Download TRIGEMINAL NUCLEUS - eCurriculum

Kimberle M. Jacobs, PhD
Sanger 11-046
827-2135
[email protected]
midline
LEARNING NEURONAL PATHWAYS REQUIRES
REPETITION
1. Details of pathway: Where are cell bodies located, where is the
synapse made, where do axons cross the midline, first structure,
second structure, etc.
SpinalCord
2. Location of nuclei and tracts within brain sections
Cortex
Thalamus
Somatosensory Systems – All senses other than Olfaction, Gustation,
Audition, Vision, and Vestibular Sensation:
Modalities
Touch (and Pressure), Vibration Sense, Proprioception, Kinesthesia,
Stereognosis, Pain & Temperature
Proprioception - sense of static and dynamic position of limbs and body
Kinesthesia - the ability to feel movements of the limbs and body
Stereognosis – ability to recognize objects based on touch alone
A. Pain and Temperature
B. Fine Discrimination Touch
Non-conscious
Proprioception
Conscious Somatosensation
Spinocerebellar Tracts
BODY
HEAD
(IPSILATERAL)
Trigeminal
System
PAIN
& Temp
Fine
Touch
Pain
Lateral
SpinoThalamic
Dorsal
Column
System
Spinal
Touch
Principal
(Main)
Information reaching consciousness goes to the Neocortex, Nonconscious Sensory
Information goes to the Cerebellum
Somatosensory Information Travels from receptors in the
Periphery (skin) to Consciousness in the Cortex
The axons of the neurons carry
action potentials that transmit the
sensory signal.
These pathways involve a serial
chain.
The first order neuron sends it’s
axon to synapse with the second
order neuron’s soma and
dendrites.
There are 4 neurons in the serial
chain and 3 synapses.
The Basic Plan for Somatosensory Information to
Consciousness
Quaternary (4o )
4
C
o
rte
x
:
rig
h
t
le
ft
Te r t ia r y
o
(3 )
3
Thalamus: left
R e c e p to r
right
S
e
c
o
n
d
a
ry
o
(2C
r
o
s
s
e
s
)
o
Primary (1 )
Crossing occurs either in spinal cord OR brainstem
2
1
S k in
• Adequate Stimulus – The stimulus
modality to which a sense organ responds
optimally.
• Generator Potentials are depolarizations
in receptors that are graded relative to the
intensity and form of the stimulus.
2nd order neuron is located either in spinal cord OR brainstem
Spinal
Cord
Dorsal Root
Ganglion
Action Potential
Initiation Site
left
Midline
Outside the CNS!
right
Key Elements of the Basic Plan: SS to Consciousness
 The basic plan for somatosensory information to consciousness involves 4 neurons and
3 synapses.
 Cell bodies of the primary afferents are located outside of the central nervous system
(in the dorsal root ganglion for body information and in the Trigeminal ganglion for head
information).
 Cell bodies of the second order neurons are located either in the spinal cord
(anterolateral system) or in the brainstem (dorsal column system).
 The axon of the second order neuron crosses the midline.
 Cell bodies of the third order neurons are located in the thalamus (within VPL for body
information and VPM for head information).
 The fourth order neuron is located within the Primary Somatosensory cortex (Brodman’s
areas 3, 1, 2).
 If you lesion the pathway before it crosses you create IPSILATERAL deficits (loss of
sensation on the same side of the body as the lesion).
 If you lesion the pathway after it crosses you create CONTRALATERAL deficits (loss
of sensation on the opposite side of the body as the lesion).
 If you lesion the pathway AS it is crossing, you create BILATERAL deficits (both sides
of the body affected).
Before = IPSI, After = CONTRA
PERCEPTION
Cortex
LEFT
RIGHT
After
Crossing
Before
Crossing Thalamus
CONTRA
STIMULUS
Skin
This is the site of
lost sensation
after the lesion
IPSI
Lesion is ipsilateral to the receptor
that begins coding the stimulus
Midline
Spinal
Cord
Non-conscious
Proprioception
Conscious Somatosensation
Spinocerebellar Tracts
BODY
HEAD
(IPSILATERAL)
Trigeminal
System
PAIN
& Temp
Fine
Touch
Pain
Lateral
SpinoThalamic
Dorsal
Column
System
Spinal
Touch
Principal
(Main)
Information reaching consciousness goes to the Neocortex, Nonconscious Sensory
Information goes to the Cerebellum
Pain and Temperature Pathway: Anterior Lateral System
QUATERNARY 4o
sy
na
ps
e
I
II
III
Primary
Somatosensory Cortex
4
IV
V
TERTIARY 3o
VI
Thalamus
3
VPL
Lateral
Spinothalamic
Tract
Crosses the midline in the
Ventral White Commissure
Of the Spinal Cord
2
Spinal Cord: Dorsal Horn
SECONDARY 2o
*ascend 2-3 spinal levels
PRIMARY 1o
Receptor (skin)
MIDLINE
DRG 1
in Lissauer’s Tract
(cap on dorsal horn)
Spinal Cord:
Lateral Funiculus
Dermatomes & Lissauer’s Tract
Dermatome - the area of skin innervated
by the sensory portion of a single
cranial or spinal nerve.
Primary afferents entering at T4
will synapse mainly in T2.
Lesion at T2 in spinal cord:
Area affected will include T4
since that is where the axons
originally entered the spinal
cord.
Key Elements - Lateral Spinothalamic Pathway
 Transmits pain and temperature sensation from the body.
 Located laterally in the spinal cord and remains relatively
lateral through the brainstem and midbrain – (you will need
to know the exact location – shown to you in video).
 Crosses in the spinal cord.
 Called the Lateral Spinothalamic Tract AFTER crossing in
the spinal cord.
 The tract travels from the spinal cord to the thalamus.
Key Questions for the Lateral Spinothalamic Tract
Where are the cell bodies of origin? Means where are the cell
bodies connected to the axons that make up the tract – not where
are the first order cell bodies.
- Contralateral Dorsal Horn of the Spinal Cord
Where does it project or terminate? Means where do those axons
SYNAPSE?
- Ipsilateral Ventral Posterior Lateral (VPL) of the Thalamus
Thalamus
MIDLINE
Lateral
Spinothalamic
Tract
Spinal Cord: Dorsal Horn
SECONDARY 2o
Spinal Cord:
Lateral Funiculus
Somatotopy is Maintained Throughout all CNS Levels
S
L
C
T
Lateral Spinothalamic Tract
– Symptoms Associated
with Lesions
LEFT
RIGHT
The Anterior Lateral System (ALS)
The Lateral Spinothalamic Tract together with the Anterior
Spinothalamic Tract is known as the ALS
Anterior Spinothalamic Tract – Coarse or ‘light’ Touch
Sy na p s e s in SI C o rte x
Sy na p s e s in VPL
C o lla te ra ls
to Re tic ula r
Fo rm a tio n
Upper Medulla
A s c e nd s in A nte rio r Funic ulus
Ve ntra l White C o m m is s ure
CROSSES
Lower Medulla
midline
Sy na p s e s in
D o rs a l H o rn
Spinal cord
Lateral Spinothalamic Tract
Sk in
Anterior Spinothalamic Tract
Non-conscious
Proprioception
Conscious Somatosensation
Spinocerebellar Tracts
BODY
HEAD
Trigeminal
System
PAIN
& Temp
Fine
Touch
Pain
Lateral
SpinoThalamic
Dorsal
Column
System
Spinal
Touch
Principal
(Main)
(IPSILATERAL)
Trigeminal Nerve – Sensory Component – pain, temperature,
touch, position sense
Trigeminal
Ganglion
Opthalmic
Maxillary
Mandibular
TRIGEMINAL NUCLEUS
Mesencephalic Nucleus (Proprioceptive)
Main Sensory Nucleus (fine touch, pressure)
Human Brain Coloring Book, 6-11
Spinal Trigeminal Nucleus (pain, temp)
Axons of Trigeminal Ganglion Cells Synapse in the
Trigeminal NUCLEUS
Trigeminal
NUCLEUS
Trigeminal
Ganglion
Opthalmic
MIDBRAIN
Maxillary
Mandibular
SPINAL CORD
Human Brain Coloring Book, 6-12
TRIGEMINAL NUCLEUS
Mesencephalic Nucleus (Proprioceptive)
Main Sensory Nucleus (fine touch, pressure)
Spinal Trigeminal Nucleus (pain, temp)
Trigeminal System: All branches of the Trigeminal Nerve
project to each of 3 components of the Trigeminal Nucleus
Tr igeminal
NUCLEUS
Mesencephal ic
Tr igeminal
Nucl eus
Tr igeminal
Ner ve
Opthalmic
Maxillary
Mandibular
Br anches
of t he
Tr igeminal
(V) Ner ve
Proprioception
Tr ig e min a l
G a n g l io n
1
Main
Tr igeminal
Nucl eus
1
Touch
1
Spinal
Tr igeminal
Nucl eus
2
Second Order
Oral Nucleus
Main Nuc to
pontomedullary
junction
Interpolar Nucleus
2
2
Spinal Trigeminal
Nucleus
Pain and Temp
Caudal Nucleus
C3 spinal
cord
Trigeminal System
Tr igeminal
NUCLEUS
Mesencephal ic
Tr igeminal
Nucl eus
Tr igeminal
Ner ve
Opthalmic
Maxillary
Mandibular
Br anches
of t he
Tr igeminal
(V) Ner ve
Proprioception
Tr ig e min a l
G a n g l io n
1
2
1
2
2
1
Main
Tr igeminal
Nucl eus
Touch
Spinal
Tr igeminal
Nucl eus
First Order
2
2
2
Second Order
Pain and Temp
Trigeminal System
Tr igeminal
NUCLEUS
Tr igeminal
Ner ve
Opthalmic
Maxillary
Mandibular
Br anches
of t he
Tr igeminal
(V) Ner ve
Tr igeminal
Gangl ion
1
1
Proprioception
1
1
2
1
Mesencephal ic
Tr igeminal
Nucl eus
2
2
1
Main
Tr igeminal
Nucl eus
Touch
Spinal
Tr igeminal
Nucl eus
First Order
2
2
2
Second Order
Pain and Temp
Trigeminal System
Tr igeminal
NUCLEUS
Tr igeminal
Ner ve
Opthalmic
Maxillary
Mandibular
Br anches
of t he
Tr igeminal
(V) Ner ve
1
1
Tr igeminal
Gangl ion
2
Main
Tr igeminal
Nucl eus
2
Touch
2
1
Proprioception
1
1
1
Mesencephal ic
Tr igeminal
Nucl eus
1
Spinal
Tr igeminal
Nucl eus
2
2
2
Pain and Temp
Similarities between Body and Face Pathways
The trigeminal ganglion is functionally similar to the dorsal
root ganglion. Both contain cell bodies of the PRIMARY
AFFERENT pseudo-unipolar neurons.
The Mesencephalic Nucleus of V is a special case because
it is the only place within the CENTRAL nervous system
that contains primary afferent cell bodies.
Trigeminal Nucleus: Spinal Component = Pain & Temp
C
o
rte
x
1
Mandibular
V II
Br anches I X
of t he
Tr igeminal
(V) Ner ve
X
2
2
2
1
1
1
2
2
2
VPM
MIDLINE
Maxillary
1
Spinal
Trigeminal
TRACT
Main
1
T
h
a
la
m
u
s
Spinal
Opthalmic
Tr igeminal
Gangl ion
1
1
1
4
Ret icul ar
For mat ion
3
VPL
Tr igeminal
Ner ve
Mesencepahl ic
Tr igeminal
NUCLEUS
V
E
N
T
R
A
L
T
R
IG
E
M
IN
0
T
H
A
L
A
M
IC
T
R
A
C
T
Key Questions for the Tracts
Spinal Trigeminal Tract
Where are the cell bodies of origin?
- Ipsilateral Cranial Nerve Ganglia of V, VII, IX, and X
Where does it project or terminate?
- Ipsilateral Spinal Trigeminal Nucleus
C
o
rte
x
1
2
2
2
Mandibular
V II 1
Br anches I X
of t he
Tr igeminal
(V) Ner ve
X
1
1
2
2
2
VPM
T
h
a
la
m
u
s
MIDLINE
1
Spinal
Trigeminal
TRACT
Main
1
1
1
1
Ret icul ar
For mat ion
3
VPL
Tr igeminal
Gangl ion
Maxillary
Where does it project or terminate?
- Ipsilateral VPM of the Thalamus
Tr igeminal
Ner ve
Opthalmic
Where are the cell bodies of origin?
- Contralateral Trigeminal Nucleus
4
Spinal
Ventral Trigeminothalamic Tract
Mesencepahl ic
Tr igeminal
NUCLEUS
V
E
N
T
R
A
L
T
R
IG
E
M
IN
0T
H
A
L
A
M
IC
T
R
A
C
T
Spinal Trigeminal Pathways
Left
Right
Ventral
Trigeminothalamic tract
Left
Right
Lesions and Clinical Deficits - Syringomyelia
Gliosis and cavitation in midline of the spinal cord – CSF enters the
cord. The larger the cavitation, the more tracts affected. One possible cause is a Chiari
Malformation. Other causes include trauma, infection. (anything that compresses the
CSF)
Symptoms:
Bilateral loss of pain and temperature at the level of the lesion (segments involved).
Area of lesion
http://www.asap4sm.com/
Lesions and Clinical Deficits - Wallenberg’s
Lateral Medullary (Wallenberg’s) Syndrome – Symptoms include loss of pain and
temperature on the ipsilateral head/face, contralateral loss of pain and temperature in
the body, and ataxia.
Spinal Trigeminal Tract
Trigeminal Nucleus
Dorsal
Spinocerebellar Tract
Ventral
Spinocerebellar Tract
ALS (lateral spinothalamic tract)
Non-conscious
Proprioception
Conscious Somatosensation
Spinocerebellar Tracts
BODY
HEAD
Trigeminal
System
PAIN
& Temp
Fine
Touch
Pain
Lateral
SpinoThalamic
Dorsal
Column
System
Spinal
Touch
Principal
(Main)
(IPSILATERAL)