Ant204 Spinal Cord Reflexes & Meninges

Front 1

How many segments are in the spinal cord?

Back 1

31: 8C+12T+5L+5S+1Co

Front 2

The spinal cord has two enlargements located where?

Back 2

cervical and lumbar regions. These are big thanks to the upper and lower limbs.

Front 3

In the adult the spinal cord ends at ...

Back 3

L1 - L2

Front 4

What ends at S2, the level of which is marked by a line through the posterior superior iliac spines (PSISs).

Back 4

Dural sac or thecal sac

Front 5

The spinal cord is attached distally to the coccyx by what structure?

Back 5

filum terminale.
Internal filum is formed by pia mater.
External filum has a covering of dura.

Front 6

What causes muscle weakness in multiple muscles rather than paralysis of those muscles?

Back 6

radiculopathy, (single nerve damage) Because a myotome contributes to more than one muscle

Front 7

Peripheral nerve injuries affect more than one dermatome and are also known as what?

Back 7

neuropathy

Front 8

Peripheral nerve injuries affect adjacent dermatomes and cause ____ of the innervated muscles

Back 8

paralysis

Front 9

why is white matter white?

Back 9

because of the myelinization by oligodendroglial cells.
It contains tracts, which are bundles of myelinated axons.

Front 10

What is contained in the gray matter?

Back 10

neuronal cell bodies and dendrites.

Front 11

where do lower motor neurons reside?

Back 11

anterior horn of spinal cord.
Their axons innervate skeletal muscle
Their axons form the motor portions of peripheral nerves
They are called “the final common pathway” because they receive input from higher brain areas such as the cerebral cortex

Front 12

Where do upper motor neurons reside?

Back 12

Upper motor neurons are in higher centers such as the motor cortex
Their axons excite or inhibit lower motor neurons

Front 13

What is this picture representing?

Back 13

There is a topographic representation of the limb (somatotopic).
Generally, the lower motor neurons that innervate axial muscles are more medial.
The lower motor neurons innervating the proximal limb muscles are lateral to those and the lower motor neurons innervating the more distal limb muscles are most lateral.
Lower motor neurons innervating flexors are more dorsal (posterior) and those innervating extensors are more ventral (anterior).

Front 14

Stroke the skin of the abdomen, underlying muscles will contract.
What spinal segments are involved?

Back 14

This is a superficial reflex.
Spinal segments
Upper abdomen: T7-T9
Lower abdomen: T10-T11

Front 15

Cremasteric reflex involves stroking the skin of the medial thigh. Cremasteric muscle contracts elevating testis.
What spinal segments does this test?

Back 15

Tests T12, L1 and L2

Front 16

Plantar reflex involves stroking bottom of foot from heel to toe. Provokes plantar flexion of toes.
What spinal segments does this test?

Back 16

Tests L4, L5, S1 and S2

Front 17

“Anal Wink” involves stimulus of perianal region. Anal sphincter contracts.
What spinal segments does this test?

Back 17

Tests S2-S4

Front 18

The following reflex tests what spinal segments:
Ankle(Achilles) reflex

Back 18

S1 and S2

Front 19

The following reflex tests what spinal segments:
Knee (patellar)

Back 19

L2, L3 and L4

Front 20

The following reflex tests what spinal segments:
Biceps reflex

Back 20

C5 and C6

Front 21

The following reflex tests what spinal segments:
Brachioradialis reflex

Back 21

C5 and C6

Front 22

The following reflex tests what spinal segments:
Triceps reflex

Back 22

C6, C7 and C8

Front 23

Back 23

Front 24

Back 24

Front 25

Back 25

Front 26

Back 26

Front 27

Back 27

Front 28

What are the basic steps involved in the deep tendon reflexes?

Back 28

Muscle spindles detect muscle length and stretch.
When a muscle is stretch by tapping its tendon with a reflex hammer, that information is carried to the spinal cord by a 1a afferent axon.
The 1a fiber is a proprioceptive afferent, i.e. carries information about deep somatic structures.
The 1a fibers synapse directly on alpha motor neurons that innervate the muscle (monosynaptic).
The alpha motor neurons fires and the muscle contracts.
Alpha motor neurons innervating the antagonist muscle are inhibited.

Front 29

Clinically, the most important descending tract, The lateral corticospinal tract, starts where and ends where?

Back 29

Arises from upper motor neurons in the motor cortex
(Motor cortex is somatotopically organized)
Axons descend and cross in the pyramidal decussation in the caudal medulla
Innervates lower motor neurons which innervate limb muscles

Front 30

What are two major sensory pathways for the somatosensory system?

Back 30

Dorsal columns (lemniscal system)

Anterolateral (spinothalamic) system

Front 31

Of the Two major sensory pathways, what sensory info does the Dorsal columns (lemniscal system) pathway send and where does it cross?

Back 31

discriminative touch, proprioception, and vibratory sense
Crosses in the medulla

Front 32

Of the Two major sensory pathways, what sensory info does the anterolateral (spinothalamic) pathway send and where does it cross?

Back 32

crude touch, pain and temperature
Crosses in the spinal cord

Front 33

Injury of corticospinal system (pyramidal tract) anywhere above the pyramidal decussation causes ___ paralysis paresis of the limbs.

Back 33

contralateral

Front 34

upper motor neuron Injury below the pyramidal decussation will cause ____ paralysis or paresis below the lesion.

Back 34

ipsilateral

Front 35

Injury to the spinal cord will cause loss of pain and temperature sense on the ____ side below the lesion.

Back 35

contralateral

Front 36

An injury to the spinal cord will cause _____ loss of fine (discriminative) touch, proprioception and vibration below the lesion.

Back 36

ipsilateral

Front 37

A lesion that involves ½ of the spinal cord at T6 vertebral level will cause:
Paralysis of the _____ lower body.
_____ loss of fine touch (2 point discrimination), proprioception and vibration sense below the lesion (lower ½ of body)
______ loss of pain and temperature below the lesion (opposite side of lower body)

Back 37

ipsilateral
Ipsilateral
Contralateral

Front 38

What are three layers of the meninges?

Back 38

dura mater, arachnoid, pia mater

Front 39

What is Separated from the periosteum of the vertebrae by the epidural space?

Back 39

dura mater

Front 40

What is Separated from the dura by a potential space, the subdural space?

Back 40

arachnoid

Front 41

what is Tightly adherent to cord, Forms denticulate ligaments, Forms internal filum terminale?

Back 41

pia mater

Front 42

Dura mater is derived from what?

Back 42

mesenchyme, hence the alternate name, pachymeninx

Front 43

the dura mater is made up of:

Back 43

Dense CT
Longitudinal collagen fibers with circular elastic fibers

Front 44

the Leptomeninx consists of what two layers?

Back 44

the arachnoid and pia mater

Front 45

the Leptomeninx is derived from embryonically?

Back 45

neural crest

Front 46

True or False: Arachnoid mater and pia mater both contain blood vessels

Back 46

True

Front 47

where does the thecal sac end? and what is it enclosed by?

Back 47

the thecal sac is also known as the dural sac as it is made of dura mater. it ends at s2.

Front 48

Below the S2 level, after the thecal/dural sac has closed, the dura continues as the ____ which then ends at the coccyx.

Back 48

filum terminale

Front 49

The subdural space is a potential space, which means:

Back 49

One cannot enter the subdural space with a needle in the living patient.

Front 50

What is the most definitive index of meningitis and how do you get this?

Back 50

The presence of Polymorphonuclear leukocytes, which can be gained by a sample of CSF.

Front 51

Where is the needle inserted for a lumbar puncture or spinal tap?

Back 51

Needle inserted through the ligamentum flavum between L3 and L4 or between L4 and L5 (Caudal to the spinal cord)
ALSO Roots of cauda equina are not damages they are pushed aside within the CSF

Front 52

What is an epidural?

Back 52

An Anesthetic infused around outside of dural sac which Allows selective block of roots without affecting cord

Front 53

What is a normal anion gap?

Back 53

4-12

Front 54

Lower 2/3 of spinal cord dependent on a medullary segmental artery that is usually larger than the others, which typically (65% of people) arises on the left at T12 or L1. What is this called?

Back 54

, the arteria radicularis magna or great radicular artery of Adamkiewicz

Front 55

Explain the clinical significance and characteristics of Metastases via the Epidural (Batson’s) Plexus?

Back 55

The epidural plexus that drains the spinal cord and meninges has no valves
Increased intra-abdominal pressure can cause a reflux of blood into the plexus and thereby carry metastatic cells, such as prostate CA and infections, such as pelvic infections, along the spinal column to more cranial levels.

Front 56

Case Presentation: A 28-year-old man was drinking around the swimming pool with friends and, on a dare, dove into the pool and struck his head on the bottom. When pulled out by friends, he couldn’t move his left upper or lower limb and, when asked, he could not wiggle the toes on his left foot or move the fingers of his left hand. He was rushed to the Emergency Department where an examination revealed left sided paralysis below the neck, left sided loss of fine touch, proprioception and vibratory sense, and right-sided loss of pain and temperature, all below the neck.
Where is his injury?
Where do the affected tracts cross?

Back 56

Left cervical spinal cord
Corticospinal and dorsal column system –caudal medulla
Anterolateral system – in the spinal cord