Class #10-Somatic & Visceral Sensation, p. 1 (Image from: Exduck.com/esxpage/useful stuff.htm) Functions: SOMATOVISCERAL SENSATION

Class #10-Somatic and Visceral Sensation, p. 2 AβAβ AδAδ C Receptors (and their axons): SOMATOVISCERAL SENSATION (cont’d) Cell bodies for nearly all bodily receptors (i.e., from skin, muscle and viscera) are located in dorsal root ganglia. For the head, receptor cell bodies are in the trigem- inal ganglion (5 th cranial n.). Most internal organs also have sensory recep- tors. The cell bodies of those receptors are loca- ted in the vagus nerve’s ganglion (the ‘nodose ganglion’ – see slide 7).

Class #10-Somatic and Visceral Sensation, p. 3 Receptors (cont’d): Adequate stimuli: Sensitivity: SOMATOVISCERAL SENSATION (cont’d)

Class #10-Somatic and Visceral Sensation, p. 4 SOMATOVISCERAL SENSATION (cont’d) Submodalities: Submodality coding:

Afferent nerves: spinal nerves (from the body) and the trigeminal nerves (from the head)* For SKIN AND MUSCLES, the input is arranged in a highly topographically organized manner – caudal to rostral Class #10-Somatic and Visceral Sensation, p. 5 * Remember DERMATOMES? - an area of skin innnervated by sensory fibers in a single spinal nerve] SOMATOVISCERAL SENSATION (cont’d) SKIN AND MUSCLES—Afferent nerves Trigemnial n. and ganglion (face) S4 C5 T8

Class #10-Somatic and Visceral Sensation, p. 6 SOMATOVISCERAL SENSATION (cont’d) INTERNAL ORGANS (output to them from CNS) BUT, for VISCERA (internal organs), the situation is complicated by the organization of the nerve supply to internal organs. Each organ is supplied by both sympathetic and parasympathetic EFFERENT nerve fibers. (See pages (“The Autonomic Nervous System”) in your text for an explanation of the function of the efferent fibers in these nerves –that is, functions of the fibers that come from the CNS to each internal organ.) vagus n.

Afferent nerves : VISCERA (cont’d) Afferent fibers from internal organs travel with both the sympathetic and parasympathetic nerves. Thus, many internal organs send input both to the spinal cord (where there is some caudal to rostral organization), and to brain via the vagus nerve. Class #10-Somatic and Visceral Sensation, p. 7 SOMATOVISCERAL SENSATION (cont’d) INTERNAL ORGANS (Afferent nerves: sensory input from them to CNS) nodose ganglion dorsal root ganglia vagus n.

AFFERENT NERVES (cont’d): VISCERA You can see the effect of this double innervation on topographic organization of input to CNS from visceral afferent nerves by looking at the two inputs superimposed. (Note: red is sympathetic; green is parasympathetic.) Class #10-Somatic and Visceral Sensation, p. 8 SOMATOVISCERAL SENSATION (cont’d) S1-S5 L2-L4

Class #10-Somatic and Visceral Sensation, p. 9 Main CNS routes of somatovisceral information SOMATOVISCERAL SENSATION (cont’d)