post midterm_quiz 3 Flashcards
What is retrograde degeneration?
When an axon is severed, the degeneration spreads proximally toward the cell body (soma).
(retro-to)
What is the Cauda Equina?
“horse”s tail”. composed of nerves exiting the vertebral column below the level of L2.
What is Wallerian degeneration?
Disintegration happens in a distal direction–toward the synaptic plate
(waller-away)
What is the Filum Terminal?
- Terminal filament. It’s an extension of the pia mater: anchors the spinal cord to the coccyx.
- spinal cord terminates here at L2
Where does the spinal cord begin and end?
Begins: within the foramen magnum
Ends: Intervertebral disk L1-L2
What are denticulate ligaments?
“tooth-shaped”. Extensions of the PIA MATER. They suspend and stabilize the spinal cord within the vertebral column.
How long and wide is the spinal cord in an adult?
45 cm long
2 cm major diameter
What is the spinal cord covered and protected by?
vertebral bones
meninges
CSF
How many spinal nerves are there?
name the segments.
31 pairs 8 cervical 12 thoracic 5 lumbar 5 sacral 1 coccygeal
How are spinal nerves formed?
by fusion of posterior/ dorsal and anterior/ventral roots.
What is the swelling called of each posterior root of the spinal nerves?
dorsal root ganglion
What does each dorsal root ganglion house?
cell bodies of sensory neurons (first order sensory neurons)
What does each dorsal root represent?
Axons of sensory neurons
–somatic and visceral afferents
What does each ventral root represent?
Axons of motor neurons
–somatic and visceral
What do spinal nerves occupy?
Intervertebral foremina
Where do spinal nerves emerge?
First 7 emerge above corresponding vertebrae
8th nerve emerges in between C7 and T1
The rest emerge below the corresponding vertebrae
When spinal nerves emerge from the foramina, what do they divide and split into?
posterior/dorsal rami, and anterior/ventral rami
What do anterior rami represent?
- roots of peripheral nerves
- they make a network of PERIPHERAL nerve plexi
Where are the lateral ventricles located?
One in each cerebral hemisphere. Separated by transparent SEPTUM PELLUCIDUM.
Where is the 3rd ventricle located?
Between the two thalami.
Where is the fourth ventricle?
Between the cerebellum and brain stem, and the pons and medulla oblongata.
What is the origin of the brain’s arterial circulation?
Pair of Internal carotid arteries
Pair of Vertebral arteries
How much oxygen does the brain need from systemic circulation?
20%
How is CSF produced?
By plasma filtration through the ependymal cell layer of the choroid plexus.
Where and what is the choroid plexus?
Within lateral and 3rd ventricles.
It is a vascular network of blood capillaries.
Describe the circulation of CSF.
- CSF is produced by plasma filtration through the ependymal cell layer of the ventricular choroid plexus in LATERAL VENTRICLES.
- THIRD VENTRICLE receives CSF through foreman of MONRO (inter ventricular foremina)
- passes through cerebral aqueduct to FOURTH VENTRICLE.
- CSF enters SUBARACHNOID SPACE thru two lateral foremina (Luschka) and one middle foreman (magendie)
- CSF now circulates around brain and spinal chord in SUBARACHNOID SPACE.
- ARACHNOID GRANULATIONS of subarachnoid space deliver CSF to SAGITTAL DURAL SINUSES, it is then returned to venous circulation.
What kind of cells are the choroid plexuses covered by?
Ependymal cells that form CSF from blood plasma filtration and secretion. They have tight junctions that prevent harmful substances to enter CSF. BLOOD CEREBRAL FLUID BARRIER.
What are the subclavian arteries, and what originates from them?
They are branches of the bracio-cephalic trunk of the aorta, and the internal carotid and vertebral arteries come from them.
What does the posterior cerebral artery supply?
occipital lobe (vision)
partially the cerebellum (equilibrium)
supplies visual areas
What does anterior cerebral artery supply?
TOP of brain.
affects LOWER body.
What does middle cerebral artery supply?
lateral aspects of brain
affects upper part of body, head
left MCA–right hand
right MCA–left hand
Between which two meninges does CSF circulate?
In the subarachnoid space, between the arachnoid and the pia mater.
Name the meninges.
Dura Mater, Arachnoid mater, Pia mater
What is the largest vein in the brain?
The superior sagittal sinus.
Describe the order of meninges, and corresponding spaces–outer to inner.
Epidural space (meningeal arteries) Superior sagittal sinus here too? Dura mater Subdural space (bridging veins) Arachnoid mater Subarachnoid space (CSF circulates) Pia Mater
What are the extensions of the Dura Mater that separate parts of the brain?
Falx cerebri (cerebrum) Falk cerebelli (cerebellum) Tentorium cerebellum (cerebrum from cerebellum)
What structures pass through the cavernous sinus?
- Internal carotid artery
- oculomotor group of cranial nerves (3,4,6)
Dural sinuses–flow of deoxygenated blood
superior sagittal inferior sagittal straight confluence of sinuses transverse pair: run by each ear, cavernous pair: receives blood from each eye. sigmoid pair internal jugular vein to RIGHT HEART. fini!
What are the major arteries of the circle of willis?
Two vertebral Basilar Posterior cerebral arteries (PCA) Posterior communicating artery Internal carotid arteries Middle cerebral arteries (MCA) Anterior cerebral arteries (ACA) Anterior communicating artery
Where does CNS and PNS originate from?
The ectoderm of the embryonic neural disc plate.
What are the anterior rami?
They are the roots for the PERIPHERAL network (plexi) of spinal nerves.
posterior rami
enervate the erector spine muscle, fascia, skin
what are the three orders of sensory nerves?
- posterior root ganglia
- grey matter, butterfly horn, posterior horn ???
- thalamus
ventral roots
motor-come out of spinal cord to tissues
GOING OUT
dorsal roots
posterior root ganglion. a swelling in dorsal root.
COMING IN
sensory (afferent/ascending) roots.
holding axons of sensory neurons
