Muscles of Back (Pages 117-129)

Questions and Answers

What is the primary function of the intrinsic back muscles?

Support the abdominal cavity

Maintain posture and control movements of the vertebral column (correct)

Facilitate arm movement

Provide respiratory assistance

Which of the following accurately describes the thoracolumbar fascia?

A covering that is thin in the lumbar region and thick in the thoracic region

A fascia that extends from the pelvis to the cranium

A thickening of the supraspinous ligament

A strong and thick covering for muscles in the lumbar region (correct)

Which layer of intrinsic back muscles is referred to as the superficial layer?

Splenius muscles (correct)

Serratus posterior

Erector spinae

Transversospinales

What are the three columns of the erector spinae muscles?

Iliocostalis, longissimus, spinalis Signup and view all the answers

How are the intrinsic back muscles innervated?

By the posterior rami of spinal nerves Signup and view all the answers

What is the anatomical position of the erector spinae muscles in relation to the vertebral column?

Lateral to the angles of the ribs Signup and view all the answers

Which of the following criteria is used to classify the intrinsic back muscles?

Layers based on their relationship to the surface Signup and view all the answers

In addition to maintaining posture, what other role do the intrinsic back muscles serve?

Control movements of the vertebral column Signup and view all the answers

What is the primary function of the intrinsic back muscles?

Maintaining posture and producing spinal movements Signup and view all the answers

Which nerve primarily innervates the trapezius muscle?

Spinal accessory nerve (CN XI) Signup and view all the answers

What is the role of serratus posterior muscles?

They are considered superficial respiratory muscles, mainly proprioceptive in function. Signup and view all the answers

Which group of muscles includes the latissimus dorsi?

Superficial extrinsic back muscles Signup and view all the answers

How does body weight distribution affect the back muscles?

It necessitates stronger back muscles to support and move the vertebral column. Signup and view all the answers

Which muscles are categorized as posterior axio-appendicular?

Rhomboids and levator scapulae Signup and view all the answers

What type of nerves innervate the intermediate extrinsic back muscles?

Intercostal nerves Signup and view all the answers

Which of the following best describes the function of the extrinsic back muscles?

They are engaged in producing and controlling movements of the limbs. 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.
Major muscle groups: extrinsic (superficial and intermediate) and intrinsic (deep) back muscles.

Extrinsic Back Muscles

Superficial Extrinsic Muscles:
- Include trapezius, latissimus dorsi, levator scapulae, and rhomboids.
- Connect axial skeleton to pectoral girdle and humerus, facilitating limb movements.
- Primarily innervated by anterior rami of cervical nerves; trapezius specifically innervated by spinal accessory nerve (CN XI).
Intermediate Extrinsic Muscles:
- Serratus posterior (superior and inferior) act as slender respiratory muscles, likely more proprioceptive in function.
- Innervated by intercostal nerves; superior part by the first four intercostals, inferior by the last four.

Intrinsic Back Muscles

Muscles specifically act on the vertebral column, maintaining posture and controlling movements.
Innervated by posterior rami of spinal nerves.
Enclosed by deep fascia, attaching medially to nuchal ligament, spinous processes, supraspinous ligament, and sacrum.

Deep Fascia

Thoracic and lumbar regions have distinct fascial structures:
- Thoracolumbar fascia serves as a thick covering for lumbar muscles and encases thoracic intrinsic back muscles.

Muscle Layers

Superficial Layer:
- Splenius muscles (splenius capitis and splenius cervicis) cover deep neck muscles, resembling a bandage.
- Arise from midline and extend to cervical vertebrae and cranium.
Intermediate Layer:
- Erector spinae muscles lie in a groove alongside the vertebral column, crucial for spinal extension.
- Divided into three columns:
  - Iliocostalis (lateral column)
  - Longissimus (intermediate column)
  - Spinalis (medial column)

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Description

Explore the structure and function of back muscles as discussed in pages 117-129. This quiz covers extrinsic and intrinsic muscle groups, their roles in movement and support of the vertebral column, particularly in the context of body weight distribution. Test your knowledge on anatomy and physiology of the back muscles.