Autonomics of the Head and Neck Quiz

See Pathways of Sympathetic Innervation. Option E is correct: the superior cervical ganglion, at the top of each sympathetic chain, contains the cell bodies of the post-ganglionic neurones that supply the head and neck. The sympathetic chains are two structures that lie alongside the spinal column, and the sympathetic ganglia sit within them. The pre-ganglionic neurones begin in the spinal cord segments from T1 to L2, which is called thoracolumbar outflow, and for the head the fibres from the upper thoracic cord ascend in the chain to synapse in the superior cervical ganglion. The post-ganglionic axons then hitch-hike along arteries to reach their targets: along the internal carotid artery to the dilator pupillae (the muscle that widens the pupil) and the superior tarsal muscle (which helps raise the eyelid), and along the external carotid artery to blood vessels and sweat glands. If this pathway is interrupted, for example by a Pancoast tumour (a tumour at the top of the lung) or carotid artery disease, the patient develops Horner's syndrome: partial ptosis, a constricted pupil and reduced sweating.

• Relay: the superior cervical ganglion holds the post-ganglionic cell bodies that supply the head and neck.
• Outflow: pre-ganglionic neurones begin in the spinal cord from T1 to L2 and ascend the sympathetic chain.
• Course: post-ganglionic axons travel along the internal carotid artery to the dilator pupillae and superior tarsal muscle.
• Interruption: loss of this pathway causes Horner's syndrome, with partial ptosis, a constricted pupil and reduced sweating.