Pierre-Robin Sequence

pierre-robin-sequence

Pierre-Robin Sequence is not a syndrome, it’s a sequence. While it is a collection of features, one happens because of the one that came before.

The features are:

  • Retrognathia/micrognathia (posterior mandible or very small mandible)
  • Glossoptosis (downwards/posterior displacement of the tongue due to the small mandible
  • Airway obstruction (because the tongue is in the way)

Pierre-Robin Sequence is associated with cleft palate (50% of children with the sequence have cleft palate). There are two proposed theories:

  1. The first is that the tongue simply gets in the way of the palate from fusing
  2. The second is that the tongue prevents the newly fused palate from staying fused (this is currently the more popular theory)

PRS, though not a syndrome itself, is associated with multiple syndromes including Stickler Syndrome, velocardiofacial syndrome, fetal alcohol syndrome and Treacher Collins Syndrome.

Types of sutures (and when to use them)

sutures

There are many types of sutures and they differ by size, material and needle. I made this handy chart to help remember how long each type of material lasts in the body and what it’s commonly used for:

50% Strength Gone Reactivity Use
Ethibond
(coated polyethylene)
indef n/an/a + Tendon
Mersilene
(uncoated polyethylene)
indef n/a + Tendon
Nylon 20%/y n/a + Skin
Silk 1 year >2y ++++ Vessel ligation, drains
Prolene
(polypropylene)
indef n/a - Skin
Steel indef n/a - Tendon, sternum
Fast Gut 6d 20d ++++ Skin
Plain Gut 7d 70d ++++ Skin
Chromic Gut 28d 90d ++++ Oral mucosa
Monocryl
(Poliglecaprone 25)
7d 110d +++ Skin, subcuticular
PDS
(Polydioxanone)
21d 100d ++ Internal organs, fascia
Vicryl
(Polyglactin 910)
21d 90d ++ Skin, soft tissue

Key:
* Monofilament
* Braided

Teeth (and how to number and name them)

Teeth are pesky things, there are a bunch of them and they all seem to have a bunch of different names. Technically speaking, a full set of adult teeth is 32. However many people end up getting their wisdom teeth taken out, bringing them down to only 28 teeth in total.

There are 4 “types” of teeth

  1. Incisors – 8 in total
  2. Cuspids aka Canines – 4 in total
  3. Bicuspids aka Premolars – 8 in total
  4. Molars – 12 in total (counting the wisdom teeth)

Of course, to say “the 2nd incisor on the top right” is just far too many words to say and write down, so different coding systems were developed to make things snappier. The most commonly used system in North America and the one that’s used by the World Health Organization is the FDI World Dental Federation notation.

The FDI system numbers the 4 quadrants of the mouth, starting at the top-right and going clockwise:

  • 1 = top right
  • 2 = top left
  • 3 = bottom left
  • 4 = bottom right

Each tooth is then numbered starting at the middle and working back:

  • 1 = first incisor
  • 2 = second incisor
  • 3 = cuspid/canine
  • 4 = first bicuspid/premolar
  • 5 = second bicuspid/premolar
  • 6 = first molar
  • 7 = second molar
  • 8 = third molar (wisdom tooth)

Anatomy of the ear

Who knew that the ear could have so many parts to it? This is getting into some detailed anatomy, but you will be able to impress your staff person with your incredible knowledge.

As a side note, you may also be able to impress your local piercer, as most of the more unusual ear piercings are simply named after the bit of ear the hole is going through.

Lip Anatomy

Lip lacerations are kind of a big deal when it comes to facial injuries. It’s because whether we admit it or not, they’re a very important part of the overall cosmetic appearance of the face.

The tricky thing is the vermillion border, which is a fancy term for where the red of the lips meets the rest of the face. The lip is then further divided into the dry vermillion (the part that you put lip stick on, because it’s the part that you can see with the mouth closed) and the wet vermillion (the part that you don’t put lipstick on unless you want it on your teeth).

So when you’re repairing lips, you need to make sure that everything lines up juuuust right. The other important considerations are that unlike fingers, you can’t just pump the lips full of local anesthetic because it will distort the anatomy, this means that a nerve block is preferred. The upper lip receives innervation from the infraorbital nerve (a branch of CNV2) and the lower lip receives innervation from the inferior alveolar nerve (more specifically the mental nerve, which originate from CNV3).

Blood supply comes from the superior and inferior labial arteries (guess which one goes to which lip), which are branches off the facial artery.

DANGER ZONE!!! (the cavernous sinus)

The danger zone on the face is a little triangle from the corners of the mouth up to the bridge of the nose. The reason it has such an epic name is because due to its venous drainage (from the facial veins and pterygoid plexus) there’s the possibility of infection traveling from that area into the cavernous sinus.

The cavernous sinuses (there’s one on each side) is an area posterior to the maxillary sinuses and lateral to the pituitary. It receives blood from the superior and inferior ophthalmic veins, superficial cortical veins and the basilar plexus. The blood then drains into the petrosal sinuses (you guessed it, there’s a superior and inferior one of those too) and then those drain into the internal jugular vein.

The thing about the cavernous sinuses a whole lot of important stuff passes through it.

  • CN III (occulomotor)
  • CN IV (trochlear)
  • CN V1 (ophthalmic branch of trigeminal)
  • CN V2 (maxillary branch of trigeminal)
  • CN VI (abducens)
  • Internal carotid (and the sympathetic fibres on the carotid)

This means that if you are so unfortunate as to have infection tract back into it, there can be some nasty consequences like meningitis and cavernous sinus thrombosis which will generally present as problems involving those nerves.

The abducens and carotid are more medial and thought to be more bathed in the warm loving venous drainage meaning these are generally the first to show signs of a problem a-brewin’.

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