Neuroanatomy Flashcards
What are the 4 types of Glial Cells in the CNS?
- Astrocytes
- Oligodendrocytes
- Microglia
- Ependymal cells
What is the role of Astrocytes?
- Star shaped
- Roles in support, maintaining BBB, environmental homeostasis
- No connective tissue in CNS
What is more common in the CNS, glial cells or neurons?
Glial cells x10 more numerous than neurones in CNS
What is the role of Oligodendrocytes?
-Produce myelin in the CNS
What is the role of Microglia?
- Cells of similar lineages to macrophages
- Immune monitoring and antigen presentation
How do Microglia change from a resting state to an activated state?
- Resting: elongated nucleus and a number of short, spiny cell processes
- Activated: rounder and take on an appearance similar to a macrophage
What is the role of Ependymal cells?
-Ciliated cuboidal/columnar epithelium that lines the ventricles
What is the difference between a fissure and a sulcus?
A fissure is deeper
What is the role of the insula?
-Has an importance role in the patient’s experience of pain, it is hidden.
White and Grey matter of the spinal cord?
- Outer layer is white
- Inner layer is grey
What is the blood supply to the spinal cord?
- Three major longitudinal arteries: one anterior and two posterior that originate from the vertebral arteries
- Segmental arteries, derived from vertebral, intercostal and lumbar arteries
- Radicular arteries that travel along the dorsal and ventral roots
Where is the primary somatosensory cortex?
-Behind the post-central gyrus
Where is the primary motor cortex?
-In the pre-central gyrus
Where do the fibres in the DCML cross?
Medulla
Which fibres does the DCML pathway carry?
-Fine touch and conscious proprioception
Where do the fibres in the STT cross?
-Cross segmentally in the spinal cord
Which fibres does the STT carry?
-Pain, temp and deep pressure
What can a CVA of the internal capsule result in?
A lack of descending control of the corticospinal tract
What is decorticate posturing?
- CVA of internal capsule causing lack of descending control of the corticospinal tract
- Spastic paralysis with hyeprflexion of the upper limbs
What does the Corticospinal tract do?
Fine, precise movement, particularly of distal limb muscles
Where do the pyramidal fibres cross?
85% cross in the caudal medulla at the decussation of the pyramids
What is the difference between crossed and uncrossed fibres from the corticospinal tract?
- Crossed form the lateral CST
- Uncrossed form the ventral CST
What makes up the extra-pyramidal tract?
- Tectospinal
- Reticulospinal
- Vestibulospinal
What is the role of the Tectospinal tract?
- Input mostly to cervical segments
- Thought to mediate reflex head and neck movement due to visual stimuli
What is the role of the Reticulospinal Tract?
- Reticular formation forms the central core of the brainstem
- It has many nuclei and receives input from virtually all parts of the CNS
- Many movements incl fluency of voluntary movement
Where do the the Reticulospinal Tract fibres originate from?
-Areas of the reticular formation in pons and medulla
What movement does fibres originating in the pons facilitate?
-Extensor movements and inhibit flexor
What movement does fibres originating in the medulla facilitate?
-Flexor movements and inhibit extensor
What is the role of the Vestibulospinal Tract?
- Excitatory input to “anti-gravity” extensor muscles
- Fibres originate in the vestibular nuclei of the pons and medulla
- Receive input from Vestibular Apparatus
What happens if there is a lesion at the brainstem resulting in lack of descending cortical control from Vestibulospinal tract?
-Domination of the extensor muscle tone and hyperextended spastic paralysis
Brown-Séquard’s Syndrome?
- Ipsilateral paralysis
- Ipsilateral hyper-reflexia and extensor plantar reflex
- Ipsilateral loss of vibration and proprioception
- Contralateral loss of paint and temp sensation
What are the 3 layers of the Cerebellar Cortex?
- Molecular (outer) (Mother)
- Purkinje cell layer (middle) (Peter)
- Granular layer (inner) (Gran)
For Molecular layer, Purkinje cell layer and Granular layer…which is outer, middle, inner?
- Molecular- outer
- Purkinje- middle
- Granular- inner
What are the afferent (input) projections to the cerebellum?
- From spinal cord, somatic proprioceptors and pressure receptors
- Cerebral cortex (relayed via pons)
- Vestibular apparatus via vestibular nuclei
How do afferent projections arrive at the cerebellum?
-Via cerebellar peduncles and project to the granule cell layer
What are the outputs of the cerebellum?
- Output is via the axons of the Purkinje cells which synapse on neurones of the deep cerebellar nuclei
- Co-ordinate the functions of all the motor tracts
How do efferent projections leave the the cerebellum?
- Most efferent axons of the deep cerebellar nuclei cross the midline and synapse in the thalamus
- Thalamus sends fibres to the motor cortex
Do cerebellar lesions lead to ipsilateral or contralateral signs?
Ipsilateral
What symptoms will a unilateral hemispheric lesion of the cerebellum cause?
- Disturbance of coordination in limbs
- Intension tremor and insteady gait in the absence of weakness or sensory loss
What symptoms will bilateral cerebellar dysfunction cause?
- Slowed, slurred speech (dysarthria)
- Bilateral incoordination of the arms and a staggering wide, based gait
What symptoms will a midline hemispheric lesion of the cerebellum cause?
- Disturbance of postural control
- Patient will tend to fall over when standing or sitting despite preserved limb coordination
What are the functions of the Basal Ganglia?
- To facilitate purposeful movement
- Inhibit unwanted movements
- Role in posture and muscle tone
What makes up the striatum?
- Caudate nucleus
- Putamen
What makes up the Lenticular Nucleus?
- Globus Pallidus
- Subthalamic nucleus
What makes up the corpus striatum
- Caudate nucleus
- Putamen
- Globus Pallidus
How do the basal ganglia work with the motor cortex to enhance normal movement?
- Work through direct pathway to enhance outflow of thalamus
- Can inhibit outflow of thalamus through indirect pathway
What side will unilateral basal ganglion dysfunction affect?
-The contralateral side will be affect
What symptoms will a unilateral lesion of the basal ganglion cause?
- Change in muscle tone
- Dyskinesias inclu: tremor, chorea, myoclonus
What are some of the disorders associated with the basal ganglia?
- PD
- HD
What movement does fibres originating in the medulla facilitate?
-Flexor movements and inhibit extensor
What is the role of the Vestibulospinal Tract?
- Excitatory input to “anti-gravity” extensor muscles
- Fibres originate in the vesticular nuclei of pons and medulla
Where does the Vestibulospinal tract receive input from?
The vestibular apparatus and cerebellum
What happens if there is a lesion of the Vestibulospinal Tract?
-There is domination of the extensor muscle tone and hyperextended spastic paralysis
Brown-Séqard’s Syndrome?
- Ipsilateral paralysis
- Ipsilateral hyper-reflexia and extensor plantar reflex
- Ipsilateral loss of vibration, proprioception
- Contralateral loss of pain and temp
Where do cranial nerves exit the brainstem and what is the exception?
-Nerves exit ventrally exit CNIV
What are the CNs which open up onto the midline of the brainstem?
- The motor nerves
- III, IV, VI, XII
What are the three trigeminal sensory nuclei?
- Mesesencephalic nucleus
- Pontine Trigeminal Nucleus
- Spinal Nucleus
Where is the location of the sensory nucleus of the trigeminal nerve of the brainstem?
- 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 Mesesencephalic nucleus of the trigeminal nerve system?
-Proprioception info from chewing muscles
What is the function of the Pontine Trigeminal Nucleus of the trigeminal nerve system?
Discriminative touch and vibration
What is the function of the Spinal nucleus of the trigeminal nerve system?
Pain, temp
Where is the only site in the CNS where the cell bodies of the primary afferent neurones live inside the CNS?
The Mesencephalic nucleus of the trigeminal sensory nucleus
If there is a lesion of the Trigeminal pain fibres, where is spared?
Oral sparing
Which CNs have several nuclei in the brainstem which are shared by more than one ?
CN VII, IX, X
What is the Corticobulbar tract?
-The part of the pyramidal tract that is motor to cranial nerves
What is reticular formation?
A network of loosely aggregated cells with cell bodies, axons and dendrite intermingling in the central core of the brainstem
What does the reticular formation centres do?
- Integrate CN reflexes
- Participate in voluntary movement
- Regulate autonomic activity
What are the functions of Superior Olivary Nucleus and Lateral Lemniscus?
Sound localisation and relay
What is the auditory pathway through the brainstem?
From inferior colliculus through inferior brachium to medial geniculate ganglion
What is the visual pathway through the brainstem?
From superior colliculus to lateral geniculate ganglion
Sound is organised in the auditory cortex. Where is low frequency sound?
Anterolateral part of the auditory cortex
Sound is organised in the auditory cortex. Where is high frequency sound?
Posteromedial part of auditory cortex
Broca’s area?
Broken speech, can comprehend language
Wernicke’s area?
Difficulty comprehending speech
Eye movements can be controlled by the visual cortex and frontal eye fields.
What eye movements does the frontal field control?
- “Movements of command”- independent of moving stimuli
- “jumpy”
Eye movements can be controlled by the visual cortex and frontal eye fields.
What eye movements does the visual field control?
- In response to visual stimuli
- Tracking moving objects
- Smooth movements
All cranial nerve the ventral aspect of the brain, except…
CNIV, exits anteriorly
Describe the location of the frontal lobe
Anterior to the central sulcus and superior to the lateral sulcus
Describe the location of the Parietal Lobe
- Posterior to the central sulcus
- Superior to the lateral sulcus
- Anterior to a line from the parieto-occipital sulcus to the pre-occipital notch
Describe the location of the Occipital Lobe
-Posterior to a line from the parieto-occipital sulcus to the pre occipital notch
Describe the location of the Temporal Lobe
- Inferior to the lateral sulcus
- Posteriorly by a line from the parieto-occipital sulcus
What is the most superior trigeminal sensory nucleus?
Mesencephalic nucleus which extends from the upper pons to the midbrain
Name the nuclei in the brainstem shared by more than one cranial nerve
Solitary Nucleus
Inferior and Superior Salivartory Nuclei
Nucleus Ambiguus
Features of the Solitary Nucleus?
Taste and Visceral Sensory info
V shape from upper to lower medulla
CN VII, IX, X
Features of the Inferior and Superior Salivartory Nuclei?
Parasympathetic efferents to ganglia of salivary glands and Pteryygopalatine ganglion
CN VII and IX
Features of the Nucleus Ambiguus?
Motor efferents to muscles of pharynx and larynx
Upper medulla
CN IX, X
Telencephalon
Cerebral hemispheres
Diencephalon
Thalamus, hypothalamus
Mesencephalon
Midbrain
Metencephalon
Pons, cerebellum
Myelencephalon
Medulla Oblongata
