Neuroanatomy Flashcards
What are the major anatomical partitions of the nervous system?
Central and Peripheral
What is in the CNS?
Brain and spinal cord
What is in the PNS?
12 pairs of cranial nerves 31 pairs of spinal nerves and their branches
What is formed from the prosencephalon?
Telencephalon and Diencephalon
What is formed from the mesencephalon?
Mesencephalon
What is formed from the rhombencephalon?
Metencephalon Mylencephalon
what age does the neural tube form primary and secondary vesicles?
4 weeks 6-8 weeks
What is the major derivative of the telencephalon?
Cerebral hemispheres
What is the major derivative of the diencephalon?
Thalamus Hypothalamus
What is the major derivative of the mesencephalon?
Midbrain
What is the major derivative of the metencephalon?
Pons, cerebellum
What is the major derivative of the myelencepalon?
Medulla oblongata
What is the brainstem?
Combination of midbrain, pons and medulla oblongata is called the brainstem
What are the principle cells of the CNS?
Neurons and Glial cells
What are neurons
Communicators, receive information, via synapses, integrate the info and transmit electrical impulses
Most neurones are _____ with many ____ and one ____
Most neurones multipolar with many dendrites and one axon
What are glial cells?
- Astrocytes - Oligodendrocytes - Microglia - Ependymal cells
What are astrocytes
Star shaped cells Role in support, maintaining BBB, environmental homeostasis
There is no ____ tissue in the CNS
There is no connective tissue in the CNS
What are oligodendrocytes?
Produce myelin in the CNS - Nucleus becomes moderately stained in typical preparations
What are microglia
Similar to macrophages (haematopeoic origin). Immune monitoring and antigen presentation
Describe resting microglia
Elongated nuclei and a number of short, spiny cell processes
Describe activated microglia
Round and take on similar appearance to macrophage
What are ependymal cells
Ciliated cuboidal/columnar epithelium that lines the ventricles
What is a fissure?
Deeper fold than a sulcus
What is contained in white matter?
Axons (most myelinated) and their support cells
What is contained in grey matter?
Huge number of neurones, cell processes, synapses and support cells
Where is white matter located in the spinal cord?
Outside the H of grey matter
How will you know what is the posterior spinal cord?
Posterior (dorsal horn) of grey matter is close to surface
What is white matter referred to as in the spinal cord?
Columns -posterior -lateral -anterior
What is the lateral fissure of the brain also called?
Sylvian fissure
What is the inter hemispheric fissure called?
longitudinal fissure
What are the two lentiform nuclei?
Putamen (superior) Globus Pallidus (inferior)
What is the name of the structure labelled red?
Corpus callosum
What is the name of the structure labelled red?
Thalamus
What is the name of the structure labelled red?
Cingulate sulcus
What is the name of this structure?
Interthalamic adhesion
What are the two blanked out structures?
Fornix
Pineal Gland
Describe the frontal lobe
large lobe anterior to the central sulcus and superior to the lateral sulcus
lobe anterior to a line drawn from the central sulcus down to the corpus callosum
Describe the parietal lobe
posterior to the central sulcus, superior to the lateral sulcus (and a backward extension of it), and anterior to a line from the parieto-occipital sulcus to the preocciptialnotch
posterior to the frontal lobe and anterior to the parieto-occipital sulcus
Describe the occipital lobe
posterior to a line from the parieto-occipital sulcus to the preocciptialnotch
Describe the temporal lobe
inferior to the lateral sulcus (and a line extending the lateral sulcus posteriorly) and posteriorly by a line from the parieto-occipital sulcus and the preoccipitalnotch.
Medially, the temporal lobe extends from the temporal pole, to a line drawn between the preoccipitalnotch and the anterior end of the calcarine sulcus.
Describe the insular lobe
Normally hidden
What are the three layers of the meninges?
From superficial to deep;
- Dura mater
- Arachnoid Mater
- Pia mater
What is found in the subarachnoid space?
CSF
What can the CSF filled ventricles inside the brain be compared to?
An alien antelope
What are the two midline ventricles?
III and IV
What is the enteric nervous system?
- Found from oesophagus to rectum
- neurons found in two plexuses in the walls of the gut (myenteric plexis between outer layers of smooth muscle, submucosal plexus in the submucosa)
The enteric nervous system conrtains the same number of neurons found in the ______ ____ (10-)
The enteric nervous system conrtains the same number of neurons found in the spinal cord (108)
What are the two systems suppling blood to the brain?
Internal carotid system
Vertebro-basilar system
What arteries arise from the internal carotid arteries?
- anterior cerebral
- middle cerebral
What arteries aries from the vertebral arteries?
Basilar artery
Posterior cerebeal arteries
What is the blood supply here?
What is the blood supply here?
Describe the venous drainage of the brain?
Drains into a system of dural venous sinuses
Where are the two enlargements of the spinal cord?
Cervical = upper limb
Lumbar= lower limb
Anterior and posterior rootlets coalesce to form a posterior and anterior ___
Anterior and posterior rootlets coalesce to form a posterior and anterior root
Roots pass through the ______ ____ until they reach the appropriate intervertebral _____
Roots pass through the subarachnoid space until they reach the appropriate intervertebral foraminae
As the roots pass through the intervertebral foramina the ____ root is _____ by the ______ ____ _______
As the roots pass through the intervertebral foramina the dorsal root is enlarged by the dorsal root ganglion
The roots fuse to form the ____ _____ nerve, which produces ___ and ____ rami
The roots fuse to form the mixed spinal nerve, which produces posterior and anterior rami
Where does the spinal cord terminate?
Conus medullaris which in turn continues as a thin connective cord tissue called the filum terminale which is anchored to the dorsum of the coccyx
What ligament suspends the spnal cord in the canal?
Denticulate ligament
What forms the denticulate ligament?
Pial and arachnoid tissue
What does the white matter of the sponal cord consist of?
Longitudinally orientated nerve fibres (axons), glial cells and blood vessels
What does the grey matter of the spinal cord consist of?
Neuronal soma, cell processes, synapses, glia and blood vessels
What opens rostrally into the IVth ventricle?
Central canal of the spinal cord
What is significant about the grey matter at T1 to L2 spinal segments?
There is also a smaller lateral horn which contains the preganglionic sympathetic neurons
What is the arterial supply to the spinal cord?
longitudinal arteries
> one anterior
- > two posterior*
- originate from vertebral arteries*
Segmental arteries
derived from intercostal and lumbar arteires
Radicular arteries
travel along the dorsal and ventral roots
Describe the venous drainage of the spinal cord
Has both longitudinal and segmental veins
What is contained within the epidural space?
Adipose tissue
Anterior and posterior epidural venous plexuses
The left side of the somatosensory cortex represents the ____ side of the body
The left side of the somatosensory cortex represents the right side of the body
How do sensory fibres for fine touch and conscious proprioception reach the somatosensory cortex?
Through the dorsal column/medial lemniscus system
- fasciculus fracilis
- fasciculus cuneatus
Where do fibres going to somatosensory cortex cross?
In the medulla and synapse in the thalamus
What does the spinothalamic tract carry?
Pain, temperature, deep pressure
Where does the spinothamic neurones cross?
Segmentally and synapse in thalamus
Describe the location of the spinothalamic tract in the spinal cord
The left motor cortex controls the..
right side of the body
The somatosensory cortex lies ____ to the central sulcus
Posterior
What is the corticospinal tract responsible for?
Descending motor tract
-fine, precise movement, particularly of distal limb muscles
The corticospinal tract forms visible _____ referred to as the ____ on the anterior surface of the ____ and so is sometimes called the _____ tract
The corticospinal tract forms visible ridges referred to as the pyramids on the anterior surface of the medulla and so is sometimes called the pyramidal tract
_____ fibres form the lateral CST
_________ fibres form the ventral CST which then cross _____
crossed fibres form the lateral CST
uncrossed fibres form the ventral CST which then cross sementally
What is decorticate posturing?
Spastic paralysis with hyperflexion of the upper limbs; caused by lack of descending control of the CST
Where do 85% of CST fibres cross?
The lower medulla- deccusation of the pyramids
What is the tectospinal tract?
Mediates reflex head and neck movement due to visual stimuli
Where does the tectospinal tract cross?
Midbrain
What is the reticulospinal tract?
Many functions, including the influencing of voluntary movement
reticular formation forms the central core of the brainstem, it has many nuclei and recieves input from virtually all parts of the CNS
Where do reticulospinal tract fibres originate?
Areas of the reticular formation in pons and medulla
What are RST fibres originating from the pons facilitators of?
Extensor movements and inhibitors of flexor movements
Fibres that originate in the medilla inhibit extensor movements and facilitate flexor movement
What is the role of the vestibulospinal tract?
Excitatory input to antigravity extensor muscles
Where do vestibulospinal tract fibres originate?
In the vestibular nuclei of pons and medulla (recieving input from vestibular apparatus and cerebellum)
Describe brown-séquard’s syndrome
Associated with hemisection of the spinal cord.
Some sensory or motor problems
Asymmetrical
What are these structures?
How is the cerebellum attached to the brainstem?
3 stalks- termed peduncles
- middle
- superior
- inferior
What are the three layers of the cerebellar cortex?
Molecular layer (outer)
Purkinje cell layer (middle)
Granule cell layer (inner)
Where do important afferents to the cerebellum arise from?
Spinal cord- from somatic proprioceptors and pressure receptors
Cerebral cortex (relayed via the pons)
Vestibular apparatus- via vestibular nuclei
How to projections to the cerebellum enter?
Via cerebellar peduncles and project to mainly the granule cell layer
What is the only output of the cerebellum?
via the axons of the purkinje cells
where do the axons of purkinje cells synapse?
on neurons of the deep cerebellar nuclei
What does the output of the cerebellum contribute to?
Coordinating the functions of the motor tracts of the brainstem and spinal cord
Where do most efferent axons of the deep cerebellar nuclei synapse
Most cross the midline and synapse in the thalamus
What is the role of the cerebellar hemispheres?
Influnce the ipsilateral side of the body
What is the role of the midline of the cerebellum?
Postural control
Describe the presentation of a unilateral hemispheric lesion of the cerebellum
Disturbance of the coordination in the limbs. can result in intention tremor and unstready gait in the absence of weakness or sensory loss
Describe bilateral cerebellar dysfunction
Slowed, slurred speech (dysarthria), bilateral incoordination of the arms and a staggering, wide based gait (cerebellar ataxia)
Describe the presentation of a midline cerebellar lesion
patient will tend to fall over when standing or sitting despite preserved limb coordination
What are the three functions of the basal ganglia?
- to facilitate all purposeful movement
- inhibit unwanted movements
- role in posture and muscle tone
What are the 5 basal ganglia
Caudate nucleus
Putamen
Globus pallidus
Subthalamic nucleus
Substantia nigra
What makes up the lenticular nucleus?
Putamen and globus pallidus
What makes up the striatum?
Caudate nucleus
Putamen
What makes up the corpus striatum
Caudate nucleus, putamen and globus pallidus
Describe the intenal capsule
Where is the substantia nigra located?
In the midbrain
What is the pathology in parkinsons disease?
Degeneration of the dopaminergic neurons of the substantia nigra
What is the direct pathway of the basal ganglia?
Enhances outflow of the thalamus, enhancing the desired movement
What is the indirect pathway of the basal ganglia?
Inhibits outflow of the thalamus
Unilateral lesions of the basal ganglia (in contrast to cerebellar lesions) affect the _____________ side of the body
Unilateral lesions of the basal ganglia (in contrast to cerebellar lesions) affect the contralateral side of the body
Lesions of the _____ _______ generally ____ cause paralysis, sensory loss, loss of power or ataxia
Lesions of the basal ganglia generally don’t cause paralysis, sensory loss, loss of power or ataxia
Lesions of the basal ganglia cause what motor signs?
Changes in muscle tone
Dyskinesias (abnormal, involuntary movements)
- tremor, chorea, myoclonus
What are sinusoidal movements?
Tremors
What is chorea?
Rapid, asymmetrical movements usually affecting distal limb musculature
What is myoclonus?
Muscle jerks
What diseases are represented by these abnormal changes in basal ganglia function?
Cranial nerves exit _________ except IV which exits ___________ and VIII which exits _________.
Cranial nerves exit anteriorly except IV which exits posteriorly and VIII which exits laterally.
What is the role of the olfactory nerve?
What is unique about its path?
Purely sensory cranial nerve
It is the only sensory modality that does not synapse in the thalamus prior to reaching the cortex
Which cranial nerves are motor?
CN III, IV, VI, XI, XII
What is the role of the occulomotor nerve?
Somatic motor to;
- Levator palpabrae superioris*
- SR, MR, IR, IO
Parasympathetic to;
- sphincter pupillae
- -ciliary muscle*
Where is the occulomotor nerve’s nuclei of origin?
Midbrain
What is the role of the trochlear nerve?
Somatic motor to superior oblique muscle
Where is the trochlear nerves nuclei of origin?
Midbrain
Where does the trochlear nerve exit?
Posteriorly
What is the role of the abducens nerve?
Somatic motor to lateral rectus
Where is the nucleus of origin for the abducens nerve?
Caudal pons
What is the role of the hypoglossal nerve?
Somatic motor to;
- genioglosus
- hyoglossus
- styloglossus
- intrinsic tongue muscles
Where is the nuclei of origin of the hypoglossal nerve?
Medulla
Where does the spinal accessory nerve arise?
From the spinal cord
What are the mixed cranial nerves?
CNs- V, VII, IX AND X
What are the functions of the trigeminal nerve
- somatosensation of face: discriminative touch, vibraiton sense, pain, temperature
- proprioception associated with chewing (TMJ, muscles of mastication, teeth)
- motor control- muscles of mastication, tensor tympanii, mylohyoid, anterior belly of digastric, tensor veli palatini
The sensory nucleus of the trigeminal forms a long _____ of neurons that stretches from the ________ down to the upper _ segments of the _______ _____ ____. It has _ parts, separated by function.
The sensory nucleus of the trigeminal forms a long column of neurons that stretches from the midbrain down to the upper 2 segments of the cervical spinal cord. It has 3 parts, separated by function.
What is the function of the mesencephalic nucleus?
Proprioception info from chewing muscles
What is the function of the pontine trigeminal nucleus (principal nucleus)?
Discriminative touch, vibration
What is the function of the spinal nucleus?
Pain, temperature
What is unusual about the mesencephalic nucleus?
The only site in the CNS where the cell bodies of primary afferent neurones live inside the CNS. It is a retained sensory ganglion.
What offers an advantage regarding the location of the mesencephalic nucleus?
Its proximity to the motor nucleus- offers advantages in terms of jaw reflexes.
Describe the ventral trigenimothalamic tract fibres
Most cross the midline, but some don’t (therefore bilateral representation of touch, vibration in cortex)
What does the spinal trigeminal nucleus merge with?
Dorsal horn of upper cervical spinal cord
What are the three functions of CN VII
- motor (muscles of facial expression, stapedius)
- parasympathetic innervation to pterygopalatine and submandibular ganglia
- Tasta (anterior 2/3 of tongue via c. tympani
What are the 4 functions of CN IX?
- tactile sense, pain and temperature sense from the posterior tongye, pharyngotympanic tube and upper pharynx
- taste (posterior 1/3 of tongue)
- parasympathetic fibres to the otic ganglion (parotid gland)
- motor (one muscle : stylopharyngeus)
What are the 4 functions of the vagus nerve?
- tactile sense, pain and temperature sense from the pharynx, larynx, trachea, oesophagus and thoracic and abdominal viscera
- taste (epiglottis)
- parasympathetic innervation to ganglia serving thoracic and abdominal viscera
- motor (striated muscle of pharynx and larynx) (cranial accessory contributes to this function)
Describe the path of the facial nerve fibres
fibres from the motor nucleus loop around the abducens nucleus
What nuclei do the components of the facial nerve originate from?
- facial motor nucleus
- salvitory nucleus
- solitary nucleus
- spinal trigeminal
What nuclei does the glossopharyngeal originate from?
- Solitary n: Gustatory nucleus – taste, v Commissural nucleus- visceral information
- Spinal trigeminal nucleus (small region of somatosensation associated with the ear)
- Inf. Salivatory n. (parasymp)
- Nucleus ambiguus (stylopharyngeus muscle)
What nuclei are involved with the 4 components of the vagus nerve?
- Dorsal (motor) Nucleus (parasymp)
- Solitary -taste
Commissural – visceral information - Spinal trigeminal nucleus (pain from dura and small region of somatosensation associated with the ear).
- Nucleus Ambiguus (motor)
Which nerves is the solitary nucleus involved with and what does it do?
taste and visceral sensory information
CNs VII, IX, X,
Which nerves use the superior and inferior salivatory nuclei and what is their function?
CNs VII and IX
Parasympathetic efferents to ganglia of salivary glands and pterygopalatine ganglion
Which nerves use the nucleus ambiguus and what is its function?
CNs IX and X (and part of cranial nerve XI)
Motor efferents to muscles of pharynx, larynx and upper oesophagus
Describe the shape of the solitary nucleus?
It extends in a V shape from upper to lower medulla
What visceral sensations does the solitary nucleus account for?
Commisural nucleus (visceral afferents)
IX- carotid sinus/body
X aortic arch and viscera (pulmonary stretch receptors)
The corticobulbar tract is the part of the pyramidal tract that is _____ to _____ nerves.
The corticobulbar tract is the part of the pyramidal tract that is motor to cranial nerves.
The corticobulbar tract includes fibres to the motor nuclei of which CNs?
V, VII, X and XII
Which part of the face has a bilateral supply from the corticobulbar tract?
Upper face (forehead and around the eyes)
Where is the input containing parasympathetic efferents to CN III, VII, IX and X from?
From the hypothalamus- its efferents reach the preganglionic autonomic neurons both directly and via synapses in the reticular formation
The reticular formation is a network of loosely aggregated cells with ____ ______, _____ and _____ intermingling in the central core of the _____ ____.
The reticular formation is a network of loosely aggregated cells with cell bodies, axons and dendrites intermingling in the central core of the brain stem.
What do the reticular formation centres do?
- integrate cranial nerve reflexes
- particupate in conduction and modulation of pain
- influence voluntary moement
- regulate autonomic activity
- integrate some basic functions, like respiration and sleep
- activate the cerebral cortex
A medial bilateral lesion of the brainstem retiuclar formation at or above the upper pons causes what?
Irreversible coma
