Clinical Neuroanatomy -- Unit 2

what type of neurology is it when a physician refers to clinico-anatomic correlations to infer what and where the lesion is from physical examination and history and knowledge of nervous system anatomy and function?

diagnostic neurology

what type of CNS lesion is it when dysfunction results from structural damage to the CNS (stroke, trauma, tumors, etc.)

anatomic

what type of CNS lesion is it when there is dysfunction in the absence of obvious anatomic abnormalities (transient ischemia)

physiologic

what is the term used to describe the subjective experiences resulting from a neurologic disorder?

symptoms

what is the term used to describe the objective abnormalities detected by healthcare professionals upon neurologic exam?

signs

what is the principle of localized function?

different parts of the nervous system serve different functions, so damage to one brain region will reciprocally affect and predict a loss of function of that area

what important statement does the principle of localized function support?

symptoms and signs reflect focal pathology within the nervous system

what type of manifestation results from the loss of nervous system function (weakness, hemiparalysis, sensation/memory loss, etc.)?

negative

what type of manifestation results from inappropriate nervous system excitation (seizure, spasticity, etc.)?

positive

what do manifestations of neurologic disease represent?

altered nervous system activity

what type of CNS lesion causes neuronal loss by interfering with the function of collections of neurons and their synapses?

gray matter lesions

what manifestations come from gray matter lesions?

positive or negative

what type of CNS lesion causes axonal loss by interfering with signal transmission between neurons?

white matter lesions

what manifestations come from white matter lesions?

negative

what is a group of signs and symptoms that are related, suggesting a common origin?

syndromes

how can destruction lead to nervous system dysfunction?

neuronal destruction (cell death from stroke, etc.) and axonal destruction (demyelinating diseases such as MS, etc.)

how can compression lead to nervous system dysfunction?

compression of the brain or spinal cord (hematomas, etc.)

how can ventricular or vascular compromise lead to nervous system dysfunction?

tumors originating in regions surrounding ventricles can obstruct CSF flow and blockage of cerebral arteries that feed into brain sites can cause cell death

what is focal pathology?

when the signs and symptoms are based on a single, geographically isolated CNS lesion (such as a stroke)

what is multifocal pathology?

when there is damage to the CNS at numerous sites (such as multiple sclerosis)

what is diffuse process pathology?

when CNS damage spreads due to exposure to toxins or metabolic abnormalities

how does the organization of the CNS help locate where the lesion is located?

organization of the CNS makes it straightforward to diagnose disorders based on clinical history (symptoms) and neurological exam (signs)

what is rostrocaudal and transverse localization?

the signs and symptoms often make it possible to localize the lesion to a specific area within the 3D axis of the brain

what must be considered when deciding what the lesion is?

age, sex, other confounding variables, and time course of the illness (recent, slowly progressing, relapsing and remitting, etc.)

what is a list of diagnostic possibilities that fit the clinical picture, allowing the healthcare provider to differentiate between two or more clinical conditions?

differential diagnosis

how many cervical spinal vertebra make up the spinal column?

7

how many thoracic spinal vertebra make up the spinal column?

12

how many lumbra spinal vertebra make up the spinal column?

5

how many sacral spinal vertebra make up the spinal column?

5

what makes the sacral spinal vertebra different from the rest of the spinal column?

all 5 parts of it are fused

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

where does the spinal cord end in the spinal column?

the lumbar region

why is there one more cervical spinal nerve than cervical spinal vertebra?

spinal nerves are located between the vertebra, including one before C1

what is the spinal column separated by?

spinal disks

what is the function of spinal disks?

acts as a shock absorber

what term is used to describe the end of the spinal cord?

conus medullaris

what term is used to describe long spinal nerves emanating from the spinal cord that dangle down and branch off to the legs?

cauda equina

what is the thecal sac/duramater?

surrounds the spinal cord

how many coccygeal spinal nerves are there?

1

how many coccyx vertebra are there in the spinal column?

1

where do spinal nerves exit?

below their associated spinal vertebra (excluding cervical spinal nerves)

where is the spinal cord wider?

the cervical and lumbrosacral regions

why are the cervical and lumbosacral regions of the spinal cord wider?

more space for lower motor neurons and large nerves to and from upper and lower extremities

what is the anterior/ventral median fissure?

the shallow but wide fissure on the anterior surface of the spinal cord

what is the posterior/dorsal median fissure?

a deep but thin fissure on the posterior surface of the spinal cord

what is the anterolateral sulcus?

the shallow groove on the anterior-lateral surface of the spinal cord → where ventral motor nerve roots exit the spinal cord

what is the posterolateral sulcus?

the shallow groove on the posterior-lateral surface of the spinal cord → where dorsal sensory nerve roots enter the spinal cord

what is the white matter in the spinal cord?

bundles of myelinated axons running up and down the length of the spinal cord

what does the white matter in the spinal cord consist of?

sensory (afferent) and motor (efferent) fibers

what is the gray matter in the spinal cord?

unmyelinated areas in the spinal cord - collections of cell bodies

what is another name for the gray matter in the spinal cord?

the central gray region

the dorsal horns of the central gray are home to what?

spinal sensory function

the ventral horns of the central gray are home to what?

spinal motor function

each segment of the spinal cord has how many spinal roots?

4

spinal roots exit the spinal cord to form what?

a spinal nerve carrying information to and from the body

what is the dorsal root ganglion?

the home to all sensory nerves in the spinal nerve system

what do the ventral spinal roots contain?

myelinated axons from lower motor neurons that lie in the ventral horn of the spinal cord

what do the dorsal spinal roots contain?

myelinated axons from secondary sensory neurons in the PNS

what are somatic efferents?

axons from lower motor neurons in the ventral horn of the spinal cord to the muscles - control voluntary movement

what are visceral efferents?

autonomic motor fibers to control involuntary smooth muscle movements

what are somatic afferents?

axons of unipolar neurons in the dorsal root ganglion that convey information from the skin, joints, and muscles

what are visceral afferents?

sensory fibers conveying information from smooth muscle

where do the cervical spinal nerves distribute to?

neck, arm, shoulders, upper back, neck

where do the thoracic spinal nerves distribute to?

chest, abdomen, back

where to the lumbar spinal nerves distribute to?

hips, low back, legs, feet

where do the sacral spinal nerves distribute to?

buttocks, crotch, back of legs, feet

where does the coccygeal nerve root distribute to?

tailbone

what are dermatomes (sensory) and myotomes (motor)?

the portions of the body that the sensory and motor components of spinal nerves distribute to

ascending tracts of axons in the spinal cord are?

sensory

descending tracts of axons in the spinal cord are?

motor

what are funiculi?

columns of axons leading to and from the brain

what are tracts?

clusters of axons within columns that have common functions

what is the corticospinal tract?

a descending tract from the upper motor neurons in the cerebral cortex to the lower motor neurons in the spinal cord 

which corticospinal tract decussates?

lateral

which corticospinal tract does not decussate?

anterior

what is the rubrospinal tract?

a descending tract from the red nucleus in the midbrain to the spinal cord that regulates large muscle movement 

what is the reticulospinal tract?

a descending tract from the reticular formation in the brain stem to the spinal cord that is important for pain control and function in the legs

what is the vestibulospinal tract?

a descending tract from the vestibular nuclei in the brain stem to the spinal cord that activates quick movements in response to sudden change in balance

what is the tectospinal tract?

a descending tract from the superior colliculus in the tectum of the midbrain to the spinal cord that coordinates head and eye movements in response to visual and auditory stimuli

what descending fiber tracts are in the lateral funiculus?

lateral corticospinal tract, rubrospinal tract, lateral reticulospinal tract

what descending fiber tracts are in the ventral funiculus?

medial reticulospinal tract, anterior corticospinal tract, vestibulospinal tract, tectospinal tract  

what is the fasciculus gracilus?

an ascending tract that carries sensory information from the lower body  

what is the fasciculus cuneatus?

an ascending tract that carries sensory information from the upper body

the fasciculus gracilus and fasciculus cuneatus are part of what system?

the medial lemniscal system

what is the (lateral + anterior) spinothalamic tract?

an ascending tract from the spinal cord to the thalamus that carries information about sharp pain

what is the (posterior + anterior) spinocerebellar tract?

an ascending tract from the spinal cord to the cerebellum that is in charge of motor control, position sense, and coordination

what ascending fiber tracts are in the dorsal funiculus?

fasciculus gracilus, fasciculus cuneatus

what ascending fiber tracts are in the lateral funiculus?

posterior spinocerebellar tract, anterior spinocerebellar tract, lateral spinothalamic tract  

what ascending fiber tracts are in the ventral funiculus?

anterior spinothalamic tract

ascending and descending fiber tracts have what type of orientation in relation to spinal cord?

medial to lateral

the first-order neuron in the sensory system is the?

first cell

where do the cell bodies of all first-order neurons in the PNS lie?

the dorsal root ganglion (DRG)

first-order neurons synapse with what neurons in the CNS?

second-order neurons

second-order neurons synapse with what in the CNS?

third-order neurons

what does it mean if a nerve fiber decusses?

it crosses the midline

a tract is __ when nerve fibers cross the midline

contralateral

a tract is __ when nerve fibers stay on the same side  

ipsilateral