Anatomy of Back Muscles

Study Notes

Quadratus lumborum:
- Active in lateral stability of the lumbar region, acting as a restraint to lateral shear of the vertebrae
- Weak lateral flexor of the lumbar spine
Latissimus dorsi:
- Plays a role in core stability with overhead movement
- Attaches to the lumbar spinous processes through its integration with the thoracolumbar fascia
- Active in providing core stabilization with trunk extension and quadruped exercises

Origin: Sacrum, lumbar, and cervical transverse processes
Insertion: Spinous processes of all vertebrae
Actions: Extension of trunk and neck, lateral flexion of trunk and neck, contralateral rotation of trunk and neck
Deep muscle located along the back of the spine, close to the midline
Functions together with transverse abdominis and pelvic floor muscles to stabilize the low back and pelvis
Important stabilizer of the back
People with low-back pain often have wasting of the multifidus muscle on the painful side

External oblique:
- Attaches proximally on the lower six ribs and runs medially and inferiorly to attach distally to the iliac crest, pubis, and linea alba
- Fiber orientation allows for flexion, side bending, and rotation of the trunk to the opposite side
- Works together with the internal oblique to produce rotation of the spine to both sides
Internal oblique:
- Attaches proximally on the lower six ribs and runs distally to attach to the iliac crest, iliopsoas fascia, thoracolumbar fascia, and inguinal ligament
- Primary actions: flexion, side bending, and rotation of the trunk to the same side
- Works together with the external oblique to produce rotation of the spine to both sides

Attaches proximally at the costal cartilage of ribs 6-12 and attaches distally to the iliac crest
Attaches posteriorly to the thoracolumbar fascia and anteriorly to the abdominal fascia
Encircles the abdomen, providing stability to the spine
Can create and increase intra-abdominal pressure, which helps stabilize the spine
Works together with the obliques to form a loop around the abdomen, stiffening and stabilizing the spine during activity

Attaches proximally to the 12th rib, transverse processes of all lumbar vertebrae, and attaches to the iliac crest and iliolumbar ligament
Often referred to as the "forgotten" muscle of the core

Simultaneous contraction with the pelvic floor muscles and abdominal muscles increases intra-abdominal pressure, which helps stabilize the spine

Covers the deep muscles of the back and trunk, including the multifidi
Important structure that connects the lower limbs (via gluteus maximus) to the upper limbs (via latissimus dorsi)
Attaches to the internal obliques and transverse abdominis muscles, providing 3D support to the lumbar spine and aiding core stability
Helps to form a "hoop" around the abdomen, creating a stabilizing corset effect
Allows the core to be included in integrated kinetic chain activities such as throwing