Neck & Back: Back Muscles

Question 1

functions of extrinsic & intrinsic groups

Answer 1

extrinsic: moves the upper limbs & ribs
intrinsic: maintains posture & moves vertebral column
movements include flexion (anterior bending), extension, lateral flexion, rotation

Question 2

functions of 3 back layers

Answer 2

superficial: movement of upper limb
intermediate: movement of thoracic wall in respiration
deep: supports & moves vertebral column & head

Question 3

trapezius (superficial)

Answer 3

origin: superior nuchal line, ligamentum nuchae, spinous processes of C7-T12
insertion: lateral 1/3rd of clavicle, acromion process, superior border of spine of scapula
action: retract, laterally rotate, elevate/depress scapula

Question 4

latissimus dorsi (superficial)

Answer 4

origin: spinous processes of T7-L5, sacral iliac crests, inferior 4 ribs (via thoracolumbar fascia)
insertion: intertubercular sulcus of humerus
action: extension, adduction, medial rotation of arm at the shoulder, draws arm inferiorly & posteriorly

Question 5

rhomboid major (superficial)

Answer 5

origin: spinous processes of T2-T5
insertion: medial border of scapula inferior to spine
action: stabilisation, elevation, adduction & downward rotation of scapula

Question 6

rhomboid minor

Answer 6

origin: spinous processes of C7-T1
insertion: medial border of scapula superior to spine
action: stabilisation, elevation, adduction & downward rotation of scapula

Question 7

levator scapulae (superficial)

Answer 7

origin: transverse processes C1-C4
insertion: superior medial boarder of scapula
action: elevation & downward rotation of scapula

Question 8

serratus posterior superior (intermediate)

Answer 8

origin: lower part of ligamentum nuchae, spinous processes of C7-T3
insertion: superior border of ribs 2-5 posteriorly
action: elevation of ribs 2-5

Question 9

serratus posterior inferior (intermediate)

Answer 9

origin: spinous processes of T11-L3
insertion: inferior border of ribs 9-12 posteriorly
action: depression of ribs 9-12

Question 10

action of superficial part of deep layer

Answer 10

extends neck

Question 11

splenius capitis (superficial part of deep)

Answer 11

origin: nuchal ligament, spinous processes of C7-T4
insertion: occipital bone, mastoid process

Question 12

splenius cervicis (superficial part of deep)

Answer 12

origin: spinous processes of T3-T6
insertion: transverse process of C2

Question 13

action of intermediate part of deep layer

Answer 13

bilaterally: extends vertebral column & head
unilaterally: lateral flexion of vertebral column

Question 14

iliocostalis (intermediate part of deep)

Answer 14

lateral
origin: iliac crest /ribs
insertion: posterior angles of ribs

Question 15

longissimus (intermediate part of deep)

Answer 15

origin: transverse processes of thoracic & lumbar vertebrae
insertion: cervical vertebrae, mastoid process

Question 16

spinalis (intermediate part of deep)

Answer 16

medial
origin: ligamentum nuchae, spinous processes of C7 & T10-L2
insertion: spinous processes of superior vertebrae & occipital bone

Question 17

semispinalis (deep part of deep)

Answer 17

origin: transverse processes of C4-T10
insertion: spinous processes of C1-T4, midline of skull between nuchal line
action: extends & contralaterally rotates head & vertebral column

Question 18

multifidus (deep part of deep)

Answer 18

origin: sacrum & posterior ilium, transverse processes of C4-C7, thoracic & lumbar vertebrae
insertion: spinous processes of 2-4 vertebrae above
action: stabilises vertebral column

Question 19

rotatores (deep part of deep)

Answer 19

origin: transverse processes of all vertebrae
insertion: laminae & spinous processes of vertebrae directly above
action: stabilises vertebral column

Question 20

quadratus lumborum

Answer 20

part of abdominal wall but functionally significant in back
origin: iliac crest & iliolumbar ligament
insertion: inferior border 12th rib & L1-L4 transverse processes
action: unilaterally: lateral flexion of lumbar spine
bilaterally: extension of lumbar vertebrae

Question 21

psoas major

Answer 21

origin: transverse processes of lumbar vertebrae
insertion: lesser trochanter of femur
action: flexion of trunk on hip (sitting up)

Question 22

thoracolumbar fascia

Answer 22

layer of dense fascia (muscle covering)
prominent in sacral, lumbar & thoracic regions
provides attachment for upper limb & abdominal wall muscles
tough sheath around back muscles
3 layers
- posterior: posterior to erector spinae muscles – (attaches mainly to lumbar & thoracic spinous processes & medial sacral crest)
- middle & anterior: anterior & posterior to quadratus lumborum (attaches to transverse processes of lumbar vertebrae)