Posterior Abdominal Wall Muscles

Study Notes

Posterior Abdominal Wall Muscles

The posterior abdominal wall is located behind the abdominal cavity and is formed by muscles, fascia, and the vertebral column.
The diaphragm, a sheet of muscle separating the thoracic and abdominal cavities, contributes to the posterior abdominal wall.
The lumbar vertebrae are large in humans, due to upright bipedal posture, shaping the posterior abdominal wall.
The psoas major muscle runs from the transverse processes of lumbar vertebrae (T12-L5) to the lesser trochanter of the femur.
Psoas major is a primary hip flexor and aids in lateral flexion of the vertebral column.
Psoas minor, a smaller muscle, runs from vertebral bodies T12 and L1 to the superior ramus of the pubis bone. Its function is less clear, but it may assist in trunk flexion.
The iliacus muscle originates from the iliac crest and ilium wing, also attaching to the lesser trochanter of the femur. Like psoas major, it's a hip flexor.
Iliacus and psoas major blend, forming a single iliopsoas tendon at the insertion point.
Iliacus also contributes to lateral rotation of the femur at the hip joint, especially during hip flexion.
The quadratus lumborum is a flat, rectangular muscle attached to the iliac crest, ilio-lumbar ligament, transverse processes of L1-L4 vertebrae, and the 12th rib.
Quadratus lumborum facilitates lateral flexion of the lumbar vertebral column and helps with extension, when the column is flexed.
The lumbar plexus, also known as the lumbosacral plexus, is in the posterior abdominal wall, forming nerves like the femoral and sciatic nerves.

Fascia of the Posterior Abdominal Wall

Fascia is a connective tissue sheet, surrounding and supporting muscles and structures, shaping the body.
The outer layer of connective tissue surrounding a muscle can become part of a larger fascial sheet.
The thoracic lumbar fascia is a broad sheet, deep in the posterior abdominal wall. It connects posterior abdominal wall muscles, including quadratus lumborum and latissimus dorsi.
The peritoneum, a serous membrane, lines the abdominal cavity, covering viscera and creating mesentery. It provides support, but is separate from the fascia.

Nerve Innervation of Posterior Abdominal Wall Muscles

Psoas major and quadratus lumborum receive innervation from anterior rami of spinal nerves (T12-L4), due to their proximity to the vertebral column.
The iliacus muscle's innervation comes from the femoral nerve, originating from the lumbar plexus (L2-L4), following the femoral vessels.

Description

This quiz focuses on the anatomy and function of the posterior abdominal wall muscles, including the diaphragm, psoas major, psoas minor, and iliacus. Explore how these muscles contribute to hip flexion and the overall structure of the abdominal cavity. Test your knowledge on their origins, attachments, and roles.