Spinal Cord Flashcards
Where does the spinal cord begin?
Foramen magnum
Where does the spinal cord end in adults?
L1 to L2
Where is the spinal cord located?
In the vertebral canal of the vertebral column
What are the functions of the spinal cord?
Sensory and motor innervation of the entire body inferior to head (via spinal nerves)
Two way condiction pathway between body and brain
Major centre for reflexes
Until what gestation does the spinal cord run the full length of the vertebral canal?
12 weeks gestation
What causes regression of spinal cord to L3/L2 by birth?
Rapid growth of vertebral canal - differential rates of growth
What is left at the caudal end of the vertebral canal due to the regression of the spinal cord during gestation?
Filum terminale
What is the filum terminale?
Fibrous tissue that is a continuation of pia mater
What is the function of the filum terminale?
Connects conus medullaris (caudal end of spinal cord) to coccyx
How many weeks post birth does the spinal cord reach L1/L2?
3 weeks post birth
What is the embryological cause of Spina Bifida?
Failure of vertebrae fusion in embryonic development
Which area of the spine does Spina Bifida usually occur?
Lumbosacral region
What are the four subtypes of Spina Bifida?
Occulta
Meningocele
Myelocele
Meningomyelocele
Where is the rostral end of the adult spinal cord?
Medulla oblongata
What is the caudal end of the adult spinal cord?
Conus medullaris
What is the cauda equina?
Collection of nerves at the caudal end of the spinal cord
At which vertebrae does the cauda equina emerge?
L3/L2
How many spinal nerves are there?
31 spinal nerve pairs
Which vertebrae do the nerve roots from the cauda equina emerge from?
L3 - S5
Which cistern is the conus medullaris located in?
Lumbar cistern
What are the meningeal layers of the spinal cord?
Pia
Arachnoid
Dura
What are the three potential spaces in the spinal cord meninges?
Epidural (outside the dura)
Subdural (between dura and arachnoid)
Subarachnoid
What is the denticulate ligament?
Anchors the dura mater to the pia mater
What is the spinal dura surrounded by?
Extradural venous plexus
What does the extradural venous plexus do?
Drains red marrow of spine
How does the extradural venous plexus facilitate metastasis of malignancies?
The plexus lacks valves, allows malignant cells to spread easily
What are the two spinal enlargements?
Cervical enlargement (brachial plexus)
Lumbar enlargement (lumbo-sacral plexus)
What does the brachial plexus innervate?
Upper extremities
How many cervical spinal nerves are there?
8
How many thoracic spinal nerves are there?
12
How many lumbar spinal nerves are there?
5
How many sacral spinal nerves are there?
5
How many coccygeal spinal nerves are there?
1
Where do the spinal nerves lay in the vertebral column?
Intervertebral foramina
What forms the intervertebral foramina?
Space between the spinal pedicles
How is the spinal cord protected?
Bone - vertebral canal
Ligaments - attach adjacent vertebrae to each other and anchors dura mater
Epidural fat - acts as a cushion
Meninges - act as a buffer
Where is CSF located in the spine?
Subarachnoid space
What is a lumbar puncture?
Procedure performed where a needle is inserted in the subarachnoid space to collect CSF
Why might a lumbar puncture be performed?
Control CSF pressure (e.g. intracranial hypertension)
Detect CSF pressure
Deliver anesthetic
Evaluate CSF for infections and inflammatory conditions
What position must the spine be in for a lumbar puncture and why is this position important?
Must be flexed so the needle can pass between spinal processes
Between which vertebrae are lumbar punctures usually performed?
L3-L5
What is at the centre of the spinal cord?
Hollow central canal
Which type of matter surrounds the central canal?
Grey matter
Where is white matter located in the spinal cord?
Around the grey matter
What is the white matter of the spinal cord composed of?
Ascending and descending axon tracts
What is in the dorsal horn of the spinal cord?
Cell bodies of sensory interneurons
What is in the ventral horn of the spinal cord?
Cell bodies of motor neurons
Which is the ‘thicker’ horn on a diagram of a coronal section of spinal cord?
Anterior horn
How are Rexed’s laminae of the grey matter of the spinal cord divided?
Based on cytoarchitecture
What are laminae 1 to 3 of the spinal cord known as?
Substantia gelatinosa
What is the substantia gelatinosa involved in?
Nociception
What medications work on the substantia gelatinosa?
Opiates
What information do the ascending fibers of the spinal cord carry?
Sensory information from body to brain
What information do descending fibers of the spinal cord carry?
Motor instructions from brain to spinal cord to stimulate muscle contraction or secretion from glands
What do commissural fibres of the spinal cord do?
Cross from one side of the spinal cord to the other
What are three major ascending pathways for somatic sensory information in the spinal cord?
Dorsal column pathways
Spinocerebellar
Spinothalamic
What are the two types of descending pathways for motor information in the spinal cord?
Pyramidal
Extrapyramidal
Which two of the three major ascending pathways in the spinal cord decussate?
Dorsal column - medial lemniscus
Spinothalamic
Which major ascending pathway in the spinal cord is ipsilateral and does not decussate?
Spinocerebellar
What information does the spinocerebellar ascending pathway provide and where does it project to?
Proprioception from skeletal muscles
Projects to cerebellum
What information does the dorsal column medial lemniscus ascending pathway provide and where does it project to?
Discriminative touch sensation
Projects through the thalamus to the somatosensory cortex
What information does the spinothalamic ascending pathway provide and where does it project to?
Nondiscriminate sensations such as pain, temp, and pressure
Projects through the thalamus to the somatosensory cortex
Where does the medial lemniscus pathway decussate?
Medulla
Where does the spinothalamic pathway decussate?
Spinal cord
Which ascending pathway decussates in the medulla oblongata?
Medial lemniscus pathway
Which ascending pathway decussates in the spinal cord?
Spinothalamic pathway
Which ascending pathway is involved with proprioception?
Spinocerebellar
Which ascending pathway is involved with discriminative touch?
Medial lemniscus
Which ascending pathway is involved with non-discriminative touch?
Spinothalamic
What is an example of pyramidal descending tracts in the spinal cord?
Lateral corticospinal
What information does the lateral corticospinal pathway provide?
Voluntary movement to limb muscles
What information does the ventral corticospinal pathway provide?
Voluntary movement to axial muscles
Which descending tract decussates in the pyramids of the medulla?
Lateral corticospinal
Which descending tract decussates in the spinal cord?
Ventral corticospinal
Which corticospinal descending tract is extrapyramidal?
Ventral corticospinal
