Nervous System Anatomy Flashcards
What drains into the superior petrosal sinus?
the cavernous sinus
What is the conus medularis?
The tapering cone of the spinal cord
Where do you sample blood from to determine if there is a subarachnoid bleed?
The CSF
Do the spinal nerves in the thoracic, sacral, and lumbar regions lie superior or inferior to their corresponding vertebrae?
Inferior
Where is the proportion of white matter greater: cervical region or lumbar region?
Cervical because there are more axons traveling down the spine there
What two things drain into dural sinuses?
Cerebral veins and arachnoid granulations
What suture separates the two parietal bones?
The sagittal suture
What do gray ramus communicans do?
Carry postganglionic sympathetic fibers from the sympathetic ganglia to the spinal nerves, and are composed of largely unmyelinated neurons.
What does CN VIII do?
Hearing
Anterior rami innervate what?
Everything the posterior doesn’t - so the entire body except for the back
What cranial nerve(s) pass through the foramen lacerum?
None
What makes up white matter? Neuron cell bodies or axons?
Axons
Loss of information from CNS to motor neuron/skeletal muscle is termed what?
Paralysis
What space in the spine do you inject a local anesthetic into for a nerve block?
The epidural space
What is the function of the occipital lobe?
Sight
What is the function of the temporal lobe?
Hearing, learning, and feelings
What does the sciatic nerve branch into at the popliteal fossa?
The tibial nerve and the common fibular nerve
What type of dura surrounds spinal cord and spinal nerves?
Meningeal dura
Name CN V. Is it sensory, motor, or both?
Trigeminal
BOTH
What molecules are not allowed to pass through the blood-brain barrier?
Urea, creatinine, proteins, some toxins, ions, and drugs
What is the main integration center for ANS activity?
the hypothalamus
What does the diencephalon do?
Acts a relay between the brainstem and the cerebral cortex
What connects the arachnoid mater to the pia mater?
Arachnoid trabeculae
What is the major medullary artery? What does it supply?
Medullary artery of Adamkiewicz
Supplies blood to lower 2/3 of the spinal cord. Originates between T9 and L1
Where is Wernicke’s area located?
The parietal lobe
What spinal nerves have both white and gray communicantes?
T1 - L2
14 pairs in total
What do dorsal roots contain?
Sensory, afferent
What cranial nerve(s) pass through the jugular foramen?
CN IX, X, and XI
What makes up gray matter?
Neuronal cell bodies
What does the medulla oblongota do?
Regulates circulation, digestion, and swallowing
Where is a needle placed during a cisternal puncture?
Between occipt and atlas
What parasympathetic ganglia is associated with CN X?
Enteric ganglia
What cranial nerve(s) pass through the foramen ovale?
V3
Name CN VIII. Is it sensory, motor, or both?
Vestibulocochlear
Sensory
What are the roots of the sciatic nerve?
L4 - S3
Is the arachnoid mater vascularized?
No
What vertebrae are associated with the brachial plexus?
C5 - T1
What myelinates axons in the CNS?
oligodendrocytes
What cranial nerve(s) pass through the foramen spinosum?
None
What crainal nerves are part of the parasympathetic NS?
CNs III, VII, IX, and X (3, 7, 9, 10)
What does the sciatic nerve innervate?
The posterior compartment of the thigh
Posterior rami innervate what?
The back
What is hydrocephalus?
Abnormal accumulation of CSF in the brain
What does the cerebellum do?
Compares what you intend to do with what you actually do and makes corrections It also assists in balance and coordination
What does the metathalamus do?
Medial (auditory relay) and lateral (visual) geniculate bodies
Anterior and posterior rami both contain what?
Motor and sensory nerve fibers
Is the pia mater vascularized?
Yes
Do the spinal nerves in the cervical region lie superior or inferior to their corresponding vertebrae?
Superior
What is the major nerve of the sacral plexus and where does it exit the pelvis?
Scatic nerve
Exits through the greater sciatic foramen
What do anterior rami innervate?
Muscles of the neck, trunk, and extremities
Stimulation of the preganglionic cells in the adrenal medulla does what?
Releases epinepherine (80%) and norepinepherine (20%) directly into the blood
Under control of the hypothalamus
What do white rami communicantes do?
Carry pregnglionic sympathetic neurons from the spinal cord to the paravertebral ganglia
What does the superficial fibular nerve innervate?
The lateral compartment of the leg
What is the preganglionic neurotransmitter in the autonomic nervous system?
Acetylcholine for both the sympathetic and parasympathetic nervous systems
A spinal nerve divides into anterior and posterior ______
rami
Name CN II. Is it sensory, motor, or both?
Optic
Sensory
What lies beneath the pterion?
The middle meningeal artery
Where are the dural venous sinuses located?
In between the two dural layers
How is the spinal cord tethered to the coccyx?
Via the filum terminale (an extension of pia mater)
What does the thalamus do?
“gateway” to the cerebral cortex; major relay center of sensory and motor signals
What do white ramus communicans do?
Carry preganglionic sympathetic fibers from the spinal nerves to the sympathetic ganglia
heavy myelinated neurons give the rami their white appearance
What spinal nerves are associated with the Lesser Splanchnic Nerve? What ganglia does it synpase with?
T10 - T11
Aorticorenal Ganglion + Superior Mesenteric Ganglion
Where are the post-ganglionic sympathetic neuron cell bodies located?
Either in the paravertebral ganglia (sympathetic chain ganglia) or in a prevertebral ganglia (celiac, superior mesenteric ganglia, etc)
What is the pterion?
The spot where the frontal, parietal, sphenoid, and temporal bones unite
The brachial plexus contains the convergence of what spinal nerves?
C5 - T1
What causes blood to accumulate in the subdural space?
Tear in a cerebral vein; often seen in the elderly
What determines whether a nerve cell releases neurotransmitters?
The summation of its positive and negative inputs
Space between cranial bones and the dura mater?
Epidural space
What is the function of the parietal lobe?
Language and touch
What is the postganglionic/effector neurotransmitter in the autonomic nervous system?
Sympathetic: Norepinepherine
Parasympathetic: Acetylcholine
What parasympathetic ganglia is associated with CN IX?
Otic ganglia
Where do we not find parasympathetic fibers?
Limbs and skin
What does the midbrain do?
Important to vision and hearing
Which layer of the dura mater is sensitive to pain?
The outer periosteal layer
What nerve provides sensory innervation to the space between the big toe and second toe?
Deep fibular nerve
Which spinal level(s) have lateral horns?
Thoracic & Sacral
Thoracic: Lateral horns are for preganglionic neurons of the sympathetic NS
Sacral: Lateral horns are for preganglionic neurons of the parasympathetic NS
Where is a spinal tap typically done? Why?
Between L3 and L4 because the cauda equina has replaced the spinal cord
What does the hypothalamus do?
Contributes to control of the ANS, endocrine system, appetite, and thirst
What is the venous drainage of the spinal cord?
2 anterior and 3 posterior spinal veins
What cranial nerve(s) pass through the internal auditory meatus?
CN VII and VIII
What percentage of the brain’s neurons are in the cerebellum?
50%
What joins the carotid and vertebral arterial systems?
The Circle of Willis (this is an anastomosis)
What are sensory receptors of the autonomic NS?
Mechanoreceptors (pressure, stretch)
chemoreceptors (chemical concentration)
nocioceptors (stretch, ischemia)
thermoreceptors (changes in temp or circulating blood)
Name CN VI. Is it sensory, motor, or both?
Abducens
Motor
What makes up the CNS?
brain, spinal cord, and CN II (optic nerve)
Descending pathways (efferent/motor) in the spinal cord are named in what way?
…….spinal
ex: lateral corticospinal tract, rubrospinal tract
What does CN II pass through in the skull base?
The optic canal
Name CN XII. Is it sensory, motor, or both?
Hypoglossal
Motor
Where in the brainstem do we also get ANS control?
Medulla oblongata and the pons
What suture separates the occipital bone from the two parietal bones?
The lambdoid suture
What is the cauda equina?
Nerves lower than L2 - rootlets mostly
Autonomic motor neurons go to what?
Smooth muscle, cardiac muscle, and glands
What does CN V do?
Sensory to face (including anterior 2/3 of the tongue!) and motor to muscles of mastication
Where is the integration center for spinal reflexes?
Gray matter of spinal cord
What level of the spinal cord is the sympathetic nervous system located? The parasympathetic?
Sympathetic: thoracolumbar (T12 - L2)
Parasympathetic: craniosacral (CN 3, 7, 9, 10) + S2-4
What is the function of the frontal lobe?
Thinking, memory, behavior, and movement
What cranial nerve(s) pass through the superior orbital fissure?
CN III, IV, VI, and V1
What does CN 1 do?
Sense of smell
What is the peripheral nervous system subdivided into?
Somatic and autonomic nervous systems
Somatic is voluntary
Autonomic is involuntary
What is a denticulate ligament?
Extensions of pia mater that pass through arachnoid mater to attached to dura
Help anchor and stablize the spinal cord
What two sinuses converge to make the sigmoid sinus?
The superior petrosal sinus and the transverse sinus
What is the end of the spinal cord refferred to as?
The conus medularis
What is the neutrotransmitter(s) used in the sympathetic NS?
Presynaptic: acetylcholine
Postsynaptic: epinephrine or norepinephrine
What innervates the sole of the foot?
The tibial nerve
What are the four plexuses of spinal nerves?
- Cervical
- Brachial
- Lumbar
- Sacral
How many lobes are in the cerebral hemisphere? Name them.
Four
Frontal, parietal, temporal, and occipital
What are the extensions of pia mater that pass through the arachnoid mater and attach to dura to help stabilize the spinal cord?
Denticulate ligament
How does the intimal pia adhere to underlying nervous tissue?
Via astrocytes
Space between the dura mater and arachnoid mater?
Subdural space
What does CN XII pass through in the skull base?
the hypoglossal canal
What spinal nerves are associated with the Greater Splanchnic Nerve? What ganglia does it synpase with?
T5 - T9
The Celiac Ganglion
What does the epithalamus do?
It contains the pineal gland (circadian rhythm) and the habenular nuclei (olfaction)
Where are the preganglionic sympathetic neuron cell bodies located?
Lateral horns of T1 - L2
How are somatic sensations characterized?
Conscious, sharp, well-localized, touch, pain, temperature, pressure, proprioception
Ascending pathways (afferent/sensory) in the spinal cord are named in what way?
spino. …
ex: spinocerebellar tracts, lateral spinothalamic tract
What does CN XI do?
Motor to SCM and trapezius
What do ventral roots contain?
Motor, efferent, from CNS
What does CN VI do?
Movement of lateral rectus muscle
What is the autonomic nervous system subdivided into?
Parasympathetic and sympathetic nervous systems
What does the obturator nerve innervate?
The medial compartment of the thigh
Space between the arachnoid mater and pia mater?
Subarachnoid space (this space is filled with CSF!)
Name CN VII. Is it sensory, motor, or both?
Facial
BOTH
What does the tibial nerve innervate?
The posterior compartment of the leg
What does CN XII do?
Movement of the tongue
What does the pons do?
Bridge between cerebral cortex and medulla; relays information between cerebrum and cerebellum
Also important site for control of respiration
What suture separates the frontal bone from the two parietal bones?
The coronal suture
What does the sigmoid sinus drain into?
the internal jugular vein
Two ways to collect CSF?
Cisternal puncture or a lumbar puncture
What is a real space (vs. a potential space) in the brain?
The subarachnoid space
Ruptured aneurysms occur there; arterial bleeds
Presents with severe headache and stiff neck
What does CN IV do?
Movement of superior oblique muscle
How are ascending sensory spinal tracts named in the spinal cord?
spino. …
ex: ventral corticospinal tract
What are the five terminal branches of the brachial plexus?
- Musculocutaneous nerve
- Median nerve
- Ulnar nerve
- Axillary nerve
- Radial nerve
What arteries supply blood to the brain?
Internal carotid and the vertebral arteries
What makes up the brainstem?
Midbrain, pons, and medulla
What does the peripheral nervous system consist of?
Crainal and spinal nerves, ganglia, and sensory receptors
What causes blood to accumulate in the epidural space?
Often a tear in the middle meningeal artery
Blood must be drained from the pterion
Are the plexuses formed by spinal nerves composed of anterior or posterior rami?
Anterior only
(remember dorsal rami/posterior rami only innervates the back; anterior/ventral rami innervate the rest of the body)
What does the falx cerebelli separate?
The two lobes of the cerebellum
Where does the tentorium cerebelli attach and what does is separate?
Petrous part of the temporal bone
Separates the cerebral cortex and the cerebellum
** Encloses the transverse sinus
What do gray rami communicantes carry?
Postganglionic sympathetic fibers away from paravertebral ganglia to spinal nerves
How many neurons are in an autonomic nervous system pathway?
Two
How many neurons extend from the CNS in the somatic nervous system?
Just one
What does CN II do?
Eye sight
What does CN X do?
Motor to heart, lungs, bronchi, GI tract
Sensory to heart, lungs, bronchi, GI tract, external ear, etc
What encloses the occipital sinus?
The falx cerebelli
What is the neurotransmitter(s) used in the parasympathetic NS?
Both pre- and postganglionic use acetylcholine
Where does the falx cerebri attach and what does it separate?
Crista gali of the ethmoid bone anteriorly and the internal occipital protuberance posteriorly
Separates the hemispheres of the cerebral cortex
What cranial nerve innervates the lacrimal gland, the submandibular gland, and the sublingual gland?
CN VII
Lacrimal via pterygopalantine ganglion
Sublingual and submandibular via submandibular ganglion
What is the only sympathetic ganglion that innervates the head and neck?
The superior cervical ganglion
What is the arterial supply to the spinal cord?
One anterior and two posterior spinal arteries
There are also radicular arteries from segmental arteries + medullary arteries from the anterior spinal artery
What does CN VII do?
Motor to muscles of the face, intermediate motor to submandibular & sublingual glands, sense of taste
What spinal nerves are associated with the Least Splanchnic Nerve? What ganglia does it synpase with?
T12
Renal Ganglion
Name CN XI. Is it sensory, motor, or both?
Accessory
Motor
How many pairs of spinal nerves are there?
31 pairs
8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal
What makes up the pia mater?
connective tissue comprised of reticular and elastic fibers
Where is a needle placed during a spinal tap?
Between L3 and L4
What makes up the diencephalon?
Epithalamus, thalamus, and hypothalamus
Name CN X. Is it sensory, motor, or both?
Vagus
BOTH
What are dermatomes?
Area of skin innervated by one single segment of the spinal cord
Which portion of the autonomic nervous system has long preganglionic fibers?
Parasympathetic
What separates the somatosensory cortex from the motor cortex?
The central sulcus
How many gray communicantes do we have in total? How many white?
Gray: 62 (31 pairs of spinal nerves)
White: 28 (14 pairs of thoracolumbar nerves in the paravertebral sympathethic ganglia)
What is dysautonomia?
Disorder of the ANS
Common causes include alcoholism, anxiety, lupus, HIV/AIDS, Lyme disease, etc
What spinal nerves are associated with the Lumbar Splanchnic Nerve? What ganglia does it synpase with?
L 1 - L2
Inferior Mesenteric Ganglion
What causes referred pain?
Crosstalk in dorsal horn
Pain is perceived as being from area of skin innervated by same segmental levels as visceral afferent (aka pain in viscera interpreted as if it came from somatic areas)
How many neurons extend from the CNS in the autnomic nervous system?
One presynaptic + one postsynaptic.
They snynapse at a peripheral ganglion
What does the common fibular nerve branch into at the fibular head?
The deep fibular nerve and the superficial fibular nerve
What neuronal cell type controls the blood-brain barrier?
Astrocytes
What cranial nerve(s) pass through the foramen rotundum?
V2
What does the femoral nerve innervate?
The anterior compartment of the thigh
Where is Broca’s area located?
the frontal lobe
Name CN III. Is it sensory, motor, or both?
Oculomotor
Motor
What molecules are able to pass through the blood-brain barrier?
Glucose, essential amino acids, and some electrolytes
What does CN IX do?
Movement to pharyngeal muscles and sensory to the posterior part of the tongue
Parasympathetic innervation to the parotid gland
What are real spaces in the meningeal layers of the brain? Of the spinal cord?
Brain: subarachnoid has CSF
Spinal cord: epidural has fat, subarachnoid has CSF
What are the four prevertebral ganglia in the ANS? Where are they located?
- Celiac
- Aorticorenal
- Superior Mesenteric
- Inferior Mesenteric
All are located anterior to the abdominal aorta
The inferior sagittal sinus drains into what?
The straight sinus
What cranial nerve innervates the parotid gland?
CN IX
Via the otic ganglia
Where are sympathetic ganglia located? Parasympathetic?
Sympathetic: adjacent to spinal cord in sympathetic chain or in prevertebral ganglia
Parasympathetic: close to or in walls of the target organ
What makes CSF?
The choroid plexus
The straight sinus and the superior sagittal sinus converge at what?
The confluence of sinuses
Where is CSF resorbed?
Arachnoid granulations
CSF reduces the weight of the brain by what percentage?
95%
What is a nerve plexi?
Axons of primary ventral rami become rearranged in interconnected networks; one nerve can contain axons from several spinal levels
Ex: brachial plexus, lumbosacral plexus
What parasympathetic ganglia is associated with CN III?
ciliary ganglia
What is a sensory nerve to the skin called?
A cutaneous nerve
Name CN IX. Is it sensory, motor, or both?
Glossopharyngeal
BOTH
Name CN IV. Is it sensory, motor, or both?
Trochlear
Motor
What parasympathetic ganglia are associated with CN VII?
Pterygopalatine + submandibular
How many neurons are in a somatic pathway?
One
Loss of sensory information from receptors to CNS is termed what?
anesthesia
What do dorsal rami contain? Ventral rami?
Both contain sensory and motor neurons
Which part of the autonomic nervous system has extensive postganglionic branching?
Sympathetic
Very little branching in the parasympathetic (its more localized)
Name CN I. Is it sensory, motor, or both?
Olfactory
Sensory
How are visceral sensations characterized?
Dull, poorly localized, cramping, irritants, blood gas and pressure
What does the subthalamus do?
Role in motor, visual, and emotional control
What are the four important spinal reflexes?
Stretch, tendon, extension, and flexor (withdrawl)
STEF
What are the five components of the reflex arc?
Receptor, sensory neuron, integrating center, motor neuron, effector
Is the cutaneous nerve map the same as the dermatome nerve map?
No
Remember that cutaneous nerves may have axons from more than one spinal cord segment whereas dermatomes are area of skin innervated by a single spinal cord segment
What does the deep fibular nerve innervate?
The anterior compartment of the leg
What do posterior rami innervate?
Skin and deep muscles of the back
What is Raynaud’s disease?
Disorder of ANS characterized by constriction of blood vessels
Provoked by exposure to cold or by emotional stress
What does CN III do?
Movement of all eye muscles except those supplied by IV and VI
How are descending motor tracts named in the spinal cord?
……spinal
ex: vestibulospinal
List the layers of meninges from the bones of the skull to the brain
Dura mater (periosteal, meningeal), Arachnoid mater, and pia mater
What nerve innervates the medial aspect of the leg and foot up to the ball of the big toe?
The saphenous nerve
(which means someone with damage to their sciatic nerve would have SOME feeling in their leg)
