The vertebral column part 4 Flashcards
Where does the pia mater end
L2- but forms part of filum terminale- a modification of the pia mater that runs down in the cauda equina.- anchors to S2
Which muscles are involved in flexion of the vertebral column
Psoas major and rectus abdominis
Which muslces are involved in extension of the vertebral column
Erector Spinae
Gluteus maximus
Which muscles are involved in rotation of the vertebral column
Splenius Sternoclamastoid Transversospinalis External Oblique Internal oblique Iliocostalis and longissimus
Which muscles are involved in lateral flexion of the vertebral column
Splenius * Sternoclamastoid Rhomboids Quadratus lumborum Anterior part of external oblique Lateral parts of internal and external oblique Gluteus medius and maximus * Internal oblique (anterior part) Adductor longus *
- don’t produce movement at IV joints
How is each spinal nerve connected to the spinal cord
Anterior and posterior roots
Describe the posterior roots
The posterior root contains the processes of sensory neurons carrying information to the CNS—the cell bodies of the sensory neurons, which are derived embryologically from neural crest cells, are clustered in a spinal ganglion at the distal end of the posterior root, usually in the intervertebral foramen.
Describe the anterior roots
The anterior root contains motor nerve fibers, which carry signals away from the CNS—the cell bodies of the primary motor neurons are in anterior regions of the spinal cord.
What do the anterior and posterior roots divide into
Medially, the posterior and anterior roots divide into rootlets, which attach to the spinal cord.
What is meant by a spinal segment
A spinal segment is the area of the spinal cord that gives rise to the posterior and anterior rootlets, which will form a single pair of spinal nerves. Laterally, the posterior and anterior roots on each side join to form a spinal nerve.
What does each spinal nerve divide into
Each spinal nerve divides, as it emerges from an intervertebral foramen, into two major branches: a small posterior ramus and a much larger anterior ramus (Fig. 2.53):
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The posterior rami innervate only intrinsic back muscles (the epaxial muscles) and an associated narrow strip of skin on the back.
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The anterior rami innervate most other skeletal muscles (the hypaxial muscles) of the body, including those of the limbs and trunk, and most remaining areas of the skin, except for certain regions of the head.
What happens near the point of division of the anterior and posterior rami
Near the point of division into anterior and posterior rami, each spinal nerve gives rise to two to four small recurrent meningeal (sinuvertebral) nerves (see Fig. 2.51). These nerves reenter the intervertebral foramen to supply dura, ligaments, intervertebral discs, and blood vessels.
What are the major somatic plexuses formed by
All major somatic plexuses (cervical, brachial, lumbar, and sacral) are formed by anterior rami.
Which muscles are innervated by the anterior and posterior rami
Anterior- extrinsic muscles
Posterior- intrinsic muscles
Describe what happens to the passage of the spinal roots as you go further down the spinal cord
Because the spinal cord is much shorter than the vertebral column, the roots of spinal nerves become longer and pass more obliquely from the cervical to coccygeal regions of the vertebral canal
Describe where the nerves emerge from in the spinal cord
In adults, the spinal cord terminates at a level approximately between vertebrae LI and LII, but this can range between vertebra TXII and the disc between vertebrae LII and LIII. Consequently, posterior and anterior roots forming spinal nerves emerging between vertebrae in the lower regions of the vertebral column are connected to the spinal cord at higher vertebral levels.
Below the end of the spinal cord, the posterior and anterior roots of lumbar, sacral, and coccygeal nerves pass inferiorly to reach their exit points from the vertebral canal. This terminal cluster of roots is the cauda equina.
At which vertebral level is a lumbar puncture performed?
A lumbar puncture is preferably performed between the spinous processes at the LIV/LV level. It can be performed at a superior level if there is degeneration or fusion of the LIV/LV articulation. By entering at the LIV/LV level, the needle will penetrate the dural sac inferior to the lower end of the spinal cord (conus medullaris), which typically ends at the level of LI/LII (Figure 11) though it may end superiorly at TXII or extend inferiorly to LII/LIII. The spinal cord usually ends somewhat more inferiorly in children than in adults.
1 or 2 vertebral spaces lower in a child
Which surface landmarks are used to locate the LIV/LV vertebral level?
The most superior points of the iliac crests are identified and connected by an imaginary line across the patient’s back. This imaginary line passes over vertebra LIV
Which structures does the needle pass through to enter the subarachnoid space?
Skin
Superficial fascia (hypodermis)
Thoracolumbar fascia
Supraspinous ligament
Interspinous ligament and interspinales muscles, which lie on each side of the ligament
Ligamentum flavum, assuming a minor degree of lateral deviation from the midline, otherwise the needle will pass through the space between the right and left ligamenta flava
Epidural (extradural) space of spinal canal
Dura
Arachnoid
Subarachnoid space
Why would you perform a lumbar puncture?
To obtain some CSF (e.g. to test for meningitis)
To inject spinal anaesthesia (into the epidural space)
Why would you never do a lumbar puncture in the case of raised intracranial pressure?
It will cause a sudden relieving of pressure, which could have brainstem herniation and deat
Lumbar punctures should NOT be taken when someone has a high intracranial pressure as the brainstem could fall through the foramen magnum.
Brain sucked down pressure gradient
What is meant by the lumbar cistern
It contains the filum terminale and the nerve roots of the cauda equina. It is from the cistern that CSF is withdrawn during lumbar puncture.
Where else can we take samples of the CSF or perform an epidural
through the sacral hiatus- no laminae- hence no spinous processes- leaving a hole through which needles can be inserted
Routinely performed in patients with severe sciatica- with a view of reducing inflammation and pain in this region and negating the prospect of disc surgery
Outline the process of diagnosing sciatica
Rule out metastases or infection
Give neurofen- see if inflamamtion is reduced
MRI- to determine extent of herniation
Injection- in fascet joint or caudal-epidural region
Surgery- may or may not work depending on extent of the injury
Difference between uses of spinal block and epidural injection
Spinal block- undertake C-section or hip replacement- when patient is not fit for general anaesthetic- particular volume- lasts a particular length of time- procedure of known length can be carried out- not infused as in epidural
Epidural- duration of labour- don’t know when it will end-large volume can be infiltrated over many hours
Why is lower back pain the most common form of back pain?
Low spine is subject to increased stresses of weight bearing so the lumbar region is most commonly affected.
· We tend to abuse our backs, particularly when lifting heavy objects.
· Extending the spine from the fully flexed position under a heavy load can inflame intervertebral joints or place unequal pressure on the intervertebral disks, leading to local joint pain and referred neurological pain, if there is also pressure on the spinal nerve
· Additional attempts to rotate the spine at the same time creates extra stress on the lumbar joints.
Summarise the common spinal pathologies
Low back pain
Prolapsed intervertebral disc - sciatica
Spondolysis (degeneration)
Spondylolysis (stress fracture of pars interarticularis)
Spondylolisthesis (forward displacement of vertebra)
Spondylitis (inflammation of vertebrae)
State some signs of cervical spine injury
Low blood pressure + high pulse
Large erection (Custer’s last stand)
Flaccid paralysis
Large bladder and inability to micturate
What steps would you take in the on scene management of a potential C-spine injury
Assume unstable fracture
Assume neck pain if unable to communicate neck pain
Use cervical collar and blocks to immobilize the neck
What steps would you take in the hospital management of a potential C-spine injury?
Take lateral and AP C-spine – if fracture, image with CT/MRI
Give steroids – could prevent the death of around 1 cm of spinal cord
Treat any other symptoms e.g. low BP
How may cervical spine injury affect breathuing
If the cervical spinal cord injury is above the level of C5, breathing is likely to stop. The phrenic nerve takes origin from C3, C4, and C5 and supplies the diaphragm. Breathing may not cease immediately if the lesion is just below C5, but does so as the cord becomes edematous and damage progresses superiorly. In addition, some respiratory and ventilatory exchange may occur by using neck muscles plus the sternocleidomastoid and trapezius muscles, which are innervated by the accessory nerve [XI].
Describe the other features of cervical spinal cord injury
The patient was unable to sense or move his upper and lower limbs.
The patient has paralysis of the upper and lower limbs and is therefore quadriplegic. If breathing is unaffected, the lesion is below the level of C5 or at the level of C5. The nerve supply to the upper limbs is via the brachial plexus, which begins at the C5 level. The site of the spinal cord injury is at or above the C5 level.
It is important to remember that although the cord has been transected in the cervical region, the cord below this level is intact. Reflex activity may therefore occur below the injury, but communication with the brain is lost.
Which ligament is fractured in a whiplash injury
In a whiplash injury the anterior longitudinal ligament is most likely to be damaged in a hyper-extended neck injury.
Summarise the epidemiology of spinal injuries
Spinal cord injury paralyses over 6 people every day
NHS Specialised Spinal Cord Injury Services Annual Statement - in 2017/18, 2429 new patients were referred to the eight specialist centres in England.
This adds to the 50,000 living here that are already paralysed.
Most common causes of spinal cord injury is a broken neck or back as a result of road traffic accidents, accidents during sports or recreation or falls (in older people).
Currently no cure – yet!
Describe the flexibility of the cervical spine in terms of flexion/extension, lateral flexion and rotation.
Cervical spine can comfortably flex, extend, laterally flex and rotate.
The articular surfaces between vertebrae are almost horizontal, so all these movement are possible.
Also the neck has less surrounding tissue than other parts of the spine.
Flexion/Extension- 45 degrees from midline
Right and left rotation- 80 degrees from midline
Lateral flexion- 45 degrees from midline
Describe the flexibility of the upper thoracic spine (T1-T6).
NO flexion/extension
Some lateral flexion
Some rotation
The articular surfaces are almost vertical, which doesn’t allow for flexion/extension.
Describe the flexibility of the lower thoracic spine (T7-T12)
Some flexion/extension
Good lateral flexion
Good rotation
Describe the flexibility of the lumbar spine (L1-sacrum).
NO rotation
Good flexion/extension
Good lateral flexion
Their articular surfaces are curled around the articular surfaces of the adjacent superior vertebrae, ensuring no rotation.
Describe the ranges of motion of the thoracolumbar spine
Extension-30 degrees
Flexion- 90 degrees
Lateral flexion- 30 degrees
Rotation- 30 degrees
What is the relevant radiologic anatomy of a fracture of the C1 ring?
A fracture of the C1 ring permits lateral displacement of the lateral masses. A radiologic view of this displacement shows the lateral masses overhanging the superior articular processes of the axis. Excessive overhang is consistent with disruption of the transverse ligament of the atlas.
How might blood flow to the brain be compromised in a C1 fracture?
Dislocation of the atlanto-occipital articulation may disrupt blood flow through the vertebral arteries as the lateral masses are displaced laterally. The posterior inferior cerebellar arteries (PICAs) are particularly vulnerable. Each PICA issues from its respective vertebral artery just before the vertebral arteries join to form the basilar artery (Figure 7). Diminished blood flow through the PICAs may result in an ipsilateral loss of cranial nerves V, IX, X, and XI, accompanied by cerebellar dysfunction. Other associated neurological symptoms are Horner’s syndrome, and contralateral loss of pain and temperature.
