Insights The Anatomy of Headaches - Part 1
Apologies for the many of you who have already read this - just skip past it. I've had some issues with Facebook, who turned my original post into a photo, which are now rectified. Please - like and share as you never know who you may be helping. Part 2 coming this weekend.
Headache and particularly migraine has developed an almost mystical quality within societies understanding. We have seemingly advanced so far in our knowledge of the human body, yet in this area, little in the public realm other than the development of new medications has changed in decades. In many circles the underlying pathology of headache is still treated as "unknown". Yet so much is known but unfortunately has not entered the public domain. I hope to change that for you in some way.
For us to sense pain anywhere, or indeed "sense" anything, nerves must be activated. The key nerve that informs our brain about what is happening in a vast majority of the head and face is the Trigeminal nerve - cranial nerve V.
This nerve, as indicated by its name, has three main branches; the opthalmic, maxillary, and mandibular nerves. From all the subdivisions of these three branches the nerve carries information back to the brain from the skin of the face and front half of the scalp (back of scalp and neck is upper cervical nerves), conjunctiva, mucous membranes of the mouth, nose and sinuses, the cornea, teeth, gums, palate, pharynx, tongue (except taste - i.e. position for speaking, pain/temperature, pressure), sensory information from the muscles in the face, temporomandibular joint (jaw), and out part of the tympanic membrane (ear drum).
Importantly it also has sensory receptors in the dura mater including blood vessels. The Trigeminal nerve has a small supply to muscles that are involved in mastication (biting, chewing) and swallowing and the ear drum.
See this diagram - courtesy of Gray's Anatomy.
Essentially, if you have a headache whichever type it is classified as, it is the Trigeminal system that is active, or over active as the case may be.
All the information from the Trigeminal nerve make their way into the skull and 'terminate' in the brainstem in an area called the Trigemino-cervical nucleus caudalis. Here the peripheral nerves of the Trigeminal system that we have just described above form a junction or synapse with the central nerves that then relay this information up to our brain.
It is in the brianstem, and particularly the Trigemino-cervical nucleus where the headache story really begins to unfold.
In part 2 of "Anatomy of a Headache" we will look at the Trigemino-cervical nucleus in more detail and see why there is so much interest in the upper cervical spine as a potential pain generator in headache and migraine.
Roger O'Toole is the Director and Senior Clinician of the Melbourne Headache Clinic and has over 10 years experience as a physiotherapist.