MLT GlobeAnatomy: Nervous system – page 2
56 Anatomy MCQs on Nervous system with answers and explanations.
The thin, parallel, leaf-like folds of the cerebellar cortex are called:
The cerebellar surface is folded into narrow folia. Gyri and sulci describe the cerebral cortex, and rugae are mucosal folds of the stomach and vagina.
A needle passed from the skull inward toward the brain will meet which meningeal layer first?
From outside in: dura mater, arachnoid mater, subarachnoid space with CSF, then pia mater adhering to the brain surface.
Which fold of the inner dural layer lies in the longitudinal fissure, separating the two cerebral hemispheres?
The sickle-shaped falx cerebri separates the hemispheres. The tentorium roofs the posterior fossa, and the falx cerebelli divides the cerebellar hemispheres.
Traditionally, each cerebral hemisphere is divided into how many lobes named after the overlying skull bones?
The frontal, parietal, temporal and occipital lobes are named for the bones above them. The insula is sometimes counted as a fifth lobe.
How many pairs of cranial nerves arise from the brain?
There are 12 pairs of cranial nerves, from olfactory (I) to hypoglossal (XII). The figure 31 refers to pairs of spinal nerves.
The corpus callosum connects the right and left cerebral hemispheres. It is therefore made of:
Commissural fibres cross the midline between hemispheres; the corpus callosum is the largest commissure. Association fibres stay within one hemisphere.
In a peripheral nerve, each bundle (fascicle) of nerve fibres is surrounded by which connective tissue sheath?
Perineurium wraps each fascicle. Epineurium encloses the whole nerve, endoneurium surrounds individual fibres, and myelin is not connective tissue.
Which feature is characteristic of mature neurones?
Neurones rely heavily on glucose, so hypoglycaemia quickly impairs brain function. Typical neurones have one axon, many dendrites, and do not divide.
The dural sac surrounding the spinal cord and cauda equina ends at approximately which level?
The dural sac ends at about S2, well below the spinal cord (L1–L2), so the subarachnoid space extends through the lumbar region.
Which spinal dermatome supplies the skin around the umbilicus?
The umbilicus is the T10 dermatome; T4 is at the nipple and L1 at the inguinal region. These landmarks help localise spinal lesions.
During a lumbar puncture to collect CSF for the laboratory, the needle tip must enter which space?
CSF circulates in the subarachnoid space between arachnoid and pia mater. The epidural space holds fat and veins and is used for epidural anaesthesia.
The fine filament anchoring the lower end of the spinal cord to the coccyx is derived from which meningeal layer?
The filum terminale is a pia mater extension from the conus medullaris; it is later wrapped by dura to reach the coccyx.
Which of the spinal nerve plexuses is the smallest?
The coccygeal plexus, from S4–Co1, is tiny and supplies skin around the coccyx. The sacral plexus forms the large sciatic nerve.
A fracture of the surgical neck of the humerus most commonly damages which nerve?
The axillary nerve winds around the surgical neck, so fractures there can paralyse deltoid. The radial nerve is at risk with midshaft fractures.
The diaphragm's motor supply, the phrenic nerve, arises from which spinal roots?
The phrenic nerve arises from C3–C5 ('C3, 4, 5 keeps the diaphragm alive'). C5–T1 forms the brachial plexus.
Which is the largest terminal branch of the brachial plexus?
The radial nerve, from the posterior cord, is the largest branch and supplies the extensors of the arm and forearm.
Dorsal and ventral roots join to form a spinal nerve, which exits the vertebral column through the:
Spinal nerves pass through intervertebral foramina between adjacent vertebrae. The vertebral foramen holds the cord; transverse foramina carry vertebral arteries.
Dorsal root ganglion cells have one short process that splits into peripheral and central branches. Such neurones are:
Pseudounipolar sensory neurones have a single process that divides in a T-shape. Bipolar neurones (retina, olfactory) have two separate processes.
Which part of the brainstem is continuous with the spinal cord at the foramen magnum?
The medulla oblongata, the lowest brainstem part, becomes the spinal cord at the foramen magnum. The pons and midbrain lie above it.
Lumbar puncture for CSF is done below L2 in adults mainly because the spinal cord (conus medullaris) ends at about:
The adult cord ends near L1–L2, so a needle at L3/L4 or L4/L5 enters CSF among cauda equina roots without hitting the cord. The dural sac continues to S2.