Exam #1: Organization of the Spinal Cord Flashcards Preview

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Flashcards in Exam #1: Organization of the Spinal Cord Deck (36):

Where is the cervical enlargement of the spinal cord?

C5- T1; this is the origin of the nerves destined for the upper limb i.e. the roots of the brachial plexus


Where is the lumbosacral enlargement?

L2-S3; this is the origin of the nerves destined for the lower limb i.e. the lumbosacral plexus


Where is the common site for a LP? Why?

L3-4 or L4-5

****Cord ends at L2 (conus medullaris)--not going to hit the spinal cord; this space below the conus medullaris is known as the lumbar cistern


Where do the cervical nerve roots emerge?

Above the vertebrae

*****Remember that there are 8 cervical spinal nerves, but only 7 cervical vertebrae


Where do the lumbar nerve roots emerge?

Below the vertebrae


What is the spinal nerve?

The distal continuation of the dorsal & ventral roots, once they join together


What is the gray matter of the spinal cord?

"H" or butterfly in the center of the cord
- Nuclei
- Processes
- Neuroglia

*Not myelinated


What is the white matter of the spinal cord?

Outside of the H
- Tracts, fasiculi, commisures



What are the cross sectional differences between the cervical and sacral regions?

- Cervical region has the most white matter/ highest white:gray ratio
- Descending the spinal cord, the amount of white matter generally decreases
- In the sacrum, white matter is the least


What are the three general areas of the gary matter?

Dorsal horn/ column
Lateral horn/ column
Ventral horn/column


What is the dorsal horn of the gray matter?

Cell bodies of the pseudounipolar neurons


What is the ventral horn of the gray matter?

Cell bodies of the motor neurons


What is the lateral horn of the gray matter?

Preganglionic sympathetic neurons


What levels of the spinal cord contain a lateral horn?

T1- L2 i.e. the levels that contain sympatheitc ganglia


What does the intermediate zone contain? Where is the intermediate zone?

This is the area between the dorsal & ventral horns of the gray matter that contains interneurons


Describe the arrangement of the ventral motor neurons in terms of function.

The regions that are innervated & the corresponding functions have a spatial arrangement in the ventral cord:
Lateral nuclei= limbs
Medial nuclei= trunk
Anterior= extensors
Posterior= flexors


What are "Rexed Laminae" of the spinal cord?

The gray matter of the spinal cord is divided into nine different regions referred to as "Rexed Laminae"

*Note that there is a 10th laminae (X), which is the gray commissure around the central canal of the cord


How are the nerve cells in the dorsal horn divided? What lamina does the substantia gelatinosa correspond to & what is its function?

The nerve cells in the dorsal horn are divided into four groups:
1) Substantia gelatinosa= II
- Unmyelinated axons mostly dealing with nociception
2) Nucleus proprius
3) Nucelus dorsalis


What lamina does the nucleus proprius correspond to? What is the function f the nucleus proprius?

- Receives central processes of the majority of unipolar neurons from the DRG
- Transmits pain, temperature, & light touch


What is Clarke's Column ? What lamina does it correspond to? What is the function?

- Clarke's Column is also referred to as the nucleus dorsalis, & corresponds to lamina VII
- C8-L3
- Receives signals from proprioceptive fibers


What is contained in the intermediolateral cell column from T1-L2? What is contained between S2-S4 in relation to the ANS?

Interomediolateral Cell Column= T1-L2
- preganglionic sympathetic cell bodies

S2-S4= preganglionic parasympathetic nerve cell bodies


What is the general function of Rexed Lamina IX?

Motor--this is the lamina associated with the ventral horn


How is the white matter of the spinal cord divided?

The white matter of the spinal cord is divided into three general columns:
1) Dorsal faniculi
2) Lateral faniculi
3) Ventral faniculi


Describe the locations of the dorsal, lateral, & ventral faniculi

Dorsal= dorsal median fissure-->dorsolateral sulcus i.e. between the dorsal midline & dorsal nerve rootlets

Lateral= Dorsolateral-->ventrolateral sulci i.e. between the nerve rootlets

Ventral= Ventrolateral sulcus--> ventral median fissure i.e. between the ventral rootlets & ventral midline


What are the two subdivisions of the dorsal faniculus? Are these divisions present throughout the entire length of the spinal cord?

Medial= fasiculus gracilis
- C1-T6
- Input from lower trunk & lower limb

Lateral= fasiculus cuneatus
- All spinal cord levels
- Input from upper trunk & upper limb


What are the different tracts of the lateral funiculus?

1) Lateral corticospinal tract
2) Ventral spinocerebellar tract
3) Dorsal spinocerebellar tract
4) Spinothalamic tract
5) Rubrospinal tract


What is the function of the Lateral Corticospinal Tract?



What is the function of the Ventral Spinocerebellar Tract?

Position sense


What is the function of the Dorsal Spinocerebellar Tract?

Position sense


What is the function of the Spinothalamic tract?



What is the function of the Rubrospinal tract?



What is the major tract of the ventral faniculus?

Anterior corticospinal tract--motor


What is the ventral white commisure?

Location of crossing over in the spinal cord


What is the dorsolateral tract of Lissauer? Where is it located?

Located at the tip of the wing of the butterfly, just distal of the gray matter, this white matter tract consists of the central processes of sensory unipolar neurons conveying pain & temperature sensation


Clinically, how does the outcome differ from complete transection of the spinal cord in the cervical region vs. the lumbar region?

Cervical= quadriplegia

Lumbar= paraplegia


Describe the presentation of an injury to T12 or L1 vertebrae that impacts that cord at that level.

These vertebrae surround motor neurons and PNS neurons that not only innervate the leg, but also carry bowel/bladder control information. Presentation is:
- Loss of bowel and/or bladder control
- Saddle anesthesia/ paresthesia
- LE weakness