4. sensory information
are received and carried by ascending tracts
• exteroceptive sensation
origin:- outside the body
e.g. temp, touch, light, sound, chemicals, mechanical
receptors:- surface layer of skin, mucosa
• proprioceptive sensation
origin:- within the body
e.g. muscles, joints, tendons
receptors – deeper layer of skin, tendons, joints, GTO, muscle
spindles, ligament
• Steriognosis , graphesthesia, and two point discrimination combind
( pc) and cortical sensation
5.
6. sensory information
from the peripheral sensory endings
is conducted through the nervous system
by a series of neurones
8. spinal cord
• Grey matter
– mostly made up of cell bodies of neurone
• White matter
– composed of nerve fibres ( ascending and descending tracts )
embedded in neuroglial cells
9. nerve fibres
• enter the spinal cord through posterior nerve root
• after entering the spinal cord
sorted out and segregated into nerve bundles, tracts
( origin, function, termination )
10. ascending tracts
bundles of nerve fibres
linking
spinal cord with higher centres of the brain
convey information
from
soma / viscera to higher level of neuraxis
11. Ascending sensory pathway are organized
in three neuronal chain
- First order neurone
- Second order neurone
- Third order neurone
12. First order neurone
• cell body in posterior root ganglion
• peripheral process connects with sensory receptor
ending
• central process enter the spinal cord through the
posterior root
• synapse with second order neuron in spinal gray
matter
14. Second order neurone
• cell body in posterior gray column of spinal cord
• axon crosses the midline ( decussate )
• ascend & synapse with third order neuron in VPL
nucleus of thalamus
16. Third order neurone
• cell body in the thalamus( ventro lateral nucleus)
• give rise to projection fibres to the cerebral cortex,
postcentral gyrus ( sensory area )
17. ascending sensory pathway
( in general form )
from sensory endings
to
cerebral cortex
( note the three neurons chain )
18. sensory sensation
Three type
1. Superficial : pain ,temperature and superficial touch
carried by spinothalamic pathway(lateral)
2. Deep : crude touch ,joint position ,vibration carried
by dorsal coloumn
3. Cortical sensation : tactile localization, tactile
discrimination,tactile extiction,astereognosis,two
point discrimination and graphasthesia
19. Arrangements Of Sensory Fibers
• Posterior column : fibers from lower limb are placed
medially while fibers upper limbs are placed laterally
• Spinothalamic tract : just opposite to posterior
column
• In central cord lesion lateral spinothalamic tract is
affected 1st
while posterior column sensations are
preserved this causes dissociative aneshesia
25. Lateral spinothalamic tract
pain and thermal impulses
( input from free nerve endings, thermal receptors )
• transmitted to spinal cord in delta A and C fibres
• central process enters the spinal cord through posterior
nerve root, proceed to the tip of the dorsal gray column
26. • The central process of 1st
order neuron synapse with cell body
of 2nd
order neuron in substantia gelatinosa of posterior gray
column of the spinal cord
• The axon of 2nd
order neuron cross to the opposite side
in the anterior gray and white commissure and ascend in
contralateral white column as lateral spinothalamic tract
• End by synapsing with 3rd
order neuron in the ventral
posterolateral nucleus of thalamus
• Axon of the 3rd
order neuron passes through the posterior
limb of internal capsule and corona radiata to reach the
postcentral gyrus of cerebral cortex ( area 3, 1 and 2 )
28. Clinical application
destruction of LSTT
• loss of
– pain and thermal sensation
– on the contralateral side
– below the level of the lesion
patient will not
respond to pinprick
recognize hot and cold
29. Anterior spinothalamic tract
light touch and pressure impulses
( input from free nerve endings, Merkel’s tactile disks )
• First order neuron
– dorsal root ganglion( all level )
• Second order neuron
– in the dorsal horn, cross to the opposite side (decussate)
– ascend in the contralateral ventral column as ASTT
– end in VPL nucleus of thalamus
• Third order neuron
– in the VPL nucleus of thalamus
– project to cerebral cortex ( area 3, 1 and 2 )
31. Clinical application
destruction of ASTT
loss of touch and pressure sense
– below the level of lesion
– on the contralateral side of the body
32. Fasciculus gracilis and fasciculus cuneatus
discriminative touch, vibratory sense and conscious
muscle joint sense
( inputs from pacinian corpuscles, Messiner’s corpuscles,
joint receptors, muscle spindles and Golgi tendon organs )
• axon of 1st
order neuron enter the spinal cord
• passes directly to the posterior white column of the
same side ( without synapsing )
33. • long ascending fibres travel upward in the posterior
column of the same side as fasciculus gracilis and
fasciculus cuneatus
– ( FG – carrying fibres from lower thoracic, lumbar and sacral regions /
including lower limbs )
– ( FC - only in thoracic and cervical segments / including upper limb fibres )
• synapse on the 2nd
order neuron in the nucleus
gracilis and cuneatus of medulla oblongata of the
same side.
34. lower 6 thoracic segments
lumbar segments
sacral segments
cervical segments
upper 6 thoracic segments
fasciculus gracilis
fasciculus cuneatus
[ nucleus G & C ]
in medulla
G
C
35. • axons of 2nd
order neuron
“ internal arcuate fibres ” cross the median plane
( sensory decussation )
• ascend as medial lemniscus
through medulla oblongata, pons, and midbrain
• synapse on the 3rd
order neuron in ventral posteriolateral nucleus of
thalamus
• axon of 3rd
order neuron leaves and passes through the internal capsule,
corona radiata to reach the postcentral gyrus of cerebral cortex area 3, 1
and 2 )
37. Clinical application
destruction of
fasciculus gracilia and cuneatus
• loss of muscle joint sense,
position sense, vibration sense
and tactile discrimination
• on the same side
• below the level of the lesion
(extremely rare to have a lesion of the spinal cord to
be localized as to affect one sensory tract only )
38. Posterior & Anterior Spinocerebellar Tract
• transmit unconscious proprioceptive information to
the cerebellum
• receive input from muscle spindles, GTOs and pressure
receptors
• involved in coordination of posture and movement of
individual muscles of the lower limb
39. First order neuron
• in dorsal root ganglion
• axons end in nucleus dorsalis of Clarke
Second order neuron
• cell body in nucleus dorsalis of Clarke
• give rise to axons ascending to the cerebellum of the
same side
( anterior – crossed & uncrossed fibres / posterior – uncrossed fibres)
41. • Spinotectal tract
– passes pain, thermal, tactile information to superior
colliculus for spinovisual reflexes
• cross the median plane
• synapse in the superior colliculus
• integrate visual and somatic sensory information
( it brings about the movement of eye and head
towards the source of information )
• Spinoreticular tract
– uncrossed fibres, synapse with neurones of reticular
formation
(important role in influencing level of consciousness)
• Spino-olivary tract
52. BRAIN STEM SYNDROME:
loss of pain ,touch and
temperature on same
side of the face and
opposite side of the body
due to involvement of
trigeminal tract and
nucleus and lateral
spinothalamic tract
53. THALAMIC SYNDROME:
loss of all type of
sensation of opposite
side of the body and
position sense more
affected than other
type of sensation.
There may be
spontaneous pain and
discomfort
54. PARIETAL LOBE SYNDROME:
A) loss of tactile localization
b) loss of tactile discrimination
C)tactile extinction
D)astereognosis
E)two point discrimination: finger pulp, lips,
palm, sole,dorsum of the foot ,back
55. HYSTERICAL:
A)complete hemianaesthesia with reduced
hearing vision taste smell ,reduced vibration,
only over one half of the skull.
B)sharply defined sensory loss not confined to
the distribution of the root or cutaneous
nerve
C)postural sense is rarely affected.
56. • It is divided into complete and incomplete
cord syndromes.
• INCOMPLETE CORD SYNDROMES.
• Brown sequards syndrome.
• Central cord syndrome.
• Anterior cord syndrome.
• Posterior cord syndrome.
• Conus medullaris syndrome.
• Cauda equina syndrome.
58. Complete Transaction Of Spinal Cord
CAUSES-
Trauma
Metastatic carcinoma
Multiple sclerosis
Spinal epidural haematoma
Autoimmune disorders
Post vaccinial syndromes.
All ascending tracts from below and descending
tracts from above are interrupted.
Affects motor sensory and autonomic functions.
59. SENSORY
all sensations are affected.
Pin prick test is very valuable.
Sensory level is usually 2
segments below the level of
lesion.
Segmental paresthesia occur
at the level of lesion.
60. Hemisection of the spinal cord
( Brown Sequard’s syndrome )
• Dorsal column damage
• Lateral column damage
• Anterolateral column damage
• Damage to local cord segment and nerve roots
62. below the level of lesion
on the side of lesion
lateral column damage
• UMNL
dorsal column damage
• loss of position sense
• loss of vibratory sense
• loss of tactile discrimination
anterolateral system damage
• loss of sensation of pain and
temperature on the side opposite
the lesion
local segment
side of lesion
Dorsal Root
• irritate
• destruction
Ventral root
• flaccid paralysis
64. CENTRAL CORD SYNDROME
Most common cause is syringomyelia.
others hyperextension injuries of neck,intramedullary
tumours,trauma.
Associated with chiari type 1 and 2.and dandy walker
malformation.
SENSORY
Pain and temperature are affected.
Touch and proprioception are preserved.
Dissociative anaesthesia.
Shawl like distribution of sensory loss.
MOTOR.
Upper limb weakness >lowerlimb
65.
66. • Other features;
– Horners syndrome
– Kyphoscoliosis
– . Sacral sparing
– Neuropathic arthropathy of shoulder and elbow
joint
– Prognosis is fair.
67. Occurs due to neurosyphilis,diabetes mellitus
Usually occurs 10 to 20 yrs after infection
SENSORY
Impaired position and vibration sense in LL
Tactile and postural hallucinations can occur.
Numbness or paresthesia are frequent complaints..
Sensory ataxia.
Positive rhomberg sign.
POSTERIOR COLUMN SYNDROME
68. POSTERO LATERAL COLUMN DISEASE
CAUSES;
VITB12 DEFICIENCY
AIDS
HTLV ASSOCIATED
MYELOPATHY.
CERVICAL SPONDYLOSIS
Paresthesia in feet
Loss of proprioception and
vibration in legs
Sensory ataxia
69. positive rhomberg sign
Bladder atony
Corticospinal tract
involvement;spasticity,hyperreflexia ,bilateral
Babinski sign.
Aids:associated dementia and spastic bladder is
present
HTLV associated myelopathy;slowly progressive
paraparesis increase in csf igG with antibodies
to HTLV1.
72. VASCULAR SYNDROMES OF SPINAL
CORD
Mostly occurs due to anterior spinal artery.
conus medullaris is frequently involved.lies
opposite to vertebral bodies T12 and L1.
Neck pain of sudden onset.
MOTOR
Flaccid and areflexic paraplegia
73. SENSORY
Loss of pain and temperature.
Preservation of positon and vibration.
AUTONOMIC
urinary incontinence.
Spinal cord infarction usually occurs in T1 to T4
segment.and L1
Occurs due to syphilitic arteritis ,aortic
dissection,atherosclerosis of aorta,SLE
,AIDS,AV malformation
75. CONUS MEDULLARIS SYNDROME
Contributes to 25%spinal cord injuries.
Lies opposite to vertebral bodies of T12 and L1.
Caused by flexion distraction injuries and burst
fractures.
Both UMN and LMN deficits occur.
Development of neurogenic bladder.
77. CAUDA EQUINA SYNDROME
•
Begins at L2 disk space distal to
conus medullaris.
MOTOR
Flaccid lower extremities.
Knee and ankle jerk absent.
SENSORY-
Asymmetrical sensory loss
Saddle anaesthesia
Loss of sensation around
perineum,anus,genitals.
AUTONOMIC-
Loss of bladder and bowel function.
Urinary retention.
Occurs due to acute disk herniation
epidural haematoma,tumour
