Lecture 7: Muscle/Joint Interaction of Cervical and Thoracic Spine Test 2 Flashcards
Roles of cervicothoracic musculature
control posture
stabilize
protect SC/internal organs
generate intrathoracic pressure
furnish mobility/placement for head and neck
features of cervicothoracic musculature
vary in length, fiber direction, shape, CSA, and leverage
muscles may cross many joints
how are spinal nerve roots formed
formed by union of ventral and dorsal nerve roots
join near or within intervertebral foramen to form root
contain combinations of sensory and motor fibers
describe ventral vs dorsal nerve roots
ventral = primarily efferent (outgoing) axons; motor
dorsal = afferent (incoming) dendrites with cell body in dorsal root ganglion (sensory)
how many spinal nerves are there (and how many in each spinal segment)
31 pairs
8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal
where do the 1st and 8th cervical nerve roots exit
1st is between occipital bone and posterior arch of C1
8th is between C7 and T1
where do all of the nerve roots below the cervical spine exit
all below the cervical region exit inferior to their respective vertebtral bodies
describe what happens to the spinal nerves when they exit the spine
split into dorsal and ventral ramus
ventral forms nerves that innervate muscles, joints, and skin of anterior lateral trunk and neck and the extremities
dorsal forms nerves that innervate muscles, joints, and skin of posterior trunk and neck
what do the intercostal nerves innervate
muscles in the anterior lateral trunk such as the intercostal and abdominal muscles
branching from ventral ramus
name some examples of what the dorsal ramus innervates
trunk and extensor muscles such as erector spinal or multifidi
sensory fibers of ventral and dorsal rami can innervate what
ligaments and other connective tissues
what is a plexus
intermingling of ventral rami
form peripheral nerves (i.e. the radial)
what are the 2 most common plexuses and where do they innervate generally
cervical (C1-C4) and brachial (C5-T1)
cervical goes mostly to axial skeleton and brachial goes mainly to UEs
what do each of the 12 ventral rami of the thoracic region innervate
each of the 12 form intercostal nerves that innervate both an intercostal muscle and an intercostal dermatome in the same place
**T1 contributes to the brachial plexus and the 1st intercostal nerve
describe recurrent meningeal nerves
a single recurrent meningeal nerve branches off proximally
sensory/sympathetic supply to the meninges (at the spinal cord) and connective tissue to the intervertebral joints (PLL and ALL)
describe how a recurrent meningeal nerve supplies in the vertebral canal
branch of spinal nerve passes in recurrent fashion back through the vertebral foramen
this supplies many areas including the outer 1/3 of the annular fibers of the disc
nerve fibers are sensory and carry signals to the brain when the tissue is damages
describe the dorsal rami spinal roots compared to the ventral
from C3 and below they are smaller than the ventral counterparts
what is the dorsal rami of C1 (motor vs sensory?)
“suboccipital nerve”
primarily motor
innervates sub occipital muscles
describe C2 dorsal rami
largest dorsal rami
innervates local muscles
contributes to greater occipital nerve which is C2 and C3 (sensory to scalp region)
what specific muscles are innervated by the sub occipital nerve
rectus capitis posterior minor and major
obliquus capitis superior
type of innervation of greater occipital nerve
sensory
what is the third occipital nerve
(TON) is a branch of the posterior root of C3
provides cutaneous sensation to a small portion of the occipital scalp and innervates the C2/3 facet joints
what is the greater occipital nerve
GON
main sensory nerve to the occipital area
associated with various pain syndromes such as occipital neuralgia, cervicogenic headaches, and migraine
what is bilateral activation/what does it produce
usually produces pure flexion or extension of axial skeleton
any potential for lateral flexion or axial rotation is neutralized by opposing forces in contralateral muscles
what is unilateral activation/what does it produce
tends to produce flexion and extension of the axial skeleton with some combo of lateral flexion and contralateral or ipsilateral axial rotation
the action of a muscle in the axial skeleton depends on what
the degree of fixation/stabilization of the attachments of the muscle
describe how gravity affects flexion of the neck
slow/moderate flexion gravity is the main flexor (extensor muscles act eccentrically to control movement and speed)
rapid flexion activates the neck flexors
superficial muscle layer of the back
trapezius
latissimus dorsi
rhomboids
levator scapulae
serratus anterior
muscles in intermediate layer of back
serratus posterior superior and inferior
Deep layer of the back (from most superficial to deep)
erector spinae
transversospinal
short segment
what are the erector spinal muscles lateral to medial
illiocostalis (thoracic and cervicis)
Longissumus (thoracis, cervicis, and capitis)
spinalis (thoracis, cervicis, and capitis)
what is the fiber direction of longissimus cervicis and capitis
cervicis = cranial and medial
capitis = cranial and lateral
what is the fiber direction of the illiocostalis cervicis
vertical and medial
what muscles make up the transversospinal
semispinalis thoracis
semispinalis cervicis
semispinalis capitis
multifidi
rotatores
what muscles make up the short segment of the back
interspinalis
intertransversarius
what are the muscles that fall into the anterior lateral craniocervical region (and what are they innervated by)
SCM
scalenes
longus colli
longus capties
rectus capitis anterior
rectus capitis lateralis
** all but SCM are innervated by small, unnamed nerves branching firm the ventral rami of the cervical plexus
what are the 2 heads of the SCM
sternal and clavicular
what are the actions of the SCM
primary (mid/lower cervical spine) = lateral flexor, contralateral rotation, bilateral flexion
above C3 acts as a small extensor torque
innervation of SCM
accessory nerve (CN 11)
function of anterior and middle scalenes
lift first rib
laterally flex cervical spine ipsilaterally (anterior has best moment arm)
posterior scalene function
lifts 2nd rib
laterally flexes cervical spine ipsilaterally
innervation of scalenes
anterior and middle = C4-C6 spinal nerves
posterior = C6-C8
anterior and middle scalene attachments
from anterior tubercles of C3-C6 TP (anterior) and C2-C7 TP (middle)
attaches to scalene tubercle on inner border of 1st rib
posterior scalene attachments
posterior tubercles of TP of C5-C7
attaches to 2nd rib
which scalene is smallest/deepest
posterior
where does the brachial plexus run in relation to the scalenes
between anterior and middle scalene
main roles of scalenes
stability to lower and middle C/spine and ventilation
where are longus Colli and longus capitis (generally) and what is their collective function
deep to trachea and esophagus
function as a dynamic ALL (vertical stability)
where is longus colli and what is its specific function
anterior to T1-3 and all cervical vertebrae bodies, TPs, and anterior arch of atlas
can flex and reduce cervical lordosis
where is longus capitis specifically and what is its function
mid/lower TPs into the basilar part of the occiput
flexes and stabilizes the upper craniocervical spine
innervation of longus colli and longus capitis
anterior rami C2-6
what are the attachments for rectus capitis anterior and rectus capitis lateralis
short deep muscles
arise form C1 TPs
insert on inferior surface of occipital bone (lateral and anterior to the condyles)
actions of rectus capitis anterior and lateralis
acts on OA joint
anterior = flexion
lateralis = lateral flexion
where do the splenius muscles attach
cervicis and capitis both arise from inferior half of ligamentum nuchae/spinous processes of C7-T6
capitis attaches to occipital bone
cervicis attaches to posterior tubercles of TPs of C1-C3 (shared with levator scapulae)
function of the splenius muscles
unilateral contraction = lateral flexion and ipsilateral rotation
bilateral contraction = extends upper craniocervical region
what are the 4 sub occipital muscles
rectus capitis posterior major/minor
obliquus capitis inferior/superior
describe the sub occipital muscles
very deep; immediately superficial to OA/AA
deep to upper trap, splenius, semispinalis capitis
attach to atlas, axis, and occipital bone
provide precise control over OA/AA
large # of muscle spindles that give neural feedback and allow hand eye coordination and balance
posterior and lateral neck musculature serves to do what
protect cervical viscera, blood vessels, discs, facet joints, and neural tissues
for stability, muscular needs to be trained to do what
contract before the “load”
describe the loads on the craniovertebral region during function
the head weighs 3x its normal weight with low-level upright standing/balancing head
with max muscle effort, the neck muscles can generate force 23x the normal weight of the head
require short stabilizing muscles and long guide wire muscles
what is ideal for neck stability
co-contractions of flexors and extensors
cervical muscles are anchored to other structures (i.e. sternum, clavicle, ribs, scapula, and vertebrae) that must be stabilized themselves as well
