Abdominal Muscles and Nerves Overview

Abdominal Muscles Overview

• Rectus Abdominis: Vertical muscle covering the front of the abdomen; important for trunk flexion.
• External Obliques: Positioned on each side of the abdomen; assist in trunk rotation and lateral flexion.
• Internal Obliques: Located beneath the external obliques; facilitate trunk rotation and abdominal compression.
• Transverse Abdominis: The deepest abdominal muscle; crucial for pelvic and lower back stabilization.

Nerves Associated with Abdominal Muscles

• Intercostal Nerves: Innervate abdominal muscles, supporting movement and respiration.
• Subcostal Nerve: Supplies the lower rectus abdominis and adjacent muscles.
• Iliohypogastric Nerve: Innervates the lower abdominal wall, aiding various abdominal functions.
• Ilioinguinal Nerve: Provides sensation to the groin and innervates lower abdominal muscles.

Nerve Roots

• T7-T11: Innervate abdominal muscles, facilitating trunk flexion and rotation.
• T12: Connects primarily with the rectus abdominis, enhancing abdominal function.
• L1 (via T12): Affects the lower abdominal muscles; significant for flexion and stabilization.

Actions of Abdominal Muscles

• Pelvic-Trunk Rotation: Vital for coordinated movement and stability in physical activities.
• Trunk Rotation: Allows twisting motions of the torso, crucial in sports and daily tasks.
• Abdominal Compression: Raises intra-abdominal pressure; essential for heavy lifting and forceful exhalation.

Major Muscle Groups

• Rectus Abdominis

  • Located vertically along the abdomen's front; functions to flex the spine, ensure core stability, and assist in breathing.
  • Segmented appearance often associated with "abs."

• External Obliques

  • Positioned on the abdomen's sides and running diagonally; involved in trunk rotation, lateral flexion, and abdominal compression.

• Internal Obliques

  • Found beneath the external obliques, running in an opposing diagonal; supports trunk rotation, lateral flexion, and abdominal compression.

• Transverse Abdominis

  • Considered the deepest layer of abdominal muscles, wrapping around the torso; crucial for stabilizing the spine and pelvis, acting similar to a corset.

Muscle Layers

• Superficial Layer: Comprises the rectus abdominis and external obliques.
• Intermediate Layer: Contains the internal obliques.
• Deep Layer: Encompasses the transverse abdominis.

Other Structures

• Linea Alba: A fibrous structure along the midline, dividing the two rectus abdominis muscles.
• Inguinal Ligament: A key band running from the pubic bone to the ilium, important for abdominal integrity.

Innervation

• Primarily affected by lower thoracic nerves (T7-T12) and iliohypogastric and ilioinguinal nerves.

Blood Supply

• Supplied by branches from the abdominal aorta and femoral artery, especially the epigastric arteries.

Functionality

• Core Stability: Essential for maintaining posture and stability during various movements.
• Movement: Facilitates actions such as bending, twisting, and lifting.
• Protection: Guards internal organs from potential injury.

Clinical Relevance

• Weakness or injury in abdominal muscles may result in back pain and postural problems.
• Conditions like hernias primarily affect abdominal muscles, especially in the inguinal region.