Intrinsic Back Muscles - Intermediate Layers Of Erector Spinae

Question 1

Iliocostalis

Answer 1

Proximal- aponeurosis tethered to iliac crest, sacrum, sacroiliac ligaments, and sacral & lumbar spinous processes

Distal- posterior ribs; transverse processes of cervical vertebrae

Action- unilateral: lateral flexion of vertebral column
Bilateral: extension of head and vertebral column

Innervation: posterior rami of spinal nerves

Question 2

Longissimus

Answer 2

Proximal- Aponeurosis tethered to iliac crest, sacrum, sacrum, sacroiliac ligaments, and sacral & lumbar spinous processes

Distal- ribs and mastoid process skull

Action- unilateral: lateral flexiob of vertebral column
Bilateral: extension of head and vertebral column

Innervation- posterior rami of spinal nerves

Question 3

Spinalis

Answer 3

Origin- aponeurosis tethered to iliac crest, sacrum, sacroiliac ligaments, and sacral & lumbar spinous processes

Distal- spinous processes in upper thoracic region and cranium

Action- unilateral: lateral flexion of vertebral column
Bilateral: extension of head and vertebral column

Innervation- posterior rami of spinal nerves