Sample Biology Paper on Spinal and Peripheral Nerve Anatomy

Paresthesia is a medical condition that is commonly described as the feeling of pins and
needles. "It is defined as a sensation of numbness, tingling or pricking of the person's skin mostly
in the legs, arms, feet, and hands with no apparent long term physical effect."(Bradley et al.,
2017, p. 332). Paresthesia condition can either be chronic or transient with a possibility of
underlying health issues. The patient only manifested the sensation of tingling feeling on her
right thigh. Skin vesicles are small raised lesions filled with fluid under the epidermis layer of
the skin. They are between 5 – 10 mm in size but appear in multiple numbers (4-10), with the
fluid inside being either yellow, white, red, or clear. In reference to our case study, 3-4 small red
vesicles are identified during the inspection. The manifestation of skin vesicles can result from
skin allergic reaction, cold sores, or dermatitis.
Dorsal and ventral are a classification of anatomical directional terms. They are used
when discussing specific points of the body or whole body parts. Using anatomical body
position, facing forward with their arms straight, palms facing forward and feet facing forward,
ventral means to the front while dorsal refers to the back. Ventral can also be explained as the
anterior while dorsal is the posterior. The term dormant refers to the state of being inactive. The
state of dormancy can also expressed as minimal metabolic activities brought about by harsh
environmental conditions or the genetic make-up of the individual.
In the human body, sensory receptors are proteins mandated to react to changes in the
surroundings. When activated, they trigger nerves impulse by sending the signals to the brain via
the spinal cord. Sensory receptors are classified depending on their location in the body,
structural complexity, and stimulus type. There are five different categories of the sensory
receptors; Chemoreceptors, Thermoreceptors, Photoreceptors, Nociceptors and

Spinal and Peripheral Nerve Anatomy 3
Mechanoreceptors sensory receptors. Mechanoreceptors are activated by touch, pressure,
vibration, and stretch. In scenarios where there is a temperature change in the environment or the
surroundings, the Thermoreceptors are activated. Light or changes in light wavelengths activate
photoreceptors. Change of the blood chemical concentration, smell, or taste triggers the
activation of the body's chemoreceptors. Lastly, in tissue injury or situations that may lead to
tissue injury or pain causing situations in the body, the Nociceptor stimulus is activated.
Nociceptors stimulus are also referred to as the pain-causing receptors. (Delasio et al., 2018)
Pain is a very important factor as it acts as a defense mechanism of telling the body when
something is not right, or intruders like viruses and bacteria are detected. Pain is initiated by
specific nerve cell endings that are located all over the body. These pain nerve cells are referred
to as Nociceptors cells. In reference to Sarah's case study, the Nociceptors cells in her right thigh
are activated due to skin vesicles' presence. Hence, they send information to the brain, leading to
the manifestation of Sarah's symptoms of pain and paresthesia.
Dorsal root ganglion (DRG), located in the epidural, is a sensory neural structure that
regulates the maintenance and development of severe pain. DRG comprises primary sensory
neurons that transports sensations like touch and pain from the peripheral to the brain. Motor and
sensory inputs are divided at the dorsal root ganglion, making it a handy place for electrical
stimulation to suppress pain. The neuron part that is located in the dorsal root ganglion is
referred to as the Somatosensory. Somatosensory is classified under the group of first-order
neurons that receives and transmits peripheral sensations like pain and touch to the spinal cord.
The dorsal root and its ganglion only carry the sensory inputs. (Walhout et al., 2018, p. 24)
Based on the skin vesicles and pain pattern, as described by the patient on her right thigh,
the infected peripheral nerves are the fibular nerves. The fibular nerves, also known as the

Spinal and Peripheral Nerve Anatomy 4
common peroneal nerves, are located from the lower part of the thigh to the lower part of the leg.
Fibular nerves provide sensation to the Posterolateral part of the leg. A nerve plexus is a bundle
of interconnected nerves that comes together and then branch out again. These plexus are
grouped into four categories namely; lumbar plexus, brachial plexus, sacral plexus, and brachial
plexus. Sacral plexus nerves supplies the muscles and skin to the lower limbs and the pelvic area.
The fibular nerves that are infected in our case study belong to the peroneal sacral peripheral
plexus nerves.
If Sarah's skin vesicles and pain were located on the neck's anterolateral region, the
infected peripheral nerves would be the Transverse Cervical Nerve, also known as the cutaneous
cervical nerve. Transverse cervical nerves are formed from fibers originating from the c-2 and c-
3 spinal roots. It gives branches that pass above and below the sternocleidomastoid to supply to
the upper sternum and neck's anterolateral skin. The transverse cervical nerve is classified under
the cervical plexus peripheral nerves located in the neck's posterior part.
As the spinal neurons are approaching the spinal cord, they separate, forming ventral
roots and dorsal roots. The ventral roots only contain axons of sensory neurons, while the ventral
roots carry axons of motor neurons. If Sarah's viral infection had affected her ventral roots'
neuron functioning, she would have portrayed different symptoms. The symptoms of an affected
motor axon are; back pain, numbness, weakness, fatigue, fever, burning, tingling of feet and
hands, pain down the legs, and loss of movement in extreme cases. Sarah's case study had small
skin vesicles, oral fever, fatigue, burning sensation, and tingling with no numbness. Comparing
the two sets of symptoms, Sarah’s symptoms can then be classified under damaged sensory
neurons.

Spinal and Peripheral Nerve Anatomy 5
Sensory pathways are chains of neurons connected to transmit signals (sensations) from
the brain's sensory organs (cerebral cortex). The cerebral lobe active in Sarah's brain during the
transmission of the sensation is referred to as Parietal lobe. This parietal lobe is located near the
central part of the brain, above the temporal love, and posterior to the frontal lobe. It is primarily
mandated to receive and process events to happen in the somatosensory: for example, touch,
pain, and temperature.

Spinal and Peripheral Nerve Anatomy 6

References

Dalesio, N. M., Barreto Ortiz, S. F., Pluznick, J. L., & Berkowitz, D. E. (2018). Olfactory, taste,
and photosensory receptors in non-sensory organs: it just makes sense. Frontiers in Physiology,
9, 1673.
https://www.frontiersin.org/articles/10.3389/fphys.2018.01673/full
Walhout, R., Verstraete, E., Van Den Heuvel, M. P., Veldink, J. H., & Van Den Berg, L. H.
(2018). Patterns of symptom development in patients with motor neuron disease. Amyotrophic
lateral sclerosis and frontotemporal degeneration, 19(1-2), 21-28.
https://www.tandfonline.com/doi/abs/10.1080/21678421.2017.1386688

Bradley, K., & Redwood City, C. A. (2017). Paresthesia-independence: an assessment of
technical factors related to 10 kHz paresthesia-free spinal cord stimulation. Pain Physician, 20,
331-341.
https://www.researchgate.net/profile/Mery_Paroli2/publication/317752400_Paresthesia-
Independence_An_Assessment_of_Technical_Factors_Related_to_10_kHz_Paresthesia-
Free_Spinal_Cord_Stimulation/links/5bea9141299bf1124fce4caa/Paresthesia-Independence-An-

Spinal and Peripheral Nerve Anatomy 7
Assessment-of-Technical-Factors-Related-to-10-kHz-Paresthesia-Free-Spinal-Cord-