Flashcards in Neuroanatomy Deck (143):
What are the 3 visible swellings/vesicles in the neural tube early in development?
What are the further subdivision of the vesicles of the neural tube?
Telencephalon, Diencephalon - Prosencephalon
Metencephalon, Myelencephalon - Rhomboencephalon
What derives from the secondary vesicle - Telencephalon?
What derives from the secondary vesicle - Diencephalon?
What derives from the secondary vesicle - Mesencephalon?
What derives from the secondary vesicle - Metencephalon?
What derives from the secondary vesicle - Myelencephalon?
During development, when do the primary and secondary vesicles form?
Primary - 4 weeks
Secondary - 6-8 weeks
What makes up the Brainstem?
What is the function of Neurones?
Receivev information (mainly via synapses), integrate the info and transfer electrical impulses to another neuron or effector cell
What are the four major types of Glial cells?
Which type of glial cells functions as a resident antigen-presenting/phagocytic cells in the brain?
What's the difference between the gyrus and sulcus?
Gyrus = bump
Sulcus = indentations (deeper than sulcus = fissure)
What's the difference between the outer grey matter and inner white matter of the brain?
Grey matter - formed by neurons (soma/cell bodies found), synapses + support cells
White matter - only axons of neurons + support cells
How is the grey and white matter arranged in the spinal cord?
Grey matter on inside (cell bodies - H-shape)
White matter - outside, surrounds grey matter (axons)
How can you tell the orientation of the spinal cord from the grey matter?
Posterior side of the H-shaped grey matter will touch edge of spinal cord.
Anterior side of grey matter will not reach edge
What are the divisions of the white matter in the spinal cord?
Posterior (dorsal) column
Anterior (ventral) column
How are the anterior and posterior ends of the grey matter referred to?
Anterior (ventral) HORNS
Posterior (dorsal) Horns
What are the gyrus on either side of the Central Sulcus?
Precentral Gyrus (anterior)
Postcentral Gyrus (posterior)
What are the 4 lobes of the cerebral hemispheres?
Which sulcus marks the boundary between the Frontal and Parietal lobes?
(continue line down from central sulcus to corpus callosum)
Which sulcus marks the boundary between the Parietal and Temporal lobes?
What two points mark the anterior/lateral boundary of the Occipital lobe?
What is the fifth hidden lobe of the cerebral hemisphere?
(important role in patient's experience of pain)
What are the three layers of the Meninges (superificial to deep)?
Arachnoid mater (subarachnoid space)
What is the deepest layer of the meninges which follows the dips of the sulcus/gyrus?
(dura + arachnoid just a general protective cover)
Between which layers of the meninges contains the cerebrospinal fluid (CSF)?
Subarachnoid space between the Arachnoid space AND Pia mater
What is the Enteric Nervous System?
Found in digestive system (oesophagus to rectum)
Neurons found in two plexuses in walls of gut (myenteric plexus between outer layers of smooth muscle, submucosal plexus in submucosa)
What is the venous drainage system of the brain?
Blood from the brain drains into a system of dural venous sinuses
Then drains into internal jugular vein
Exits via Jugular Foramen
What is the name for the con-shaped end of the spinal cord?
True or False:
The spinal meninges are continuous with the cranial meninges via the foramen magnum
True or False:
The spinal cord is suspended in the canal by a ribbon of tissue on the lateral aspect called the Denticulate Ligament?
True or False:
The denticulate ligament is formed of arachnoid and dura tissue?
Formed of pial and arachnoid tissue
Attaches to dura at points along length of cord
What does the white matter of the spinal cord consist of?
Longitudinally oriented 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 added feature exists in the T1 to L2 spinal segments?
Lateral Horn (of grey matter)
Contains preganglionic sympathetic neruons
What are the three arterial supplies to the spinal cord?
What is the origin of the Longitudinal arteries and where do they run?
1 anterior and 2 posterior that originate from the vertebral arteries
Run the length of the cord
Where are the Segmental arteries derived from?
Vertebral, Intercostal and Lumbar arteries
Where do Radicular arteries travel?
Along the dorsal and ventral roots
What is the space between the dura and the bone called in the spinal cord?
What does it contain?
Contains adipose tissue, anterior + posterior epidural venus plexuses
What two parts is the dorsal (posterior) column of the spinal cord?
What sensory info does the dorsal column/medial Lemniscus system transmit?
Fine touch and conscious proprioception (particularly from upper limb)
Where do fibres cross in the medial lemniscus system?
What is Proprioception?
Sense of self-movement and body position
What sensory info does the Spinothalamic tract transmit?
Carries pain, temperature and deep pressure
Where do fibres cross in the spinothalamic tract?
Fibres cross segmentally (at the vertebrae level they enter)
True or False:
The Ascending tract of the spinal cord contains motor information
Ascending tract is sensory information
Descending tract is Motor
What motor functions does the Corticospinal Tract transmit?
Fine, precise movement
Particularly of distal limb muscles, e.g. digits
Why is the Corticospinal Tract also called the Pyramidal tract?
Tract forms visible ridges referred to as 'pyramids'on the anterior surface of the medulla
Where does the Corticospinal Tract (CST) fibres cross?
About 85% of fibres cross in caudal medulla at decussation of pyramids
Crossed fibres form Lateral CST
Uncrossed fibres form the Ventral CST (cross segmentally)
What is the Internal Capsule?
White matter structure containing ascending and descending axons going to and from the cerebellum.
All modalities travel through the internal capsule
What are the three motor systems outside of the pyramidal tract (aka Extrapyramidal system)?
What motor functions is the Tectospinal tract involved?
Input mostly to cervical segments
Responsible for movement of head + upper body
What reflex is the Tectospinal tract though to be involved in?
Mediated reflex head and neck movement due to visual stimuli
What is the Reticular formation?
Forms the central core of the brainstem. Has many nuclei + receives input from virtually all parts of CNS
Where do fibres originate in the reticular formation?
Pons and Medulla
What is the motor function of the Reticulospinal Tract?
Pons - facilitate extensor movements + inhibit flexor movements
Medulla - opposite
Where do the fibres originate in the Vestibulospinal Tract?
Originate in the vestibular nuclei of pons and medulla
(in turn receive input from vestibular apparatus + cerebellum)
What is the motor function of the Vestibulospinal Tract?
Excitatory input to 'antigravity' extensor muscles
Pushed from behind > will stumble and catch yourself
What causes Brown-Sequard's Syndrome?
Lateral hemisection of spinal cord (destroys one side of spinal cord but other left intact)
Where is the Primary motor area?
What attaches the brainstem to the cerebellum?
Peduncles (3 stalks)
Superior, Middle (largest) + Inferior
What is the function of the Peduncle?
Stump of white matter than carries fibres in and out of cerebellum
What are the Deep Cerebellar Nuclei?
Embedded grey matter within white matter of cerebellum
What are the 3 layers of the Cerebellar Cortex (outer to inner)?
Outer = Molecular layer
Middle = Purkinje cell layer
Inner = Granule cell layer
Where to afferents to the cerebellum tend to arrive from?
- Spinal cord (somatic proprioceptors + pressure receptors)
- Cerebral cortex (relayed via pons)
- Vestibular apparatus (vis vestibular nuclei)
How do afferent projections (input) enter the cerebellum
Enter via cerebellar peduncles and project mainly to granule cell layer
How do efferent projections (output) leave the cerebellum?
From all 3 lobes the only output is via axons of Purkinje cells
Synapse on neurons of deep cerebellar nuclei + contribute to function of all motor tracts of brain stem + spinal cord
Where do efferent fibres from Cerebellum cross the midline?
Most efferent axons of deep cerebellar nuclei cross the midline + synapse in the THALAMUS
Thalamus then sends fibres to motor cortex
What are the signs of a unilateral hemispheric lesion of the cerebellum?
Disturbance of coordination in limbs
Can result in tremor + unsteady gait in absence of weakness or sensory loss
What are the signs of a Bilateral cerebellar dysfunction?
Results in slowed, slurred speech (dysarthria), bilateral incoordination of arms, staggering wide-based gait (cerebellar ataxia)
What common thing can cause bilateral cerebellar hemisphere dysfunction?
Acute alcohol exposure
Cerebellum is very sensitive to alcohol
True or False:
Cerebellar hemispheres influence ipsilateral side of body = lesions lead to ipsilateral signs + symptoms
What are the functions of the Basal Ganglia?
- To facilitate purposeful movement
- Inhibit unwanted movements
- Role in posture and muscle tone
What is a basal ganglia?
A number of masses of grey matter located near the base of each cerebral hemisphere
What are the 5 structures making up the basal ganglia?
Which structures make up the Striatum?
Caudate nucleus +
Which structures make up the Lenticular Nucleus?
Which structures make up the Corpus Striatum?
Caudate nucleus +
Why is the Substantia Nigra recognisable within the brain?
Structure stains itself black
Produces dopamine and by-product dyes structure darker colour than surrounding (neuromelanin)
What is the pathology of Parkinson's Disease?
Degeneration of dopaminergic neurons of substantia nigra
True or False:
Unilateral lesions of basal ganglia affect the ipsilateral side of body
Affects contralateral side of body (cerebellar lesions affect ipsilateral side)
True or False:
Lesions of basal ganglia generally DO NOT cause paralysis, sensory loss, loss of power or ataxia
What motor signs are seen with lesions of basal ganglia?
Changes in muscle tone
Dyskinesias (abnormal involuntary movements) - tremor, chorea, myoclonus
Why do lesions affecting the indirect pathway of the basal ganglion cause jerky movements?
Involuntary exaggerated jerky movements can occur because the inhibitory system is not preventing them
What is the pathology of Huntington's Disease?
Progressive degeneration of basal ganglia and cerebral cortex
What are some signs of Parkinson's and Huntington's Disease?
Parkinson's - akinesia, rigidity, resting tremor
Huntington's - chorea, progressive dementia
How many pairs of cranial nerves are there?
Name the twelve cranial nerves in order
Which of the cranial nerves are purely sensory modality?
Which of the cranial nerves are purely motor modality?
Which of the cranial nerves have mixed modality?
True or False:
All of the cranial nerves exit ANTERIORLY
All exit anteriorly
CN IV (trochlear) - posteriorly
CN VIII (vestibulocochlear) - laterally
Which of the twelve cranial nerves is the only one not the synapse in the thalamus prior to reaching the cortex?
Explain the structure of the olfactory nerve where it penetrates the cribiform plate of the ethmoid bone
Olfactory tract travels through the cranium and forms the Olfactory Bulb which sits superior to cribiform plate
The olfactory nerves exit the bulb and penetrate the bone to sit within the olfactory membrane
What muscles does the Oculomotor nerve innervate?
Extraocular muscles - SR, MR, IR, IO
Levator pupillae sphincter
Sphincter pupillae + cilliary muscle (parasympathetic)
Which three cranial nerves innervate the extraocular muscles of the eye?
Which muscles foes the Hypoglossal nerve innervate?
(All muscles of the tongue except one)
What are the three main functions of the Trigeminal nerve?
1. Somatosensation of face
2. Proprioception associated with chewing (TMJ, mastication muscles, teeth)
3. Motor Control (muscles of mastication, tensor tympani, mylohyoid, etc.)
What are the three parts of the trigeminal sensory nuclei?
Pontine Trigeminal Nucleus
What are the three different functions of the nuclei of the trigeminal sensory column?
Mesencephalic nucleus - Proprioception info from chewing muscles
Pontine nucleus - discriminative touch, vibration
Spinal nucleus - pain, temperature
What is the only site in the CNS where cell bodies of primary afferent neurones live inside the CNS?
What are some of the functions of the Facial nerve?
1. Motor - muscles of facial expression, stapedius
2. Parasymp. - pterygopalatine, submandibular ganglia
3. Taste - anterior 2/3rds of tongue (via chorda tympani)
What are some of the functions of the Glossopharyngeal nerve?
1. Tactile sense, pain and temperature from posterior tongue, pharyngotympanic + upper pharynx
2. Taste - posterior 1/3rd tongue
3. Parasymp. - fibres to otic ganglion (parotid gland)
4. Motor - stylopharyngeus
What are some of the functions of the Vagus nerve?
1. Tactile sense, pain + temp sense from pharynx, larynx, trachea, oesophagus + viscera
2. Taste - epiglottis
3. Parasymp. - inn. to ganglia serving thoraxix + abdominal viscera
4. Motor - striated muscle of pharynx + larynx
True or False:
The motor fibres of the facial nerve loop around the abducens nucleus before reaching the facial motor nucleus
What are the four nuclei of the glossopharyngeal nerve in the upper medulla?
Solitary nucleus - gustatory nucleus
Spinal Trigeminal nucleus (small region of somatosensory assoc. with ear)
Inf. Salivatory nucleus (parasymp.)
Nucleus Ambiguus (stylopharyngeus)
What are the 4 components of the vagus nerve in the upper medulla?
Dorsal (motor) nucleus (parasymp)
Spinal trigeminal nucleus
Which cranial nerves share the solitary nucleus?
VII (Facial) - ant 2/3 tongue
IX (Glossopharyngeal) - post 1/3 tongue
X (Vagus) - epiglottis
Taste + visceral sensory information
Which cranial nerves share the Sup. and Inf. Salivatory nuclei?
Parasympathetic efferents to ganglia of salivary glands + pterygopalatine ganglion)
Which cranial nerves share the Nucleus Ambiguus?
Motor efferents to muscles of pharynx, larynx + upper oesophagus)
What is the part of the pyramidal tract that is motor to cranial nerves?
(includes fibres to the motor nuclei of CN V, VII, X, XII)
Which cranial nerves get input containing parasympathetic efferents?
III, VII, IX, X
What is the path of input to CN's containing parasymp. efferents?
- Input mainly from hypothalamus
- Efferents reach preganglionic autonomic neurons (directly + via synapses in reticular formation)
(Hypothalamus influenced by physiological status + input from many brain regions)
What is the Reticular Formation?
Network of loosely aggregated cells with cell bodies, axons and dendrites intermingling in central core of brainstem
What are the three bones of the middle ear?
What is the main cranial nerve for hearing & balance (number + name)?
What is the Organ of Corti?
Sensitive element in inner ear which is the receptor organ for hearing (body's microphone)
Situated on basilar membrane in one of the three compartments of the Cochlea (contains 4 rows of hair cells protruding from surface)
Why is the Superior Olivary nucleus important in hearing?
Important in sound localisation - knowing where the sound comes from
What is the bulletpoint pathway from cochlea to primary auditory cortex?
Ventral cochlea nucleus + Dorsal Cochlear nucleus >
2nd order neurones ascend bilaterally >
Superior olivary nucleus >
Inferior colliculus >
Thalamus (synapse in thalamus = medial geniculate body) >
Primary auditory cortex
Would you be concerned about a brainstem injury if someone had unilateral hearing loss?
Bilateral projection in brainstem from cochlea so a unilateral hearing loss indicates a pathology earlier in pathway
Which of these coloured areas shows the Primary Auditory Cortex?
INSERT PICTURE (lecture 11 - slide 9)
Which of these coloured areas shows the Somatosensory cortex?
Which of these coloured areas shows the Primary Motor Cortex?
How is the auditory cortex tonotopically organised?
Fibres carrying info regarding LOW frequency sound end in anterolateral part of cortex
HIGH frequency sounds end in posteromedial part
What is Aphasia?
Inability to use language
What occurs if there is damage to Broca's area?
Difficulty producing language
Use few words or only say important words
Have no difficulty comprehending language
What occurs if there is damage to Wernicke's area?
Difficulty comprehending language
Can manifest defects ranging from words out of order to meaningless words
Which parts of the inner ear are important in balance?
+ Vestibular nerve (CN VIII)
True or False:
The projection of vestibular information onto the cerebral cortex is bilateral
How are the visual fields on the retina often described?
What is the bulletpoint pathway from the Retina of the eye to the visual cortex?
Optic nerve >
Optic chiasm >
Optic tract >
Lateral geniculate nucleus (of thalamus) >
Temporal or Parietal for sup./inf. fields >
What is the mneumonic for distinguishing between temporal and parietal as superior or inferior fields?
Which of these coloured areas shows the Primary Visual Cortex?
Where does the macula project to?
Posterior pole of visual cortex
How is the Meyer's Loop related to the visual pathway?
- Fibres of geniculocalcarine tract initially form part of internal capsule
- Those carrying visual info from upper half of visual field LOOP ANTERIORLY around temporal part of lateral ventricle in MEYER'S LOOP
- End below calcarine sulcus
What are the two forms of eye movement?
Movements of command (jump/jerk, comes from frontal eye fields)
Tracking movements (smooth, controlled by visual cortex)
What is the Pupillary Light Reflex?
Shine light into one eye = pupil constricts (direct light reflex)
Other pupil also constricts (Consensual light reflex)
Edinger-Westphal nucleus is in midline = bilateral projection activates both eyes
How does the accommodation reflex involve?
Convergence of gaze
Contraction of ciliary muscles
Where does the accommodation reflex require input from?
Oculomotor and Edinger-Westphal nucleus from visual cortex
What is Hemianopia?
Blindness for half the field of vision in one or both eyes