Neurosciences 1.7 -- Spinal Cord, Meninges, Skull
Terms
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- cervical enlargement
- gives rise to nerve roots which form the brachial plexus innervating the upper limbs
- lumbar enlargement
- gives rise to fibers that form the lumbar plexus and the sacral plexus innervating the lower limbs
- describe where spinal nerves exit in relation to the vertebrae
-
C1-C7 exit above vertebrae of same #
C8 exits below vertebra C7
T1-Co exit below vertebrae of same # - cauda equina
- resulting collection of descending dorsal and ventral nerve rootlets beyond the termination of the spinal cord
- posterior intermediate sulcus
- marks the separation between the fasciculi gracilis and cuneatus
- posterolateral sulcus
- position of entrance of dorsal roots of spinal nerve
- anterolateral sulcus
- where ventral roots of spinal nerve exit
- epidural space
-
separates dura from vertebral periosteum; contains the internal vertebral venous plexus
is a site for injection of local anaesthetics and narcotics - coccygeal ligament
- extension of the dura, attached to the coccyx
- arachnoid trabeculae
- a filamentous meshwork of delicate CT that extends from the arachnoid to the inner pia
- lumbar cistern
-
widest part of the subarachnoid space, extends from the conus medullaris (lower border of the first lumbar vertebra) to about the level of the second sacral vertebra
site from which CSF is withdrawn in a lumbar spinal puncture - leptomeninges
- arachnoid and pia mater
- what are the two layers of the pia mater?
-
(1) intima pia -- composed of fine reticular and elastic fibers
(2) epipial layer -- collagenous fiber bundles continuous with the arachnoid trabeculae; contains the blood vessels that supply the spinal cord, including the posterior spinal arteries and veins and the single anterior spinal artery and vein - spinal cord is anchored to the inner surface of the dura mater how?
- by a series of 18-24 flattened bands of epipial tissue, the denticulate ligaments, on each side of the lateral surface of the cord
- which laminae correspond to the dorsal horn / intermediate zone / ventral horn
-
Laminae I-VI dorsal horn
Laminae VII intermediate zone
Laminae VIII & IX ventral horn - give the nuclei that laminae I-V, VII, & IX
-
Lamina I -- posteromarginal nucleus
Lamina II and upper III -- substantia gelatinosa
lower III, IV, and upper V -- nucleus proprius
Lamina VII -- dorsalis of Clarke
Lamina IX -- motor cell columns in the ventral horn - what does the dorsal ramus innervate?
- general region and intrinsic musculature of the back
- what does the ventral ramus innervate?
- general region and musculature of the neck, thorax, abdomen, perineum, and extremities
- describe the plexuses formed by the ventral rami of several spinal nerves
-
C5-T2 brachial plexus
T12-L4 lumbar plexus
L4-S1 sacral plexus
S4-Co coccygeal plexus - what do the plexi give rise to?
- peripheral nerves (e.g. radial N, tibial N, etc)
- endoneurium
- surrounds single peripheral nerve fibers; delicate collagenous fibers outside the axis cylinder and myelin sheath
- perineurium
- surrounds fascicles of nerve fibers; dense concentric layers of strands of collagen
- epineurium
- surrounds entire peripheral nerve; dense fibrous connective tissue that is continuous centrally with the dura mater of the spinal nerves and cord
- GSA
- from receptors in skin and skeletal muscle
- GVA
- from receptors in smooth muscle lining the walls of the organs and blood vessels
- GSE
- to skeletal muscle
- GVE
- autonomic fibers to smooth and cardiac muscle
- five essential elements required for most spinal reflexes
-
(1) peripheral receptors
(2) sensory neurons
(3) internucial neurons
(4) motor neurons
(5) terminal effectors (muscle) - conus medullaris
- end of the neural spinal cord, corresponds to vertebral level L1 or L2
- describe the two layers of the pia mater
- The pia mater is a vascular membrane composed of an inner membranous layer, the intima pia (composed of fine reticular and elastic fibers), and an outer epipial layer (collagenous fiber bundles continuous with the arachnoid trabeculae).
-
lumbar cistern
- extends from where to where? - from vertebral level L1/L2 -> S2
- fxn of the coccygeal ligament
- joined pia/arachnoid/dura, anchors the spinal cord vertically to the coccyx
- denticulate ligaments are derived from what?
- epipial tissue (outer layer of pia mater)
- how many dendticulate ligaments and fxn?
-
18-22
anchor the spinal cord horizontally (to the dura) - where is the CSF located?
- in the subarachnoid space
- which levels contain the posterior intermediate sulcus?
- upper thoracic and cervical
- compare amount of white matter in the cervical vs. lumbar enlargements
- more white matter in the cervical enlargement
- compare amount of white matter in the thoracic vs. lumbar enlargements
- more white matter in the lumbar enlargement
- what is associated with the cribiform plate?
- the olfactory nerve, CN I
- what traverses the foramen spinosum?
- middle meningeal artery
- what traverses the internal acoustic meatus?
- CN VII & VIII
- what traverses the jugular foramen?
- IX, X, XI, and the internal jugular vein