Functional Anatomy of the Spine Flashcards
functions of the vertebral column
support
posture
protection
locomotion
components of the vertebral column
vertebrae plus intervertebral discs - 75% vertebrae, 25% discs
separate elements for flexibility/mobility/shock absorption
ligaments and muscles
What are the divisions of the vertebral column?
cervical 7 - all mammals have these
thoracic 12 - defined by the ribs
lumbar 5
sacral 5
coccygeal 4
Why is there a curvature in the vertebral column?
acts as a spring, the “S” shape gives a lot more shock absorption
kyphosis - convex posteriorly
lordosis - convex anteriorly
scoliosis - lateral curvature
lordosis vs. kyphosis
lordosis - when curvature is in the front (primary - thoracic and sacral)
kyphosis - when curvature is in the back (secondary - cervical and lumbar)
What is the common finding in Scheuermann’s disease?
abnormal kyphosis - common in adolescents
What are the common causes in abnormal lordosis?
obesity
pregnancy
achondroplasia
spondylolysthesis
What are the different parts of a vertebral segment? What are their functions?
body or centrum - weight support, intervertebral discs are placed between the bodies
vertebral arch - pedicle, lamina, vertebral foramen for spinal cord
transverse process, spinous porcess - attachment of muscles
superior and inferior articular facets - articulation with vertebrae above and below, shape and oridentation determines kinds of movements allowed
intervertebral foramen - for passage of spinal nerves
What are the parts of the vertebral arch?
lamina
pedicle
spinous process
articular process
transverse process
vertebral foramen
What are the defining features of the cervical vertebra?
has a transverse foramen
What are the defining features of the thoracic vertebra?
rib articular facets
What are the defining features of the lumbar vertebra?
large bodies
What is the role of ligaments in the spine?
prevents excessive/unwanted movement between the vertebrae in order to protect joints and nerves
instability of the vertebral column can compress and damage the spinal ord or spinal nerves leading to pain, paresthesia, muscle weakness, or paralysis
What are the ligaments in the spine and what are their functions?
anterior lingitudinal - prevents hyperextension (whiplash)
posterior longitudinal - prevents hyperflexion
ligamentum flavum - between laminae
suprspinous - along spines, ligmentum nuchae
interspinous - unites two adjacent spines
How does the three column model of Dennis reflect the stability of the vertebral column?
spinal stability is dependent on at least two intact columns
whent two of the three columns are distrupted, abnormal segmental motion is allowed
this leads to instability, and the spinal nerves and spinal cord are at risk of injury as a result
What feature of the spinal chord is a common cause of pain?
facet joints are common sites of pain
osteophytes here are implicated
What determines the range of motion in a particular segment of the vertebral column?
compressibility and elasticity of the discs
shape and orientation of the articular facets
condition of back muscles and ligaments
rib attachment
Describe the mobility of the cervical, thoracic, and lumber regions of the spine.
cervica is the most mobile - all movements allowed
thoracic region - flexion-extension is restricted by the ribs
lumber - very little rotation due to the mediolaterally facing articular facets
spondylolisthesis
anterior or posterior displacement (slippage) of one vertebrae relative to another
the spinal cord and nerves can be compromised
spondylolysis
a defect (separation) in the vertebral pars interarticularis, usually in the lower lumbar vertebrae, particularly L5
see the “Scotty dog” sign in x-rays
sciatica
radiating pain in the L4-S2 dermatones
What is the role of the intervertebral disc?
acts as a shock absorber and mediates movement between vertebral bodies
What makes up the intervertebral disc?
fibrocartilage annulus
fibrogelatinous nucleus pulposus which is a remnant of the embryonic notochord
extrensic vs. intrinsic muscles of the back
extrinsic - develop from hypomere, anterior (ventral) rami innervation, attache to limbs (except serratus posterior), and function is to move limbs
intrinsic - develop from epimere, posterior (dorsal) rami innervation, attach to vertebral column and ribs, function is to move vertebral column
epaxial muscles
muscles that develop from the epimere
form intrinsic muscles of the vertebral column - mainly extensors and rotators
ex. splenius, erector spinae, transversospinalis
hypaxial muscles
muscles that develop from the hypomere
extrnsic to the vertebral column
may not attach to parts of vertebrae but form body wall or limb muscles
ex. flexor muscles of the vertebral column, rects abdominis, intercostals, abdominal obliques, rhomboids, levator scapulae, latissimus dorsi
function of the trapezius
rotates and retracts scapula
innervated by the cranial nerve XI
function of the latissimus dorsi
extends and adducts the arm
function of the levator scapulae
elevates the scapula
function of the rhomboids
retract scapula
What are the movements of the vertebral column?
extension - flexion
lateral bending
rotation
What determines the range and types of motion of the vertebral column?
compressibility and elasticity of the discs
shape of articular facets
conditions of back muscles and ligaments
rib attachment
What is the range of motion in each of the regions of the vertebral column?
cervical most mobile - all movements
thoracic region - flexibility is restricted by ribs
lumbar - very little rotation
function of the splenius muscles (capitis and cervicis)
ipsilateral rotation
lateral bending
extension
What are the functions of the erector spinae?
lateral bending
extension
What are the different subcategories of the erector spinae?
spinalis
longissimus
iliocostalis
What are the components of the transversospinalis and what is its function?
semispinalis, rotatores, and multifidus
function - contralateral rotation and extension
