Neuro Anatomy (Felts) Flashcards
What makes up the Diencephalon?
The Thalmus and Hypothalmus
What structures make up the brainstem?
- Midbrain
- Pons
- Medulla Oblongata
What are the 4 major types of Glial cells in the CNS?
- Astrocytes
- Oligodendrocytes
- Microglia
- Ependymal cells
What is the role of Astrocytes in the CNS?
Support
Maintenence of the blood-brain barrier
Environmental homeostasis
What cells are responsible for the production of myelin in the CNS?
Oligodendrocytes
(Schwann cells in the PNS)
What is the structure shown?
Node of Ranvier
Periodic gap in the myelin sheath. Allows APs to jump from one node to the next.
What is the name of the immune and antigen presenting cells in the CNS?
Microglia
What are Ependymal cells?
Cells that line the ventricles of the CNS
Ciliated cuboidal/columnar epithelium
What is the difference between a fissure and a sulcus?
A fissure is deeper
Within the brain, where is grey and white matter found?
Grey matter on the outside
White matter in the medullary centre
Within the spinal cord, where is grey and white matter found?
Grey matter on the inside in an H shape
White matter on the outside
What does the insula do?
The insula plays an important role in the patient’s experience of pain
What are the layers of the meninges of the brain from superficial to deep?
- Dura Mater
- Arachnoid Mater
- Subarachnoid space contains CSF
- Pia Mater
How does blood from the brain drain?
Drains into a system of Dural Venous Sinuses
The dural venous sinuses drain into the internal jugular vein
What are the denticulate ligaments?
A ligament formed of pial and arachnoid tissue that anchor the spinal cord, along its length at each side, to the dura mater.
What are the lateral horns and at which spinal level are they found?
T1-L2
Contain the preganglionic sympathetic neurons
Describe the arterial supply to the spinal cord
- 3 major longitudanal arteries- 1 anterior, 2 posterior. Origninate from vertebral arteries and run full length of cord
- Segmental arteries- derived from vertebral, intercostal and lumbar arteries
- Radicular arteries- travel along dorsal and ventral routes
What is the epidural space?
The space between the dura and the bone which contains adipose tissue and anterior and posterior epidural venous plexuses.
Describe Ascending tracts
Ascending tracts carry sensory information from the body to the brain. A good example is pain perception.
Describe descending tracts
Descending tracts carry motor instruction (e.g. to move the arm), down the spinal cord to the body
Give examples of ascending tracts
Dorsal Column (medial lemniscus system)
Spinothalamic Tract
What is the role of the Dorsal Column/Medial Lemniscus System and where do the fibres cross?
Fine touch and proprioception
Fibres cross in the medulla
What is the role of the spinothalamic tract and where do the fibres cross?
Carries pain, temperature and deep pressure
Fibres cross segmentally
Does this region of the brain pick up sensory or motor signals?
Sensory
This image shows the sensory cortex located in the parietal lobe, just posterior to the central sulcus
Where is the motor cortex located?
An area of the frontal lobe, immediately amterior to the central sulcus
What is the role of the corticospinal/pyramidal tract?
Motor tract
Role in fine and precise movement, partcularly in the distal limb muscles (e.g. digits)
Describe what happens at the decussation of the pyramids in the medulla
Arount 85% of the fibres of the corticospinal tract cross at the caudal medulla at the decussation of the pyramids
Crossed fibres form the lateral CST
Uncrossed fibres form the ventral CST which cross segmentally
What are some of the motor tracts known collectively as the ‘extrapyramidal system’ and what do they do?
- Tectospinal Tract- Mediate reflex head and neck movement due to visual stimuli
- Reticulospinal Tract- Influences voluntary movement and reflexes
- Vestibulospinal Tract- Excitatory input to ‘antigravity’ extensor muscles
What are the lobes of the cerebellum?
- Anterior lobe
- Posterior Lobe
- Flocculonodular Lobe
How is the cerebellum attached to the brainstem?
Via 3 cerebellur peduncles- superior, middle (largest) and inferior
What is the ‘Arbor Vitae’?
‘Tree of Life’
The branching core of white matter in the cerebellum
What are the layers of the cerebral cortex?
Molecular layer (outer)
Purkinje cell layer
Granule cell layer (inner)
Where do afferent inputs to the cerebellum enter?
They enter via cerebral peduncles and project mainly into the granule cell layer
In which layer of the cerebral cortex do efferent projections arise?
Purkinje layer
True or False?
Cerebellar hemispheres influence the contralateral side of the body
False
They influence the Ipsilateral side
This means that lesions also lead to ipsilateral signs and symptoms
What might occur due to a midline cerebellar lesion?
Disturbance of postural control
Patient will tend to fall over when standing or sitting depite preserved limb coordination
What would a unilateral cerebellar lesion result in?
Disturbance of coordination in the limbs
What occurs due to bilateral cerebellar dysfunction?
Slowed slurred speech, bilateral incoordination of the arms and a staggering wide based gait (cerebral ataxia)
Acute alcohol exposure typically results in bilateral cerebral hemisphere dysfunction and presents with cerebral ataxia
What are the basal ganglia and what is there role?
A number of masses of grey matter located near the base of each cerebral hemisphere
- Facilitate purposeful movement
- Inhibit unwanted movements
- Play a role in posture and muscle tone
What makes up the basal ganglia?
- Caudate nucleus
- Putamen
- Globus Pallidus
- Subthalmic Nucleus
- Substantia Nigra
What structures make up the striatum?
The caudate nucleus and putamen
What structures make up the Corpus Striatum?
Caudate Nucleus, Putamen and Globus Pallidus
What structures make up the Lenticular Nucleus?
Putamen and Globus Pallidus
What structures are highlighted here?
The substantia nigra
How do the basal ganglia work with the motor cortex to enhance normal movement?
Direct Pathway
Works to enhance the outflow of the thalamus, which enhances the desired movement
How do the basal ganglia work with the motor cortex to supress unwanted movement?
Involves the subthalmic nucleus
Inhibits the outflow of the thalamus
What side of the body do unilateral lesions to the basal ganglia affect?
The Contralateral side
What motor signs do lesions to the basal ganglia cause?
Changes in muscle tone
Dyskinesis (abnormal involuntary movements):
- Tremor (sinusoidal movements)
- Chorea (rapid, asymetrical movements, affecting distal limb musculature)
- Myoclonus (muscle jerks)
What disease is shown in this midbrain?
Parkinsons
The dark colour of the substantia nigra disappears due to the degeneration of the dopaminergic neurons
What signs does Parkinsons cause?
Akinesia, rigidity and resting tremor
What type of inheritence is Huntingtons disease?
Autosomal Dominant
Describe the Pathology and signs of Huntingtons
Pathology= progressive degeneration of the basal ganglia and cerebral cortex
Signs= chorea and progressive dementia
What structure is highlighted here?
The olfactory bulb
What are the motor cranial nerves?
CNIII, IV, VI, XI, XII
What does the edinger-westphall nucleus do?
Supplies preganglionic parasympathetic fibres to the eye
Constrics pupil, accomodating the lens, convergence of the eyes
What are the modalities of the occulomotor (CNIII) nerve?
Somatic motor and parasympathetic
- Edinger-Westphall Nucleus (preganglionic parasympathetic neurons)
- Occulomotor nucleus (somatic motor neurons)
What nuclei of CNVIII influence the eye muscles?
- Edinger-Westphal- parasympathetic
- Sphincter Pupillae
- Ciliary muscle
- Occulomotor nucleus- somatic motor
- Levator palpebrae superioris
- SR, MR, IR, IO
What cranial nerves have mixed modalities?
CNs V, VII, IX, X
What are the Trigeminal Sensory Nuclei?
- Mesencephalic Nucleus
- Propriception info from chewing muscles
- Pontine Trigeminal Nucleus/ Principle Nucleus
- Discriminitive touch, vibration
- Spinal Nucleus
- Pain, temperatue
What cranial nerves share the Solitary nucleus?
CNs VII, IX and X
Taste and visceral sensory information
What cranial nerves share the superior and inferior salivatory nuclei?
CNs VII and IX
Parasympathetic efferents to the ganglia of salivary glands and the pterygopalatine ganglion
What cranial nerves share the nucleus ambiguus?
CNs IX and X ( cranial part of XI)
Motor efferents to pharynx, larynx and upper oesophagus
What is the reticular formation?
A set of interconnected nuclei located throughout the brainstem
Describe the tonopic organisation seen in the auditory cortex
Fibres that carry information related to low frequency sounds end in the anterolateral part of the auditory cortex
Those carrying high frequency information end in the posteromedial part
Define Aphasia
Inability to use language
What is this area of the brain and what is its role?
Brocas area
Responsible for generating speech
What occurs if Broca’s area is damaged?
Patient will have difficulty producing language- often will only use a few words or the most important words in a sentence
Do not usually have any difficulty comprehending language
What is the name of this region of the brain and what is it responsible for?
Wernicke’s area
Important for language development
What occurs if Wernicke’s area is damaged?
Patients have difficulty comprehnding language
Can have defects ranging from words out of order or speaking gibberish
Where is the primary visual cortex concentrated?
The calcarine sulcus
Describe the representation of the visual field on the visual cortex
The lower visual field is projected to the gyrus superior to the calcarine sulcus
The upper visual field is projected to the gyrus inferior to the calcarine sulcus
Describe Meyers loop
Fibres from the geniculocalcarine tract initially form part of the internal capsule
Those carrying visual information from the upper half of the visual field, first loop anteriorly around the temporal part of the lateral ventricle in Meyer’s loop, ending below the calcarine sulcus
Describe the pupillary light reflex
Shine a light into the right eye
The right pupil will constrict= direct light reflex
Left pupil will also constrict= consensual light reflex
What are association fibres?
Bundles of axons (white matter tracts) that connect cortical sites lying in the same hemisphere
What are commisural fibres?
Connect one hemisphere to the other
E.g. the corpus collosum
What are projection fibres?
Connect hemispheres to deeper structures including the thalamus, corpus striatum, brain stem and spinal cord
