Terms in this set (104)
Where is a good place to start counting spines?
C7 (the vertebrae prominent). To palpate, flex your head and feel the large spine at base of your neck; you can count spines from here.
What vertebrae is the superior angle of the scapula?
The T2 vertebral level.
What vertebrae is the inferior angle of the scapula?
The T7 vertebral level.
Located on midline, superficial to vertebral spines; it separates the erector spinal muscles on either side.
Where is an ideal place on the back to take spinal taps?
Where is an ideal place on the back to withdraw CFS?
Where is an ideal place to administer spinal anesthesia?
Where is the typical inferior extent of the dural sac defined?
S2 level of vertebral column- dimples on the lower back are located over the posterior superior iliac spine- a line drawn between them defines the S2 level. This is the typical inferior extent the dural sac.
Describe the significance of the superior end of natal (intergluteal) cleft
This is located superficial to the sacral hiatus- an important landmark since most epidural anesthetics are administered here.
Describe the vertebral column schematic
There are 33 vertebrae:
5 S (sacral-these are fused),
4Cx (coccygeal- these are fused into the structure called the coccyx).
What parts on the vertebral column do not have intervertebral discs?
Atlas/Axis, and the coccyx.
Is it okay if there are pronounced curvatures in the vertebral column?
It is normal to have pronounced curvatures in the vertebral column located at the cervical and lumbar regions.
(hump back): excessive thoracic curvature.
Older people/ hunch back of notre dame
excessive lateral curvature. The cause can be idiopathic (starts in childhood, developmental); secondary structural (due to a defomity such as hemivertebra); sciatic or ischiadic (caused by muscle spasms responding to painful conditions), or compensatory (due to shortening of a lower limb).
(sway back): excessive lumbar curvature (obesity/beer belly), pregnancy
How is scoliosis most readily revealed?
This is most really revealed when the patient is asked to flex the vertebral column by bending forward. In some cases, it is very apparent; it can also be much less prominent
another name for c1 and c2
atlas and axis (respectively)
articulate with ribs
how is scapula attached to the spine
it is free floating, and is connected to the back by extrinsic back muscles. Thus, it is hooked to the spine, using musculature.
what does the atlas articulate with
the occipital bone of the skull. The dens of axis plays a role here as well. .
What are the important parts of the posterior skull
the occipital condyles (these articulate with the atlas), superior and inferior nuchal lines of the occipital bone, mastoid process of the temporal bone.
What is the occipital condyle/atlas complex abbreviated as
Where are the superior and inferior angles of the vertebral column
T2 and T7 respectively.
Where can the acromion be found
This is the palpable endpoint of the shoulder
Where can the coracoid process be found
This faces anteriorly
What do the sacral vertebrae articulate with
The iliac bones at sacroiliac joint that are held firmly in place by a number of ligaments.
continuous with spinal cord and covering sit
Parts of a typical vertebra
Pop off lamina, which opens up the vertebral foramen
(made up of the inferior vertebral notch, as well as the superior vertebral notch). This is where the spinal nerves exit the vertebral column.
Zygapophysial (facet) joints
Made between the inferior and superior articular processes. These articulate with each other.
Found between the bodies of the vertebrae (letter c in this picture).
simply the portion of the vertebral lamina that is between the superior and inferior articular processes. Fractures in this region (pars fractures) are also called spondylolysis.
Causes major shifting
anterior and posterior arches
Cervical vertebrae notable charactieristics
These are distinguished because all have a hole in the transverse process through which the vertebral artery passes (foramen transversarium). The atlas (C1) and the axis (C2) are unique.
Lumbar Vertebrae notable charcacteristics
Are large with heavy bodies; they also have an extra set of processes- the mammilalary processes which are located between the spine and the transverse processes
Thoracic vertebrae notable characteristics
Specialized articulation regions for ribs
Dens, and sits underneath C1
Where you'd find the vertebral artery
Differences between the C1 vertebra and C2
(the atlas): has no spine but has anterior and posterior arches, large superior articular facets for articulation with the occipital condyles of the skull (at the atlanto-occipital articulation).
(the axis): has the dens (odontoid or tooth-like process) which articulates with the homologue of the body of the atlas (its anterior arch)--- forming the atlanto-axial joint.
The 5 sacral vertebrae are fused forming this bone. Note the sacral hiatus (the lower opening into the sacral (vertebral) canal). This sacral bone is ridged on the posterior side but has a smooth anterior surface. The sacral foramina are openings for sacral spinal nerves (analagous to the intervertebral foramen at superior levels of the vertebral column).
The coccygeal vertebrae (4) are fused forming this tail-like process
Runs along the vertebral spines as a cord. It continues the length of the vertebral column; it merges with the strong nuchal ligament (ligament nuchal) in the cervical curvature region. The nuchal ligament substitutes for bone in providing muscle attachments in this region.
Anterior longitudinal ligament
Lies on the anterior side of the bodies of lumbar vertebrae; it continues the length of the vertebral column. This ligament has an important potential splinting action that should be use whenever fracture of the vertebral column is suspected (except cervical fractures that result from hyperextension). When a fracture of vertebral column occurs, the patient is typically held in hyperextension- the pull of the anterior longitudinal ligament will help realign fragments of bone and minimize further injury to the spinal cord.
run from lamina to lamina, covering most of the space between these vertebral regions. The ligament flava contain elastic fibers that give them a yellow color. During flexion, the vertebra tend to move apart and the ligament lava stetch to accommodate this. The ligament flava stay relatively taut during extension except in severe, violent hyperextension (whip-lash type injuries). In this case, the elasticity of the ligaments is overridden and they may buckle inward- a situation that may injure the underlying spinal cord.
Posterior Longitudinal Ligament
runs along the posterior side of vertebral bodies. In the schematic, the pedicles have been cut and the posterior half of the vertebrae as well as dura mater and neural tissue were removed to visualize this ligament. Note that this ligament is actually anterior to the spinal cord! The positions of interspinous ligaments between adjacent vertebral spines and inter-transverse ligaments between adjacent transverse processes are also shown.
Craniovertebral ligaments (anterior)
The ligaments of the vertebral column continue across the atlanto-occipital juncture. They have special names here:The anterior longitudinal ligament is called the anterior atlanto-occipital membrane at the C1-skull junction.The ligamentum flavum continues as the posterior atlanto-occipital membrane at the C1-skull junction
Craniovertebral ligaments (posterior)
Craniocervical ligaments (continued)
The posterior longitudinal ligament continues as the tectorial membrane at the C1-skull junction.
Spcial ligaments for these C1-C2 articulation
Cruciform ligament - Cross shaped ligament with longitudinal and transverse parts.
The alar or check ligament of the dens lies deep to the cruciform ligament.
These important ligaments stabilize the articulation of the dens with the anterior arch of the atlas. Should these ligaments rupture due to injury, the dens could be driven into the upper cervical spinal cord and/or brainstem with certain and immediate death. (Damage to the spinal cord above the level of the phrenic nerve outflow from C3-5 typically results in death).
IV disks are numbered according to the vertebrae they lie between (e.g C5-6 disk is between the 5th and 6th Cervical vertebrae)!
There are only 23 intervertebral disks (none between the skull and C1, none between C1-2, and none in the sacral or coccygeal regions). The L5-S1 disk is the lowest IV disk).The IV disks provide strong attachments between the vertebral bodies and act as shock absorbers at these weight bearing joints.
Two parts of an intervertebral disk and describe
The two parts of an intervertebral disk are the outer annulus fibrosis (arranged in concentric layers of parallel fibers that crisscross those of the next layer) and the inner nucleus pulposus. DISK PROLAPSE: Intervertebral disks can prolapse (herniate) and cause painful clinical problems. In disk prolapse, a tear or weakness of the annulus fibrosis occurs, resulting in a bulging out of the nucleus pulposus. This typically occurs the POSTEROLATERAL DIRECTION (Where the annulus is the thinnest and thus weakest). At this position, the protruding material may impinge on and compress spinal nerves that are exiting the vertebral column via the intervertebral foramen.
Note the term "slipped disk" refers to prolapse/herniation (disks actually don't slip from between the vertebra!).
CT scan- can it show disk prolapse?
CT scan showing disk prolapse.
Disk prolapse occurs with about equal frequency at cervical and lumbar levels.
At those levels the overwhelming majority of prolapses occur at L4-5 or L5-S1, and at C5-6 or C6-7.
Where do we not have intervertebral disks
None between skull and C1
None between C1 and C2
None in Sacral Region
None in Coccygeal Region
Numbering Scheme and relationships of spinal nerves, vertebrae and intervertebral disks.
SPINAL NERVES: There are 31 pairs of spinal nerves that exist via the intervertebral foramina (vs. 33 vertebrae). 8C (cervical), 12T (thoracic), 5L (lumbar), 5S (sacral), 1 Cx (coccygeal) pairs of nerves.
The cervical nerves leave above their same numbered vertebra. (For example, C1 nerve leaves above the atlas (between the C1 - skull juncture). The exception is C8 nerve (there is no C8 vertebra!) which leaves at the C7-T1 vertebral junction.
Thoracic and lumbar nerves leave below their same numbered vertebra.
Where does the spinal cord end within the adult
L1/L2-Cx1 region. Here, we do not have a spinal cord, so it's a safe area to get cerebral spinal fluid.
For thoracic and lumbar nerves, do they leave below or under their same numbered vertebra?
BELOW (because of the C 8 nerves)
Spinal cord ends her
Disc prolapse occurs at curvature. T/F
Describe the second number rule for disk prolapse for cervical and lumbar levels
For cervical and lumbar levels:
use the "second number rule" for disk prolapse:
The nerve affected by posterolateral disk prolapse
is designated by the second number in the disk's
name (e.g. disk C5-6 typically impinges on nerve C6).
In the cervical region this is the nerve leaving at that level.
In the lumbar level, this is the nerve leaving at the
next lower vertebral level.
The second number rule does not work for the thoracic level, but prolapse in that part of the spine is very rare.
How do you fix a herniated lumbar disk?
T/F- you can NEVER see a thoracic level disc prolapse.
FALSE! in the elderly population, you very well can. second number rule still doesn't work here
Movements of the vertebral column
Movements of the vertebral column: Flexion of vertebral column is done by abdominal musculature (e.g. rectus abdominus). Flexion is also done by gravity when the intrinsic back muscles aren't functioning to hold the spine erect. The intrinsic muscles of the back accomplish extension, rotation and lateral bending of the vertebral column (and head). Note that extension refers to the return to the "anatomical position" and continued movement beyond that plane is called hyperextension.The extrinsic musculature of the back which is superficial to the intrinsic back muscles has to do with movements of the upper extremity (or respiration) - not with movements of the vertebral column.
Extrinsic Back Muscles
Superficially located on the back
Move the upper extremities or are involved in respiration.
Rhomboid Minor and Major,
Posterior Superior & Inferior Serratus
Triangle of Auscultation
this means 'listen' and the triangle is located at the 6th intercostal space. To 'open up' this space for listening, have the patient protract (abduct) the scapula by bringing their arms together in front of their body. Now, the space between the lower border of the trapezius, the upper bored of the latissimus doors and medial border of the scapula is covered only by skin and intercostal muscles. This is an excellent place for listening to thoracic sounds.
Muscles act here
Origin: superior nuchal line of occipital bone, nuchal ligaement, and spines of all thoracic vertebrae.
Insertion: spine of scapula and accordion, lateral portion of clavicle.
Nerve: cranial nerve XI- the spinal accessory nerve.
Function: elevates, retracts and superiorly rotates scapula to face the gleaned cavity skyward (this is needed for full aBduction of the arm to occur); the trapezius can also depress the scapula *when just the inferior fibers are used)
Arterial supply: superficial branch of transverse cervical artery
Origin: iliac crest, spines of T7-L5, thoracolumbar fascia, inferior 3-4 ribs.
Insertion: floor of inter tubercular (bicipital) groove of humerus
Nerve: thoracodorsal nerve
Function: adducts, extends and medially rotates the humerus (picture the power stroke of swimming)
Arterial supply: thoracodorsal artery
Inserts into the scapula
Inserts into the scapula
straighten up shoulders
Origin: transverse processes of C1-C4
Insertion: scapula at its superior angle
Nerve: dorsal scapular n.
Function: elevates scapula (or inclines neck if scapula is fixed)
Arterial supply: deep branch of transverse cervical a.
Origin: vertebral spines: rhomboid minor from C7-T1, Rhomboid major from T2-5
Insertion: medial border of the scapula (the rhomboid minor inserts more superiorly than the major)
Nerve: dorsal scapular n.
Function: adduct and rotate scapula
Arterial: deep branch of transverse cervical a.
Serratus posterior muscles
These are the deepest of the extrinsic muscles of the back. They are very thin muscles that assist respiration.The superior group extends from the spinous process of C7-T3 and inserts on the superior border of ribs 2-5. The inferior group originates from the spinous processes of T11-L2 and inserts on the inferior border of the lower 3-4 ribs.
Intrinsic or True back Muscles
Extend the vertebral column/head
Rotate the vertebral column/head
Innervated by dorsal rami of spinal nerves
Erector Spinae Muscles
The "True" back muscles are concerned with maintenance of posture and the movements of the vertebral column. They are all deep to the extrinsic musculature of the back. They are found in three layers:
The most superficial layer (splenius group - located on the back of the neck) has fibers passing superolaterally.
The intermediate layer (erector spinae group) has fibers running longitudinally.
The deep layer (transversospinalis group) has fibers that run superomedially. ALL intrinsic back muscles are innervated by dorsal rami of spinal nerves.
What are the three columns of the erector spinal muscles
These are examples of the intrinsic muscles of the back. The three columns on each side of the spine are iliocostalis, spinals, and longisimus.
iliocostalis (lateral group)- ilium to costal (rib)
Longissimus (between the two)
(part of bandage of back of neck)
Origin: lower half of ligament nuchal, spines of C7-T3
Insertion: mastoid process of temporal bone and lateral part of occipital bone
Nerve: dorsal rami (No name)
Function: together they extend head, acting alone (one side only) it laterally tilts the head)
Arterial supply: superficial branch of transverse cervical.
(note this muscle is mostly covered by the splenius captious)
Origin: spines of T3-T6
Insertion: transverse processes of upper 3-4 cervival vertebrae
Nerve: dorsal rami
Function: acting together they extend the neck, acting alone it laterally till the neck (and thus the head).
This large muscle group runs longitudinally from sacrum to skull. As a whole, this group extends the vertebral column.
The most lateral division is the iliocostalis muscles.
The longissimus muscle group lies intermediate.
The spinals muscle group is closest to midline and is the least well developed.
The longissimus and iliocostalis are large bundles of musculature with numerous slips of origin and insertion.
In short, they are columns of muscles that are all innervated by dorsal rami of spinal nerves.
The transversospinalis muscle group
Below the erector spinae muscles are several shorter muscles. These are seen in the grooves between the transverse processes and spines of the vertebrae. Their course is superior and medial. Generally they originate from transverse processes and insert into a vertebral spinous process located more superiorly.
As a group, they extend and rotate the vertebral column (and head)
This group has three mean division that present in the following order from superficial to deep (the size also decreases as you go deeper)
These span about 6 vertebrae and are represented in only the upper half of the column (T10 and superior).
There are 3 parts: the semispinalis thoracic and semispinalis crevices originate from transverse processes of thoracic vertebrae and generally insert onto spines of higher vertebrae.
This is a large muscle and distinguished anatomically by a number of imperfect tendinous intersections that are present in its medial part. Origin: tips of transverse processes of upper thoracic and lower cervivcal vertebrae. Insertion: occipital bone between the nuchal lines. The large dorsal rami of spinal nerves C2 (greater occipital nerve) and C3 pierce this muscle).
These are represented in the entire vertebral column but are heaviest and best developed in the lumbar region (note at the level the semispinalis muscles are not present and this is a good place to dissect and visualize the multifid). Generally, these muscles span 2-5 vertebrae, originating from a transverse processes and inserting on the base of a vertebral spine. A main origin for the heavy lumbar portion of the multifid group is the sacrum and mammillary processes of lumbar vertebrae.
The rotatores longus muscles cross 1 entire vertebrae. They originate from a transverse process and insert on the spinous process of a more superior vertebrae. The rotatores brevis: arise from a transverse process of one vertebrae and insert into the base of the spinous process immediately superior to it.
These are best studied in diagrams and not the lab.
This is located at the base of the posterior neck. The 4 sub occipital muscles are visible when the trapezius, splenius captious, and semispinalis captious muscles are reflected.
2 nerves are associated with the sub occipital region: C1, the sub occipital n, is located within the triangle and C2, the great occipital n, exists inferior to this region.
The vertebral artery can be located deep within the floor of the sub occipital triangle.
ALl 4 suboccipital muscles are innervated by the sub occipital nerve (the dorsal rams of C1) . The greater occipital nerve (the dorsal rams of spinal nerve C2) is a sensory nerve to the scalp. Muscles of the sub occipital region extend and rotate the head.
Rectus Capitis Posterior Minor/Major
Rectus Capitis Posterior Minor:
Origin: posterior tubercle of atlas C1
Insertion: occipital boneRectus Capitis Posterior Major is located inferior and lateral to the minor.
Origin: axis (C2) spine
Insertion: occipital bone Both muscles function to extend and laterally rotate the head; both are innervated by the suboccipital nerve (dorsal ramus of C1)
Oblique Capitus Superior/ Inferior
Oblique Capitus Superior: Origin: transverse process of the atlas C1 Insertion: occipital boneOblique Capitus Inferior Origin: spine of axis (C2) Insertion: transverse process of the atlas (C1)Innervation: Both oblique muscles are innervated by the suboccipital nerve (dorsal ramus of C1). These muscles function to laterally rotate the head; the oblique capitus superior also aids in extension of the head.
Describe development of vertebrae
The mid-saggital images in the right 2 panels illustrate that the spinal cord does not occupy the entire vertebral column. In the adult (far right figure), the spinal cord occupies only the upper 2/3 of vertebral column - running from the medulla oblongata of the brain stem to about the L1-2 intervertebral disc level. Sometimes the ending is as high as T12 and sometimes it extends as low as the L3 vertebral level.
In a 6 month fetus (middle figure), the spinal cord extends to the S1 vertebral level; in the newborn (not shown), it usually extends to L3. Because neurons in the spinal cord do not divide after birth, nor grow as extensively as the vertebrae, the cord occupies relatively less and less of the vertebral column as development proceeds.
Distal end of the spinal cord
Schematic enlargement of the distal end of the spinal cord.
The spinal cord ends in a cone shaped structure called the conus medullaris. Inferior to that, dorsal and ventral nerve roots that are within the vertebral column and still heading inferiorly to their points of exit from the vertebral column are present. This structure, a collection of dorsal and ventral roots, is called the cauda equina. (This term means "horses tail") The dural sac which covers the spinal cord and cauda equina ends at the S2 level of the vertebral column.
Covering of the spinal cord: The MeningesThis connective tissue material is present as 3 layers:Dura mater ("tough mother"): The outermost, leathery-like layer of connective tissue that covers the spinal cord (and brain), the dorsal and ventral roots as they enter the intervertebral foramen, and the spinal ganglia. Arachnoid mater: This is the intermediate layer of meninges which has a 3 dimensional appearance in the living. Wisps of arachnoid trabeculae span the space between the outer surface of the arachnoid mater and the deeper lying pia mater. The subarachnoid space is filled with cerebrospinal fluid (CSF). Pia mater: This layer is very thin and intimately invests blood vessels, dorsal and ventral roots and the entire surface of spinal cord and brain.
Note that the meninges also extend as a "sleeve" into the intervertebral foramen, covering the spinal ganglia before blending with the epineurial connective tissue layer that inverts peripheral nerves.
These are specialized regions of pia mater. They are located midway between each set of dorsal and ventral rootlets but are typically found only above the T12 level of the vertebral column.
Filum terminale (Terminal filum)
When the spinal cord tapers to its distal ending as the conus medullaris, it is covered by pia mater. This pia mater tapers into a string which continues as the filum terminale interna or the internal terminal filum (shown in red). This structure lies among the caudal dorsal and ventral nerve roots which form the cauda equina and can usually be distinguished in the lab by its very white shiny color.
At the inferior ending of the dural sac (S2 vertebral level), the filum terminale picks up a dural covering and is then called the filum terminale externa.
Filum Terminale Externa
At the S2 level, the "string" of pia mater called the filum terminale interna (internal terminal filum) becomes invested with dura mater (as the dural sac ends) and continues inferiorly. At this point, it is called the filum terminale externa (external terminal filum). This structure continues to the sacral hiatus level where it anchors to bone.
This is a procedure commonly used in OB-GYN, to relieve pelvic floor pain during vaginal childbirth. The anesthetic drug is administered to the space outside of the lower dural sac (into the "epidural" space). Remember that the dural sac ends at S2.Typically, the needle is inserted through the sacral hiatus and positioned in the sacral canal. It is also possible to administer drug epidurally via a "trans-sacral" approach where the needle is inserted through one of the lower sacral foramina.Anesthetic drugs applied to the epidural space affect spinal nerves S2 - Cox1 which lie outside of the main dural sac enroute to their point of exit from the sacrum.
Where does the spinal tap occur
This is typically done between the L3- L4, or L4-L5.This is done at a level of the vertebral column inferior to the ending of the spinal cord (which typically ends at the L1-L2 disk level).
Thus, lumbar punctures are done at either the junction of the L3-4 vertebrae or the junction of the L4-5 vertebrae. The subarachnoid space is large in this region (the "lumbar cistern") and this is a common point for either removing CSF or introducing drugs. The location of the L4 vertebral spine can be determined by palpating the high points of the iliac crest and drawing an imaginary line between those points.
Lumbar "taps" are done to sample CSF from the subarchnoid space for a variety of clinical tests, or to administer imaging fluids for myelography. The same landmarks are used to administer anesthetic agents.
In this procedure, anesthetic agents are introduced into the subarachnoid space; this is a common method used for cesarean sections in child birth.
A needle is pushed into the space between the vertebral lamina (on or very close to the midline) and positioned in the subarachnoid space. Usually, the L3-4 or the L4-5 interval is used, in either case, it is important to locate the position of L4.
While the needle could theoretically hit caudal dorsal and ventral nerve roots that make up the cauda equina, in practice these nerve roots but easily move out of the way since they are floating in the CSF
SPinal cord segment
Know the concept of a spinal cord segment. A segment of spinal cord is that portion which gives rise to a given pair of ventral roots and which receives a pair of dorsal roots. For example, all of the motor axons that form the C5 ventral root (and that exit as the C5 spinal nerve) come from a contiguous stretch of spinal cord grey matter in the ventral horn (thousand of neurons over the span of a few millimeters). The rootlets converge to form the C5 ventral root that then forms part of the C5 spinal nerve.
The extremities (arms and legs) are served by only ventral rami of spinal nerves while the dorsal rami innervate the dermatomes of the back. All spinal nerves have a dermatome except for C1. Some very general knowledge of dermatome maps is useful: C2 (dorsal ramus) ~ back of the head; C3-4 ~ neck and top of shoulder, C5-T1 ~ upper extremity (C7 = the middle finger, C8 = the little finger; T4 is ~level with the nipple line, T6 is ~ bottom of sternum, T10 is ~ belly, T12 is ~ pubic bone, L1-S2 are lower extremity, S3-Cox1 are perineal (genital) area.
White and grey matter in spinal cord
The relative proportion of white and grey matter differs at higher compared to lower levels of the spinal cord. Relatively more white matter is present at upper levels of the cord since most of the descending axons destined for inferior levels as well as ascending axons which are heading to the brain from lower levels are represented here. There are enlargements of the spinal cord grey matter at cervical and lumbar levels since these regions contain the neurons that innervate the extremities.
Blood supply to spinal cord...where does it come?
The blood supply to the spinal cord at the cervical level begins with the vertebral arteries.
Before the vertebral arteries pass superiorly and merge to form the basilar artery at the base of the brain stem, they give off the arterial branches which form the spinal arterial system.
The vertebral arteries give off 1 anterior spinal artery and 2 posterior spinal arteries. The anterior spinal artery lies in the anterior (ventral) median fissure and supplies the anterior 2/3 of the spinal cord; the paired posterior spinal arteries supply the posterior 1/3 portion of the cord.
A series of radicular and segmental arteries contribute to the spinal cord arterial tree at all levels. These arise from spinal branches of vertebral, deep cervical, ascending cervical, posterior intercostal, (and at lower levels from lumbar and sacral arteries).
Typically, one of the segmental feeder arteries is quite large (then it is termed the great anterior segmental medullary artery, clinically referred to as the 'great radicular'). It usually branches from an inferior intercostal art and contributes very substantially to the anterior spinal artery. PARAPLEGIA can be caused by inadvertent ligation of the 'great radicular' because it deprives the spinal cord of arterial blood. Neural tissue is intolerant of anoxia and even brief loss of oxygenated blood will permanently damage spinal cord neurons, resulting in functional loss.
Spinal arteries and spine relationship
The spinal arteries receive anastomotic feeds all along the spine by segmental and radicular arteries that travel through the intervertebral foramina (following along the dorsal and ventral roots).
Segmental arteries contribute to the anterior and spinal arterial system, radiculars stay with and nourish the nerve roots.
INJURY TO SPINAL CORD
DIRECT Injuries to the spinal cord:
These are typically penetrating injuries such as stab wounds, gunshot or other missile wounds. Often these pass to the cord between (or through) vertebral laminae. When the dura mater is compromised, they are called open injuries.
INDIRECT Injuries to the spinal cord:
These are typically closed injuries (the dura is not broken or compromised). Some of the ways this type of injury occurs are shown: Hyperflexion injuries (falls, diving, etc). Crush injuries (being pinned under a collapsing structure or overturned automobile etc.) Hyperextension injuries (whip lash; being thrown from auto, etc.) This type can result from the inward (anterior) buckling or bulging of the ligamenta flava if the elasticity of these ligaments is overcome during rapid and violent hyperextention. Such a transient inward buckling event will damage the spinal cord. The clinical presentation is often confusing since no vertebral dislocation or fracture maybe present - but the patient presents in a severely neurologically compromised manner. It takes very little to permanently damage the spinal cord.
of spinal cord damage. After a spinal cord injury (SCI), voluntary motor function will be lost at all levels below the injury. There will be "upper motor neuron signs" present.
Below the level of an SCI, muscles remain innervated by their peripheral nerves (thus there is no "flaccid paralysis" , muscle tone is present - lower motor neuron signs are absent except for muscles innervated by the specific region of spinal cord that was damaged)
After SCI there is no connection between the output motor neurons and the "master controller" (higher brain centers). Thus, descending commands from the brain to initiate and mediate smooth sequential and coordinated movements are not relayed through the SCI site. With time, the patient will exhibit atrophy from non-use of musculature.
How can we use dermatome maps to pinpoint spinal cord injuries?
Dermatome maps are most useful in pinpointing the level of a spinal cord injury.
After an SCI, sensory loss will be seen at all levels of the body (all dermatomes) BELOW (inferior to) the level at which the SCI occurred.
Thus, determining the dermatome at which a patient can no longer "feel" a pin prick can fairly accurately target the level at which the injury occurred.
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