Lecture 22 - Muscles Of The Dorsal Trunk

Question 1

What are the characteristics of dorsal trunk muscles?

Answer 1

• Most body weight lies anterior to the vertebral column
• need strong muscles attaching to the spinous processes & transverse processes to help support and move the vertebral column

Question 2

What are the main groups of dorsal trunk muscles?

Answer 2

• extrinsic
• intrinsic

Question 3

What are the 5 muscles located in the extrinsic group?

Answer 3

• trapezius, latissimus dorsi, levator scapulae, rhomboids major/minor
• located in the dorsal trunk but produce & control upper limb movement

Question 4

What are the 2 groups of intrinsic muscles?

Answer 4

• intermediate; 3 muscles & deep; 3 muscles
• these muscles extend from the pelvis to the skull

Question 5

What is the group of muscles within the intermediate group of the dorsal trunk?

Answer 5

• erector spinae group; contains the iliocostalis, Longissimus, & Spinalis

Question 6

What is the origin/insertion/innervation/main action of the iliocostalis?

Answer 6

• O: Posterior iliac crest, posterior surface of sacrum, sacro-iliac ligaments, sacral & lumbar spinous processes, supraspinous ligament
• I: angles of the ribs above & transverse processes of C4-C7
• Inn: Segmental
• MA: Bilaterally - vertebral column (spine) extension, Unilaterally - vertebral column (spine) side flexion

Question 7

What is the origin/insertion/innervation/main action of the Longissimus?

Answer 7

• O: Posterior iliac crest, posterior surface of sacrum, sacro-iliac ligaments, sacral & lumbar spinous processes, supraspinous ligament
• I: transverse process of the vertebrae above & up as far as the mastoid process
• Inn: Segmental
• MA: Bilaterally - vertebral column (spine) extension, Unilaterally - vertebral column (spine) side flexion

Question 8

What is the origin/insertion/innervation/main action of the Spinalis?

Answer 8

• O: Posterior iliac crest, posterior surface of sacrum, sacro-iliac ligaments, sacral & lumbar spinous processes, supraspinous ligament
• I: spinous processes up to C2
• Inn: Segmental
• MA: Bilaterally - vertebral column (spine) extension, Unilaterally - vertebral column (spine) side flexion

Question 9

What muscle group is part of the deep layer of the dorsal trunk?

Answer 9

• transverseospinalis group
• Occupy the ‘gutter’ between transverse & spinous processes

Question 10

What are the 3 muscles apart of the transverseospinalis group?

Answer 10

• semispinalis
• multifidus
• rotatores

Question 11

What are the common attachment points & main actions of the semispinalis, multifidus, & rotatores?

Answer 11

• Common attachment points: Transverse process of one vertebrae to spinous processes of more superior vertebrae
• MA: Assist with vertebral column (spine) extension & stabilizing individual vertebrae

Question 12

What are the 3 muscles of the posterior abdominal wall?

Answer 12

• psoas major
• iliacus
• quadratus lumborum

Question 13

What is the origin/insertion/innervation/main action of the psoas major?

Answer 13

• O: Anterior bodies, discs, transverse processes of the lumbar vertebrae
• I: Lesser trochanter of the femur
• Inn: Anterior rami of L1-L3
• MA: Hip flexion

Question 14

What is the origin/insertion/innervation/main action of the iliacus?

Answer 14

• O: Superior 2/3 iliac fossa, anterior sacro-iliac ligaments
• I: Lesser trochanter of the femur
• Inn: Femoral nerve
• MA: Hip flexion

Question 15

What is the origin/insertion/innervation/main action of the quadratus lumborum?

Answer 15

• O: Transverse processes of L5, iliolumbar ligament, iliac crest
• I: Inferior border of rib 12, transverse processes of L1-L4
• Inn: anterior rami of T12 & L1-L4
• MA: Side flexion of the lumbar spine (unilateral)