skanuj0025 (166)

Diaphragm

(C4)

Heart

(T3-T4)

Esophagus

(T4-T5)

Stornach

(T6-T9)

Kidney, testis (T10-L1)

B Referred pain

It is believed that nociceptive afferent fi bers from dermatomes (somatic pain) and internal organs (visceral pain) terminate on the same relay neurons in the posterior horn of the spinał cord. The convergence of somatic and visceral afferent fibers (see b) confuses the re-lationship between the perceived and actual sites of pain, a phenomenon known as referred pain. The pain is typically perceived at the somatic site, as somatic pain is well-localized while visceral pain is not. Pain impulses from a particular internal organ are consistently pro-jected to the same well-defined skin area (a); the pattern of pain projection is very helpful in determining the affected organ.

Convergence at relay neuron

Dorsal

root

■

Yentral

Somatic afferent fiber

Spinał ganglion

'.Tsceral

IbeKnoer

Myotome

Dermatome (T3-T4)