how many vertebrae are in the vertebral column?
how many individual vertebrae are there?
what is the organization of the vetebrae of the vertebral column?
7 cervical, 12 thoracic, 5 lumbar, 5 fused sacral (sacrum), 4 fused coccygeal (coccyx)
what are pedicles?
processes that project dorsally to attach the body to the arch
what are laminae?
unite to form the spinous process
what fails to use in spina bifida?
laminae fail to fuse to form a spinous process
compare the following types of spina bifida:
1. spina bifida occulta
2. spina bifida cystica
a. with meningocele
b. with meningomyelocele
c. with myeloschisis or rachischisis
1. one or more spinous processes fail to form at lumbar or sacral levels; asymptomatic; marked by tuft of hair over defect usually
2. cyst protrudes through the defect
a. cyst lined by the dura and arachnoid and contains CSF
b. lumbosacral spinal cord is displaced into the cyst which stretches lumbosacral spinal nerves and may result in bladder, bowel, or lower limb weakness
c. caudal end of the neural tube fails to close in the dorsal midline and is exposed on the surface of the back
at what vertebral levels is spina bifida most commonly seen?
lumbar or sacral
what are costal processes?
usually form transverse processes that project laterally at the junction between each lamina and pedicle
label the components of the vertebrae
what are the primary curvatures of the vertebral column and how are they directed? secondary curvatures?
primary are the thoracic and sacral curvatures, convex directed posteriorly
secondary are the cervical and lumbar curvatures, convex directed anteriorly
what is kyphosis?
abnormal increase in the posterior curvature of the spine
thus, increased curvature in the thoracic or sacral regions
what are possible causes of kyphosis? which is the most common?
postural (most common)
anterior wedge-shaped thoracic vertebrae
resorption of the anterior parts of the thoracic vertebral bodies from osteoporosis
what is lordosis? what is a common cause?
abnormal increase in the anterior curvature of the spine
thus, increase in curvature in the lumbar or cervical regions
weakening of the anterior abdominal wall as a result of weight gain can cause
what is scoliosis? what is a common cause?
abnormal lateral curvature that may be caused by an absent half of a vertebra or a wedge-shaped vertebra or by an asymmetric weakness of back musculature
where are the zygapophyseal or facet joints located? what is their function?
between the facts of superior and inferior processes at the junction of each pedicle and lamina
permit gliding motion
acted on by intrinsic or deep back muscles
where are intervetebral disks located? what are their components? what is their function?
situated between bodies of most adjacent vertebrae
consist of a fibrocartilaginous annulus fibrosus surrounding a nucleus pulposus
functions to absorb shock and distribute weight over the entire surface of vertebral bodies durring compression and tension
what is the nucleus pulposis a remnant of?
where is the anterior longitudinal ligament found and what is its function?
covers the anterolateral parts of the vertebral boes and the disks to limit vertebral extension
where is the posterior longitudinal ligament found and what is its function?
covers the posterior part of the vertebral codies and the disks and functions to limit vertebral flexion
which is greater (thicker/stronger), the anterior or posterior longitudinal ligaments?
where are the elastic ligamentum flavum and what are their functions?
between the laminae of adjacent vertebrae
function to limit vertebral flexion and help maintain normal vertebral curvatures
where are the interspinous and supra spinous ligaments located?
interspinous ligaments a ligament connect the spinous processes of two adjacent vertebra
supraspinous ligaments a ligament connect the tips of the spinous processes of thoracic and lumbar vertebrae
where are the intervertebral foramina located? what are they bounded by? what do they transmit?
an opening between the pedicles of adjacent vertebrae, separating individual vertebrae
bounded by the pedicles of adjacent vertebrae, posteriorly by facet joints and anteriorly by the bodies/intervertebral disks
transmit dorsal and ventral roots of the spinal nerves
where/what is the vertebral canal? what does it contain?
the opening formed by the combination of the body and the vertebral arch as well as the ligaments/disks that interconnect them
contain the meninges, spinal cord, and roots of spinal nerves
where is the epidural space and what does it contain?
outside the dural layer of the meninges and contains fat and the internal vertebral venous plexus
what is the internal venous plexus? what is significant about it clinically in relation to cancer?
connects veins that drain the thorax, abdomen, and pelvis with dural venous sinuses of the cranial cavity
provides routes for metastasis of neoplasms of the prostate, uterus, and rectum to the cranial cavity
what is the dura mater and where is it located?
outermost covering of the spinal cord, it forms the dural sac containing the spinal cord within vertebral canal
continuous with the meningeal dura of the cranial cavity and ends at S2, with lateral extensions at the roots of spinal nerves
what is the subdural space?
potential space between the dura and the arachnoid mater
what is the arachnoid mater and where is it located?
intermediate one of the three layers of meninges
also extends to S2 and is pressed against the dura by the pressure of CSF
where is CSF contained in the spinal region?
the subarachnoid space (which has a spider web-like filaments)
what is the normal pressure of CSF?
100 mm H20
what is the function of CSF?
cushions the brain and spinal cord, absorbs waste products, transports hormones
has few cells, low protein content, and a lower glucose concentration than serum
what is the pia mater?
covers the spinal cord and roots of the spinal nerves
most delicate of the meningeal layers
what are the two specializations of pia mater and their functions?
denticulate ligaments: lateral extensions of the pia that anchor the spinal cord to the dura
filum terminale: consists of pia that extends from the inferior end of the cord at L2 and joins the dura and arachnoid to end in the sacral canal at S2
what is the spinal cord located in relation to the vertebral column?
occupies he superior 2/3 of the vertebral canal and ends inferiorly at L2
where/what is the conus medullaris?
tapered inferior end of the spinal cord that contains sacral and coccygeal cord segments and is located at L2
going down the vertebral canal, where do spinal nerves exit?
first 7 cervical nerves exit SUPERIOR to the cervical vertebra for which they are named
beginning with T1, all other spinal nerves exit INFERIOR to the vertebra for which they are named
the 8th cervical nerve exits through intervertebral formen between C7 and T1 (8 cervical nerves, but only 7 cervical vertebrae)
what forms the cauda equina and where is it located?
formed by dorsal and ventral roots of lumbar and sacral spinal nerves that extend inferior to the end of the spinal cord at L2
what is a lumbar puncture and where is it typically performed?
used to sample CSF or introduce anesthetic agents into the subarachnoid space
typically performed between L4 and L5 below the inferior end of the spinal cord
in a midline lumbar puncture, what layers will the needle transverse?
skin, superficial and deep fascia, supraspinous and interspinous ligaments, intralaminar space, epidural space, dura, arachnoid
in an off the midline lumbar puncture, what will the needle transverse?
ligamentum flavum instead of the supraspinous and interspinous ligaments and the intralaminar space
what are radiculopathies? what are typical symptoms?
compression of the roots of spinal nerves in the intervertebral foramina or in the vertebral canal
symptoms are pain and paresthesias in dermatomes supplied by affected sensory roots or weakness of skeletal muscles in myotomes supplied by compressed motor roots
what can radiculopathies be caused by?
osteoarthritis- inflammation that results in additional bone growth by osteophytes at the facet joints
spondylitis- inflammation that results in additional bone growth by osteophytes at the margins of the vertebral bodies; anterior longitudinal ligament and sacroiliac joint may undergo calcification; may exhibit ankylosis (joint stiffening) or bamboo spine (marie-strumpell disease)
spondylosis- degenerative changes in intervertebral disks, usually combined with osteoarthritis at the margins of the vertebral bodies
what are characteristics of the cervical vertebrae?
small bodies, short spinous processes (some with bifid tips), transverse processes that transmit vertebral arteries (have openings)
have facet joints of C3-C7 oriented at 45 degree angle relative to transverse plant-->permits flexion, extension, lateral bending, and rotation
uncinate processes on bodies of C3-C7 that form uncovertebral synovial joints with the vertebral bodies superior to them
describe the location and characteristics of the atlas vertebra?
has posterior arch and arnterior arch but no body or spinous process
no intervertebral disk in between C1 and C2
superior articular processes articulate with occipital condylesof the skull forming "yes" joints for flexion and extension
describe the location and chracteristics of the axis vertebra?
dens/odontoid process of the axis articulates with the anterior arch of the atlas and forms the "no" or pivotjoints to permit rotation of the atlas and skull
what holds the dens in place and what is the function of the dens/associated ligaments? what can happen clinically if damaged?
dens held in place by transverse ligament of the atlas (rupture can cause dislocation of the atlantoaxial joint and displacement of the dens posteriorly into the cervical spinal cord and if the cord is compressed quadriplegia can result)
dens is attached to margins of the foramen magnum by alar ligaments (reupture can cause excessive rotation of the skull)
describe the location and characteristics of vertebra prominens
long spinous process and small transverse formina that does not transmit the vertebral arteries
what is a herniated disk and which spinal nerves are they most likely to affect?
when a nucleus pulposis protrudes at the posterolateral part of an annulus fibrosus resulting in compression of roots of lower cervical or lower lumbar spinal nerves
the compressed roots are most commonly the more inferior spinal nerve (ex. at C5-6 disk, compresses C6 root)
where do herniated disks most often occur at the cervical level?
at cervical levels, most common herniations between C6-C7-->C7 spinal nerve compression: referred pain in neck and shoulder and index and middle fingers; diminished triceps reflex and weakness in extension of forearm at the elbow or wrist and fingers
less common is at C7-C8-->C8 spinal nerve compression: pain in neck and shoulder and ring and little fingers; weakness in hypothenar and interosseous muscles of the hand
what can occur with a cervical rib and what are the symptoms?
rib arising from costal process of C6
T1 spinal nerve and subclavian artery may be compressed as they course superior to cervical rib instead of first thoracic rib
diminished fadial pulse and pain and paresthesias in medial forearm
Horner's syndrome signs seen (drooping of the eyelid (ptosis) and constriction of the pupil (miosis), sometimes accompanied by decreased sweating (anhidrosis) of the face on the same side)
what are the characteristics of thoracic vertebrae?
"heart-shaped" or more rounded bodies ith ong obliquely oriented spinous processes
have costal facets on body and tranverse processes for articulation with ribs
also have facet joints oriented at a 60 degree angle relative to transverse plane which permits mainly lateral bending and rotation (flexion and extension limited by fixation by ribs)
what are the characteristics of lumbar vertebrae?
large kidney-shaped bodies, short flat horizontally oritented spinous processes; long transverse processes
facet joints oriented perpendicular to the transverse plane for flexion, extension, and lateral bending with limited rotation
superior and inferior articular processes interconnected by an observable isthmus or pars interarticularis
-->"Scottie dog" shape
what is spondylolysis?
defect or fracture of the isthmus with no anterior displacment of the vertebral body
what is spondylolisthesis? where does it most commonly occur?
unilateral or bilateral defect or fracture of the isthmus accompanied by anterior displacement of the vertebral body
most commonly occurs between L5 and sacrum streching roots of lumbosacral spinal nerves in cauda equina
where do herniated disks most often occur at the lumbar level?
between L4-L5-->compression of L5: results in sciatica (pain radiates from back into posterior thigh, anterolateral leg, and dorsum of the foot), weakness in extension of great toe and dorsiflexion (tibialis anterior)
between L5-S1-->compression of S1: pain and paresthesias in posterolateral leg, heel, and lateral side of foot; weakness in flexion of leg at knee (hamstring) and plantar flexion (gastrochemius and soleus), diminished Achilles tendon reflex
what do the median crest of the sacrum and the intermediate crests represent?
median crests= fused sacral spinous processes
intermediate crests= fused articular processes
what is the promontory?
forms ventral surface of the S1 vertebra (boundary of the pelvic inlet for obstretrics)
what trasmist the dorsal and ventral rami of S1-S4?
four pairs of dorsal sacral foramina and four pairs of ventral sacral foramina
what is contained in the sacral canal? the sacral hiatus?
canal, which ends at the sacral hiatus in the dorsal midline, contains the roots of the S1-coccygeal spinal nerves
sacral hiatus transmits the S5 and coccygeal spinal nerves
where is an epidural or caudal block performed?
through sacral hiatus which diffuses through the meninges and anesthetizes the roots of the sacral and coccygeal spinal nerves in the cauda equina
what forms the sacroiliac joints?
lateral surfaces of superior sacrum and medial surface of each ilium
what is the coccyx attachment sites for?
anococcygeal ligaments which are attachment sites for muscles of pelvic diaphragm
what are the muscle groups of the back?
superficial, intermediate, deep or intrinsic
where do the superficial muscles of the back attach?
attached to pectoral girdle and act on the upper extremity
what muscles are included in the superficial muscles of the back?
trapezius, latissimus dorsi, rhomboid major, rhomboid minor, levator scapulae
what innervates the superificial muscles of the back?
ventral rami of spinal nerves through branches of the brachial plexus (except for trapezius which is supplied by CN XI/acessory nerve)
where do the intermediate muscles of the back attach to?
attach to the ribs and act as acessory muscle of respiration
what muscles are included in the intermediate muscles of the back?
serratus posterior superior, serratus posterior inferior, 12 pairs of levator costarum muscles
what innervates the intermediate muscles of the back?
ventral rami of spinal nerves
where do the deep/intrinsic muscles of the back attach?
attach mainly to transverse and spinous processes of vertebrae and act on the vertebral column at the intervertebral joints
what muscles are included in the deep/intrinsic muscles?
erector spinae (contain 3 parallel muscle groups, from lateral to medial: iliocostalis, longissimus, and spinalis)
splenius capitis and splnius cervicis
transversospinalis muscles (consist of 3 muscle groups, superifical to deep: semispinalis, multifiduc, rotatores)
muscles of the suboccipital triangle
what are the muscles of the erector spinae and what are their actions?
from lateral to medial: iliocostalis, longissimus, spinalis
acting bilaterally, extend the vertebral column at intervertebral joints
acting unilaterally, produce lateral bending of the vertebral column at intervertebral joints
where are the splenius capitis and splenius cervicis located and what are their actions?
supeficial to erector spinae in the neck
spleni capitis acts to extend the head; splenius cervicis acts to rotate the head
acting unilaterally, both will produce lateral bending of the cervical vertebrae
where are the transversospinalis muscles located? what are they and what are their actions?
deep to erector spinae
from superficial to deep: semispinalis, multifidus, rotatores
acting bilaterally, act to extend the vertebral column
acting unilaterally, produce rotation of the vertebral column
what are the actions of the suboccipital triangle muscles?
contribute to the extension at the atlantooccipital joints and rotation at the atlantoaxial joints
what innervates the deep muscles of the back?
dorsal rami of spinal nerves
A 45-year-old man complains of low back pain that radiates into both lower limbs and leg weakness. An MRI scan reveals the body of the L5 vertebra is displaced laterally. A diagnosis of the patient's condition would be:
E. spinal stenosis
D- spondylolisthesis- unilateral or bilateral defect or fracture of the isthmus accompanied by anterior displacement of the vertebral body-->bilateral lower back pain that radiates into both lower limbs and weakness in muscles of legs
spondylolysis-defect or fracture of the isthmus with no anterior displacement of the vertebral body
spondylosis- degenerative changes in intervertebral disks
spondylitis- inflammation that results in additional bone growth by steophytes at the margins of vertebral bodies; also calcification of anterior longitudinal ligament and sacroiliac joints-->anylosis (joint stiffening) and a bamboo spine (marie-srtumpell disease)
A spinal anesthesia is used for a patient undergoing surgery. A lumbar puncture is performed in the midline between L4 and L5. Which of the following will not be transvered?
A. interspinous ligament
B. posterior longitudinal ligament
C. epidural space
B. posterior longitudinal ligament- covers posterior parts of the vertebral bodies and intervening disks and is anterior to the dural sac
Which of the following structures in the vertebral canal will be anesthetized in a spinal procedure?
A. dorsal and ventral rami
B. lumbar spinal nerves
C. sacral spinal nerves
D. dorsal and ventral roots
E. lumbosacral plexus
D. dorsal and ventral roots are in the cauda equina found in the vertebral canal (others are found in intervertebral foramen or outside of the vertebral canal)
An MRI reveals a patient has a posterolateral herniation of the nucleus pulposus of the intervertebral disk between L5 and the sacrum. Which might you observe?
A. weakness in dorsiflexion
B. altered sensation on the dorsum of the foot
C. weakness in plantar flexion
D. altered sensation in the anterior thigh
E. weakness in extension of the leg at the knee
C. roots of S1 compressed which results in altered sensation in posterolateral leg, heel lateral side of the foot, weakness in flexion of the leg at the knee, weakness in plantar flexion
A 50-year-old man complains of bak pain and has difficulty walking. Diagnostic imaging reveals calcifications of the sacroiliac joints and anterior longitutinal ligament resulting from additional bone growth by osteophytes. This suggests the patient has:
D. spinal stenosis
A 64-year-old man presents with pain that radiates from the back, through the posterior thigh, and into the leg and foot. The diagnosis is a herniated nucleus pulposus of the intervertebral disk between the L4 and L5 vertebrae. What else might the patient experience?
A. altered sensation in the L3 dermatome
B. weakness of muscles innervated by the L5 spinal cord segment
C. inability to contract and empty the bladder
D. fecal incontinence
E. weakness in the ability to extend the leg at the knee
B. from compression of L5
A patient develops a peripheral neuropathy that results in the degeneration of nerve fibers in dorsal rami. All of the following may be evident EXCEPT:
A. sensation may be altered in skin covering the trapezius
B. iliocostalis muscle might be weak
C. axons firing through the dorsal sacral foramina may be affected
D. motor fibers in the dorsal scapular nerve may be affected
E. sensation from facet joints may be altered
C. dorsal scapular nerve is a ventral ramus of the C5 spinal nerve (few dorsal rami have names)
Your patient suffers from a herniated disk between the L5 vertebra and the sacrum. If the herniation is small, what neural structure might be subject to compression?
A. L4 spinal nerve
B. L5 spinal nerve
C. S1 spinal nerve
D. conus medullaris
E. lumbar splanchnic nerve
C- S1 spinal nerve