Deep Deep Layer

• Transversospinal
  • Semispinalis
    • Bony Attachments:
      • 1. Transverse Process (TP) of T4-T12
      • 2. Thoracis, cervicis, and capitis fibers run superomedially to occiput bone (capitis) and SP in thoracic and cervical regions, spanning 4-6 segments
    • Innervation: Post. rami of spinal nerves (cervical)
    • Arterial Supply: Dorsal branch of Post. Intercostal a.
    • Action: Extend head and thoracic and cervical regions of Vertebral Column and rotates them contralaterally
  • Multifidus
    • Bony Attachments:
      • 1. Sacrum, ilium, lamina & Transverse process (TP) of T1-T3, and articular processes of C4-C7
      • 2. Fibers pass superomedially to SP of vertebrae above spanning 2-4 segments
    • Innervation: Post. rami of spinal nerves
    • Arterial Supply: Dorsal branch of Post. Intercostal a.
    • Action: Stabilizes the V.C.
  • Rotatores
    • Bony Attachments:
      • 1. Transvers Process (TP) of vertebrae
      • 2. Pass superomedially to attach to junction of lamina and Spinous Process (SP) of vertebra above their origin, spanning 1-2 segments
    • Innervation: Post. rami of spinal nerves
    • Arterial Supply: Dorsal branch of Post. Intercostal a.
    • Action: Extension and rotatory movements of V.C.
• Interspinalis
  • Bony Attachments:
    • 1. Base of spinous processes (SP)
    • 2. Base of spinous processes (SP) of higher vertebrae
  • Innervation: Post. rami of spinal nerves
  • Arterial Supply: Thoracic branch of intercostal a., lumbar a.
  • Action: Aids in stability of spinal flexion and extension
• Intertransversii
  • Bony Attachments:
    • 1. Transverse Process (TP)
    • 2. TP of higher vertebrae
  • Innervation: Post. rami of spinal nerves
  • Arterial Supply: Thoracic branch of intercostal a., lumbar a.
  • Action: Assist in lateral flexion of the spine