...髓段之侧角)? Th th ti di i i d The parasympathetic division does not innervate sweat glands(汗腺), arrector pili (竖毛肌)or blood vessels Sympathetic?ganglia(交感分系的神经节)： 交感 经节 椎旁 经节 ‐‐‐ sympathetic?trunk?ganglia?(交感神经节...
When our ancestors were covered in fur, muscles in their skin called "arrectorpili" contracted when they were upset or cold, making their fur stand on end.
Along one side of the follicle, two buds are formed: an upper, which develops into the sebaceous gland, and a lower, which becomes the attachment for the arrectorpili muscle.