CNS - 1 - Spinal cord Flashcards
- Classification of fibers in peripheral nerves and dorsal root
a/ Characteristics and function of A⍺ or Ia
Characteristics: Thick, myelinated fibers
Function:
- Motor to skeletal muscle
- Sensory from annulospiral endings of muscle spindles
- Classification of fibers in peripheral nerves and dorsal root
b/ Characteristics and function of Fiber Aβ Type Ib
Characteristics: Thick, myelinated fibers
Function:
-Sensory from Golgi tendon organs and Ruffini endings of skin
- Classification of fibers in peripheral nerves and dorsal root (sensory)
c/ Characteristics and function of Fiber Aβ Type II
Characteristics: Thick, myelinated fibers
Function:
-Sensory from flowerspray endings of muscle spindles, Meissner’s and Pacinian corpuscles, and large hair follicles
- Classification of fibers in peripheral nerves and dorsal root
d/ Characteristics and function of Fiber A𝛾
Motors to intrafusal fibers of muscle spindles
- Classification of fibers in peripheral nerves and dorsal root
d/ Characteristics and function of Fiber A𝛿 or III
Characteristics: thin, myelinated fibers
Function: Sensory from small hair follicles and free nerve endings mediating pain and temperature sensation
- Classification of fibers in peripheral nerves and dorsal root
e/ Characteristics and function of Fiber C or IV
Characteristics: unmyelinated fibers
Function:
- Postganglionic autonomic fibers supplying smooth muscle, glands
- Sensory for pain, and temperature
- Smell (olfactory nerves)
- Meninges around the spinal cord
- Endorachis: the „real” periosteum
- Epidural space contain internal vertebral plexus and adipose tissue
- Denticulate ligaments between the pia and arachnoid
- The spinal cord – from outside
- Posterior and anterior radices make up the spinal nerve
- The posterior radix runs close to and is in connection to the spinal ganglion situated in the intervertebral foramen
- The radices exit (or enter) to the SC with more fila
- The arachnoid mater and the dura mater covers the radices as well.
- White matter and gray matter compose the SC.
- What are the components of spinal cord?
White and gray matter
- Gray matter 1
What are the parts of the gray matter?
1/ Dorsal horn
2/ Intermediate zone
3/ Ventral horn
4/ Lateral horn
- Gray matter 2 - Dorsal horn
a/ What are the components of dorsal horn?
1/ Mainly interneurons
2/ The Lissauer tract/zone can be found
3/ Full of approaching afferent fibers (dorsal root) which go through this zone to enter deeper parts of the dorsal horn and synapse on other neurons
4/ Substantia gelatinosa can also be found here, which is an important zone in the modulation of pain
- Gray matter 2 - Dorsal horn
b/ What is the function of dorsal horn?
1/ Receive central processes of pseudounipolar neurons
2/ Sensory information is processes and transmitted to higher regions
- Gray matter 2 - Dorsal horn
c/ What are the laminae corresponding to the dorsal horn?
Laminae I – VI correspond to dorsal horn
- Gray matter 2 - Dorsal horn
d/ Characteristics of Lamina I
Lamina I (marginal zone):
- spindle-shaped neurons,
- afferentation from the periphery, nociceptive and heat impulse.
- Interneurons (reflexes) and funicular (projection) neurons (spinothalamic tract)
- Gray matter 2 - Dorsal horn
e/ Characteristics of Lamina II
Lamina II (substantia gelatinosa – Rolando’s substance):
1/ small neurons,
2/ fibres are afferents from the skin: Aδ and C- fibers
3/ receive monoaminergic input from the brainstem
4/ Mainly inhibiting and stimulating interneurons, procession of pain
- Gray matter 2 - Dorsal horn
e/ Characteristics of Lamina III - IV
Lamina III – IV (proper nucleus of dorsal column):
- mainly Aβ fibres from the skin (mechanoreception)
- Inhibiting interneurons and funicular (projecting) neurons transmitted to the spinothalamic tract
- Gray matter 2 - Dorsal horn
e/ Characteristics of Lamina V - VI
Lamina V - VI
- various types of afferents , interneurons and funicular (spinothalamic tract) neurons
- Gray matter 3 - Intermediate zone
a/ Which laminae belong to intermediate zone?
Laminae VII and X correspond to the intermediate zone
- Gray matter 3 - Intermediate zone
a/ Characteristics of laminae X
- central gray matter
- several intraspinal connections
- Gray matter 3 - Intermediate zone
b/ Characteristics of laminae VII (nuclei and their role)
1/ Clarke-Stilling nucleus:
- proprioceptive and epicritic information from the lower limb
- large neurons project to the cerebellum through the dorsal spinocerebellar tract
2/ Intermediomedial nucleus: sympathetic and parasympathetic preganglionar neurons
3/ Intermediolateral nucleus: sympathetic preganglionar neurons, in the thoracic and upper lumbar levels the lateral horn is formed
- Gray matter 3 - Intermediate zone
c/ Classification of nerve fiber contained in the intermediate zone
Visceromotor nerve classification:
- B: preganglionic fibers, thin, lightly myelinated
- C: postganglionic fibers, non-myelinated
- Gray matter 4 - Ventral horn
a/ Which laminae belong to ventral horn?
Laminae VIII and IX correspond to the ventral horn
- Gray matter 4 - Ventral horn
b/ Characteristics of Lamina IX
1/ groups of Aα- and Aγ-motoneurons, innervating the skeletal muscles
2/ Interneurons
- e.g: Renshaw-cells: inhibiting nearby motor neurons
- Gray matter 4 - Ventral horn
c/ Characteristics of Lamina VIII
1/ various neurons.
2/ Commissural nucleus of Lenhossék: crossing fibres in the commissura alba
- Gray matter 4 - Ventral horn
c/ Classification of nerve fibers contained in ventral horn
Motor nerve classification:
- Aα: extrafusal fibers
- Aγ: intrafusal fibers
- Gray matter 4 - Ventral horn
d/ Typical motor neuron in the ventral horn. Identify
- White matter 1
a/ What are the components of white matter?
1/ The white matter contains axons of the neurons in the gray matter (NOT neurons)
2/ Axons coursing in the white matter of spinal cords form bundle of fibers with similar origin, courses and destinations
=> These bundles are called tracts
- White matter 1
b/ Organization of white matter?
Organized into 3 funiculi
- Contain ascending and descending nerve tracts hat connect the peripheral nerves with the brain
- Dorsal funiculus is a collection of ascending tracts
- White matter 1
c/ What are the special parts of white matter?
1/ The Lissauer tract at the dorsal root entrance
2/ The anterior white commissure ventral to the central canal
- White matter 1
a/ What are the components of white matter?
1/ The white matter contains axons of the neurons in the gray matter (NOT neurons)
2/ Axons coursing in the white matter of spinal cords form bundle of fibers with similar origin, courses and destinations
=> These bundles are called tracts
- White matter 2
a/ What are the 5 important tracts in white matter?
1/ Gracile fascicle and cuneate fascicle
2/ Anterior and posterior spinocerebellar tracts
3/ Anterior and lateral spinothalamic tracts
4/ Anterior and lateral corticospinal tracts
5/ Extrapyramidal tracts
- White matter 2
a/ What are the 5 important extrapyramidal tracts in white matter?
1/ Medial longitudinal fascicle
2/ Tectospinal tract
3/ Vesticulospinal tract
4/ Reticulospinal tract (anterior and lateral)
5/ Rubrospinal tract
- White matter 2
c/ What is the role of The role of Anterior and posterior spinocerebellar tracts?
transmit proprioceptive (from tendons, mucles, joints) information to the cerebellum via mossy fibres.
- Posterior (Th9-L3): from the dorsal nucleus (Clarke-Stilling)
- Anterior (L4-S3)
- White matter 2
d/ What is the role of The role of Anterior and lateral spinothalamic tracts?
protopathic sensibility (crude touch (anterior), heat and pain (lateral))
- White matter 2
e/ What is the role of The role of Extrapyramidal tracts?
coordination and processing motor commands at a subconscious level
- White matter 2
f/ What is the role of The role of Anterior and lateral corticospinal tracts?
voluntary movements from the cortex („pyramidal tract”)
