“Cervical Plexus?”
“I’m in.”
I mean, what else was I supposed to say when my dissection partner suggested one of the hardest projects conceivable? Visions of fame, fortune, and even the hint of a prize flashed before our eyes as a reward for our daring quest. We would be celebrated and our skill as dissectors would become legend. However, the path to reaching this goal was far from pleasant. Our grim reality had us see every Monday afternoon for months on end spent with more formaldehyde in our lungs than oxygen. There was also the unshakable feeling of being at the Second Battle of Ypres where at any moment you could fall back, reeling and gagging whilst your eyes and throat burned from the mustard formaldehyde.
No doubt, you are now probably wondering: ‘Why Ali? What makes the Plexus so hard to dissect?’
Well dear reader, I am glad you asked. For starters, its most superficial fibres sit beneath the skin of the neck much like the first page behind the cover of a paperback book. Meanwhile, the deeper branches of the plexus are more akin to one page glued between two others – the added twist being that the pages have the frailty of damp tissue paper. And let us not forget, dear reader, the most challenging aspect of all: these nerves are so intertwined with the fascia that to separate them from each requires the same level of skill to discern a blonde strand of hair from a bale of hay. It is for these reasons and these reasons alone, that dissections of this area are rarely attempted and fewer still are successful. Actually, there is one other reason: the slightest slip of a scalpel could severe a nerve and end the project in a complete disaster. It is strange then, that during one auspicious Monday afternoon I found myself swinging a scalpel with wild abandon. Perhaps with the same abandon one might use to bisect the superficial fascia of a cadaver with a BMI of 40. Unfortunately, in my case the cadaver had a BMI of 17.
A prompt “What the hell are you doing?!” from an overly anxious partner strayed my hand away from delivering further lacerations. For the first time that day, I set the blade down and we inspected the scene that lay before us. It then dawned on us that something wasn’t exactly…right.
“What is that?”
“That’s the Vagus”
“I’m telling you it’s not the VAGUS!”
“Sure it is”
“Then why is it stopping at sternothyroid?”
As to which of us spotted this anomaly I’ll leave to the fields of your imagination. We approached our seniors with this revelation but they could not see the reason, and so we were left to solve the dispute for ourselves. Naturally, the best rational course of action was to crack open the cadaver’s ribs and trace the vagus back through the neck. Snip, Snip, Crunch, Crunch, Ouch! Bones, particularly ribs, are very sharp! The good news was that we found the tail end of the vagus sitting snuggly in the thorax. The bad news? Well, it had been severed from its proximal end in the neck several weeks ago. Whoops. So, the riddle of the vagus had been solved but the puzzle of this anomalous nerve remained. As our nerve inserted itself into sternothyroid the only thing left to do was to trace it back through the fascia, sinew, muscle and bone to find its origin point at the spinal cord. It was time to get medieval.
“Hammer?”
“Check.”
“Chisel?”
“Check.”
“Assortment of tools from a torturer’s arsenal?”
“Also check.”
I’d like to say that I swung that hammer like Thor swinging Mjolnir against the Jotuns, but it is probably more accurate to say it was more akin to Michelangelo sculpting David. If anyone tells you that chiseling away at the spinal column is easy, they are definitely lying. We continued hammering away for three days straight, not taking rest for food nor sleep but persisted through multiple twilights and waning moons until the wings of the Atlas and Axis were reduced to powder (which took around 15 minutes). Inevitably, the powder had crept into our nostrils and we were sneezing out bone dust for the rest of the week, a trivial price to pay for being on the cusp of a revolutionary breakthrough. Regardless, we looked upon our work and I doubt that Gray or Hippocrates could have envisaged the scene laying before us.
The Cervical Plexus is compromised of the superficial cutaneous fibres, and a ring of motor nerves providing motor function to the infrahyoid muscles of the neck. This ring is called the ansa cervicalis (gooses neck) and is formed by a superior root from the ventral ramus of C1, and an inferior root formed from the ventral rami of C2 and C3. Our aberrant nerve provided an additional nerve to the sternothyroid which came directly from C2, bypassing the ansa.
Given that this nerve originated superiorly to the ansa, I decided to christen it ‘Superior Nerve to Sternothyroid’ much to the chagrin of my fellow dissectors. What? It was either that or the Nerve of Amin-Baig-Zaidi which, whilst immortalizing my name in history, would have also immortalized my ridiculousness and lack of creativity.
So, let’s do a final tally shall we? Fame? Nope. Fortune? Nah. The Prize? Definitively not. Instead, it went to some shmucks exposing the external carotid (do you know how easy that is?). But I did end up with a PubMed ID [1] and get cited by the Russians [2]. Oh, and this blog post.
References
1. Amin, M.S.A., Baig, U., Zaidi, S.Y., Brennan, P.A. and Parry, D., 2020. Sternothyroid receives a supplementary innervation separate to the ansa cervicalis: a case report of a variation. British Journal of Oral and Maxillofacial Surgery, 58(4), pp.472-474.
2. Khmara, T.V., Lopushniak, L.Y., Boichuk, O.M., Halahdyna, A.A., Gerasym, L.М. and Leka, M.Y., 2020. FETAL ANATOMICAL VARIABILITY OF STRUCTURES IN INFRAHYOID AREA. Актуальні проблеми сучасної медицини: Вісник Української медичної стоматологічної академії, 20(3), pp.164-169.