrinsic back muscles covers the deep neck muscles?
Which layer of intrinsic back muscles covers the deep neck muscles?
What is the role of the thoracolumbar fascia?
What is the role of the thoracolumbar fascia?
Which muscle group is considered the chief extensor of the vertebral column?
Which muscle group is considered the chief extensor of the vertebral column?
How are the erector spinae muscles organized?
How are the erector spinae muscles organized?
Which structure does the deep fascia of the intrinsic back muscles attach to laterally?
Which structure does the deep fascia of the intrinsic back muscles attach to laterally?
What does the term 'splenion' refer to in the context of intrinsic back muscles?
What does the term 'splenion' refer to in the context of intrinsic back muscles?
What type of innervation do intrinsic back muscles receive?
What type of innervation do intrinsic back muscles receive?
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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.
- Splenius Muscles: Thick and flat, covering deeper neck muscles. Includes:
- 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.
- Erector Spinae Muscles: Chief extensors of the vertebral column, positioned in a groove alongside the spine.
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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