MLT GlobeAnatomy: Nervous system – page 3
56 Anatomy MCQs on Nervous system with answers and explanations.
A patient speaks fluently but cannot understand spoken words. Which cortical area is most likely damaged?
Wernicke area in the superior temporal gyrus handles comprehension of language (sensory speech). Broca area in the frontal lobe controls speech production.
Which bundle of commissural fibres connects the right and left cerebral hemispheres?
The corpus callosum is the largest commissure linking the two cerebral hemispheres. The internal capsule carries projection fibres; the uncinate fasciculus and cingulum are association bundles.
After a stroke a patient understands speech but cannot produce fluent words. The damaged motor speech (Broca) area lies in which lobe?
Broca area is in the inferior frontal gyrus, usually of the left hemisphere. Wernicke (comprehension) area is in the temporal lobe.
The white matter lying between the posterior grey horns of the spinal cord is the:
The dorsal funiculus lies between the posterior horns and contains the gracile and cuneate fasciculi.
Which cranial nerves carry preganglionic parasympathetic fibres?
The cranial parasympathetic outflow travels in the oculomotor, facial, glossopharyngeal and vagus nerves.
Which nerve is the direct continuation of the medial cord of the brachial plexus?
The medial cord ends as the ulnar nerve. The median nerve forms from both medial and lateral cords; the radial and axillary come from the posterior cord.
Which feature correctly describes the cerebrum?
The cerebral cortex is grey matter folded into ridges (gyri) and grooves (sulci). The longitudinal fissure divides left and right hemispheres, and the posterior fossa holds the cerebellum and brainstem.
Nerve fibres linking the frontal lobe with the occipital lobe of the same hemisphere are classed as:
Association fibres connect regions within one hemisphere. Commissural fibres (e.g. corpus callosum) cross between hemispheres, and projection fibres link cortex with lower centres.
A knife cuts into a peripheral nerve from the outside. Which connective tissue layer is divided first?
The epineurium wraps the whole nerve; the perineurium surrounds each fascicle and the endoneurium each axon, so an external cut meets the epineurium first.
The inferior sagittal sinus runs in the free lower edge of the falx cerebri. It drains into the:
The inferior sagittal sinus joins the great cerebral vein to form the straight sinus, which runs to the confluence of sinuses.
Large myelinated alpha motor fibres supplying skeletal muscle have a diameter of about:
Aα motor fibres are the thickest (about 12–20 µm) and fastest-conducting. Unmyelinated C fibres are around 0.2–1.5 µm.
Testing ankle plantar flexion (standing on tiptoe) mainly assesses which spinal nerve roots?
Plantar flexion by gastrocnemius and soleus is S1–S2, also tested by the ankle reflex. L3–L4 relates to knee extension.
The deep (intrinsic) extensor muscles of the back, such as erector spinae, are supplied by:
Dorsal rami supply the deep back muscles and overlying skin. Ventral rami supply limbs and the anterolateral trunk; the accessory nerve supplies trapezius.
Which myotome pairing is INCORRECT?
Knee extension (quadriceps) is L3, L4, tested by the knee jerk. The other pairings are standard myotome values.
The median nerve enters the forearm by passing between the two heads of which muscle?
The median nerve passes between the humeral and ulnar heads of pronator teres. The ulnar nerve passes between the heads of flexor carpi ulnaris.
The uncrossed (anterior) corticospinal tract descends in which part of the spinal white matter?
About 10–15% of corticospinal fibres do not cross in the medulla and descend in the anterior funiculus; the crossed fibres run in the lateral funiculus.