Back Musculature

Question 1

Trunk ROM is limited by

Answer 1

• IV discs- elasticity, compressibility
• facet joint orientation
• facet joint capsular tightness
• back muscle & ligamentous resistance
• thoracic (rib) cage attachment

Question 2

What are the 2 main classifications of back muscles?

Answer 2

intrinsic & extrinsic

Question 3

What is the general function of the intrinsic back muscles?

Answer 3

maintain posture and control movements of the vertebral column

Question 4

What are the 3 groups of intrinsic back muscles? What are the muscles within each group?

Answer 4

• superficial group (splenius capitus, splenius cervicis)
• intermediate group (erector spinae)
• deep group (transversospinales)

Question 5

What are the 2 groups of extrinsic back muscles? What are the muscles within each group?

Answer 5

• superficial group (trapezius, latissimus dorsi, levator scapule, rhomboids)
• intermediate group (serratus posterior superior, serratus posterior inferior)

Question 6

Extrinsic superficial group:

1) What is their skeletal-spatial relationship?
2) Function?
3) Innervation?

Answer 6

1) posterior axioappendicular muscles
2) produce and control movements of upper limbs
3) innervated by ventral rami of cervical nerves (except trapezius)

Question 7

Extrinsic intermediate group:

1) What is their skeletal-spatial relationship?
2) Function?
3) Innervation?

Answer 7

1) attached to thoracic wall
2) superficial respiratory muscles & proprioception
3) innervated by ventral rami of intercostal nerves

Question 8

Innervation of intrinsic back muscles?

Answer 8

dorsal rami of spinal nerves

Question 9

Blood supply of intrinsic back muscles?

Answer 9

thoracic area: posterior intercostal arteries
lumbar area: subcostal and lumbar arteries
in general:
-multiple sources
-arteries generally supply structures they contact

Question 10

Attachments of the splenius?

Answer 10

proximal: nuchal ligament & spinous processes C7-T4
distal:
-for splenius capitis, mastoid process & superior nuchal line
-for splenius cervicis: transverse processes of C1-C4

Question 11

Actions of the splenius?

Answer 11

unilateral: laterally flex neck & rotate head side to side
bilateral: extend head and neck

Question 12

What are the 3 subdivisions of the erector spinae?

Answer 12

spinal thoracis
longissimus
iliocostalis

Question 13

Attachments of the erector spinae?

Answer 13

proximal: iliac crest, posterior sacrum, lumbar and sacral spinous processes
distal: angles of the ribs, thoracic and cervical transverse processes, mastoid process

Question 14

Actions of the erector spinae?

Answer 14

bilaterally: extends vertebral column & head
unilaterally: flexes vertebral column

Question 15

What are the 3 subdivisions of transversospinales?

Answer 15

semispinalis
multifidus
rotatores

Question 16

Proximal attachments of the transversospinales?

Answer 16

proximal: mainly transverse processes
- semispinalis: thoracic & lower cervical t. processes
- multifidus: sacrum, ilium, lumbar t. processes
- rotatores: t. processes

Question 17

Distal attachments of the transversospinales?

Answer 17

fibers run superomedially and attach to spinous processes of more superior vertebrae

• semispinalis: spans 4-6 segments
• multifidus: spans 2-4 segments
• rotatores: spans 1 (brevis) - 2 (longus) segments

Question 18

What is exceptional about the trapezius’ innervation?

Answer 18

only extrinsic back muscles not innervated by ventral rami of spinal nerves;
innervated by CN XI, spinal accessory nerve

Question 19

Attachments of the trapezius?

Answer 19

proximal: nucal ligament, spinous processes of C2-T12
distal: clavicle, acromion (shoulder blade), spine of scapula

Question 20

Innervation of the trapezius?

Answer 20

spinal accessory nerve, CN XI

Question 21

Blood supply of the trapezius?

Answer 21

superficial branch of the transverse cervical artery

Question 22

Actions of trapezius?

Answer 22

scapular elevation, retraction, & depression

Question 23

Proximal attachments of latissimus dorsi?

Answer 23

• spinous processes of inferior 6 thoracic vertebrae
• inferior 3 or 4 ribs
• thoracolumbar fascia
• iliac crest

Question 24

Distal attachments of latissimus dorsi?

Answer 24

floor of the intertubercular groove of humerus

Question 25

Innervation of latissimus dorsi?

Answer 25

thoracodorsal nerve

Question 26

Blood supply of latissimus dorsi?

Answer 26

thoracodorsal artery

Question 27

Actions of latissimus dorsi?

Answer 27

extends, adducts, and medially rotates humerus