Spinal Pathways 1: Objectives
Concepts:1. Review: the general anatomical and functional regions within
the gray and white matters of the spinal cord.
2. Conceptualize the arrangement of nucleus groups in the graymatter.
3 a. Identify the major ascending and descending pathways.b. Conceptualize the somatotopic organization of the pathways.
Descending Pathways:3. Trace the pathway of the corticospinal/pyramidal tracts.
Objective 1: Anatomical & Function Regions
CD-ROM, Introduction to Nervous System, Spinal Cord, frame 3-4, 23-24Notes: p. 53, Sections 7.1.1 – 7.1.2
Objective 3a: Major Ascending & Descending Tracts
Notes: p. 55, Sections, Fig.7-3
Major ascending pathway:
• dorsal column / lemniscal pathway• spinothalamic tract• dorsal spinocerebellar tract • ventral spinocerebellar tract• spinoreticular tract
Major descending pathways:
• corticospinal tract (lateral and anterior)• vestibulospinal tract • descending autonomic tract• tectospinal tract• reticulospinal tract
FYI Only
Objective 4-1: Lateral Corticospinal /Pyramidal Tract
Case V, Frame 4 Notes: p. 56-57, Sections 7.4.1, Fig. 7-4
Upper motor neuron from L.L., Trunk, and U.L areas of the motor cortex descends in the pyramidal tract
Corona radiata and internal capsule
Through:
Crus cerebri
Deep to the pontine n. and pontocerebellar tract
Pyramid
Crosses to the contralateral side at the decussation of the pyramid
Then:
Descends as lateral corticospinal tract in the lateral funiculus
Enters ventral horn, and
Objective 4-2: Ant. (Ventral) Corticospinal /Pyramidal Tracts
Case V, Frame 5 Notes: p. 56-57, Sections 7.4.2, Fig. 7-4
Upper motor neuron from Trunk area of the motor cortex descends in the pyramidal tract
Corona radiata and internal capsule
Through:
Crus cerebri
Deep to the pontine n. and pontocerebellar tract
Pyramid
Ventral funiculus of the spinal cord
Then:
At the level of exit, crosses to contralateral side of the spinal cord via the ant. white commissure and enters ventral horn.Synapses with alpha motor neuron (lower motor neuron) which then exits via ventral root to innervate deep muscles in the back in the cervical and upper thoracic levels.
Review: Corticobulbar Tract
Case V, Frame 6 (Frame 6 typo: …except CN I, II, VIII)Notes: p. 56-57, Sections 7.4.3
Summary: Spinal Pathways 1 - Introduction and Descending Pathways
1. Concepts: Organization of the gray and white matter.
2. Laminae of the gray matter.
3. Somatotopic representation of the tracts.
4. Corticospinal tracts: Lateral (90%, crosses at caudal pyramid) & anterior (10%, crosses at level of exit).
Spinal Pathways 2: Objectives
Ascending Pathways:4. Trace the dorsal column/lemniscal pathway.5. Trace the pathway of the spinothalamic tract.6. Trace the pathway of the dorsal spinocerebellar tract.
Spinal cord lesions:7. Examine the effects of lesions in the spinal cord.
Objective 4: Dorsal Column/Lemniscal tracts
Case V, Frame 9 - 12Notes: p. 58-59, Fig. 7-5
Upon reaching caudal medulla, axons of the f. gracilis and f. cuneatus synapse with 2nd order neurons in n. gracilis and n. cuneatus respectively.
1st order neuron from thoracic and cervical levelsenter dorsal horn, and ascend in f. cuneatus
1st order neuron from sacral and lumbar levelsenter dorsal horn, and ascend in f. gracilis
Axons of the 2nd order neurons immediately decussate to contralateral caudal medulla and ascends in medial lemniscus
M
Medial lemniscus
Upon reaching VP nucleus of the thalamus, axons in the Medial lemnisus synapse with 3rd order neurons which travel to respective areas of sensory cortex
Objective 4: Somatotopic Representation of Dorsal Column/Lemniscal tracts
FG: Fasciculus Gracilis
FC: Fasciculus Cuneatus
NG: Fasciculus GracilisNC: Fasciculus Cuneatus
Trigeminal Nucleus
Objective 5: Spinothalamic tractCase V, Frame 13Notes: p. 60-61, Fig. 7-6
1st order neuron entersenter dorsal horn, and synapses with 2nd order neuron
2nd order neurons immediately decussate to lateral funiculus and
ascend as spinothalamic tract
2nd order neurons ascend through the brain stem
Upon reaching VP nucleus of the thalamus, axons of spinothalamic tract synapse with 3rd order neurons which travel to respective areas of sensory cortex
Objective 6: Dorsal Spinocerebellar tractCase V, Frame 14 (FYI: 15)Notes: p. 60-61, Fig. 7-7
1st order neuron entersenter dorsal horn, and synapses with 2nd order neuron.
Axons of 2nd order neurons immediately enter lateral funiculus
on the ipsilateral side and ascend to brain stem
Upon reaching rostral medulla, 2nd order neuron enters cerebellum via
inferior cerebellar peduncle
Objective 7-1: Spinal Cord Lesion – Ascending and Descending Tracts
Case V, Frame 7, 16; Case Description and Discussion Notes: p. 60
Objective 7-2: Syringomyelia
Case V, Frame 17Notes: p. 60
• Occurs mostly in the cervical area of the spinal canal.
• Results in bilateral loss of sensitivity to pain and temperature because of obliteration of spinothalamic tract decussating in the white commissure.
Objective 7-3: Arterial supply of the Spinal Cord
Case V, Frame 18 TYPO in Frame 18: Radiculospinal artery,Notes: p. 60 not radicular artery
Spinal Pathways: Summary
4. Dorsal column/lemniscal tract: (x medulla oblongata)
5. Spinothalamic tract: (x level of entry)
6. Dorsal spinocerebellar tract: (no x)
7. Lesions
Limbic System
CD-ROM Case VII: A Confused AlcoholicNotes: p. 62-63
Objectives:
1a. Identify the cortical components of the limbic system.
1b. Identify the subcortical components of the limbic system
2. Describe a general pathway of the Circuit of Papez.
Cingulate Gyrus
(Mamillary Body)
Uncus/Amyglada
Parahippcampal Gyrus
Hippocampal Formation
Fornix
Objective 1a: Cortical Limbic Structures
Cerebral Cortex
• Septal area• N. accumbens• Basal Forebrain
Cingulate
Parahippocampal
Prefrontal
Association
VisualAssociation
Cortical:NeocortexMesocortexArchiocortex
Subcortical:Diencephalon
Brain Stem
Hippo. F.
Hippocampal Formation Fornix (axonal tract)Amygdala (?)
AF
F
F
T
HT
MB: Mamillary BodyTH: HypothalamusT: Ant. Thalamic N.
MB
Reticular FormationAutonomic & Locomotive Ctr.
BS
CircuitOfPapez
RecentlyDescribedCircuits
Notes:p. 63,Fig. 8-1