superficial intrinsic back muscles

Question 1

splenius capitis

Answer 1

• origin: ligamentum nuchae and spines of C7-T6
• insertion: mastoid process and superior nuchal line
• action: extends and laterally bends the neck and head, rotates head to the same side

Question 2

splenius cervicis

Answer 2

• origin: ligamentum nuchae and spines of C7-T6
• insertion: transverse processes of C1-3 and posterior tubercle of C3
• action: extends and laterally bends neck and head, rotates head to the same side

Question 3

erector spinae

Answer 3

• erector spinae spinalis: most medial
• erector spinae longissimus: intermediate
• erector spinae iliocostalis: most lateral
• spinalis and longi: thoracis, cervicis and capitis portions
• iliocostalis: lumborum, thoracis and cervicis portions
• To maintain the upright posture.
  Acting unilaterally they can laterally
  flex the trunk.