Neuroscience Flashcards
Define colliculus
Swellings on the roof of the midbrain involved in vision and hearing
Superior colliculus - vision
Inferior - hearing
Define ganglion
An area of concentrated cell bodies
Define sulcus
A groove between two sulci
Define gyrus
A ridge or fold between two clefts i.e. a raised area
Which cells myelinate the PNS and CNS?
PNS - Schwann cells
CNS - oligodendrocytes
What are microglial cells?
What is their origin?
Immune cells
Mesoderm
Which cell types make up the grey matter?
Neurone cell body and dendrites
Microglial cells
Astroglial cells
Which cells make up the white matter?
Myelinated axon
Microglial cells
Oligodendrocytes
Which conditions occur due to failure of the neural tube to close..
a) cranially
b) caudally
a) anencephaly
b) spina bifida
The neural tube forms three primary brain vesicles.
Name them and their corresponding adult features.
Prosencephalon - forebrain
Mesencephalon - midbrain
Rhombencephalon - hindbrain
Which secondary brain vesicles form from the proscenphalon?
What are the corresponding adult features?
Telencephalon - cerebral cortex and basal ganglia
Diencephalon - thalamus and hypothalamus
Which secondary brain vesicles form from the rhombencephalon?
What are the corresponding adult features?
Metencephalon - pons and cerebellum
Myelencephalon - medulla
From what secondary brain vesicle does the basal ganglia develop?
Telencephalon
From what PRIMARY brain vesicle does the medulla develop?
Rhombencephalon
Which cells make up the blood-brain barrier?
Astrocytes
What are the two different types of astrocyte?
Fibrous - white matter, cover nodes of Ranvier
Protoplasmic - grey matter, cover synapses
What is the function of ependymal cells?
THey line the ventricles and monitor + circulate CSF.
They are also concentrated in the choroid plexus where they make CSF.
Name the 6 layers of the cerebral cortex from the surface to deep. Give important functions.
I - molecular
II - outer granular layer
III - outer pyramidal layer
IV - inner granular layer - major input from thalamus
V - inner pyramidal - major output
VI - multiform cell layer - output to thalamus
What is the difference between agranular and hypergranular cortex? Give examples.
Agranular - thin IV layer, thick V layer. An example is the motor cortex as this needs lots of output.
Hypergranular - thick IV, thin V layer. An example is the sensory cortex as it needs lots of input.
What is the archicortex? Give en example.
3 layers.
e.g. hippocampus
What is the difference between unipolar and multipolar neurones?
Multipolar - multiple neurites coming from the cell body. They are motor neurones. Their cell body is in the spinal cord.
Unipolar - single neurite coming from cell body. They are sensory neurones with their cell body in the dorsal root ganglion.
What information do Ib peripheral nerves carry?
Golgi tendon organs
What information do Abeta peripheral nerves carry?
Touch, kinaesthesia, muscle spindle
What information do A-delta peripheral nerves carry?
pain, crude touch, pressure and cold temperature
What information do B peripheral nerves carry?
Preganglionic automatic signals
What information do IV peripheral nerves carry?
pain, touch, pressure and temperature
Which of Rexed’s laminae do A-delta fibres terminate?
I and V
What is the function of Merkel Cells?
touch and pressure
What is the function of meissner’s corpuscles?
Detect low frequency vibrations
What is the function of Ruffini corpuscles?
Skin stretch and slippage
What is the function of pacinican corpuscles?
High frequency vibrations
By which type of nerve are free nerve endings innervated?
Adelta = myelinated and fast
C = unmyelinated and slow
Which types of nerves are rapid adapting?
What are rapid adapting nerves?
Meissner’s corpuscle, Pacinian corpuscle and hair follicle receptors
They respond to application and removal, and lose their response if the stimulus is prolonged.
What types of nerves are slow adapting?
What are slow adapting nerves?
Merkel Cells, hair follicles, Ruffini’s corpuscles
They remain active for the length of the stimuli. Increasing pressure increases the firing rate.
What is the receptive field of a receptor?
It is the space it occupies that can elicit a response to a stimulus.
What information is carried by the lateral and anterior corticospinal pathways? Where do they cross?
Lateral - fine movement of limbs; crosses at level of pyramids
Anterior - fine movement of axial muscles; crosses at the spinal level
What information is carried by the anterior and lateral spinothalamic pathways?
Anterior - pressure and crude touch
Lateral - temperature and pain
What information is carried by the anterior and posterior spinocerebellar pathways?
Both carry proprioceptive information
Where do they anterior and posterior spinocerebellar pathways cross over?
Anterior - performs a double cross, once at the spinal level and again further up to enter the cerebellum
Posterior - does not cross at all as it ascends
What is the substantia gelatinosa and what is its relevance?
It is Rexed’s laminae II + III and it is where the spinothalamic tract synapses in the dorsal horn.
Where in the thalamus does the spinothalamic tract synapse?
Ventroposterolateral (VPL) nucleus
Where is the lesion likely to be if pain and temperature AND fine touch is lost on one side of the body?
It indicates that the lesion is above the level of the spinal cord.
What is sensory ataxia?
It is a movement disorder associated with sensory loss:
1) broad gait with stamping
2) Romberg’s sign +ve
3) Pronator drift
4) Loss of two-point discrimination
Which part of the trigeminal nucleus receives information about facial proprioception?
Mesencephalic
Which part of the trigeminal nucleus receives information about facial pain and temperature?
Spinal nucleus
Which part of the trigeminal nucleus receives information about facial fine touch?
Chief sensory nucleus
What is a motor unit?
A motor neurone and the skeletal muscle fibres it innervates
What are some symptoms of lower motor neurone lesions?
Flaccid paralysis Paresis Loss of reflexes Loss of tone Fasciculations Fibrillations
What is the function of the reticulospinal tract?
locomotion and posture control,
What is the function of the corticobulbar tract?
From cortex –> medulla
Innervate cranial nerves V, VII, XI and XII
Is CNV innervated bilaterally by the corticobulbar tract?
Yes.
Cranial nerves V and XI are innervated bilaterally, but VII and XII are innervated contralaterally.
What is the functionof the vestibulospinal tract?
Controls anti-gravity muscles of hip and back.
It is one of the outputs of the cerebellum so it works ipsilaterally.
What is decorticate posturing? How does it occur?
It is abnormal flexion of the upper extremities.
It is caused by a lesion ABOVE the red nucleus, as this leads to loss of control of flexor reflexes.
What is decerebrate posturing? How does it occur?
It is abnormal extension of upper extremities.
It is caused by a lesion AT OR BELOW the level of the red nucleus.
Describe the corneal reflex.
Touching the cornea with cotton wisp leads to both eyes blinking.
The sensory limb is the trigeminal nerve. Then it goes to spinal nucleus of V, then motor nucleus of VII, then through CNVII to orbicularis oculi.
What cell type lines the pharyngeal clefts, arches and pouches?
Clefts - ectoderm
Arches - mesoderm
Pouches - endoderm
What cranial nerve is associated with pharyngeal arch 1-6?
1 - V 2 - VII 3 - IX 4 - X 5 - doesn't have one 6 - X
From which pharyngeal arch does the styloid process come from?
2
From which pharyngeal arch does the hyoid bone derive?
3
Which structures derive from the first pharyngeal arch?
Bones of middle ear, Meckel’s cartilage (which becomes the mandible)
From which pharyngeal arches do the tongue develop?
1st, 3rd and 4th
Which bones make up the external nose?
2x nasal bones
Ethmoid bone
Maxilla
Which bones make up the nasal septum?
Vomer forms inferior part
Ethmoid (perpendicular plate) forms posterior part
Cartilage forms anterior part
Where do the superior, middle and inferior conchae come from?
Superior and middle - from ethmoid bone
Inferior - from its own bone
What drains into the sphenoethmoidal recess?
sphenoid sinus
What drains into the middle meatus?
Frontal, maxillary, ethmoidal sinuses
What drains into the inferior meatus?
Nasolacrimal duct
Which vessels make up Little’s area?
Anterior ethmoidal arteries
Sphenopalantine artery and greater palatine artery (from maxillary)
Septal branch of superior labial artery (facial)
Describe the innervation of the tongue?
Anterior 2/3:
Sensation - Lingual (V3)
Taste - chorda tympani (VII)
Posterior 1/3 - IX
What is Stensen’s duct?
Parotid duct
Describe the innervation of the muscles of the tongue?
Intrinsic muscle - XII
Extrinsic - all XII except palatoglossus which is X
Which nerve runs through the mandible? What foramen does it exit?
Inferior alveolar branch of V3.
Mental foramen - exit of the mental nerve.
What are the two halves of the articular disc?
Upper - forwards/horizontal movement
Lower - rotational movement
What innervates the muscles of mastication?
Trigeminal - V3
What is the only muscle which opens the jaw?
Lateral pterygoid
Which nerve runs through the infratemporal fossa? Through which foramen does it get there?
Trigeminal.
V3.
Enters via foramen ovale.
Describe the anterior and posterior borders of V3.
Anterior - mainly MOTOR. Except buccal and meningeal.
Posterior - mainly SENSORY. Except myohyoid nerve.
Which ganglion is found within the infratemporal fossa?
Otic ganglion
Which artery runs through the infratemporal fossa?
Where does it go from there?
Middle meningeal artery (branch of maxillary / ext carotid)
Goes into skull via foramen spinosum.
Which venous plexus supplies the infratemporal fossa?
Pterygoid venous plexus.
Which cranial nerves are found at the pontomedullary junction?
VI, VII, VIII
Which cranial nerves will be affected by a cerebellopontine angle lesion? What symptoms will there be?
VII, VIII
Facial paralysis, hearing and equilibrium loss
Which cranial nerves are found in the preolivary sulcus?
XIII
Which cranial nerves are found in the post-olivary sulcus?
IX, X, XI
Which two muscles make up the floor of the mouth?
Mylohyoid
Geniohyoid
Which muscle makes up the bulk of the tongue?
Genioglossus
