1. Sensory and motor pathways
Dr. Petra Balogh
Semmelweis University
2014

2. Reorganization of gray matter
Closed part of medulla
Opened part of medulla
Spinal cord
Pontomedullary junction
pons
midbrain

3. The division of information
DORSAL-SENSORY
VENTRAL-MOTOR
AGAIN!!! SENSORY=AFFERENT MOTOR=EFFERENT

4. Basic definitions General sensation: Special sensation: Pain
Temperature
Pressure, vibration
Proprioception (information from joints, tendons, muscles)
Special sensation:
Taste

5. Sensory pathways
Sensory information is induced from the environment (=stimulus) and forwarded to the central nervous system (=spinal cord, brain) through receptors and afferents (=axons of sensory neurons)
All the first order neurons of sensory pathways are pseudounipolar cells and the cell body is located in the dorsal root ganglia (spinal cord) or in ganglia of cranial nerves

6. General organisation of spinal cord
Pseudounipolar cell

8. Division of sensory information
Epicritic sensation:
fine touch, fine vibration-pressure, proprioception, two point discrimination
B) Protopathic sensation:
rough touch, rough vibration-pressure
pain and temperature

9. Ascending (sensory) tracts of spinal cord

10. Epicritic sensory pathways of SC I.
Cuneate and gracile fasciculi
Carry information about (fine touch, vibration, pressure, two point discrimination, proprioception
There are synapting points (medulla and thalamus Vpl nucleus)till the information reaches the cortex
From the level of medulla the fibers cross the midline and named as medial lemniscus
the fibers project to primary somatosensory area (Brodman 3,1,2)
This pathway is considered a CONSCIOUS epicritic one!!
General rule: all the tracts going through the thalamus and reaches the cortex is a consciuos tract
Medial lemniscus

11. Epicritic sensory pathways of SC II.
Dorsal(posterior) spinocerebellar tract (uncrossed)
Ventral (anterior) spinocerebellar tract (crossed-at the level of spinal cord)
Terminate in the cerebellar cortex as mossy fibers
Both carry information about epicritic sensation but they do not reach the thalamusUNCONSIOUS tracts

12. Protophatic pathway of SC (anterolateral system)
Ventral and lateral spinothalamic tracts (crossed)
Ventral spinothalamic tract carries information about rough touch, vibration, pressure
Lateral spinothalamic tract carries information about pain and temperature
Both terminate in the thalamus VPl nucleus (conscius tract) and the fibers after synapse reach the primary somatosensibility area (Brodman 3,1,2 area)
Anterolateral system

13. Epicritic and protophatic pathway in the head and neck region
Afferent information arrives to CNS through branches of trigeminal nerve
Into the spinal trigeminal nucleus
After synapse via the trigeminal lemniscus the information forwarded to thalamus Vpmcortex (primary somatosensory area, Brodman 3,1,2)

14. Epicritic and protophatic pathway of head and neck region II.
The distribution of trigeminal nerve and its branches:
V/1: ophtalmic nerve
V/2: maxillary nerve
V/3: mandibular nerve

15. Epicritic and protophatic pathway of head and neck region III.

16. Taste information (special sensation)
In the epithelium of papillae of tonguetaste buds
The stimuli(sweet, salty, sour, bitter, water) are forwarded to the CNS through branches of cranial nerves
Repeat the innervation of tongue!!!!

17. Taste pathway I.

18. Taste pathway II. Primary gustatory area-cortex (Brodman 43)
Solitary tract nucleus
Peripheral nerves-carrying tasting fibers

19. Summary of sensory pathways
Epicritic, protopathic info
via trigeminal lemniscus
Head and neck
Thalamus Vpm
Taste info via solitary tract
Sensory cortex
Epicritic info via medial lemniscus
Spinal cord
(trunk and limbs)
Thalamus Vpl
Protopathic info via spinothalamic tract

20. Motor pathways (descending tracts)

21. Motor pathways I. Pyramidal tract =corticospinal tract
Anterior corticospianltract (crosses at the level of SC)
Lateral corticospinal tract (crosses at the level of medulla=pyramidal decussation)
The motor axis of the body
Gives the command to the skeletal muscles ‘what to do’

22. Innervation of skeletal muscles
Alpha motor neurons innervate the skeletal muscles of trunk and limbs (neuromuscular junctions-motor end plates)

23. Motor pathways II. Extrapyramidal system
Refine the activity of corticospinanl tract and gives the command ‘how to do’
Maintain a continous muscle tone (mainly in antigravitation muscles=extensors)
Synchronize the movements of eyeball and head-neck muscles
Reset the sensitivity of muscle spindle!!

24. The tracts of extrapyramidal system
Vestibulospinal tract
Reticulospinal tract
Reubrospinal tract
Olivospinal tract
Tectospinal tract

25. Brodmann Areas: cortical representatives of sensory and motor functions

26. anatomical localizaton
Brodmann areas
functions
anatomical localizaton
3, 1, 2
primer somatosensory area
postcentral gyrus
paracentral lobul
secundary somatosensory area
dorsalwall of lateral cerebral sulcus
5,7
associative somatosensory area
parietal eye centre
superior parietal gyrus 17
primer visual area
sulcus calcarinus
striated area 18 19
secundary visual area
tercier visual area
parastriate area
peristriate area
41, 42
auditory area
transversal temporal gyri =
Heschl gyrus
(22), 40, 39
Wernicke area 22
sensory speech centre
memorizing of voices, recognizing of words
supramarginal gyrus ( 40)
angular gyrus (39)
planum temporale ( 22)
45,44
motor speech area of Broca
pars opercularis, pars triangularis 43
primary taste area
lower part of postcentral gyrus
4, 4s, 6a, 6b
primary motor area
precentral gyrus
paracentral lobule
secundary motor area
dorsal wall of lateral cerebral sulcus
6aß 8
premotor area
frontal eye field
anterior to precentral sulcus
post part of middle frontal gyrus
9, 10, 11, 12
prefrontal area

27. Sensory homunculus
Picture of the body with proportions of its cortical map

28. Thank you for the attention!