Lecture 3: Muscle/Joint interaction of axial skeleton Flashcards
how does the ventral ramus divide
4 major plexi:
-cervical (c1-4)
-thoracic (c5-t1)
-lumbar (12-L4)
-Sacral (L4-S4)
individual intercostal and recurrent meningeal nerves
how does the dorsal ramus branch
branches from every spinal root
dermatome across posterior trunk
what is internal torque equal to
product of the muscle force and its internal moment arm
I torque = MF + MA
what is the axis of rotation for the axial skeleton
T6??
what two factors affect strength of a muscle
distance and spatial relationship of the muscles line of force relative to the axis of rotation
describe the force of the external oblique muscle
vertical lateral flexion and flexion torque
horizontal force rotation torque
what occurs with bilateral vs unilateral contraction of the external oblique
bilateral = pure flexion/ext
unilateral=adds component of lateral flexion/rotation
relative stabilization by external oblique
with erector spinae T/S ext or anterior pelvic tilt
superficial layer of the trunk posterior muscles
trapezius
lats
rhomboids
levator scapula
serratus anterior
intermediate layer of the trunk posterior muscles
serratus posterior superior and inferior
deep layer of the trunk posterior muscles
3 groups:
erector spinae (spinalis, longissimus, and iliocostalis)
transversospinal (semispinalis, multifidi, and rotatores)
short segments group (interspinalis muscles, intertransversarius muscles)
characteristics/landmarks of the erector spinae muscle group
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
general characteristics of the transversospinal group
run from TP of one vertebra to SP of more superiorly located vertebra
cranial - medial fibers
bilateral contraction = extension
contralateral RT and lateral flexion
characteristics of the multifidi
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
describe the rotatores
deepest
most well developed in T/S
goes from the TP to the lamina/base of SP 1-2 vertebra above
characteristics of the short segment group of deep trunk muscles
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
what muscles fall into the 2nd group for the anterior lateral trunk
rectus abdominus
obliquus externus abdominis
transversus abdominis
importance of the anterior lateral trunk muscles
support/protect viscera
increase intrathoracic and intraabdominal pressure
characteristics of the rectus abdominus muscle
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
function of rectus abdominus
flexes thorax and upper lumbar spine
tilts pelvis posterior
characteristics of external oblique muscle
most superficial of lateral muscles
travels inferior and medial
acts as lateral flexor and contralateral rotator
bilateral trunk flexor; posterior tilt of pelvis
characteristics of internal oblique
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
describe the transversus abdominis
deepest
stabilizes via thoracolumbar fascia
most extensive attachments to thoracolumnbar
runs from ribs to iliac crest to inguinal ligament to TL fascia
roles of transversus abdominis
stabilization for other ab muscles
increases tension in TL fascia
compresses abdominal cavity
describe quadratus lumborum
muscle in posterior abdominal wall
attaches to IC and iliolumbar lig
bilateral contraction = ext and vertical stabilization
unilateral = lateral flexion
“hip hiker” muscle
where does the iliopsoas run
iliacus = fossa to lateral sacrum
psoas = TP T12-L5 and discs
iliopsoas action
move femur to pelvis or move pelvis to femur
anterior tilt and lumbar ext
lateral flexion of trunk
strong bilateral contraction of what 2 muscles provides good stability
QL and iliopsoas
importance of core stability or lumbopelvic stability
intervertebral control
controls lumbopelvic orientation
controls whole nbody equilibrium (keeps COG over base of support)
describe short/deep local muscles
controls precise alignment and stiffness
high density muscle spindles
varying angles act as guidewires
sail boat analogy
describe global extrinsic muscles
longer
important torque generators
provide strong links between regions
poor activation of what muscle is associated with LBP
transversus abdominis
contraction of TA decreases laxity in SI joint much more than the “bracing “ action of the other abdominal muscles
what happens to the lumbar multifidus following a low back injury
segmental atrophy develops at level of pathology
changes persist beyond time of symptoms
indicates a neurologically mediated process rather than disuse/weakness
what are the 2 phases of a full sit up
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
clinical notes for sit ups/curl ups
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
pros/cons with the “stoop” lifting
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
pros/cons of a squat lift
lumbar spine can stay extended
reduced moment arm of load which means less trunk extensor torque
larger demand on knees
requires greater work metabolicallly
what mechanical/structural factors favor a herniated NP in L/S
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
