Lecture Notes: Skeletal Muscles of the Abdomen

Introduction

• Presented by Patrick.
• Focus on tips and tricks for remembering skeletal muscles of the abdomen.
• Information presented in manageable chunks (4-8 muscles).
• Sponsored by Kenhub.

Abdominal Muscles

1. Rectus Abdominis

   • Known as "abs" or six-pack muscles.
   • Surrounded by connective tissue sheath.
   • Accompanied by pyramidalis muscle (triangular, located at pubic symphysis).

2. External Oblique

   • Wraps around the abdomen; fibers point upwards.

3. Internal Oblique

   • Deep to external oblique; fibers point downwards.
   • Memory aid: extroverts look up, introverts look down.

4. Transverse Abdominis

   • Wraps around abdomen from vertebrae to ribs and pelvis.

5. Quadratus Lumborum

   • Located on the back side of the abdominal wall.
   • Square-shaped, located in lumbar region.

Back Muscles

• Importance of knowing vertebrae anatomy (spinous and transverse processes).
• Some muscles span entire spinal column, others are between vertebrae.

1. Erector Spinae Group

   • Muscles that straighten the spine: Iliocostalis, Longissimus, Spinalis.
   • Organized from medial to lateral.
     • Spinalis: Attaches to spinous processes, most medial.
     • Longissimus: Longest and thickest, runs from pelvis to skull.
     • Iliocostalis: Connects ilium to ribs.

2. Transversospinalis Group

   • Includes Semispinalis, Multifidus, Rotators.
   • Semispinalis: Connects spinous to other processes.
   • Multifidus: Stabilizes spine, made of tiny segments.
   • Rotators: Connect transverse process to lamina and spinous process above.

3. Interspinalis & Intertransversarii

   • Interspinalis: Between spinous processes.
   • Intertransversarii: Between transverse processes.

Thoracic Wall Muscles

• Intercostal Muscles: External and internal, between ribs.

  • Subcostal Muscles: Under the ribs, on inside surface.
  • Levator Costarum: Attaches ribs to thoracic vertebrae, lifts ribs.

• Serratus Posterior

  • Superior and Inferior: Jagged, saw-tooth pattern.
  • Serratus anterior will be discussed later.

• Transversus Thoracis

  • Located on inside of chest wall.

• Diaphragm

  • Main muscle for breathing, separates thoracic and abdominal cavities.

Conclusion

• Memory aids and devices to help remember muscle names and locations.
• Promotion of Kenhub as a resource for learning anatomy.
• Encouraged to subscribe and explore more content.