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UKCD Spinal Cord
learning objectives for spinal cord
| Question | Answer |
|---|---|
| List the enlargements of the spinal cord. | Cervical enlargement (C4-T1) and the lumbar enlargement (L2-S3). |
| Why do the cervical and lumbar enlargements exist? | They contain the additional neuron cell bodies responsible for the movements/sensations of the limbs. |
| What is the specific function of the cervical enlargement? | innervates upper limbs via the brachial plexus |
| What is the specific function of lumbar enlargement? | innervates lower limbs/perineum via the lumbosacral plexus. |
| Define Conus medullaris. | is the cone-shaped termination of the spinal cord |
| Define filum terminale | is a thin strand of pia mater that comes off the cord and passes down into the coccyx |
| Define cauda equine | are all the spinal nn. exiting the neural/spinal canal lower than the termination of the spinal cord at L2. |
| At which vertebral level does the spinal cord terminate? | L2. Preferably between L4/L5 |
| Why is lumbar puncture performed this way? | It ensures that the needle does not puncture the spinal cord after entering the dural sac. It bounces off the floating components of the cauda equina. |
| Why are there 8 cervical spinal nn. but only 7 cervical vertebrae? | From C 1 through C7 the spinal nn. exit the intervertebral foramena above the respective vertebra. Starting at T1 they exit below the respective vertebrae. That leaves the intervertebral foramen between C7 and T1 empty so C8 exits there |
| List the three meninges that wrap the spinal cord, in order from superficial to deep? | Dura mater, arachnoid and pia mater. |
| What fills the subarachnoid space? | Cerebrospinal fluid (CSF). |
| What is the function of this fluid-filled space? | It provides a fluid-filled buffer or shock absorbing layer for the delicate components of the CNS (brain and spinal cord). |
| Where is the epi (extra) dural space and what is found within it? | Between the inner bony boundaries of the spinal (neural) canal and the dural sac. It contains extradural (epidural) fat and an extensive venous plexus |
| What is the denticulate ligament? | A tooth-like lateral extension of pia mater off the spinal cord tacking to the dural sac. It stabilizes the cord side-to-side within the dural sac. |
| How do ventral/dorsal roots differ from ventral/dorsal rootlets? | Rootlets arise from the cord - extending along the thickness of each cord segment (ie. C4). These numerous rootlets coalesce into a single dorsal and ventral root for each cord segment. |
| How do ventral/dorsal roots differ from ventral/dorsal rami? | dorsal & ventral roots from spinal cord fuse to form true spinal nerve that exits intervertebral foramen. Once passes through bony opening, it immediately branches into 2 main dorsal & ventral rami. |
| Be familiar with the sulci of the cord as well as its vascular supply. | Be aware that the posterior (dorsal) aspect of the cord has two arteries applied to its surface, one over each of the posterior intermediate sulci. The anterior (ventral) aspect has a single artery applied to its surface. |
| What does the dorsal ramus innervate? | Dorsal rami innervate the muscles and blood vessels of the back (posterior/dorsal surface of the trunk). |
| What does the ventral ramus innervate? | Ventral rami innervate the muscles and blood vessels of the anterolateral aspects of the body wall. |
| Which specific branches off the dorsal/ventral rami are responsible for distributing the cutaneous innervation? | The lateral and anterior cutaneous branches from the ventral ramus, coupled with the branches of the dorsal rami, innervate a band of skin/muscles and blood vessels of the body wall - a dermatome. |
| What vertebral levels exhibit "typical" (segmental) spinal nerves? | T2 through T11/12. |
| How would you define a “typical spinal nerve”? | A spinal nerve whose ventral rami do not form a plexus but rather remain separate and innervate a specific body dermatome. The dorsal rami always remain segmental (separate). |
| What is a dermatome? | A band of skin on the body wall innervated (sensory, motor and sympathetic) by the dorsal and ventral ramus of a specific spinal cord level (ie. T4). |
| For complete cutaneous sensory loss, how many spinal nerves would have to belesioned? Why? | Three spinal nn. Because there is some overlap (collateral branches) from each spinal nerve into the dermatome above and below it. |
| What types of fibers (modality) are found in the dorsal/ventral roots? | Dorsal root = sensory; ventral root = motor and preganglionic sympathetic. |
| Where is the first point where a nerve becomes "mixed"? (ie. contains motor andsensory innervation?) | At the union of the dorsal and ventral roots - the formation of the true spinal nerve. |
| How does the structural organization between the motor/sensory and ANS differ? | Motor and sensory tracts utilize a single neuron to link the CNS with the effector organ in the PNS. The ANS utilizes two neurons to link these structures. |
| What does the PNS contain to facilitate this difference? | The PNS contains ANS ganglia as the site of synapse between the two neurons involved in linking the CNS with the effector organ in the PNS: the pre- and post-ganglionic neurons. |
| What does the dorsal rami innervate? | back |
| What does the ventral rami innervate? | anterolateral aspects of body wall |
Created by:
wiechartm
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