Table of Contents
Overview – Axial Skeleton Muscles
The axial skeleton muscles are essential for posture, spinal movement, and maintaining trunk stability. These muscles, which span the length of the vertebral column, are commonly grouped into superficial, intermediate, and deep layers. A solid understanding of their anatomy and function is crucial for diagnosing and treating musculoskeletal and neurological conditions affecting spinal movement and back pain.
Erector Spinae (Superficial Group)
The erector spinae muscles form the most superficial group of deep back muscles and are responsible for maintaining upright posture and controlling spinal extension and lateral flexion.
Iliocostalis
- Subdivisions: Lumborum, thoracis, cervicis
- Position: Lateral-most column
- Origin: Iliac crest
- Insertion: Ribs (lumbar & thoracic) and transverse processes of cervical vertebrae
Longissimus
- Subdivisions: Thoracis, cervicis, capitis
- Position: Intermediate column between iliocostalis and spinalis
- Origin: Transverse processes of lumbar, thoracic, and cervical vertebrae
- Insertion: Ribs (superior to origin), or transverse processes of thoracic and cervical vertebrae
Spinalis
- Subdivisions: Thoracis, cervicis, capitis
- Position: Medial-most column
- Origin: Spinous processes of upper-lumbar and lower-thoracic vertebrae
- Insertion: Spinous processes of upper-thoracic and cervical vertebrae
Transversospinalis (Intermediate Group)
These muscles lie deep to the erector spinae and contribute to vertebral stability, rotation, and extension.
Semispinalis
- Spans several vertebral segments
- Prominent in the thoracic and cervical regions
Multifidus
- Runs from sacrum to cervical spine
- Thickest in lumbar region
- Major stabiliser of vertebral column
Rotatores
- Most prominent in thoracic region
- Short muscles spanning 1–2 vertebrae
- Assist in local rotation and proprioception
Deep Group (Minor Deep Layer)
These are the deepest intrinsic muscles of the back and assist with fine-tuned movements and postural control.
Intertransversarii
- Connect adjacent transverse processes
- Aid in lateral flexion of the spine
Interspinales
- Connect adjacent spinous processes
- Assist with spinal extension and stability
Summary – Axial Skeleton Muscles
The axial skeleton muscles include the erector spinae, transversospinalis, and deep stabilising muscle groups. These intrinsic back muscles are essential for posture, movement, and vertebral column support. For a broader context, see our Musculoskeletal Overview page.