Back & Vertebral Column - Muscles

Question 1

what is the extrinsic superficial back muscle group also called? why are they not considered true back muscles?

Answer 1

also called posterior axioappendicular muscles - not considered true back muscles as they work on the upper limb

Question 2

list the extrinsic intermediate back muscles (2) - what do they do?

Answer 2

serratus posterior superior - elevates ribs during inspiration

serratus posterior inferior - depresses ribs during expiration

Question 3

what rami innervates all extrinsic back muscles?

Answer 3

anterior rami

Question 4

what are the two muscles of the spinotransversalis group of back muscles? what are their unilateral & bilateral actions?

Answer 4

splenius capitus & splenius cervicis

unilateral action - ipsilateral (same side) rotation & lateral flexion

bilateral action - head & neck extension

Question 5

what is the spinotransversalis group?

Answer 5

the intrinsic superficial muscle group

Question 6

what is the erector spinae group?

Answer 6

intrinsic intermediate back muscles - spinalis, longissimus, iliocostalis

Question 7

origin and insertion of splenius capitus?

Answer 7

origin: nuchal ligament & spinous processes C7-T4

insertion: temporal & occipital bones

Question 8

origin and insertion of splenius cervicis?

Answer 8

origin: spinous processes of T3-6

insertion: transverse processes of C1-3

Question 9

what are the three muscles of the erector spinae group? they all share a common origin, but where do they each insert?

Answer 9

spinalis - inserts on transverse processes, closest to spine

longissimus - inserts on skull, longest

iliocostalis - inserts on ribs, most lateral

Question 10

unilateral & bilateral actions of the erector spinae group?

Answer 10

unilateral - ipsilateral (same side as contracting muscle) lateral flexion

bilateral - VC extension, prevents spine from flexing when bending forward

Question 11

muscles of the transversospinalis/ intrinsic deep back muscle group? (3) where are they each located?

Answer 11

semispinalis - located in upper half of spinal cord, consists of 3 parts (capitus, cervicis, thoracis)

multifidus - from sacrum to C2

rotatores - most pronounced in thoracic region

Question 12

clinical significance of atrophy of the multifidus muscle?

Answer 12

multifidus is a major stabiliser of the spine

atrophy of this muscle = higher risk of back pain - physiotherapy rehab focuses on strengthening this muscle

Question 13

bilateral & unilateral action of transversospinalis muscles?

Answer 13

unilateral - contralateral (opposite side) rotation

bilateral - extension of VC