unit1.3 spinal column

Question 1

Where does the spinal cord end? describe the nerve location and numbers.

Answer 1

spinal cord

1. ends inferiorly ~L2, has a cone shape conus medullaris
2. 31 spinal segments
   
   1. 8C,12T,5L,5S,1C
3. spinal cord innervate entire body except head

Question 2

What happens to the spinal cord and vertebrae during development.

Answer 2

In the 3rd month of fetal life, spinal cord length equals vertebral canal length. Afterwards, length differs due to growth difference where vertebral column grows faster than the spinal cord. leading to the spinal cord ending ~IVD of L1-L2. The cauda equina(collection of obliquely descending nerve roots below cord) and fulim terminale form.

The spinal cord has cervical(C5-T1) and lumbar(L2-S4) due to origins of brachial and lumbosacral nerve plexuses for upper and lower extre

Question 3

gross anat. define and list structures

Answer 3

1. External surface-marked by a number of fissures and sulci
   
   1. anterior median fissure-extends the length of anterior surface
   2. posterior medial sulcus-exteds along posterior surface
   3. posterolateral sulcus-on each side of posterior surface where the posterior rootlets of spinal nerves enter the cord
2. internal structure-spinal cord has a small central canal surrounded by gray and white matter
   
   1. gray matter is rich in nerve cells bodies, which form longitudinal columns along the spnal cord and in a cross section these columns form an “H” shaped appearance in the central region of the cord.
   2. white matter surrounds the gray matter and is rich in nerve cells proccesses which form large bundles or tracts that ascend and descend in the spinal cord

Question 4

discuss nomenclature of the spinal nerves

Answer 4

There are 31 pairs of spinal nerves.

• C1-C7 exit vertebral canal above the vertebra of the same number
• nerve C8 exit above vertebra T1
• nerves T1-Co1 exit vertebral canal caudal to the vertebra of the same number

Question 5

Discuss the flow of the spinal nerve.

Answer 5

• medially
  
  • the posterior and anterior roots divide into rootlets, which attach to the spinal cord
• laterally
  
  • the posterior and anterior roots on each side join to a spinal nerve
• spinal segment
  
  • area of the spinal cord that gives rise to the anterior and posterior rootlets
    
    • form a single nerve

Spinal nerve is formed of the union of a dorsal root carrying sensory nerve fibers and ventral root carrying motor nerve fibers.

both root fibers join together forming a mixed spinal nerve (containing motor and sensory).

posterior root-contains the processes of sensory neurons carrying information to the CNS

1. cell bodiesof sensory neurons lie in the posterior horn of spinal cord
2. posterior root ganglion is a collection of sensory nerve cell bodies of pseudounipolar sensory neurons

anterior root contains the motor fibers, traveling away from the CNS

1. cell bodies of the primary motor neurons are in the anterior horn of the spinal cord

Question 6

What divisions arise after the spinal nerve travels from the spinal column through the intervertebral foramen?

Answer 6

each spinal nerve diveides as it emerges from an intervertevral foramen into the poaterior and anterior rami

• posterior ramus
  
  • innervates intrinsic back muscles(erector spinae, transversospinalis)
• anterior ramus
  
  • innervate all other trunk muscles and all extremities.

Question 7

discuss and organize the four different types of nerve fibers

Answer 7

a typical nerve has four functional components

1. general somatic afferent=GSA
2. general visceral afferent=GVA
3. general somatic efferent=GSE
4. general visceral efferent=GVE

Question 8

What is the composition/orgination of major nerve plexuses list major ones.

Answer 8

all major nerve plexuses are formed of anterior rami of different spinal nerves.

1. cervical plexus
   
   1. supply the neck structures
2. brachial plexus
   
   1. supply upper extremity
3. lumbosacral plexus
   
   1. lower extremity

Question 9

Jerry presents to his doctor with pain on his rib cage and red bumps. Discuss the suspected disease and pathology.

Answer 9

herpes zoster virus produces chicken pox in children. The virus can lie dormant in the cells of the spinal ganglia and under circumstances the virus becomes activated. traveling along the neuronal bundles to the areas supplied by the nerv(dermatome) a rash developes and can be extremly painful.

Question 10

Answer 10

spinal meninges- are three connective tissue membranes surrounding the spinal cord-dura mater, arachnoid mater, pia mater

pia mater- is continuous with the spinal column and CANNOT be seperated from the tissue when comparing to other tissues keep this in mind.

Question 11

describe organizatio of the dura mater on the spinal cord and significant structures, functions and mention cancer pathology.

Answer 11

1. outer tough membrane
2. continues superiorly with cranial duramater and inferiorly the dural sac narrows at the lowerborder of Sv2 and forms the investing sheath for the pial part of filum terminale of the spinal cord.
   
   1. filum terminale- cord like extension of duramater attaches to the posterior surface of the vertebral bodies of the coccyx
3. forms a sleeve saround the_spinal nerves and their roots_ merging with the epineurium of the nerves
4. it is seperated from vertebral canal walls by the extradural space.
   
   1. ​extradural space contains fat and the internal venous plexus
      
      1. internal venous plexuses connect to Thoracic, Abdominal and Pelvic veins providing pathway for metastasis of cancer cells to vertebral clumn, spinal cord and brain.

Question 12

Answer 12

Question 13

Describe the organization/structures and functions involved with the arachnoid layer and the spinal cord.

Answer 13

arachnoid mater- delicate transclucen membrane pressed against internal surface of dura

1. subarachnoid space lies between arachnoid and pia mater
   
   1. this space contains CSF
   2. continuous at the foramen magnym with the subarachnoid space surrounding the brain.
   3. subarachnoid space enlarges caudal to conus medullaris and ends ends at SV2
      
      1. ​lumbar cistern, the name for the space where the subarachnoid space enlarges

Question 14

a child is seizing in the ER, across the room a woman is nearing closer tochild delivery, and a man is rushed in from a motorcycle accident. What procedures are considered for these three individuals?

Answer 14

lumbar puncture will be used for the child

1. The doctor wants to access to childs CSF to run lab test for possible sepsis. The CSF is located in the subarachnoid space
   
   1. the needle will go through the following structures
      
      1. posterior side of the skin, between vetebra L3-L5
      2. fascia
      3. supraspinous longitudinal ligament
      4. interspinous ligament
      5. ligamentum flavum
      6. extradural space
      7. duramater
      8. arachnoid mater
      9. subarachnoid mater

lumbar puncture for medicating the woman

1. medication will be introduced in the extradural space(epidural space)
2. the needle will peirce
   
   1. skin
   2. fascia
   3. supraspinous ligament
   4. interspinous ligamet
   5. ligamentum flava
   6. epidural space( contains fat and internal venous plexuses)

the motorcylist will be assesed for intracranial pressure. If the pressure is too high than lumbar puncture will be a contraindication.

Question 15

describe the pia mater and important structures/function.

Answer 15

pia mater-vascular ultrathin membrane inseperable from spinal cord

1. continues caudal from the conus medullaris as the filum terminale.
   
   1. ​a thin filament connected the the tip of coccyx Sv2, covered by the sheath extension of the dura mater
   2. gives rise to deniculate ligaments
      
      1. ​ lateral extensions that attach to dura to help horizontal stability of spinal

Question 16

Describe the blood supply to the spine. how can the arteries feed the spinal column

Answer 16

blood supply of the spinal cord

1. one anterior spinal artery
   
   1. located in anterior median fissure and supplies anterior 2/3 of spinal cord
2. two posterior spinal arteries
   
   1. supply posterior 1/3 of spinal cord
3. segmental medullary artiers
   
   1. many arteries enter the spinal cord
   2. great anterior segmental medullary artery(adamkiewicz) is usually a branch of left inferior intercostal or upper lumbar artery; it is expecially important for theblood supply of the lower 2/3 of the spinal cord and its occlusion may result in paraplegia

Question 17

Discuss the venous supply/structures/functions of spinal cord

Answer 17

veins of the spinal cord

1. form a number of longirudinal channels
   
   1. two paris of veins on each side bracket the connections of anterior and posterior roots to the cord
   2. one midline channel parallels the anterior median fissure
   3. one midline channels passes along the posterior median sulcus
2. drain in part into the internal vertebral venous plexus
   
   1. this plexus communicates with the externel venous plexus around the vertebral column
      3.