neurosciences part 1

Question 1

Three categories within the somatosensory system

Answer 1

Descriptive touch → pressure, vibration & texture
Pain & Temperature
Proprioception which targets the cerebellum

Question 2

Cells used in the descriptive touch

Answer 2

Meissner’s corpuscles
Pacinian corpuscles
Merkel’s disks
Ruffini endings

Question 3

Names of the two columns used in the dorsal pathway for the somatosensory pathway

Answer 3

Dorsal columns are made of different tracts → Gracile fasciculus and Cuneate fasciculus

Gracile fasciculus carries info from the low half of the body → legs and trunk

Cuneate fasciculus carries info from the upper half→ trunk and arms

Question 4

Where do the dorsal columns synapse (somatosensory Pathway)

Answer 4

They synapse at the medulla → cuneate nucleus and gracile nucleus

Then send afferents which form a new tract Medial lemniscus

Then they travel to the thalamus called the Ventro Posterior Nucleus (VPL)

Then they synapse at the primary somatosensory cortex

Question 5

Pain travels to the thalamus through?

Answer 5

Pain travels through the Thalamus (ventroposterior nucleus) via the spinothalamic tract

Question 6

Proprioception travels through which tract

Answer 6

via the dorsal spinocerebellar tract to the cerebellum.

Nuclei involved here are Clarke’s nucleus and external cuneate nucleus

Question 7

What is the basic Motor Pathway

Answer 7

Primary motor uses the corticospinal tract

Starts at cortex ( precentral gyrus) and ends at spine

The main pathway is called the lateral (anterior) Corticospinal pathway

Question 8

Central Visual Pathway

Answer 8

Ganglion cells axons leave the retina

They travel through the optic nerve

The optic tract wraps around the cerebral
Peduncles of the midbrain at the LGN

The LGN is part of the thalamus

Almost all axon synapse on the optic tract, therefore LGN

Question 9

Pupillary light reflex

Answer 9

Light enters the retina

Synapses first at the ciliary ganglion

The travels to the pretectal area (midbrain area)

Synapses at the Edinger-Westphal nucleus

Via the cranial nerve III. This activates pupillary constrictor muscles.

Question 10

Auditory Pathway

Answer 10

Auditory nerve synapses at the cochlear nucleus (located in the brain stem).

Cochlear Nucleus is made of two –> Ventral cochlear nucleus (timing and volume) & Dorsal Cochlear ( quality)

They then synapse at the superior olive (brain stem)

Travel via the lateral lemniscus to the inferior colliculus

Then to the thalamus –> Medial Geniculate Nucleus

Auditory centre - Temporal lobe

Question 11

What are the components of the limbic system?

Answer 11

Hippocampus
Fornix
Mamillary bodies
Ant nucleus of the thalamus
Cingulate gyrus