Neuroanatomy Flashcards
2 Major Partitions of the Dura Mater
- Falx cerebri 2. Tentorium Cerebelli
Anterior Fossa
Contains the frontal lobes
Anterior Spinal Artery
(p. 219)
- originates from the vertebral arteries
- runs along the ventral surface of the spinal cord
Apraxia
- a deficit in higher-order motor planning and execution despite normal strength
- lesions to regions of the association cortex
Arachnoid Granulations
Reabsorbs CSF in the subarachnoid space.
Arachnoid mater
The 2nd meningeal membrane that adheres to the inner surface of the dura
Avascular Very thin and delicate
Attached to the 3rd membrain by cobweb-like strands of tissue
Closely follows the conformation of the outer layer of the brain and spinal cord
Blood vessles of the brain are distributed in the arachnoid mater and send branches through the pia to supply the outer layer of the cerebral hemispheres
CSF percolates over the surface of the brain within the subarachnoid space
Are migraines genetic?
Yes
About 75% of cases have a family history
Are migraines often unilateral?
Yes, but if they are always on the same side, you should get an MRI.
Astroglia
Gives structural support to and repair neurons
Atrium
Connects 3 parts of the lateral ventricle:
1) The body
2) The Posterior (Occipital) Horn
3) The Inferior (Temporal) Horn
Basis Pedunculi
- Where the internal capsule goes through the midbrain cerebral peduncles (aka, “feet of the brain”)
- The white matter in the ventral portion of the cerebral peduncles
- The middle 1/3 contains corticobulbar and corticospinal fibers with the face, arm, trunk, and leg axons arranged from medial to lateral
Bridging Veins
Traverse the subdural space.
They drain the cerebral hemispheres.
They pass through the subdural space en route to several large dural venous sinuses.
Cerebellum
- Motor coordination - skilled movements
- Control of muscle tone
- Equilibrium
- Postural reflexes
Cerebral Aqueduct
AKA - Aqueduct of Sylvius
Where the 3rd ventricle communicates with the 4th ventricle
Cerebrospinal fluid (CSF)
Crystal-clear, colorless, fluid composed largely of water Acts as a buffer to protect the brain and spinal cord Helps to provide constant pressure within the bony cavity under normal conditions
Choroid Plexus
Produces CSF
Lie inside the ventricles
Cistern
Areas where the subarachnoid space widens to form larger CSF collections
Cisterna Magna
AKA - Cerebellomedullary cistern
The largest cistern
Located beneath the cerebellum near the formen magnum
Cluster Headaches
- 5x more in men
- 1+/day every day for a few weeks then vanishes for months
- Severe headaches, constant boring sensation behind one eye
- Lasts 30-90 minutes
- Usually accompanied by unilateral autonomic sx (tearing, red eye, flushing, sweating, nasal congestion, or Horner’s Syndrome)
- Inhaled oxygen often effective in aborting attacks
Complicated Migraine
Accompanied by focal neurological deficits, such as:
- Sensory phenomena
- Motor deficits (hemiplegia)
- Visual loss
- Brainstem findings (basilar migraine)
- Impaired eye movement (ophthalmoplegic migraine)
Coronal sections
(aka frontal sections) Parallel to a vertical plane through both ears
Corpus callosum
Thick band of white matter that unites the two hemispheres of the brain
Corticospinal Tract Fibers Cross Over Where?
(p. 225)
- At the cervicomedullary junction (where the medulla and spinal cord meet)
- They cross over in the pyramidal decussation to enter the lateral white matter columns of the spinal cord, forming the lateral corticospinal tract (arm, trunk, leg; from medial to lateral)
- 85% of fibers cross over (pyramidal decussation)
- 15% continue into the ipsilateral spinal cord and enter the anterior white matter columns to form the anterior corticospinal tract (trunk)
Diencephalon
- Thalamus
- Epithalamus
- Hypothalamus
- Pineal body
- Third ventricle
Dorsal Grey Horns
- location where sensory nerve fibers synapse onto interneurons in the spinal cord
Dura mater
Tough, outermost layer. Closely attached to the inner surface of the skull. Consists of 2 fibrous layers: 1) Periosteal (outer), which is adherent to the inner surface of the skull & 2) Meningeal (inner), which forms folds that descend far into the cranial cavity. The two layers are fused except for at the falx cerebri and tentorium cerebelli.
Dural Venous Sinus
Large venous channels that lie enclosed within the two layers of dura.
They drain blood mainly via the sigmoid sinus to reach the internal jugular vein.
Ependymal Cells
Line the brain’s ventricles and produce CFS
Ependymal Cells
Line the walls of the ventricles
Epithalamus
- Not well understood
- Encompasses the pineal gland
Falx cerebri
A vertical partition b/t the major divisions of left and right cerebral hemispheres. Its narrow end is attached to the skull anteriorly. Its upper edge is attached to the vault of the skull in the midline Its lower edge arches over the upper edge of the corpus callosum to join onto the tentorium cerebelli
Foramen Magnum
The largest foramen at the base of the skull. It’s where the spinal cord meets the medulla (cervicomedullary junction)
Foramina
Holes, which allow cranial nerves, spinal cord, and blood vessels to enter and leave the intracranial cavity
Foramen Spinosum
Where the middle meningeal artery enters the skull.
Fossae
Compartments in the inner surface of the skull
Frequency of migraines
Several times per week to once every few years.
Ganglia
- collection of neuron cell bodies outside of the CNS
Great Radicular Artery of Adamkiewicz
(p. 220)
- a prominant radicular artery (anywhere from T5 to L3) that provides the major blood supply to the lumbar and sacral cord
Grey matter
Nerve-cell collections
Hematocrit Effect
When with mixed-density hematomas, the denser acute blood settles to the bottom
Hemiplegia or Hemiparesis
- Locations ruled out
- Corticospinal tract below the motor cortex above the medulla, b/c the face is spared
- Muscle or peripheral nerve
- Not below C5, b/c some arm muscles would be spared
- Locations ruled in
- Arm and leg area of motor cortex
- Corticospinal tract from lower medulla to C5
- Side of lesion
- Motor cortex or medulla (above pyramidal decussation) - contralateral
- Cervical spinal cord (below pyramidal decussation) - ipsilateral
- Associated features:
- Upper motor neuron signs
- Affect proximal more than distal muscles (“man in barrel”)
- Cortical lesions may be associated with aphasia or hemineglect
Horizontal sections
At right angles to the other two (coronal & sagittal)
How does CSF leave the ventricular system so it can percolate around the brain and spinal cord?
Through either:
1) The Lateral Foramina of Luschka
2) Teh Midline Foramen of Magendie
Humunculus
(p. 216)
- “little man”
- depicts localization of anatomical motor/senory functioning
- Generally:
- Lateral: tongue, face, hands
- Dorsal: arms, shoulders, torso
- Interhemispheric: legs, feet
Innervated areas that can cause headache pain are?
Blood vessels
Meninges
Scalp
Skull
Insula
Cortical area buried within the lateral sulcus Can only be seen when the lips of the fissure are drawn apart
Interpeduncular Cistern
Located on the ventral surface of the midbrain, between the cerebral peduncles.
The 3rd nerve (occulomotor nerve) exits the midbrain through here.
Internal Capsule
- internal portion of white matter tracks
- 3 parts:
- anterior limb - separates head of caudate from globus pallidus & putamen
- posterior limb - separates thalamus from globus pallidus & putamen; where the corticospinal tract lies
- genu - “knee”
Intraventricular Foramen of Monro
Where the lateral ventricles communicate with the 3rd ventricle
Lateral Corticospinal Tract
- essential for rapid, dextrous movements at individual digits or joints
- controls the contralateral extremities
- fibers cross in the pyramid in medulla
- >50% of fibers originate in the primar motor cortex
-
Lateral Grey Horns
- Present only at the thoracic and lumbar levels of the spine
- Location of autonomic motorneuron cell bodies (sympathetic preganglionic)
Lateral Motor Systems: Spinal Cord
(p. 221; p.39 Netter)
- Lateral corticospinal tract
- Rubrospinal tract
- synapse on the more lateral groups of ventral motor neurons (cells for distal muscles of extremities)
Lateral sulcus
A very deep division between the frontal and temporal lobes anteriorly and portions of the parietal and temporal lobes posteriorly
Longitudinal Fissure
Separates the two hemispheres of the brain
Lower Motor Neuron Lesion
- Limited to a small group of muscles
- Muscle atrophy - the muscle fibers innervated by the lower motor nuclei become deprived of trophic (pertaining to nutrition) factors and eventually atrophy
- Weakness - b/c of atrophy weakness is profound
- Fasciculations - damaged neurons can produce spontaneous action potentials, so the muscle twitches
- Decreased tone - since lower motor neurons are the only source of stimulation to the muscle fibers, tone decreases
- Hyporeflexia - b/c the lower motor neurons that cause muscle contraction are damaged
Lumbar Cistern
Located in the lumbar portion of the spinal column
Contains the cauda equina
The region where spinal taps or lumbar punctures are done
Medial Motor Systems: Spinal Cord
(p. 221, p. 39 Netter)
- Anterior corticospinal tract
- Vestibulospinal tracts
- Reticulospinal tracts
- Tectospinal tract
- synapse on the more medial groups of ventral horn motor neurons (cells for proximal trunk muscles)
- controls proximal axial and girdle muscles involved in postural tone, balance, orienting movements of the head and neck, and automatic gait-related movements.
- they descent either ipsilaterally or bilaterally
- some extend only to the upper few cervical segments
Meningeal arteries
Embedded in the dura mater Provide blood supply for skull bones and avascular dura mater
Mesencephalon
- Midbrain
- AKA - Midbrain
- Part of the brainstem
Mesencephalon
- Tectum
- Tegmentum
- Cerebral aqueduct
Metencephalon
- Cerebellum
- Pons
- Fourth ventricle
Middle Cerebral Artery
It’s a branch of the internal carotid artery.
Supplies the brain.
Microglia
Perform phagocytosis
- eliminates cell debris and pathogens
Middle Fossa
Contains the temporal lobe
Middle Meningeal Artery
Enters the skull through the formen spinosum.
Runs in the epidural space between the dura and skull
It’s a branch of the external carotid artery.
It supplies the dura
Migraine duration
30 min to 24 hours
Most headaches can be classified into which 2 categories?
- Vascular
- Tension
Myelencephalon
- Medulla oblongata
- Fourth ventricle
Nucleus
A large number of cell bodies grouped together
- they usually have a particular function
Oligodendroglia
Insulate and speed transmission of CNS neurons
Opercula
AKA - lids Areas of the cortex that overlay the insula
Parasympathetic Neurotransmitters
Acetylcholine
Parietal Association Cortex
(p. 215)
- Location: Posterior to the primary sensory cortex
- Function: Higher-order sensory processing
Pia mater
Inner meningeal membrane
Closely follows the convolutions or gyri of the cerebral hemispheres and dips down into the fissures or sulci
Surrounds the initial portion of each blood vessel as it penetrates teh brain surface, forming a perivascular space, and then fuses with the blood vessel wall
Pineal Gland
- Regulates body rhythms
Posterior Fossa
Contains the cerebellum and the brainstem
Posterior Spinal Arteries (2)
(p. 219)
- arise from the vertebral or posterior inferior cerebellar arteries
- supplies the dorsal surface of the spinal cord
Premotor Cortex
(p. 215)
- Location: Anterior to the primary motor cortex and inferior to the supplementary motor cortex
- Function: higher-order motor planning
Prepontine Cistern
Located just ventral to the pons.
Contains the basilar artery & 6th cranial nerves
Primary Motor Cortex
(p. 215)
- Location: Precentral gyrus
- Function: Motor functioning of the contralateral body
Primary Senory Cortex
(p. 215)
- Location - Postcentral gyrus
- Function: Senory functioning of contralateral body
Pure Motor Paresis (Face, Arm, Leg Weakness or Paralysis) w/ no Associated Sensory Deficits
- Locations ruled out:
- Cortical - would have to involve entire motor strip
- Muscle or peripheral nerve
- Spinal cord or medulla - b/c then the face would have been spared
- Locations ruled in:
- Corticospinal and corticobulbar tract fibers below the cortex and above the medulla
- Posterior limb of internal capsule
- Basis pontis
- Middle 1/3 of the cerebral peduncle
- Side of lesion: Contralateral (above pyramidal decussation)
Prosencephalon
- Telencephalon (endbrain)
- Diencephalon (between-brain)
- AKA - forebrain
Quadigeminal Cistern
Posterior to the midbrain
Beneath the posterior portion of the corpus callosum and above the cerebellum
The name comes from the four bumps of the superior and inferior colliculi
Reticular Formation
- AKA - reticular activating system
- Named for its networklike appearance of its fibers
- Extends throughout the central portions of the brainstem from the medulla to the midbrain
- The lower portions (caudal), in the lower pons and medulla, tend to be involved in motor and autonomic functions
- The upper portions (rostral), in the upper pons and midbrain, plays an important role in regulating level of consciousness
- It influences higher areas mainly through modulation of thalamic activity
- Lesion can cause lethargy and coma
Reticular Matter
- from Latin “rete” meaning net
- area where cell bodies (grey matter) and axons (white matter) are mixed together giving it a mottled, or netlike, appearance
Rhombencephalon
- Metencephalon
- Myelencephalon
- AKA - hindbrain
- Part of the brainstem
Sagittal sections
(aka - longitudinal) At right angles to the coronal plane in a vertical direction a median or midline sagittal section would divide the brain into its two hemispheres
Schwann Cells
Insulate and speed transmision of PNS neurons
Spinal Arterial Plexus
(p. 219)
- where the anterior and posterior spinal arteries surround the spinal cord
Spinal Cord Gray Matter: 3 Parts
(p. 217)
- Dorsal (posterior) horn
- Intermediate zone
- Ventral (anterior) horn
Spinal Cord White Matter: 3 Parts
(p. 217)
- Dorsal (posterior) columns
- Lateral columns
- Ventral (anterior) columns
Subarachnoid space
The fluid-filled space that separates the arachnoid from pia mater
Filled with CSF.
Major arteries of teh brain travel through here, sending smaller penetrating branches inward through the pia.
Subdural space
The narrow potential space between the dura and arachnoid mater.
Supplementary Motor Area
(p. 215)
- Location: Anterior to primary motor cortex and superior to the premotor cortex
- Function: higher-order motor planning
Supratentorial Dura
The brain region located above the tentorium cerebelli
Sympathetic Neurotransmitters
Norepinephrine
Symptoms of low CSF
Headache that is worse whie standing than lying down
T/F Brain parenchyma have pain receptors
False
Telencephalon
- Neocortex
- Basal ganglia
- Limbic system
- Olfactory bulb
- Lateral ventricles
Tentorial Incisura
AKA: Tentorial notch - it’s where the midbrain passes through a narrow opening in the tentorium cerebelli
Tentorium cerebelli
Separates the base of the posterior parts of the cerebral hemispheres from the cerebellum below.
Thalamus
- All sensory systems, except olfaction, have relays here on their way to the cortex
- Different parts of the cortex communicate with one another via relays through the thalamus
Basal Ganglia: Comprised of which structures?
- Globus pallidus
- Caudate nucleus
- Amygdala
- Putamen
Typical aura (warning symptoms) of a migraine
- Visual blurring
- Shimmering
- Scintillating distortions (rapidly oscillating pattern)
- Fortification scotoma (a region of visual loss bordered by zigzagging lines resembling the walls of a fort)
Tract
A large collection of axions from a nucleus
AKA - fiber pathway
Involved in carrying informatino from one place to another
Typical symptoms of a migraine
- Photophobia
- Phonophobia
- Pain is throbbing
- Exacerbated by sudden head movement
- Nausea/vomiting
- Tender scalp
Upper Motor Neuron Lesion
- Effects large groups of muscles
- Atrophy is rare, b/c trophic factors remain from the lower motor neurons; they may become somewhat atrophied from disuse, but not as much as with LMN lesions
- Weakness of movement
- No fasciculations b/c lower motor neurons are spared
- Hypertonia - loss of descending input leads to increased firing of lower motor neurons, which results in increase resting level of muscle activity, which equates to increased tone
- Hyperreflexia - b/c of loss of inhibitory modulation, the stretch reflex is exaggerated
- Clonus - when the muscle is rapidly stretched and held at a certain length, it will contract a number of times quickly, making a jerking movement.
- Spasticity - clasp-knife reflex
- Babinski - postive (toes go up and fan out)
Vascular headache
Migraine or cluster headache
Not fully understood, but thought to involve conditions that influence the blood vessel caliber (diameter) in the head, such as:
1) Inflammatory
2) Autonomic
3) Serotonergic
4) Neuroendocrine
Ventral Grey Horns
- location of somatic motorneuron cell bodies
Ventricles
Lateral ventricles - one located in each hemisphere 3rd ventricle - midline, thin, circular structure 4th ventricle - in the brainstem behind the pons
What cranial nerve innervates the supratentorial dura?
V - Trigeminal
What cranial nerve(s) innervate the dura of the posterior fossa?
Mainly by X - Vagus
IX - Glossopharyngeal
First 3 cervical nerves
What is the normal total volume of CSF in adults?
150cc
What is the rate of CSF production?
20/cc/hr or 500cc/day
Where does CSF ultimately go?
It gets reabsorbed by the arachnoid granulations.
Then it goes into the dural venous sinuses, and thus back into the blood stream.
White matter
Cell fibers, which unite the various regions of the brain with each other
Hypothalamus
- Consists of:
- ~22 small nuclei
- Fiber systems pass through it
- Pituitary gland
- Involved in nearly all aspects of behavior, including:
- Feeding
- Sexual behavior
- Sleeping
- Temperature regulation
- Emotional behavior
- Endocrine function
- Movement
Superior Colliculi
- AKA - upper hills
- receive projections from the retina and mediate many visually related behaviors
Inferior Colliculi
- AKA - lower hills
- receive projections from the ear and they mediate many auditory-related behaviors.
Cranial Nerve I
- Olfactory
- Sensory
- Lesion = loss of sense of smell (anosmia)
