“approved” icon

“approved”




Скачати 101.62 Kb.
Назва“approved”
Сторінка1/3
Дата28.06.2012
Розмір101.62 Kb.
ТипДокументи
  1   2   3

Ministry of Health of Ukraine

Bukovinian State Medical University


APPROVED”


on methodical meeting of the Department of Anatomy, Topographical anatomy and Operative Surgery

…………………………….2007 р. (Protocol №……….)

The chief of department


professor ……………………….……Yu.T.Achtemiichuk

…………………………….2007 р.


METHODICAL GUIDELINES



for the 3d-year foreign students of English-spoken groups of the Medical Faculty

(speciality “General Medicine”)

for independent work during the preparation to practical studies



the Theme of studies

“TOPOGRAPHICAL ANATOMY AND OPERATIVE SURGERY OF THE VERTEBRAL COLUMN, SPINAL CORD AND THE TUNICS OF IT


Module 2

“Topographical anatomy and operative surgery of the regions and organs of the lumbar region, pelvis and extremities”


Semantic module

“Topographical anatomy and operative surgery of the vertebral column and extremities”


Chernivtsi – 2007

^ 1. Actuality of theme:

The topographical anatomy and operative surgery of the vertebral column, spinal cord and the tunics of it are very importance, because without the knowledge about peculiarities and variants of structure, form, location and mutual location of their anatomical structures, their age-specific and sexual properties it is impossible to diagnose in a proper time and correctly and to prescribe a necessary treatment to the patient. Surgeons of the different specialization usually pay much attention to the topographic anatomy of the spinal cord. Topography of the spinal cord is important for surgeons, traumatologists, neuropathologist and anesthesiologists. Small measures of the spinal canal, availability a number of the nerves and vessels causes the certain difficulties for surgical interventions for clinical and topical diagnosis.


^ 2. Duration of studies: 2 working hours.


3. Educational purpose (concrete purposes):

To know peculiarities and variants of structure, form, location of vertebral column and spinal cord.

To be able to define the skeletotopy and projectors of the vertebral column.

To master practical skills to make the manipulation on the vertebral column (puncture, blockade and so on).


^ 4. Base knowledges, abilities, skills, that necessary for the study themes (interdisciplinary integration):


The names of previous disciplines

The got skills

1. Normal anatomy

2. Physiology


To describe the structure and function of the different organs of the human body, to determine projectors and landmarks of the anatomical structures.


^ 5. Advices to the student.

5.1. Table of contents of the theme:

The vertebral column

The spinal, or vertebral, column is made up of thirty-three vertebrae, of which twenty-four are discrete vertebrae and nine are fused in the sacrum and coccyx. In the embryo the spine is curved into a gentle C shape but, with the extension of the head and lower limbs that occurs when the child first holds up its head, then sits and then stands, secondary forward curvatures appear in the cervical and lumbar region, which produce the sinusoidal curves of the fully developed spinal column.

The basic vertebral pattern is that of a body and of a neural arch surrounding the vertebral canal. The neural arch is made up of a pedicle on either side, each supporting a lamina which meets its opposite posteriorly in the midline. The pedicle bears a notch above and below which, with its neighbour, forms the intervertebral foramen. The arch bears a posterior spine, lateral transverse processes and upper and lower articular facets.

The intervertebral foramina transmit the segmental spinal nerves as follows: C1–7 pass over the superior aspect of their corresponding cervical vertebrae, C8 passes through the foramen between C7 and T1, and all subsequent nerves pass between the vertebra of their own number and the one below.

Now to consider the individual vertebrae in turn.

^ The cervical vertebrae (7)

These are readily identified by the foramen transversarium perforating the transverse processes. This foramen transmits the vertebral artery, the vein, and sympathetic nerve fibres. The spines are small and bifid (except C1 and C7 which are single) and the articular facets are relatively horizontal.

The atlas (C1) has no body. Its upper surface bears a superior articular facet on a thick lateral mass on each side which articulates with the occipital condyles of the skull.

Just posteriorly to this facet, the upper aspect of the posterior arch of the atlas is grooved by the vertebral artery as it passes medially and upwards to enter the foramen magnum.

The axis (C2) bears the dens (odontoid process) on the superior aspect of its body, representing the detached centrum of C1.

Nodding and lateral flexion movements occur at the atlanto-occipital joint, whereas rotation of the skull occurs at the atlanto-axial joint around the dens, which acts as a pivot.

C7 is the vertebra prominens, so called because of its relatively long and easily felt non-bifid spine; it is the first clearly palpable spine on running one’s fingers downwards along the vertebral crests, although the spine of T1 immediately below it is, in fact, the most prominent one.

The vertebral artery enters its vertebral course nearly always at the foramen transversarium of C6; it is not surprising, therefore, that the foramen of C7, which transmits only the vein, is small or even sometimes absent.

^ The thoracic vertebrae (12)

These vertebrae are characterized by demifacets on the sides of their bodies for articulation with the heads of the ribs and by facets on their transverse processes (apart from those of the lower two or three vertebrae) for the rib tubercles. The spines are long and downward sloping and the articular facets are also relatively vertical. The lowest couple are rather ‘lumbar’ in appearance, have a single facet on the side of the body and no facet on the transverse process.

The bodies of T5 and T8 are worth noting; they come into relationship with the descending aorta and are a little flattened by it on their left flank. If the descending aorta becomes aneurysmally dilated, these four vertebral bodies become eroded by its pressure, although their avascular intervertebral discs remain intact. You can make this diagnosis confidently when shown a specimen of four partly worn-away vertebrae with normal intervening discs.

^ The lumbar vertebrae (5)

These are of great size with strong, square, horizontal spines and with articular facets which lie in the sagittal plane. L5 is distinguished by its massive transverse process which connects with the whole lateral aspect of its pedicle and encroaches on its body; the transverse processes of the other lumbar vertebrae attach solely to the junction of pedicle with lamina.

^ The sacrum (5 fused)

The coccyx (3, 4 or 5 fused)

These are considered with the bony pelvis.

The intervertebral joints

The spinal column is made up of individual vertebrae which articulate body to body and their articular facets. Although movement between adjacent vertebrae is slight, the additive effect is considerable. Movement particularly occurs at the cervicodorsal and dorsolumbar junctions; these are the two common sites of vertebral injury.

The vertebral laminae are linked by the ligamentum flavum of elastic tissue, the spines by the tough supraspinous and relatively weak interspinous ligaments, and the articular facets by articular ligaments around their small synovial joints. All these ligaments serve to support the spinal column when it is in the fully flexed position.

Running the whole length of the vertebral bodies, along their anterior and posterior aspects respectively, are the tough anterior and posterior longitudinal ligaments.

The vertebral bodies are also joined by the extremely strong intervertebral discs. These each consist of a peripheral annulus fibrosus, which adheres to the thin cartilage plate on the vertebral body above and below, and which surrounds are gelatinous semifluid nucleus pulposus. The intervertebral discs constitute approximately a quarter of the length of the spine as well as accounting for its secondary curvatures.

In old age, the discs atrophy, with resulting shrinkage in height and return of the curvature of the spine to the C shape of the newborn.

^ Clinical features

1..Fractures of the spine most commonly involve T12, L1 and L2. The cause is usually a flexion–compression type of injury (for example, a fall from a height landing on the feet or buttocks, or a heavy weight falling on the shoulders), with resultant wedging of the involved vertebrae. If, in addition to compression, there is forceful forward movement, one vertebra may displace forward on its neighbour below with either dislocation or fracture of the articular facets between the two (fracture dislocation) and with rupture of the interspineous ligaments.

The cervical vertebrae (particularly C7), may be fractured or, more commonly, dislocated by a fall on the head with acute flexion of the neck, as might happen on diving into shallow water. Dislocation may even result from the sudden forward jerk which may occur when a motorcar or aeroplane crashes. Note that the relatively horizontal intervertebral facets of the cervical vertebrae allow dislocation to take place without their being fractured, whereas the relatively vertical thoracic and lumbar interverbral facets nearly always fracture in forward dislocation of the dorsolumbar region.

2..The comparatively thin posterior part of the annulus fibrosus may rupture, either due to trauma or to degenerative changes, allowing the nucleus pulposus to protrude posteriorly into the vertebral canal - the socalled ‘prolapsed intervertebral disc’. This may sometimes occur at the lower cervical intervertebral discs (C5/6 and C6/7), very occasionally in the thoracic and upper lumbar region or, by far the most commonly, at the L4/5 or L5/S1 disc. The diagnosis of this and other spinal conditions has been greatly facilitated by the introduction of MRI scans which give excellent anatomical details of this region.

Aprolapsed L4/5 disc produces pressure effects on the root of the 5th lumbar nerve, that of the L5/S1 disc on the 1st sacral nerve. Pain is referred to the back of the leg and foot along the distribution of the sciatic nerve. Hip flexion with the leg extended (‘straight leg raising’) is painful and limited due to the traction which this movement puts upon the already irritated and stretched nerve root. There may be a weakness of ankle dorsiflexion and numbness over the lower and lateral part of the leg and medial side of the foot (L5) or the lateral side of the foot (S1). L5 involvement may cause weakness of extension of the great toe (extensor hallucis longus). If S1 is affected, the ankle jerk may be diminished or absent and there may be weakness of plantar flexion.

Occasionally the disc prolapses directly backwards, and, if this is extensive, may compress the whole cauda equina, producing paraplegia.

^ 3..Lumbar puncture.

Lumbar puncture to withdraw C.S.F. from the spinal subarachnoid space must be performed well clear of the termination of the cord. A line joining the iliac crests passes through the 4th lumbar vertebra and therefore the intervertebral spaces immediately above or below this landmark can be used with safety. The spine must be fully flexed (with the patient either on his side or seated) so that the vertebral interspinous spaces are opened to their maximum extent. The needle is passed inwards and somewhat cranially exactly in the midline and at right angles to the spine; the supraspinous and interspinous ligaments are traversed and then the dura is penetrated, the latter with a distinct ‘give’. Occasionally root pain is experienced if a root of the cauda equina is impinged upon, but usually these float clear of the needle.

At spinal puncture C.S.F. can be obtained for examination; antibiotics, radio-opaque contrast medium or anaesthetics may be injected into the subarachnoid space, and the C.S.F. pressure can be estimated (normal, when lying on the side, 80–180 mm C.S.F.). Ablock in the spinal canal above the point of puncture, produced, for example, by a spinal tumour, can be revealed by Queckenstedt’s test as follows:

Pressure is applied to the neck in order to compress the internal jugular veins; this reduces venous outflow from the cranium and raises the intracranial pressure. Consequently, C.S.F. is displaced into the spinal sac and the C.S.F. pressure, as determined by lumbar puncture and manometry, rises briskly by at least 40 mm. This rise in pressure is not seen if a spinal block is present.

Extradural block..The extradural space can be entered by a needle passed either between the spinal laminae or via the sacral hiatus.

Sacral (caudal) anaesthesia

The sacral hiatus, between the last piece of sacrum and coccyx, can be entered by a needle which pierces skin, fascia and the tough posterior sacrococcygeal ligament to enter the sacral canal. The hiatus can be defined by palpating the sacral cornua on either side immediately above the natal left.

Anaesthetic solution injected here will travel extradurally to bathe the spinal roots emerging from the dural sheath, which terminates at the level of the 2nd sacral segment. The perineal anaesthesia can be used for low forceps delivery, episiotomy and repair of a perineal tear.


^ The spinal cord

The spinal cord is 18 in (45 cm) long. It is continuous above with the medulla oblongata at the level of the foramen magnum and ends below at the lower level of the 1st, or the upper level of the 2nd lumbar vertebra. Inferiorly, it tapers into the conus medullaris from which a prolongation of pia mater, the filum terminale, descends to be attached to the back of the coccyx.

The cord bears a deep longitudinal anterior fissure, a narrower posterior septum and on either side, a posterolateral sulcus along which the posterior (sensory) nerve roots are serially arranged.

These posterior roots each bear a ganglion which constitutes the first cell-station of the sensory nerves.

The anterior (motor) nerve roots emerge serially along the anterolateral aspect of the cord on either side. Both the anterior and posterior nerves arise by a series of rootlets from the cord.

At each intervertebral foramen the anterior and posterior nerve roots unite to form a spinal nerve which immediately divides into its anterior and posterior primary rami, each transmitting both motor and sensory fibres.

The length of the roots increases progressively from above downwards due to the disparity between the length of the cord and the vertebral column; the lumbar and sacral roots below the termination of the cord at vertebral level L2 continue as a leash of nerve roots termed the cauda equina.

^ Age differences

Up to the 3rd month of fetal life the spinal cord occupies the full extent of the vertebral canal. The vertebrae then outpace the cord in the rapidity of their growth so that, at birth, the cord reaches only the level of the 3rd lumbar vertebra.

Further differential growth up to the time of adolescence brings the cord to its definitive position at the approximate level of the disc between the 1st and 2nd lumbar vertebrae.

Structure

In transverse section of the cord is seen the central canal around which is the H-shaped grey matter, surrounded in turn by the white matter which contains the long ascending and descending tracts. Within the posterior horns of the grey matter, capped by the substantia gelatinosa, terminate many of the sensory fibres entering from the posterior nerve roots. In the large anterior horns lie the motor cells which give rise to the fibres of the anterior roots. In the thoracic and upper lumbar cord are found the lateral horns on each side, containing the cells of origin of the sympathetic system. The more important long tracts in the white matter will now be dealt with.

^ Blood supply

The anterior and posterior spinal arteries descend in the pia from the intracranial part of the vertebral artery. They are reinforced serially by branches from the ascending cervical, the cervical part of the vertebral, the intercostal and the lumbar arteries.

^ Clinical features

1..Complete transection of the cord is followed by total loss of sensation in the regions supplied by the cord segments below the level of injury together with flaccid muscle paralysis. As the cord distal to the section recovers from a period of spinal shock, the paralysis becomes spastic, with exaggerated reflexes. Voluntary sphincter control is lost but reflex emptying of bladder and rectum subsequently return, provided that the cord centres situated in the sacral zone of the cord are not destroyed.

2..Destruction of the centre of the cord, as occurs in syringomyelia and in some intramedullary tumours, first involves the decussating spinothalamic fibres so that initially there is bilateral loss of pain and temperature sense below the lesion; proprioception and fine touch are preserved till late in the uncrossed posterior columns.

3..Hemisection of the cord is followed by the Brown-Sequard syndrome; there is paralysis on the affected side below the lesion (pyramidal tract) and also loss of proprioception and fine discrimination (dorsal columns). Pain and temperature senses are lost on the opposite side below the lesion, because the affected spinothalamic tract carries fibres which have decussated below the level of cord hemisection.

4..Tabes dorsalis, which is a syphilitic degenerative lesion of the posterior columns and posterior nerve roots, is characterized by loss of proprioception; the patient becomes ataxic, particularly if he closes his eyes, because he has lost his position sense for which he can partially compensate by visual knowledge of his spatial relationship (Romberg’s sign).

5..Intractable pain can be treated in selected cases by cutting the appropriate posterior nerve roots (posterior rhizotomy) or by division of the spinothalamic tract on the side opposite the pain (cordotomy). A knife passed 3 mm into the cord anterior to the denticulate ligament and then swept anteriorly from this point will sever the spinothalamic tract but preserve the pyramidal tract lying immediately posterior to it.

^ The membranes of the cord (the meninges)

The spinal cord, like the brain, is closely ensheathed by the pia mater. This is thickened on either side between the nerve roots to form the denticulate ligament, which passes laterally to adhere to the dura. Inferiorly, the pia continues as the filum terminale, which pierces the distal extremity of the dural sac and becomes attached to the coccyx.

The arachnoid mater lines the dura matter, leaving an extensive subarachnoid space, containing cerebrospinal fluid (C.S.F.), between it and the pia. Both pia and arachnoid are continued along the spinal nerve roots.

The dura itself forms a tough sheath to the cord. It ends distally at the level of the 2nd sacral vertebra. It also continues along each nerve root and blends with the sheaths of the peripheral nerves.

The extradural (or epidural) space is the compartment between the dural sheath and the spinal canal. It extends downwards from the foramen magnum (above which the dura becomes two-layered) to the sacral hiatus.

It is filled with semiliquid fat and contains lymphatics (although there are no lymphatics within the nervous system deep to the dura), together with arteries and large, thin-walled veins. These can be considered equivalent to the cerebral venous sinuses which lie between the two layers of cerebral dura. Whereas the arteries of this space are relatively insignificant, the extradural veins form a plexus which communicate freely and also receive the basivertebral veins, which emerge from each vertebral body on its posterior aspect. In addition, the veins link up with both the pelvic veins below and the cerebral veins above—a pathway for the spread of both bacteria and tumour cells. This accounts, for example, for the ready spread of prostatic cancer to the sacrum and vertebrae (Batson’s ‘valveless vertebral venous plexus’).

^ Clinical features

Lumbar puncture to withdraw C.S.F. from the spinal subarachnoid space must be performed well clear of the termination of the cord. A line joining the iliac crests passes through the 4th lumbar vertebra and therefore the intervertebral spaces immediately above or below this landmark can be used with safety. The spine must be fully flexed (with the patient either on his side or seated) so that the vertebral interspinous spaces are opened to their maximum extent. The needle is passed inwards and somewhat cranially exactly in the midline and at right angles to the spine; the supraspinous and interspinous ligaments are traversed and then the dura is penetrated, the latter with a distinct ‘give’. Occasionally root pain is experienced if a root of the cauda equina is impinged upon, but usually these float clear of the needle.

At spinal puncture C.S.F. can be obtained for examination; antibiotics, radio-opaque contrast medium or anaesthetics may be injected into the subarachnoid space, and the C.S.F. pressure can be estimated (normal, when lying on the side, 80-180 mm C.S.F.). Ablock in the spinal canal above the point of puncture, produced, for example, by a spinal tumour, can be revealed by Queckenstedt’s test as follows:

Pressure is applied to the neck in order to compress the internal jugular veins; this reduces venous outflow from the cranium and raises the intracranial pressure. Consequently, C.S.F. is displaced into the spinal sac and the C.S.F. pressure, as determined by lumbar puncture and manometry, rises briskly by at least 40 mm. This rise in pressure is not seen if a spinal block is present.

Extradural block..The extradural space can be entered by a needle passed either between the spinal laminae or via the sacral hiatus.

  1   2   3

Схожі:

“approved” icon“approved”

“approved” icon“approved”

“approved” icon“approved”

“approved” icon“approved”

“approved” icon“approved”

“approved” icon“approved”

“approved” icon“approved”

“approved” iconApproved

“approved” iconApproved

“approved” icon“approved”

Додайте кнопку на своєму сайті:
Документи


База даних захищена авторським правом ©zavantag.com 2000-2013
При копіюванні матеріалу обов'язкове зазначення активного посилання відкритою для індексації.
звернутися до адміністрації
Документи