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Ascending & Descending nerve tracts Sanjaya Adikari Department of Anatomy.

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Presentation on theme: "Ascending & Descending nerve tracts Sanjaya Adikari Department of Anatomy."— Presentation transcript:

1 Ascending & Descending nerve tracts Sanjaya Adikari Department of Anatomy

2 Control of the body by the brain L R Contralateral representation Contralateral = Opposite side Ipsilateral = Same side Decussation = Crossing

3 Medulla Sensory organs L R Sensory

4 Medulla Sensory organs L R Sensory

5 Medulla Effecter organs L R Motor

6 Medulla Effecter organs Motor L R

7 Medulla Sensory organs Effecter organs L R

8 Medulla Thalamus First order neuron Second order neuron Internal capsule Third order neuron Corona radiata Ascending tracts

9 Medulla Internal capsule Sensory Posterior surface Upper medulla

10 Internal capsule Upper motor neuron Lower motor neuron (Final common pathway) Descending tracts Motor Anterior surface Lower medulla

11 Internal capsule 20%

12 Internal capsule Corticobulbar Corticospinal L Cranial nerves Spinal nerves

13 Left Ascending tracts

14 White columns Posterior white column Lateral white column Anterior white column Anterior nerve root Posterior nerve root

15 Lateral spinothalamic Pain & temperature

16 Anterior spinothalamic Crude touch & pressure

17 Medulla Thalamus First order neuron Second order neuron Internal capsule Third order neuron

18 Pain & temperature Crude touch & pressure Crosses within one spinal segment Crosses within several spinal segments

19 Fine touch, vibration, Conscious muscle & joint sense Fasciculus gracilis Fasciculus cuneatus

20 Medulla Internal capsule

21 Muscle & joint sense to cerebellum Anterior & posterior spinocerebellar

22 Superior, middle & inferior cerebellar peduncles

23 Left

24 Descending tracts Olivospinal Vestibulospinal Tectospinal Rubrospinal Lateral corticospinal Anterior corticospinal

25 Left

26 Clinical Neuroanatomy by Richard S. Snell

27 Lemniscus This term is used for some ascending (sensory) nerve tracts in the upper part of the medulla, pons and midbrain –Spinal lemniscus combination of spinothalamic, spinotectal tracts –Medial lemniscus crossed posterior column fibers –Lateral lemniscus 3 rd neuron of auditory pathway

28 sensorymotor 1 – All sensory and motor loss on contralateral side 1 RR Fine touch and vibration and motor weakness on the ipsilateral side, pain and temperature loss on the contralateral side (Brown-Sequard) 2 2 – Fine touch and vibration loss on the ipsilateral side, pain and temperature and motor weakness on the contralateral side

29 ThalamicMid-braintem Unilateral cord lesion (Brown-Sequard) Weakness (UMN) Clinical Medicine by Kumar & Cleark’s

30 1 – All sensory and motor loss on contralateral side 2 – Fine touch and vibration loss on the ipsilateral side, pain and temperature and motor weakness on the contralateral side 3 - Fine touch and vibration and motor weakness on the ipsilateral side, pain and temperature loss on the contralateral side

31 D A B Spinal cord lesions C Refer Clinical Medicine by Kumar & Cleark’s

32 A A – Syringomyelia

33 Loss of pain and temperature sense without loss of fine touch. Discontinuous sensory loss Loss of upper limb reflexes Symptoms progress when the cavity enlarges Clinical Medicine by Kumar & Cleark’s

34 B B – Poliomyelitis

35 C – Tabes dorsalis C Demyelination

36 C – Tabes dorsalis (of neurosyphilis) Demyelination of dorsal roots –Lightening pains, sensory ataxia, reflex and sensory loss, muscle wasting, charcot joints –Argyll Robertson pupils

37 Sensory ataxia of tabes dorsalis This is due to loss of proprioception (position sense) - stamping gait - positive Romberg’s test Argyll Robertson pupils No reaction to light. Constricts to convergence Lesion in the cerebral aqueduct

38 Anterior spinal artery occlusion Bilateral loss of motor function due to damage to corticospinal tracts and anterior gray horns Bilateral thermoanesthesia and analgesia due to damage to spinothalamic tracts Loss of bladder and bowel control due to damage to descending autonomic tracts Vibration, fine touch & position sense normal

39 Refer Clinical Medicine by Kumar & Cleark’s


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