Sympathetic trunk
Truncus sympathicus
NervousNervesWhole bodyLeft and right
View left in 3D View right in 3D
- What it is
- A beaded nerve cord running the whole length of the spine beside the vertebral bodies, from the base of the skull to the coccyx, where the two trunks meet. Each bead is a sympathetic ganglion: three in the neck (superior, middle and cervicothoracic or stellate), eleven thoracic, four lumbar and four sacral; thin white and grey rami link them to the spinal nerves.
- Function
- Distributes the "fight or flight" outflow: preganglionic fibres from cord segments T1-L2 enter through white rami, relay in the ganglia, and postganglionic fibres return through grey rami to every spinal nerve (sweat glands, blood vessels, hair muscles) or go directly to the head, heart and lungs.
- Size
- About 45 cm long; ganglia 3-6 mm, the superior cervical ganglion 2.5-3 cm, the stellate ganglion ~1.5 cm
- Clinical note
- Interrupting the cervical chain (apical lung tumour, carotid dissection, neck surgery) causes Horner syndrome - a drooping lid, small pupil and dry skin on that side of the face. Cutting the T2-T3 ganglia cures severe hand sweating.