Ascending spinal tracts Flashcards
Terminology
Lemniscus: ribbon
Fasciculus: ‘bundle’
Gracilis: ‘slender’.
Cuneatus: “to make wedge-shaped,” / “a wedge, wedge- shaped thing.
Ipsilateral: “self”or “same side”.
Contralateral= “against, in opposition”.
List the Ascending spinal tracts and their role
- POSTERIOR COLUMN-MEDIAL LEMNISCAL PATHWAY
- general sensation
- fine touch, vibration, proprioception - ANTEROLATERAL/ SPINOTHALAMIC TRACT
- pain and temperature - TRIGEMINAL PATHWAY
- pain and temperature - ANTERIOR SPINOCEREBELLAR TRACTS
- unconscious proprioception - POSTERIOR SPINOCEREBELLAR TRACTS
- unconscious proprioception.
PSOTEROIR COLUMN-MEDIAL LEMNISCAL PATHWAY
- what is contains? =4
- THREE-NEURON CHAIN PATHWAY
- Carries GENERAL SOMATIC AFFERENT (A-beta fibres) information about DISCRIMINATIVE TOUCH, PRESSURE, VIBRATION, and PROPRIOCEPTION from PNS to CNS.
- LARGE MYELINATED AXONS which Transmit IMPULSES at HIGH SPEED ( up to 120m/s!)
- PROJECTS to CONTRALATERAL VENTRAL POSTERIOR LATERAL THALAMUS —> POSTCENTRAL GYRUS
posterior column medial leminiscal pathway —EXPLAIN THE THREE-NEURON PATHWAY
- ***PRIMARY NEURON:
- receptors in Periphery, cell body in root ganglion, axon ascends in posterior column
- FASICULUS GRACILIS: LOWER LIMB
- FASICULUS CUNEATUS: UPPER LIMB
- SYNAPSES in named NUCLEI IN MEDULLA OBLONGATA
2.*** SECONDARY NEURON:
cell body in NUCLEUS CUNEATUS: upper limb, NUCLEUS GRACILIS: lower limb
- AXON DECUSSATES in MEDIAL LEMNISCUS
-SYNAPSES in the VENTRAL POSTERIOR LATERAL THALAMUS
- *** TERTIARY NEURON: cell body in VPL THALAMUS,
AXON ASCRNDS in INTERNAL CAPSULE, synapses in POSTCENTRAL GYRUS
What are the three Ascending Trigeminal Pathways?
VI = OPHTHALMIC BRANCH of CN V
V2: MAXILLARY BRANCH of CN V
V3: MANDIBULAR BRANCH of CN V
TRIGEMINAL PATHWAY:
DISCRIMINATIVE TOUCH FIBRES SYNAPSE in …
PAIN AND TEMPERATURE FIBRES SYNAPSE…
DISCRIMINATIVE TOUCH FIBRES SYNAPSE in …
—- CHIEF SENSORY NUCLEUS OF V
PAIN AND TEMPERATURE FIBRES SYNAPSE…
—– SPINAL NUCLEUS
——- and TRACT OF V.
Pathway of trigeminal nerve from MESENCEPHALIC NUCLEUS OF V
5.
- MESENCEPHALIC NUCLEUS OF V
- GANGLION OF V
- MANDIBULAR V3 PATHWAY
- THROUGH FORAMEN OVALE
- PROPRIOCEPTION: from muscles of mastication
Pathway of trigeminal nerve from Chief sensory nucleus of V
6.
- Chief sensory nucleus of V
- GANGLION OF V
- -OPHTHALMIC
- MAXILLARY
- MANDIBULAR - ophthalmic: SUPEROIR ORBITAL FISSURE
- maxillary: FORAMEN ROTUNDUM
- mandibular: FORAMEN OVALE
- ophthalmic: DISCRIMINATIVE TOUCH
- maxillary: DISCRIMINATIVE TOUCH
- mandibular: DISCRIMINATIVE TOUCH
6.ophthalmic: SENSORY = from upper face, orbit, eye
- maxillary: SENSORY = from midface, upper teeth
- mandibular: SENSORY = from lower face, lower teeth
Pathway of trigeminal nerve from MOTOR NUCLEUS OF V
-5
- MOTOR NUCLEUS OF V
- GANGLION OF V
- MANDIBULAR NERVE
- FORAMEN OVALE
- MOTOR: to muscles of mastication
Pathway of trigeminal nerve from SPINAL NUCLEUS AND TRACT OF V
- 6
- SPINAL NUCLEUS AND TRACT OF V
- GANGLION OF V
3.
OPTHALMIC
MAXILLARY
MANDIBULAR
- Ophthalmic: SUPEROIR ORBITAL FISSURE
maxillary: FORAMEN ROTUNDUM
mandibular: FORAMEN OVALE
5.Ophthalmic: PAIN AND TEMPERATURE
maxillary: PAIN AND TEMPERATURE
mandibular: PAIN AND TEMPERATURE
6.Ophthalmic: SENSORY FROM UPPER FACE, ORBIT AND EYE
maxillary: SENSORY FROM MIDFACE AND UPPER TEETH
mandibular: SENSORY FROM LOWER FACE AND LOWER TEETH
EXPLAIN THE Trigeminal discriminative touch three-neuron pathway
1 ***PRIMARY NEURON:
RECEPTORS in skin & mucosa lining cavities in the face,
AXONS in CN V,
CELL BODY in trigeminal ganglion,
SYNAPSE in CHEIF SENSORY NUCLEUS OF V IN PONS
2.** SECONDARY NEURON:
CELL BODY:Chief Sensory nucleus,
AXONS ascends and decussates in TRIGEMINOTHALAMIC LEMNISCUS TO SYNAPSE IN VENTRAL POSTERIOR MEDIAL NUCLEUS OF THALAMUS
- ***TERTIARY NEURON:
CELL BODY : VPM THALAMUS ASCENDS through
INTERNAL CAPSULE TO POSTCENTRAL GYRUS
Trigeminal pain & temperature three-neuron pathway
1 ** PRIMARY NEURON: RECEPTORS in skin & mucosa lining cavities in the face, AXONS in CN V, CELL BODY in trigeminal ganglion, synapse in SPINAL NUCLEUS OF V
2*** SECONDARY NEURON: CELL BODY IN Spinal Nucleus of V, AXON ascends in Spinal Nucleus tract, axon ascends and decussates in trigeminothalamic lemniscus to SYNAPSE in VENTRAL POSTERIOR MEDIAL NUCLEUS OF THALAMUS
3** TERTIARY NEURON: CELL BODY in VPM Thalamus ascends through iINTERNAL CAPSULE to POSTCENTRAL GYRUS
EXPLAIN THE Anterolateral (spinothalamic) tract PROPERTIES
- 3-neuron chain.
2 * CARRIES GENERAL SOMATIC AFFERENT ( A-DELTA, AND C FIBRES) information from stimuli of PAIN, TEMPERATURE, OR ITCH, FROM PNS TO CNS
3 * SMALL DIAMETRE FIBRES WITH LOW CONDUCTION VELOCITY
- PROJECTS TO CONTRALATERAL VENTRAL POSTERIOR LATERAL THALAMUS THEN TO POSTCENTRAL GYRUS
EXPLAIN the Anterolateral (spinothalamic)
three-neuron pathway
-
**PRIMARY NEURON: nociceptors/thermoreceptors in
PERIPHERY, CELL BODY in posterior root ganglion, AXON enters POSTEROIR ROOT TO TRAVEL IN LAMINAE 1 AND SYNAPSE IN LAMINAE 2 OF SPINAL CORD GREY
2.**SECONDARY NEURON:
CELL BODY in laminae III or IV of spinal cord grey, AXON decussates in anterior white commissure of spinal cord, ASCENDS in anterolateral funiculus to SYNAPSE IN CONTRALATERAL VENTRAL POSTERIOR LATERAL THALAMUS
- **TERTIARY NEURON: CELL BODY: CELL BODY in VPL thalamus, AXONS ascends INTERNAL CAPSULE AND SYNAPSES IN CORRESPONDING POSTCENTRAL GYRUS
Anterior spinocerebellar tract PROPERTIES = 4
- 2- NEURON CHAIN
2 * Carries GENERAL SOMATIC AFFERENT (Ia fibres from muscle spindles and 1b from Golgi Tendon Organs as well as flexor reflex afferents) regarding postural stability of the lower limb from PNS to CNS.
3 * MEDIUM DIAMETER FIBRES WITH MEDIUM CONDUCTION VELOCITY
- Projects to IPSILATERAL CEREBELLUM (BY X2 DECUSSATIONS)
