Kmi

Sensory Receptors in Muscles, Joints, and Visceral Organs B. Cranial nerve V, trigeminal nerve

Spinal nerve C2

D Diaphragm

S Stomach

A Appendix U Uterus K Kidney

Sensory Receptors in Muscles, Joints, and Visceral Organs B. Cranial nerve V, trigeminal nerve

Spinal nerve C2

D Diaphragm

S Stomach

A Appendix U Uterus K Kidney

H Heart

meningial pain above tentorium cranial nerve V tentorium below tentorium spinal nerve C2

H Heart cross section of spinal cord at level of spinal nerve C8

FIGURE 5 Instances of referred pain. Painful irritation of a given internal organ (A) is perceived as pain in a specific area of skin, called a dermatome (see Chapter 50), as shown on the right (B). This occurs because the nociceptive neurons from the two areas converge on the same secondary neurons in the spinal cord. For example, (C) pain afferents from the heart converge on the same spinal cord neurons as those from the skin of the left shoulder and arm (the C8 dermatome). Note that intracranial head pain arises from irritation of blood vessels and meninges (A). Pain does not occur from irritation of the neuronal tissue of the brain.

reflexes and contributes to feelings of hunger and thirst as well as to an overall feeling of malaise or well-being. These receptors provide relatively few centrally projecting fibers, accounting for less than 10% of the sensory fibers found in the spinal cord. They synapse on some of the same spinal neurons that receive somatic sensory input. For this reason, visceral pain is often referred, providing a perception that the sensation (in many cases, discomfort) actually originates from skin or muscle that may be some distance from the painful organ (Fig. 5). For example, angina pectoris (heart pain) is usually referred to the left chest, shoulder, and upper arm. Visceral sensory neurons also have broad overlapping receptive fields, which further decrease the ability to localize visceral pain precisely.

Suggested Readings

Bear MF, Connors BW, Paradiso MA. Neuroscience: exploring the brain. Baltimore: Williams & Wilkins, 1996. Kandel ER, Schwartz JH, Jessell TM. Principles of neuroscience.

New York: Elsevier, 1991. Martin JH. Neuroanatomy. Stamford: Appleton and Lang, 1996.

Psychology Of Weight Loss And Management

Psychology Of Weight Loss And Management

Get All The Support And Guidance You Need To Be A Success At The Psychology Of Weight Loss And Management. This Book Is One Of The Most Valuable Resources In The World When It Comes To Exploring How Your Brain Plays A Role In Weight Loss And Management.

Get My Free Ebook


Post a comment