Muscles_of_the_Trunk_-_Lecture_Slides__1_

Spine & Thorax Overview

• Focuses on understanding the anatomy and function of spinal and thoracic muscles.

Learning Objectives

• Palpate spine and thorax muscles from origin to insertion, noting shape, edges, and fiber direction(s).

• Describe the relationship between topographical contours and underlying musculoskeletal structures, including skin and fascial texture, thickness, and mobility.

• Identify and locate muscles of the spine and thorax, detailing origins and insertions.

• List and demonstrate actions of each spinal and thorax muscle.

Week 1 Muscles of the Spine and Thorax

• Erector Spinae Group:

  • Iliocostalis

  • Longissimus

  • Spinalis

• Transversospinalis Group:

  • Semispinalis

  • Multifidus

  • Rotatores

• Interspinales and Intertransversarii

• Serratus Posterior Group:

  • Superior and Inferior

• Quadratus Lumborum

• These muscles are found on the posterior surface of the trunk; some are deep and not easily palpated.

• Additional bony palpations will be conducted in lab.

Muscle Locations and Functions

• Muscles that Move the Vertebral Column:

  • Major muscles include the Semispinalis, Oblique Capitis, among others.

• Important landmarks include:

  • Superior nuchal line, spinous processes, and various specific vertebral sections (C-2, C-7, L-3, T-8).

Muscle Anatomy

1. Erector Spinae Group

• Function (A):

  • Unilaterally: Laterally flex vertebral column.

  • Bilaterally: Extend vertebral column.

• Origin (O):

  • Common tendon (thoracolumbar fascia) attaching to the posterior surface of sacrum, iliac crest, and spinous processes of lumbar and last two thoracic vertebrae.

• Insertion (I):

  • Various attachments including posterior ribs and spinous processes of thoracic and cervical vertebrae.

2. Spinalis

• Origin (O):

  • Thoracis: Spinous processes of upper lumbar and lower thoracic vertebrae (T11-L2).

  • Cervicis: Ligamentum nuchae and spinous process of C7.

• Insertion (I):

  • Thoracis: Spinous processes of upper thoracic vertebrae (T4-T8).

  • Cervicis: Spinous processes of all cervical vertebrae (except C1).

3. Longissimus

• Origin (O):

  • Thoracis: Common tendon (TVPs of L1-L5).

  • Cervicis and Capitis: Transverse processes of upper five thoracic vertebrae (T1-T5).

• Insertion (I):

  • Thoracis: Lower nine ribs and transverse processes of thoracic vertebrae.

  • Cervicis: Transverse processes of cervical vertebrae; Capitis: Mastoid process of the temporal bone.

4. Iliocostalis

• Most Lateral (Ribs):

• Origin (O):

  • Lumborum: Common tendon (sacrum, iliac crest).

  • Thoracis and Cervicis: Posterior surface of ribs 1-12.

• Insertion (I):

  • Lumborum: TVPs of lumbar vertebrae and posterior surface of ribs 6-12.

  • Thoracis: Posterior surface of ribs 1-6; Cervicis: Transverse processes of lower cervical vertebrae (C4-C6).

5. Multifidi

• Function (A):

  • Unilaterally: Rotate vertebral column to the opposite side.

  • Bilaterally: Extend the vertebral column.

• Origin (O):

  • Sacrum and transverse processes of lumbar through cervical vertebrae.

• Insertion (I):

  • Spinous processes of lumbar vertebrae through second cervical vertebra.

6. Rotatores

• Function (A):

  • Unilaterally: Rotate vertebral column to the opposite side.

  • Bilaterally: Extend the vertebral column.

• Similar to Multifidi in origins and insertions.

7. Semispinalis Capitis

• Function (A):

  • Extend the vertebral column and head.

• Origin (O):

  • Transverse processes of C-4 to T-5.

• Insertion (I):

  • Between the superior and inferior nuchal lines of the occiput.

8. Quadratus Lumborum

• Function (A):

  • Unilaterally: Laterally tilt/elevate pelvis; laterally flex vertebral column; assist in extension.

  • Bilaterally: Fix last rib during forced inhalation/exhalation.

• Origin (O):

  • Posterior iliac crest.

• Insertion (I):

  • Last rib and transverse processes of first through fourth lumbar vertebrae.

9. Serratus Posterior Superior and Inferior

• Functions:

  • Superior: Elevate ribs during inhalation (ribs 2-5).

  • Inferior: Depress ribs during exhalation.

• Superior Origin (O):

  • Spinous processes of C-7 to T-3.

• Inferior Origin (O):

  • Spinous processes of T-12 to L-3.

10. Intertransversarii and Interspinalis

• Intertransversarii A:

  • Unilaterally: Laterally flex vertebral column; Bilaterally: Extend vertebral column.

  • Spanning transverse processes of cervical (C-2 to C-7) and lumbar (L-1 to L-5) vertebrae.

• Interspinalis A:

  • Extend the vertebral column, spanning the spinous processes of cervical and lumbar vertebrae.

Practical Applications

Lab Preparation

• Upcoming Weeks:

  • Week 4: Palpation of trunk muscles.

  • Week 5: Competency Evaluation #2 (Written).

    • Must identify muscles based on image and description (origin/insertion/action).

    • Details like contralateral/ipsilateral actions are important.

    • Understanding comparative muscle location is crucial (medial/lateral, deeper/superficial).

Assignment Guidelines

• First assignment: Due February 7th.

• Original work required; AI tools are prohibited. Ensure to cite any sources used.

• Late submissions incur a 10% deduction per day unless prearranged.

• Review the assignment details on Moodle for full marks.