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Anatomy of the Abdominal Cavity: Muscles

• Anatomy of the abdominal cavity: Muscles
• Anatomy of the abdominal cavity: Nervous system
• Anatomy of the abdominal cavity: Arteries
• Anatomy of the abdominal cavity: Veins and lymphatic system

Muscles of the Abdominal Wall

Ventral and Lateral Abdominal Wall Muscles

Rectus Abdominis Muscle:

Latin: Musculus rectus abdominis. Long, flat, paired muscle. Origin from the ribs and proc. xiphoideus. Insertion at the pubic bone [fig. ventral abdominal muscles right].

Ventral and lateral muscles of abdominal wall: left: Musculus obliquus abdominis externus (M. obl. abd. ext.) = abdominal external oblique muscle. middle: Musculus obliquus abdominis internus (M. obl. abd. int.) = abdominal internal oblique muscle. right: Musculus transversus abdominis (M. trans. abd.) = transverse abdominal muscle. Musculus rectus abdominis (M. rect. abd.) = rectus abdominis muscle. Further muscles: M. pect. maj.: Musculus pectoralis major = pectoralis major muscle. M. serr. ant.: Musculus serratus anterior = serratus anterior muscle. M. lat. dors.: Musculus latissimus dorsi = latissimus dorsi muscle. Fasc. thor.: Fascia thoracolumbalis = thoracolumbar fascia. Figure modified from Gray's Anatomy, Lea and Febinger 1918, Philadelphia, USA.

Rectus Sheath

The rectus abdominis muscle is embedded within the aponeurosis of the lateral abdominal muscles, the rectus sheath. The cranial part of the rectus sheath, above the arcuate line, the aponeuroses divide into a anterior and posterior laminae of the rectus sheath. The caudal part of the rectus sheath, below the arcuate line, all parts of the aponeuroses pass in front of the rectus muscle. For the exact anatomy of the rectus sheath, see fig. rectus sheath.

Anatomy of the rectus sheath: the cranial part of the rectus sheath (top figure) consists of a tendinous anterior and posterior laminae. The anterior laminae consists of the aponeuroses from the external oblique and internal oblique abdominal muscle. The posterior laminae is formed by the aponeuroses of the internal oblique abdominal muscle and transverse abdominal muscle. The arcuate line occurs about half of the distance from the umbilicus to the pubic crest. Below the arcuate line, all parts of the aponeurosis pass in front of the rectus muscle. Figure modified from Gray's Anatomy, Lea and Febinger 1918, Philadelphia, USA.

External Oblique Abdominal Muscle:

Latin: M. obliquus externus abdominis, most superficial of the three flat muscles of the lateral and anterior abdominal wall. Origin from the 6th to 12th ribs. Insertion at the rectus sheath and linea alba [fig. ventral abdominal muscles left].

Internal Oblique Abdominal Muscle:

Latin: M. Obliquus internus abdominis. Muscle layer of the anterior and lateral abdominal wall layered in the middle between the external oblique muscle and transverse abdominal muscle. Origin from the inguinal ligament, iliac crest and the lumbodorsal fascia. Insertion: 9th to 12th ribs, rectus sheath and linea alba [fig. ventral abdominal muscles center].

Transverse Abdominal Muscle:

Latin: M. transversus abdominis. Inner muscle layer of the anterior and lateral abdominal wall layered below the internal oblique muscle. Origin from ribs 6-12, fascia thoracolumbalis, and crista iliaca. On the posterior and posterior sheath of the rectus sheath [fig. ventral abdominal muscles right].

Cremaster muscle:

Latin: M. cremaster. Thin layer of skeletal muscle between the external and internal layers of the spermatic fascia, surrounding the testis and spermatic cord. Origin: internal oblique abdominal muscle. The muscle contraction elevates the testes towards the inguinal canal (cremaster reflex).

Dorsal Muscles of the Abdominal Wall

Quadratus Lumborum Muscle:

Latin: M. quadratus lumborum. Origin from the 12th rib and transverse processes of the lumbar spine, insertion to the iliac crest [fig. dorsal abdominal wall muscles].

Psoas Major Muscle:

Latin: M. psoas major.The psoas muscle forms together with the spine the dorsal boundary of the abdominal cavity. Origin at the vertebral column. The psoas muscle, together with the iliac muscle, passes through the muscular lacuna to the thigh, and acts as a hip flexor by its attachment to the lesser trochanter of the femur. On the ventral side of the psoas muscle, the tendon of the psoas minor muscle may be present in 30-50% (fig. dorsal abdominal wall muscles].

Dorsal abdominal wall muscles: horizontal section in height of the kidney. Figure modified from Gray's Anatomy, Lea and Febinger 1918, Philadelphia, USA.

References

  Deutsche Version: Anatomie Abdomen