spinal cord Flashcards
where does the spinal cord end
L1-L2
where does the spinal cord end at birth
L3
what is the function of the spinal cord
- receive afferent fibres from sensory receptors of the trunk and limbs
- control movement of the trunk and limbs
- provide autonomic innervation for most of the viscera
what is the end of the spinal cord
a conical termination the conus medullaris.
what is the denticulate ligamment
a flat continuation of the pia mater taht teters the spinal cord to the arachnoid and the dura
what is the function of the two spinal cord enlargments
to accommodate a greater number of nerve cells and connections needed to process information rekated to the upper and lower limbs
where does cervical enlargement run
- Consists of spinal segments C4—T1;
where does the lumbar enlargement run
Consists of spinal segments L1—S3
what does the cervical enlargement innervate
corresponds to the upper limbs
Provides innervation via brachial plexus
what does the lumbar enlargement innervate
corresponds to the lower limbs
Provides innervation via lumbosacral plexus
how many nerve pairs attach to the spinal cord
31 pairs of spinal nerves
8 cervical
12 thoracic
5 lumbar
5 sacral
1 coccygeal
what is the cauda equina
collection of nerve roots at inferior end of vertebral canal
cervical spinal nerves exit ____ the respective vertebra
above
what is a ventral root
allow motor neurons to exit the spinal cord (efferent).
(anterior)
what is a dorsal root
allow sensory neurons to enter the spinal cord (afferent).
(posterior)
what are the two branches of a spinal nerve
- one composed of sensory fibres, enters the spinal cord via the dorsal root; its cell bodies lie in a spinal ganglion that is outside the spinal cord.
- The other branch, composed of motor fibres, leaves the spinal cord via the ventral root; its cell bodies lie in specific areas of the spinal cord itself.
what are the major neurotransmitters of parasympathetic postganglionic neurons
Acetylcholine and nitric oxide
what are Parasympathetic preganglionic neurons
neurons have their cell bodies in the central nervous system and make synapses in the ganglia close to or in the walls of the organs they supply.
the motor components of the parasympathetic nervous system run in which cranial nerves
nerves III, VII, IX, and X and in the sacral nerves.
where are the sympathetic nervous system’s outflows from
outflows are from the thoracic and upper lumbar spinal cord.
what is the function of the parasympathetic division
It exerts its effects on autonomically controlled organs of the head, thorax, abdomen, and pelvis
what is the denticulate ligament
a flat continuation of the pia mater that runs between the dorsal and ventral roots of the spinal cord
how does CSF protect the spinal cord
buffers CNS
lightens brain
removes toxic metabolites
transports hormones
what divides the spinal cord in half
by a posterior median sulcus and an anterior median fissure.
what is the outer part of the spinal cord
white matter
what is in the dorsal half of the spinal cord
cell bodies of interneurons
what is in the ventral half of the spinal cord
cell bodies of motor neurons
is there more white or grey matter in higher levels of the spinal cord
white
what is the function of the dorsal horn
the main site of termination of primary afferent (sensory) fibres
includes the substantia gelatinosa which is important in transmission of nociceptive impulses to the brain (pain
what is the function of the ventral horn
skeletal muscle innervation
what does the lateral horn contain
preganglionic sympathetic neurons.
what does the ventral horn contain
alpha and gamma motor neurons
what is the function of white matter
stimulates contraction of body muscles
stimulates secretion from body’s glands
what are the major motor (descending) fiber tracts in the spinal cord
lateral reticulospinal tract
lateral corticospinal tract
rubrospinal tract
medial reticulospinal tract
anterior corticospinal tract
vestibulospinal tract
tectospinal tract
what are the major sensory (ascending) fiber tracts in the spinal cord
anterior and posterior spinocerebellar tract
lateral and anterior spinothalamic tract
dorsal white column (fasciculus gracillis and fasciculus cuneatus)
which major ascending pathway for the somatic senses is unconscious
spinocerebellar tracts
what is the function of the spinocerebellar tract
muscles to cerebellum
proprioception from skeletal
what tracts of the major ascending pathways for the somatic senses are conscious
dorsal column- medial lemniscal pathway
spinothalamic pathway
what is the function of the Dorsal column-medial lemniscal pathway
discriminative touch pathway
what is the function of the spinothalamic pathway
conveys nociception (temperature) and non discriminative (crude) touch and pressure information.
what tracts of the major descending pathways are pyramidal (conscious)
corticospinal and corticobulbar
what is the function of the corticospinal tract
Carries information from the cerebral cortex to the spinal cord and controls movement of the torso, upper and lower limbs.
what is the function of the corticobulbar tract
controls Themusclesof the face, head and neck
what are the extrapyramidal (unconscious) tracts of the major descending pathways
Rubrospinal tract
Tectospinal tract
Vestibulospinal tract
Reticulospinal tracts
Olivospinal tracts
what is the function of the Olivospinal tracts
Coordinates movements of the head and neck and upper limbs contralateral to its origin.
where does the olivospinal tract arise from
the inferior olivary nucleus
where does the Reticulospinal tracts arise from
the pontine and medullary reticular formation
what is the function of the Reticulospinal tracts
Control automatic movements in locomotion.
where does the Vestibulospinal tract arise from
the lateral vestibular nucleus in the rostral part of the medulla
what is the function of the Vestibulospinal tract
Controls the muscles which maintain normal posture and balance.
where does the Tectospinal tract arise from
in the colliculi
what is the function of the Tectospinal tract
Control reflex, turning of the head and neck to auditory or visual stimuli.
where does the rubrospinal tract arise from
in the midbrain from the red nucleus
what is the function of the rubrospinal tract
Controls the tone of the flexor muscles.
