DB - neuroanatomy week 1 Flashcards
What is hypomyelination?
Diminished amounts of myelin sheath
What is dysmyelination?
Disorders resulting in malformations or defects in the myelin sheath.
What is demyelination?
Disorders causing damage to pre-existing normal myelin.
What is the function of general somatic afferent nerves?
Touch, temperature and pain from non-visceral structures.
What is the function of general somatic efferent nerves?
Motor to skeletal muscles.
What is the function of general visceral afferent nerves?
Distension, touch, temperature and pain from visceral structures.
What is the function of general visceral efferent nerves?
Motor to viscera, smooth muscles and glands.
What is the function of special somatic afferent nerves?
Vision, hearing and balance.
Innervated by the optic nerve.
What is the function of special visceral afferent nerves?
Taste and olfaction.
Innervated by the facial and glossopharyngeal nerve.
What is the function of special visceral efferent nerves?
Innervates the branchial arches.
Embryological regions within the head and neck that causes skeletal muscle to grow.
What is the difference between funiculi and fasciculi?
Funiculi - white matter in the spinal cord.
Fasciculi - Axons of the same origin, destination and function.
What structures are derived from the forebrain (prosencephalon)?
Telencephalon - cerebral hemispheres and basal nuclei.
Lumen: lateral ventricle, which is found between the cerebral hemispheres.
Diencephalon - thalamus, hypothalamus.
Lumen: 3rd ventricle, which is found between the thalamus and hypothalamus.
What structures are derived from the midbrain (mesencephalon)?
Tectus - roof
Tegmentum - floor
Cerebral aqueduct, which allows the flow of CSF.
What structures are derived from the hindbrain (rhombencephalon)?
Metencephalon - pons and cerebellum
Myelencephalon - medulla oblongata
Lumen: 4th ventricle
What is the embryological cause of spina bifida?
Failure of the caudal neuropore to close.
Surrounding tissues fail to meet and fuse.
Nervous tissue can be exposed and is only protected by skin and subcutaneous tissue.
What is the embryological cause of a dermoid sinus?
Neuroectoderm tissue fails to detach from normal ectoderm.
Resembles a tube down the cervical and thoracic regions of the back.
Sometimes there is communication between the skin and spine.
What is the embryological cause of anencephaly?
Failure of the rostral neuropore to close.
Forebrain structures fail to form and this is not compatible with life.
What is the significance of the ratio of the size of the cerebrum to the cerebellum?
The smaller the ratio of cerebrum to cerebellum, the more complicated the gait cycle.
Where is the lateral horn of the grey matter situated?
In the thoracolumbar regions. It contains sympathetic nerve bodies.
What are the functional areas of the cortex?
Frontal lobe - motor cortex
Parietal lobe - somatosensory cortex
Temporal lobe - olfactory and auditory cortex
Occipital lobe - visual cortex
Why is there a cranial shift of the spinal cord segments?
The spinal cord grows at a much faster rate than the vertebrae.
What is the main blood supply to the rostral portion of the brain via the circle of Willis?
Internal carotid artery
What is the main blood supply to the caudal portion of the brain via the circle of Willis?
Vertebral arteries anastomose to form the basilar artery.
Which artery of the circle of Willis supplies the medial hemisphere?
Rostral cerebral artery
Which artery of the circle of Willis supplies the lateral and ventral hemisphere?
Middle cerebral artery
Which artery of the circle of Willis supplies the occipital lobes of the brain?
Caudal cerebral artery
How is the blood supply to the brain different in a cow?
The proximal 2/3 of the internal carotid artery is occluded by 18 months.
Anastomoses between the ICA and maxillary artery.
Anastomoses between the vertebral and maxillary artery.
What is the significance of the species difference is blood to the brain?
If the animal is killed by slaughter at the neck, then this cuts the CCA, which supplies the ICA.
However, blood supply would not be occluded due to the anastomoses between the vertebral and maxillary artery. Therefore, prolonging the suffering of the cow.
This is overcome by the practice of stunning.
How is venous blood drained from the brain?
Dorsal and ventral sagittal sinus
Straight sinus
Transverse sinus
Maxillary vein
These sinuses run between the periosteal and meningeal layer. Arachnoid granulations allow CSF to drain back through.
What is the cause of hydrocephaly?
Abnormal production or drainage of CSF from the ventricular system.
Can be caused by tumours of the midbrain or congenital issues.
What are the symptoms of cerebellar ataxia?
Ataxia - abnormal co-ordination of movement.
Spasticity - loss of inhibitory cerebellar function to fine tune motor control
Hypermetria - overshooting movements of the limbs.
Tremor - postural shaking/instability from failure to balance activities of opposing muscle groups.
Why is loss of muscle power not seen with cerebellar lesions?
Because the cerebellum feeds into and tunes the motor outputs of the brain and does not directly generate the movement.
What is the filum terminale?
A strand of pia mater that tapers off of the conus medullaris.
Where is the subarachnoid space found?
Between the arachnoid mater and the pia mater.
Where is the subdural space found?
Between the dura mater and the arachnoid mater.
What is the falx cerebri?
The fold of dura between the cerebral hemispheres
What is the tentorium cerebelli?
The fold of dura between the cerebrum and the cerebellum
What is the difference between the gyri and the sulci?
Gyri - folds or ridges
Sulci - indentations/grooves
Where is the longitudinal fissure found?
Runs down the midline and separates the left and right cerebrum
Where is the deep transverse fissure found?
Between the frontal, temporal and parietal lobes.
What is the tract that CSF can travel through the brain, starting at the lateral ventricle?
Lateral ventricle -> 3rd ventricle -> cerebral aqueduct -> 4th ventricle
