Neuroanatomy Exam II

How long is the spinal cord?

40-45 cm, 16-18 in

Where is the spinal card the largest in diameter?

Cervical enlargement, occupying 75% at C5-C6

How much of the CNS weight does the spinal cord constitute?

2%

What constitutes the superior boundary of the spinal cord?

Foramen magnum

What marks the inferior boundary of the spinal cord in adults?

L1-L2 disc level

How many pairs of spinal nerves are there?

31

What does the Bell-Magendi Law state?

Dorsal roots are sensory, ventral roots are motor

What type of structures are rootlets?

PNS

Rootlets explicitly carry ______ or _______ information, while rami are _______

Motor; sensory; mixed

Where does C1 exit?

Between occipital and atlas

Where does C4 exit?

Intervertebral foramina between C3 and C4

Where does C8 exit?

Intervertebral foramina between C7 and T1

Where does T1 exit?

Intervertebral foramina between T1 and T2

Where does T6 exit?

Intervertebral foramina between T6 and T7

Where does T12 exit?

Intervertebral foramina between T12 and L1

Where does L1 exit?

Intervertebral foramina between L1 and L2

Where does L5 exit?

Intervertebral foramina between L5 and S1

Where do S1-S4 nerves exit?

Dorsal and ventral sacral foramina

Where does S5 exit?

Sacral hiatus

Where does Co1 exit?

Sacral hiatus

During the first 3 months of development, compare size of cord and vertebral column?

About same length

At birth, where is the Co1 cord level?

L1-L3 vertebral level

In adults, where is the Co1 cord level?

L1-L2 vertebral level

What is the tapering end of the cored at L1-L2 called?

Conus medullaris

What widens in the conus medullaris as a terminal ventricle?

Central canal

What is the continuation of roots for lumbar, sacral, and coccygeal nerves called?

Cauda equina

Where does the cauda equina exit?

Lumbar cistern

What is the difference between the terminal ventricle and the lumbar cistern?

Terminal ventricle is inside spinal cord, lumbar cistern is distal to conus medullaris outside of spinalcord

What is the difference between a quadriplegic and a paraplegic?

Quadriplegic injury is at or above C8, paraplegic injury is at or below T1

Where on the cord is the cervical enlargement? (Nerve roots and vertebral)

C3-T2 nerve roots, C5 and C6 vertebral

Where is the lumbar enlargement on the cord? (Nerve roots and vertebral)

T9-T12 nerve roots, T11-L2 vertebral

What does the lumbar enlargement include?

Lumbar and sacral plexus

Why is the mature spinal cord offset from the vertebral column?

Short cord and cauda equina

Which structure separates posterior portions of cord into halves containing the posterior median septum?

Posterior median sulcus

What is the posterior median septum?

Thin layer of pia

What is the groove along the anterior midline that divides spinal cord incompletely into symmetrical halves?

Anterior median fissure

What's another name for gray matter?

Substantia grisea

What's included in gray matter?

Cell bodies and dendrites

What's another name for white matter?

Substantia Alba

What is included in white matter?

Ascending and descending information

Which horn receives sensory information?

Dorsal (posterior) horn

Which horn includes autonomic preganglionic neurons?

Lateral horn

Is the lateral horn present at every level?

No

In what levels of the lateral horn would you find parasympathetic preganglioinc neurons?

S2-S4

In what levels of the lateral horn would you find sympathetic preganglionic neurons?

T1, L2-L3

Which horn receives motor information and relays it to muscles from PNS?

Ventral (anterior) horn

What are columns of white matter and axons traveling up and down the cord?

Funiculi

What are funiculi divided into?

Fasciculi or tracts

The gray matter has a lot of _______ bodies and ______ beds

Cell; capillary

What type of cells are used in gray matter for support?

Glial cells

What are groups of cell bodies in gray matter called?

Nuclei

Rexed laminae

columns of axons in the spinal cord that carry ascending and descending information

What makes myelin in white matter?

Interfascicular oligodendrocytes

White matter is _______ dense in blood vessels compared to gray matter

Less

What is the diameter of axons in white matter?

2 to 30 microns including sheath

Are all axons in white matter myelinated?

No

How do fibers associate with each other?

Nerve cell adhesion molecules

T/F: white matter is observable with general staining techniques

FALSE, can only be identified with lesion studies

T/F: every tract is present at all cord levels

False

What are the two ascending tracts that terminate in the cerebral cortex and relay two point touch discrimination, vibratory sensation, and kinesthetics?

Gracilis and cuneatus

How many neurons do gracilis and cuneatus use to reach their target?

3

What are the fibers of gracilis and cuneatus called when they cross to the opposite side in the medulla oblongata?

Internal accurate fibers

Are gracilis and cuneatus contralateral or ipsilateral? Why?

Contralateral because info enters and terminates on opposite side

How can you tell that a tract is gracilis and cuneatus?

Ascends on same side of entrance

Which funiculus is gracilis located in?

Medial dorsal funiculus

Where does the first neuron in gracilis synapse?

Nucleus gracilis in medulla oblongata

Where does the second neuron in gracilis and cuneatus synapse? Via what?

Ventral posterior lateral nucleus of thalamus via medial lemniscus

Where does the third neuron in gracilis and cuneatus synapse?

Cerebral cortex

Where does gracilis receive input?

Below T6 from lower extremities

T/F: gracilis is located at all cord levels

True

Which funiculus is cuneatus located in?

Lateral dorsal funiculus

Where does the first neuron in cuneatus synapse?

Nucleus cunateus in medulla oblongata

Where does cuneatus receive input?

T6 and above from upper extremities

What does romberg's test do?

Tests dorsal funiculi including gracilis and cuneatus

How is Romberg's test performed? What does a positive finding indicate?

Patient stands with feet together and eyes closed, loss of balance indicates cerebellar disfunction

Which senses are tested using romberg's? How many of these senses are needed for proper function?

Vestibular input, vision, and proprioception; 2/3 needed

Which ascending tract deals with pain and temperature sensation?

Lateral spinothalamic

Which rexed laminae is the spinothalamic tract concerned with?

II

Where does the first neuron of the lateral and anterior spinothalamic tracts synapse?

Gray matter of posterior horn

Where does the second neuron of the lateral spinothalamic tract synapse? Via what?

Ventral posterior lateral nucleus of thalamus via lateral spinothalamic

Where does the third neuron of the lateral and anterior spinothalamic tract synapse?

Cerebral cortex

Does the lateral spinothalamic tract gradually or abruptly cross the cord?

Abruptly

Which ascending tract relays light tough and pressure?

Anterior spinothalamic

Which rexed laminae is the anterior spinothalamic tract concerned with?

III and IV

Where does the second neuron of the anterior spinothalamic tract synapse? Via what?

Ventral posterior lateral nucleus via anterior spinothalamic

Does the anterior spinothalamic tract gradually or abruptly cross the cord?

Gradually

How many neurons do the lateral and anterior spinothalamic tracts use to reach their target?

3

Are the lateral and anterior spinothalamic tracts present at every cord level?

Yes

Are the lateral and anterior spinothalamic tracts contralateral or ipsilateral? What does that mean?

Contralateral meaning info enters and terminates on opposite sides

How can you tell that a pathway is lateral and anterior spinothalamic?

Info ascends on opposite side of entrance

How would a cord hemisection (one sided lesion) at the R side of C5 impact gracilis and cuneatus? Why?

Loss of 2 point touch discrimination, vibratory sensation, and kinesthetics below C5 on R side of body because info enters on R side

How would a cord hemisection (one sided lesion) at the R side of C5 impact the spinothalamic tracts? Why?

Loss of pain and temperature sensation on L side of body because info enters on L side

Which ascending tract relays gross movement proprioception, as well as the anticipation of movement?

Anterior spinocerebellar

Where does the anterior spinocerebellar tract originate?

Lumbosacral region

Where does the first neuron in the anterior spinocerebellar tract synapse?

Gray matter of posterior horn

On what side of the cord does the axon ascend in the anterior spinocerebellar tract? What does it ascend in?

Opposite of where information enters; lateral funiculus

Once the axon enters the midbrain via the anterior spinocerebellar tract, how does it enter the cerebellum?

Superior cerebellar peduncle

What is unique about the axon that reaches the cerebellum via the anterior spinocerebellar tract?

Crosses back over to terminate in cerebellum on the same side where it initially entered the cord

Differentiate between the travel pattern and the termination site of the axon in the anterior spinocerebellar tract

Travels contralateral and terminates ipsilateral

Which ascending tract relays fine movement proprioception?

Posterior spinocerebellar