lecture 10 - the spinal cord & autonomic nervous system Flashcards
What are the components of the CNS?
Brain, brain stem & spinal cord
How many pairs of cranial nerves are there?
12
How many pairs of spinal nerves are there?
31
What is the spinal cord a continuation of proximally?
The brain stem (medulla oblongata)
What vertebral level does the spinal cord extend to?
L1/L2
What is the terminal part of the spinal cord?
Conus medullaris
What covers the spinal cord?
Meninges
What are the 3 layers of the meninges?
Dura mater, Arachnoid mater, pia mater
What are the 2 enlargements of the spinal cord?
Cervical & Lumbosacral
What is an enlargement in the spinal cord?
An area where the cord has more neurons
What is the filum terminale?
A fine filament of connective tissue (part of the pia mater) that fixes the conus modularis to stabilise the spinal cord
What are the 2 parts of the filum terminale?
superiorly: Pial part
inferiorly: dural part
At what level does the subarachnoid space end?
S2
What layer of the meninges does the CSF circulate in?
Sub-arachnoid space
What is the outermost layer of the meninges?
Dura mater
What is the middle layer of the meninges?
Arachnoid mater
What is the innermost layer of the meninges?
Pia mater
What is the role of the denticulate ligament?
Lateral stabilisation of the spinal cord
What tissue forms the denticulate ligament?
Pia mater of the meninges
What structure is formed by the pia mater to stabilise the spinal cord?
Denticulate ligament
What is the name for the space between the outer meninges (dura mater) and the vertebral canal?
Epidural/extradural space
What is the name for the strands of conective tissue that make up the arachnoid mater?
Arachnoid trabeculae
What part of the spine is a lumbar puncture done on?
Between the spinous processes of L3 and L4 or L4 and L5
What are the key arteries that supply the spinal cord?
2 posterior spinal arteries, 1 anterior spinal artery, segmental spinal arteries (1 on each side at each level)
How many posterior spinal arteries supply the spinal cord?
2
How many anterior spinal arteries supply the spinal cord?
1
What are the segmental spinal arteries supplied by?
The left and right intercostal artery
How many segmental spinal arteries supply the spinal cord?
2 on each side of the spinal cord at each level
What are the key veins that drain the spinal cord?
3 posterior spinal veins, 3 posterior spinal veins, the internal vertebral plexus
How many anterior spinal veins drain the spinal cord?
3
How many posterior spinal veins drain the spinal cord?
3
What are the components of the grey matter of the spinal cord?
Anterior/ventral horn, posterior/dorsal horn, lateral horn (some parts)
At what levels is the lateral horn found in the spinal cord?
T1-L2
What is found in grey matter?
Nerve cell bodies
What is found in white matter?
Nerve cell processes/tracts
What are the parts of the white matter of the spinal cord?
Anterior, posterior, lateral columns
What is the name for the ‘hole’ in the middle of the spinal cord?
Central canal
What is found in the central canal of the spinal cord?
CSF
Does the ventral or dorsal horn grey matter reach to the edge of the spinal cord?
Dorsal/posterior
What are the 2 types of somatic nerves?
Motor (efferent), somatic (afferent)
What type of somatic nerve is efferent?
motor
What type of somatic nerve is afferent?
sensory
What are the 2 types of visceral nerves?
motor (efferent), sensory (afferent)
What are visceral nerves?
Nerves that control involuntary/autonomic functions of the visceral organs
What is the path of somatic motor information?
Anterior/ventral horn, anterior rootlets, anterior root, spinal nerve, anterior/posterior ramus, muscle
What is the path of soamtic sensory information?
sensory nerve ending, anterior/posterior ramus, spinal nerve, spinal ganglion, posterior root, posterior rootlets, posterior/dorsal horn
What somatic nerves are found in the posterior ramus?
Motor and sensory neurons of the intrinsic back muscles
What somatic nerves are found in the anterior ramus?
Motor and sensory nerves for all muscles except intrinsic back muscles
What neuron cells bodies are found in the dorsal/posterior root?
Sensory
What neuron cells bodies are found in the ventral/anterior root?
motor
What spinal levels have sympathetic nerves?
T1-L2
What is the paravertebral sympathetic trunk?
A chain of sympathetic ganglion on either side of the spinal cord and vertebral column
What does the symapthetic trunk/chain communicate to the spinal cord via?
Communicates with the anterior ramus via the white and grey ramus communicans
Where are the pre-vertebral sympathetic ganglia found?
In front of the abdominal aorta on the anterior part of the spine
Which ramus communicans do preganglionic efferent sympathetic fibres pass through?
White ramus communicans
What does the white ramus communicans contain?
Myelinated axons of efferent sympathetic nerves
What does the grey ramus communicans contain?
Unmyelinated postganglionic axons
What are the 4 possible pathways of preganglion sympathetic fibres entering a paravertebral ganglion ?
1.) peripheral innervation from the level of origin of preganglionic fibre
2.) peripheral innervation above or below level of preganglionic fibre.
3.) innervation of thoracic and cervical viscera (internal organs)
4.) innervation of the abdomen, pelvic regions, adrenals
What is the pathway of peripheral sympathetic nerves innervating above or below the level of origin of the preganglionic fibre?
spinal nerve, anterior ramus, white rami communicans, sympathetic ganglion, ascend/descend trunk to sympathetic ganglion, gray ramus communicans, innervation
What is the pathway of sympathetic nerves innervating the thoracic and cervical viscera?
spinal nerve, white ramus communicans, sympathetic ganglion, leave ganglia medially to viscera (may combine to form visceral nerves)
What is the pathway of sympathetic nerves when innervating the abdomen, pelvis and adrenal glands?
Abdomen/Pelvis: Preganglionic fibres pass through sympathetic trunk and paravertebral ganglia without synapsing and form splanchnic nerves
Adrenal glands: Preganglionic fibres directly innervate adrenal glands
