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
