Abdominal Wall

TERMINOLOGY

Definitions

• Abdomen: Region between diaphragm and pelvis

GROSS ANATOMY

Anatomic Boundaries of Anterior Abdominal Wall

• Superiorly: Xiphoid process and costal cartilages of 7th-10th ribs
• Inferiorly: 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 also formed by these aponeuroses as they surround rectus muscle
• Linea semilunaris is vertical fibrous band at lateral edge of rectus sheath bilaterally

Aponeuroses of internal and transversus abdominis join in linea semilunaris before forming rectus sheath
• 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
• Transversus abdominis (transversalis) 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
• 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
• Quadratus lumborum: Thick sheet of muscle lying adjacent to transverse processes of lumbar vertebrae

Invested by lumbodorsal fascia

Origin: Iliac crest and transverse processes of lumbar vertebrae

Insertion: 12th rib

Actions: Stabilizes position of thorax and pelvis during respiration, walking; bends trunk to side

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

TERMINOLOGY

Definitions

GROSS ANATOMY

Anatomic Boundaries of Anterior Abdominal Wall

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Abdominal Wall

Abdominal Wall

Muscles of Anterior Abdominal Wall

Muscles of Posterior Abdominal Wall

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Abdominal Wall

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