Lecture 3: Muscle/Joint interaction of axial skeleton

Question 1

how does the ventral ramus divide

Answer 1

4 major plexi:
-cervical (c1-4)
-thoracic (c5-t1)
-lumbar (12-L4)
-Sacral (L4-S4)

individual intercostal and recurrent meningeal nerves

Question 2

how does the dorsal ramus branch

Answer 2

branches from every spinal root

dermatome across posterior trunk

Question 3

what is internal torque equal to

Answer 3

product of the muscle force and its internal moment arm

I torque = MF + MA

Question 4

what is the axis of rotation for the axial skeleton

Answer 4

T6??

Question 5

what two factors affect strength of a muscle

Answer 5

distance and spatial relationship of the muscles line of force relative to the axis of rotation

Question 6

describe the force of the external oblique muscle

Answer 6

vertical lateral flexion and flexion torque

horizontal force rotation torque

Question 7

what occurs with bilateral vs unilateral contraction of the external oblique

Answer 7

bilateral = pure flexion/ext

unilateral=adds component of lateral flexion/rotation

Question 8

relative stabilization by external oblique

Answer 8

with erector spinae T/S ext or anterior pelvic tilt

Question 9

superficial layer of the trunk posterior muscles

Answer 9

trapezius
lats
rhomboids
levator scapula
serratus anterior

Question 10

intermediate layer of the trunk posterior muscles

Answer 10

serratus posterior superior and inferior

Question 11

deep layer of the trunk posterior muscles

Answer 11

3 groups:

erector spinae (spinalis, longissimus, and iliocostalis)

transversospinal (semispinalis, multifidi, and rotatores)

short segments group (interspinalis muscles, intertransversarius muscles)

Question 12

characteristics/landmarks of the erector spinae muscle group

Answer 12

ill defined

1 hand from SP

deep to thoracolumbar fascia

common tendon located at sacrum (broad/thick)

gross mvmts vs finer control

large extension torque

Question 13

general characteristics of the transversospinal group

Answer 13

run from TP of one vertebra to SP of more superiorly located vertebra

cranial - medial fibers

bilateral contraction = extension

contralateral RT and lateral flexion

Question 14

characteristics of the multifidi

Answer 14

posterior sacrum to C2

TP to SP one or 2-4 vertebrae above

thickest/most developed in lumbar and has 2/3 muscular stabilizing capacity

fills the space between TP/SP

relatively large CSA

Question 15

describe the rotatores

Answer 15

deepest

most well developed in T/S

goes from the TP to the lamina/base of SP 1-2 vertebra above

Question 16

characteristics of the short segment group of deep trunk muscles

Answer 16

very short
crosses only 1 IV joint

most developed in cervical region

bilateral; blends with interspinous ligament

contribute to EXT (interspinalis) and lateral FLX (intertransversarius)

rich in muscle spindles for sensory feedback

Question 17

what muscles fall into the 2nd group for the anterior lateral trunk

Answer 17

rectus abdominus
obliquus externus abdominis
transversus abdominis

Question 18

importance of the anterior lateral trunk muscles

Answer 18

support/protect viscera

increase intrathoracic and intraabdominal pressure

Question 19

characteristics of the rectus abdominus muscle

Answer 19

strap like

longest fascicle length
smallest CSA

intersected by transverse fibrous bands (tendinous insertions)

runs from xiphoid process to the crest of the pubis

connects to 5-7 cartilaginous portion of ribs

Question 20

function of rectus abdominus

Answer 20

flexes thorax and upper lumbar spine

tilts pelvis posterior

Question 21

characteristics of external oblique muscle

Answer 21

most superficial of lateral muscles

travels inferior and medial

acts as lateral flexor and contralateral rotator

bilateral trunk flexor; posterior tilt of pelvis

Question 22

characteristics of internal oblique

Answer 22

deep to EO

largest CSA of abs

travels cranially and medially

ips RT and lat flexion

bilateral flexion of trunk, posterior pelvic tilt, and increases tension in TL fascia

Question 23

describe the transversus abdominis

Answer 23

deepest

stabilizes via thoracolumbar fascia

most extensive attachments to thoracolumnbar

runs from ribs to iliac crest to inguinal ligament to TL fascia

Question 24

roles of transversus abdominis

Answer 24

stabilization for other ab muscles

increases tension in TL fascia

compresses abdominal cavity

Question 25

describe quadratus lumborum

Answer 25

muscle in posterior abdominal wall attaches to IC and iliolumbar lig bilateral contraction = ext and vertical stabilization unilateral = lateral flexion "hip hiker" muscle

Question 26

where does the iliopsoas run

Answer 26

iliacus = fossa to lateral sacrum psoas = TP T12-L5 and discs

Question 27

iliopsoas action

Answer 27

move femur to pelvis or move pelvis to femur anterior tilt and lumbar ext lateral flexion of trunk

Question 28

strong bilateral contraction of what 2 muscles provides good stability

Answer 28

QL and iliopsoas

Question 29

importance of core stability or lumbopelvic stability

Answer 29

intervertebral control controls lumbopelvic orientation controls whole nbody equilibrium (keeps COG over base of support)

Question 30

describe short/deep local muscles

Answer 30

controls precise alignment and stiffness high density muscle spindles varying angles act as guidewires sail boat analogy

Question 31

describe global extrinsic muscles

Answer 31

longer important torque generators provide strong links between regions

Question 32

poor activation of what muscle is associated with LBP

Answer 32

transversus abdominis contraction of TA decreases laxity in SI joint much more than the "bracing " action of the other abdominal muscles

Question 33

what happens to the lumbar multifidus following a low back injury

Answer 33

segmental atrophy develops at level of pathology changes persist beyond time of symptoms indicates a neurologically mediated process rather than disuse/weakness

Question 34

what are the 2 phases of a full sit up

Answer 34

trunk flexion phase = stong activatuion of ab muscles especially rectus abdominis hip flexion phase = continued activation of abs but more important also the hip flexors

Question 35

clinical notes for sit ups/curl ups

Answer 35

curl up is less demanding on hip flexors and requires less lumbar felxion full sit up puts more pressure in discs and more spine flexion if abs are weak the hip flexors dominate and the early hip flexion causes a risk of shear

Question 36

pros/cons with the "stoop" lifting

Answer 36

long external moment arm of load greater forces of trunk extensors are needed compression and shear forces are large spine flexion poses a risk to discs

Question 37

pros/cons of a squat lift

Answer 37

lumbar spine can stay extended reduced moment arm of load which means less trunk extensor torque larger demand on knees requires greater work metabolicallly

Question 38

what mechanical/structural factors favor a herniated NP in L/S

Answer 38

preexisting disc degeneration with radial fissures, cracks, or tears in the posterior annulus that allow a path for the flow of nuclear material sufficiently hydrated nucleus capable of exerting high intradiscal pressure inability of posterior annulus to resist pressure from the migrating nucleus sustained or repetitive loading applied over a flexed and rotated spine