Abdominal Wall and Paraspinal Structures

TERMINOLOGY

Definitions

• Abdomen: Region between diaphragm and pelvis

GROSS ANATOMY

Anatomic Boundaries

• Anterior abdominal wall is bounded superiorly by xiphoid process and costal cartilages of 7th-10th ribs
• Anterior wall is bounded inferiorly by iliac crest, iliac spine, inguinal ligament, and pubis
• Inguinal ligament is inferior edge of aponeurosis of external oblique muscle

Muscles of Anterior Abdominal Wall

• Consist of 3 flat muscles (external oblique, internal oblique, and transverse abdominal) and 1 strap-like muscle (rectus)
• Combination of muscles and aponeuroses (sheet-like tendons) act as corset to confine and protect abdominal viscera
• Linea alba is fibrous raphe stretching from xiphoid to pubis

Forms central anterior attachment for abdominal wall muscles

Formed by interlacing fibers of aponeuroses of oblique and transverse abdominal muscles

Rectus sheath is also formed by these aponeuroses as they surround rectus muscle
• External oblique muscle

Largest and most superficial of 3 flat abdominal muscles

Origin: External surfaces of ribs 5-12

Insertion: Linea alba, iliac crest, pubis via broad aponeurosis
• Internal oblique muscle

Middle of 3 flat abdominal muscles

Runs at right angles to external oblique

Origin: Posterior layer of thoracolumbar fascia, iliac crest, and inguinal ligament

Insertion: Ribs 10-12 posteriorly, linea alba via broad aponeurosis, pubis
• Transverse abdominal muscle

Innermost of 3 flat abdominal muscles

Origin: Lowest 6 costal cartilages, thoracolumbar fascia, iliac crest, inguinal ligament

Insertion: Linea alba via broad aponeurosis, pubis
• Rectus abdominis muscle

Origin: Pubic symphysis and pubic crest

Insertion: Xiphoid process and costal cartilages 5-7

Rectus sheath: Strong fibrous compartment that envelops each rectus muscle

– Contains superior and inferior epigastric vessels

3 tendinous intersections divide rectus sheath into distinct muscle bellies

– This gives rise to 6-pack appearance of well-developed rectus abdominis musculature

Arcuate line lies about midway between umbilicus and pubic crest

– Above arcuate line, internal oblique aponeurosis splits to enclose rectus muscle

– Below arcuate line, internal oblique passes wholly in front of rectus muscle so that rectus muscle lies directly on transversalis fascia
• Actions of anterior abdominal wall muscles

Support and protect abdominal viscera

Help flex and twist trunk, maintain posture

Increase intraabdominal pressure for defecation, micturition, and childbirth

Stabilize pelvis during walking, sitting up
• Transversalis fascia

Lies deep to abdominal wall muscles and lines entire abdominal wall

Separated from parietal peritoneum by layer of extraperitoneal fat

Muscles of Posterior Abdominal Wall

• Consist of psoas (major and minor), iliacus, and quadratus lumborum
• Psoas: Long, thick, fusiform muscle lying lateral to vertebral column

Origin: Transverse processes and bodies of vertebrae T12-L5

Insertion: Lesser trochanter of femur (passing behind inguinal ligament)

Action: Flexes thigh at hip joint; bends vertebral column laterally
• Iliacus: Large, triangular sheet of muscle lying along lateral side of psoas

Origin: Superior part of iliac fossa

Insertion: Lesser trochanter of femur (after joining with psoas tendon)

Action: Iliopsoas muscle flexes thigh

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Apr 9, 2020 | Posted by admin in MUSCULOSKELETAL IMAGING | Comments Off

TERMINOLOGY

Definitions

GROSS ANATOMY

Anatomic Boundaries

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Abdominal Wall and Paraspinal Structures

Abdominal Wall and Paraspinal Structures

Muscles of Anterior Abdominal Wall

Muscles of Posterior Abdominal Wall

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Abdominal Wall and Paraspinal Structures

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