May 2009 Archives

Student tracker

A Tokyo University have given out iPhones to staff & students to encourage use of elearning materials (great idea). As an extra feature, students will be using the phones to register their attendance, verified by the inbuilt GPS. That's an interesting thought.

CNET Crave - Japanese university uses iPhone to keep tab of students

Automation

I'm feeding the kids breakfast and they really know how to make a mess. I'm sure the lino floor is getting thinner with the constant sweeping and washing. I reckon we need one of these:

iRobot Scooba

or one of these:

ilovedogs.com - Dog licks floor constantly.

Online Calendars

If any of you subscribe to my online calendars to synchronise with your own (e.g. anatomy, DGR), note that I'm just about to move them to MobileMe. You can subscribe to the calendars from the links at the bottom right of the medicine page of this website.

Swansea - Cardiff commute

Now this is serious bike commuting:

Tredz Talk: Cycling to work, Tredz style

(43 miles from Swansea to Cardiff, and then back again).

Map

DSC_0024, originally uploaded by samwebster.

I love this. Walking this weekend I tried to teach Jack (Indiana Jones) some map reading skills. He wasn't convinced that I had any idea of where we were or what we were doing.

Anatomy of the infratemporal fossa (continued)

OK, where were we? By looking at the medial and lateral pterygoid muscles we found ourselves in the infratemporal fossa.

This space is bounded superiorly by the sphenoid bone (and the temporal bone), laterally by the ramus of the mandible, medially by the lateral plate of the pterygoid process and anteriorly by the maxilla. You can reach this place on a skull by sticking your finger down through the zygomatic arch and deep to the mandible, or from posterior to the ramus of the mandible. By doing this you also see the routes by which structures may enter or leave the infratemporal fossa.

What's so special about this region? It has some important structures running through it, and by knowing where the infratemporal fossa is you will also know where these structures run. As you find out more about the sphenoid bone and the nerves and vessels that pass through it you will become aware that they all pass from or to the infratemporal fossa. It'll give you a chance to link parts of the head together in your own mind.

The common carotid artery ascends in the neck and splits into internal and external carotid arteries. The internal carotid artery disappears inside the skull and the external carotid artery continues to ascend posterior to the mandible. It terminally bifurcates as the maxillary artery and the superficial temporal artery. The maxillary artery dives through the infratemporal fossa, its branches extending to parts of the face (e.g. the mandible, teeth, the cheek, the scalp) and supplying blood to those muscles of mastication that we also looked at. Importantly, it also gives off a branch called the middle meningeal artery that passes superiorly through a small foramen (spinosum) in the sphenoid bone. This artery is important in supplying blood to the dura mater (connective tissue surrounding the central nervous system), and very important when considering blows to the side of the head, such as encountered in boxing.

So now you can locate the maxillary artery as it runs from the external carotid artery through the infratemporal fossa, and if you pick up a skull and take a look at this region hopefully you will be able to imagine its course in three dimensions.

In this same region the blood is drained through a plexus of veins known as the pterygoid venous plexus (or simply, pterygoid plexus). We're starting to see that the term pterygoid is associated with the infratemporal region, because of those pterygoid processes (Arnold's glossary says, "pterygoid: adjective, Greek pteryx = wing, and eidos = shape; hence, wing-shaped"). This plexus of veins surrounds the structures here, draining blood from the cavernous sinus inside the cranium, and linking to the facial vein, a more superficial structure. There's an important anatomical link here between superficial and intracranial venous structures, and this has an interesting clinical relevance. There are no valves in the veins here, so infection may pass from superficial or oral structures back to the cavernous sinus, causing serious problems.

So there are two important blood vessels in this region. What about nerves? If we talk about cranial nerves in general, we have 3 cranial nerves involved in the infratemporal fossa. Hopefully you'll remember that the facial nerve (CN VII) passes through the parotid salivary gland (but doesn't innervate it) and branches to supply the muscles of facial expression. The parotid gland lies over the region that we've been looking at, so the facial nerve must pass very near to the infratemporal fossa. In fact, the facial nerve drops out of the skull from the stylomastoid foramen, a little posterior to the infratemporal fossa.

However, parasympathetic fibres from the facial nerve making their way down to the sublingual and submandibular glands do pass through the infratemporal fossa. The chorda tympani, a nerve carrying those fibres, passes through the middle ear and leaves the skull via the petrotympanic fissure, a fissure in the temporal bone a little anterior to the stylomastoid foramen. The chorda tympani passes through the infratemporal fossa to join with the lingual nerve, and passes inferiorly to the lower salivary glands.

Aha - the lingual nerve. Do you remember what that's a branch of? Our next cranial nerve is the trigeminal nerve (CN V). The lingual nerve is a sensory branch from the mandibular nerve (also known as V3), the third branch of the trigeminal nerve. The mandibular nerve leaves the cranium through the foramen ovale (see here, and here), passing into the infratemporal fossa. All its branches pass through the infratemporal fossa, including those motor branches passing to the muscles of mastication that we looked at earlier (making the infratemporal fossa a great landmark for finding and remembering where all these nerves are).

Ok, the final cranial nerve. If the facial nerve passes through the parotid gland but doesn't supply secretomotor fibres to tell it to squeeze juice, what parasympathetic fibres do? The glossopharyngeal nerve (CN IX) sends fibres on a fascinating route through the skull (described here, but best looked at with a skull or a model, and multiple sources to work it all out) that eventually makes it to the infratemporal fossa. Here, right next to the mandibular nerve shortly after it appears from the oval foramen, these glossopharyngeal fibres synapse at the otic ganglion. There are a few ganglia in the head that you should know about, and this is one of them. Postganglionic parasympathetic fibres then pass from the otic ganglion as part of the auriculotemporal nerve to the parotid gland, and it's these fibres that tell the parotid gland to secrete saliva.

So just by finding one region in the skull you can now locate 2 major vascular structures, important parts of 3 cranial nerves, and you've started to learn about the bones and foramina of the skull itself. It's a good region to spend time looking at.

Anatomy of the infratemporal fossa

In my anatomy session this week we started looking at the anatomy of the head (as I may have mentioned several times, probably my favourite area, anatomically-speaking). In this station, we looked at the movements of the jaw, the muscles that make those movements, some of the bones involved (bones of the skull - get looking at skulls now because this is crucial for this term) and found that we were looking at the infratemporal fossa. We described what this was and noted a number of important structures passing through it.

So what are the movements of the mandible? The temporomandibular joint (TMJ), between the temporal bone and the condylar process of the mandible, allows for some interesting movements, and the left and right TMJs work together to allow us to bite, chew and express ourselves. It isn't a particularly standard synovial joint structurally, histologically, or in the way that it articulates. Opening the mouth involves both the hinging of these joints and the forward translocation of the mandible out from the joint cavity.

Back to movements. We can elevate the jaw, depress it, move it from side to side, protrude it, and retract it. Combining these movements and making slightly different movements on either side allows us to get to grips with our food and chew it. There is a great deal of power exerted through our teeth when we bite. So what muscles give what movements? We can feel the masseter muscle getting thicker as it contracts if we palpate the region just anterior to our ears when we clench our jaws (yes, do it now). The masseter muscle is a superficial muscle attached to the zygomatic arch and to the ramus and angle of the mandible.

We can also palpate the temporalis muscle (touch your "temples", or temporal region) when we clench our jaws. This is another superficial muscle but has a broad, curving attachment to the bones that it covers (frontal, parietal and temporal bones). Its fibres all come together to pass deep to the zygomatic arch and insert into the coronoid process of the mandible, giving it not only great power from its size but also a mechanical advantage relative to the pivot point of the TMJ. This is a really powerful biting (or mandible elevating) muscle. It's really, really powerful and much larger in animals that need to rip other animals apart with their teeth.

So if the temporalis muscle is a major elevator of the jaw, the masseter aids this movement, but is also involved in the side to side movement. There are two more muscles of mastication, and both are deep to the mandible. The medial and lateral pterygoid muscles both attach to the lateral plate of the pterygoid process of the sphenoid bone. You can see what this is here on Wikipedia, but you really need to go to the lab and pick up a skull to get the best feel for where it is.

The lateral pterygoid muscle is rather different to the other muscles of mastication as its fibres run horizontally. All the other muscles run in almost vertical directions, but the horizontal fibres of the lateral pterygoid muscle are able to protract the jaw. The sphenoid bone doesn't move, the fibres of the lateral pterygoid muscle contract, and they pull the head of the mandible anteriorly in the TMJ.

The medial pterygoid muscle runs inferiorly from the pterygoid process down to the deep surface of the mandible, on the other side of the mandible from the masseter muscle. This muscle also helps elevate the mandible.

What causes depression? I mean, what muscles depress the mandible? Gravity has a role here, but the strap muscles in the anterior neck (digastric, geniohyoid, mylohyoid) are able to pull the mandible down. The masseter and temporalis muscles are able to retract a protruded jaw, by the way.

By looking at the pterygoid plates and the muscles there, we've put ourselves into the infratemporal fossa. What's that then? Well, I'm a bit worn from writing all that so I'll write up the infratemporal fossa stuff a bit later.

Where to poke?

Palpating the masseter muscle.

Palpating the temporalis muscle.

Me & Toby

SS851343.JPG, originally uploaded by webster.susan.

And my sister (Toby's mum). This is from my mum's Flickr account. Sounds good, right? I uploaded it for her.

Upload more photos to Flickr, mum! You take loads and have a very nice MacBook. Maybe I should buy you the new iLife, as iPhoto 9 has a button to let you upload automagically.

Galactic Center of Milky Way Rises over Texas Star Party

Wow. Follow the link.

Video: Galactic Center of Milky Way Rises over Texas Star Party

Needle or toothpick, acupuncture helps

A study comparing the treatment of chronic low back pain using general acupuncture, individually prescribed acupuncture, acupuncture that didn't pierce the skin (but poked the acupuncture "points") or contemporary medical treatment suggests that acupuncture can help, and that you don't need to pierce the skin.

I've only come across this brief Reuters report and haven't found the full study yet, but if accurate it puts an interesting spin on the theory that the needles affect the fascia, and the idea that those fascial cells communicate across wide distances.

Links:

Reuters: Acupuncture, real or fake, helps aching back: study
International Fascia Research Congress

Race report: Tewkesbury half-marathon

The race at Tewkesbury went pretty well yesterday. Check out my splits:

Mile 1: 5:44 (stupid, stupid, stupid!)
Mile 2: 6:17
Mile 3: 6:17
Mile 4: 6:01
Mile 5: 6:06
Mile 6: 6:21
Mile 7: 6:31
Mile 8: 6:29
Mile 9: 6:05
Mile 10: 5:37
Mile 11: 7:08
Mile 12: 5:28
Mile 13: 6:12
Last little bit: 0:33

My aims and strategies were a little different to those at Llanelli. I felt I was fitter, faster, lighter and stronger, and the weather was great yesterday so I aimed to run harder from the first few miles. No wind and a long drag or two on the course with no major hills meant I thought I could beat my previous best time by almost 3 minutes, and I wanted to race for a top 10 position. I didn't think it would be likely that I'd achieve that, but I wanted to race for it.

I saw another Cardiff Tri vest at the end of my warm up and found James Nunn was racing, and aiming for the same time as me. How's that for company?

The starter had a little trouble with his hooter (fnar, fnar), but we all started at the end of his countdown without him. There was a little down slope at the start of the run through Tewkesbury but I ran that first mile stupidly, stupidly fast. I was trying to balance the idea of running hard with managing a sensible RPE (rating of perceived exertion) but a 5:44 is unforgivable. I'm going to have to start flagellating myself if I do that again. I eased up over the next 2 miles to limit the damage, and then brought the pace back to about the right level. Nunney was well ahead with a number of runners between us by now.

The twisty, quiet roads avoiding the main road were pretty nice, and we were all straightening out the corners and running through the whole road in a very satisfying manner. The few cars that were around were very kind to us. Around the army storage depot and onto the country lanes out towards Kemerton were draggy. There was a subtle incline over a mile or so (mile 6) that I'd not noticed on the maps before we hit the main drag. We didn't gain much elevation but it was a long way up to the village and it allowed me to pick up a couple of places. It was hard but I probably got my effort level almost spot-on up there, gaining ground and maintaining a 6:30 pace. I was getting closer to James, and he had a couple of looks back.

Through Kemerton and dropping down through Bredon was a key part of the race. Pushing the pace downhill meant I picked up another 2 or 3 places before passing under the motorway at mile 10, where everyone's mindset starts to change (10 done, running to the finish now). The drag up from the underpass just went on, and on, and on. I was expecting a little rise and then a run down into Tewkesbury but it was never-ending. Looking at my times I wonder if the mile markers were in the right place, because the mile with that drag in it took over 7 minutes.

I caught Nunney on the drag. I'd had a bit of a mental battle as to what to do. I was really hurting, and had been hurting all the way. The thought of a sprint or a battle in the last few miles horrified the part of my brain that was already unhappy with what I was doing to my legs. "Just run the pace, and shut up, brain". So when I caught James I gave him a thumbs up and tried to encourage him to stick to my shoulder and keep the pace up. He was breathing hard, but I really wasn't enjoying that drag much either. When we hit the mile 11 marker and I saw the time I yelped, and those old racing instincts took over again. I pushed, and James stayed. I eased. I pushed, and James stayed. I eased. Repeat. My brain seemed to be happier with this and stopped complaining. Weird, huh? I pushed, and James shouted a cheery goodbye, wishing me the best and I finished off that damned drag. You can see from the graphs below that the drag continued mucking us about until halfway through mile 12.

I charged back down the hill into Tewkesbury worrying only about the runners ahead that I could see, and catch, and I'm really impressed with my last 2 miles. I'd planned the pace for this race half expecting to flameout at around mile 10 or 11. You can see that my heart rate was above 90% of maximum for the entire race, and it rose for those last 2 miles. Those miles were painful, but I took at least one more place from a less fortunate runner from Clevedon that was fading. Trying to maintain decent form ("it’s what you're left with when you’re buggered" - Gordo Byrn) my race face was gone, with some masque of pain in it's place.

I was so happy to see the 13 mile marker. 33 seconds later the finish line gave me a new PB of 1:20:51 and 9th place. James came in just a handful of seconds behind for 11th and 1:20:58. Not bad for a couple of triathletes in a running race, eh? After congratulations amidst choking back vomit Kim found me and took me to collapse and rehydrate with some good friends from Cheltenham that had come to see the race.

Great race, good course, awesome weather, wonderful results. Check out the data below and a few snaps on Flickr. I think I'm going to leave the 1:20 barrier until 2010.

Race prep

Race prep, originally uploaded by samwebster.

1kg of pasta and 8kg of ice. That should do it.

Tewkes Half Course

Here's a link to Sunday's half-marathon course. I know at least one medical student from Swansea is racing. You can see the elevation changes if you click the elevation links on the left-hand side. Mile 8 has the drag (that's from mile markers 7 to 8 if you're running).

Gmaps Pedometer - Tewkesbury Half-Marathon Course

Runnersworld.com: Good Buzz

See, caffeine is good for sports performance, as I've been twittering on about for a while now:

Article - Good Buzz.

Caffeine helps endurance, helps speed, helps recovery, and helps you think. Without this wonder chemical I probably wouldn't even be able to get out through the door and train. Unfortunately the article is seriously lacking references, but hey, I like articles that agree with me.

Here's a better article with properly referenced statements:

Peak Performance - caffeine effects.

I'd agree with the idea that caffeine, as a stimulant, is going to mask some of the signs of fatigue (hey, that's why I need to drink coffee to function) so you're not going to be so aware of when your body is tired. Also, I'm very used to caffeine and my body seems to tolerate and respond well to it. Your mileage may vary and taking too much of anything can be an extremely bad idea.

I'd bet I still don't ingest enough caffeine to be illegal under the old rules.

Just another 10 seconds

The measurements say that I'm faster, more efficient, lighter, stronger and have greater stamina than 8 weeks ago. So I should be able to race 10 seconds per mile faster, right? Maybe. If I can get my legs fresh for Sunday I could have a really good race.

The course is pretty flat (very flat by Welsh standards): Gmaps' Tewkesbury half-marathon route. The times don't look very fast though. I guess I'll soon find out why. Maybe the previous course (they've changed it this year) was slower.

Daddy's shoes

Daddy's shoes, originally uploaded by samwebster.

I'll be wearing these in Tewkesbury on Sunday, so Annabel's breaking them in for me.

Art student's invisible car

I love this:

BBC: Art student's car vanishing act

A design student has painted a Skoda to blend it into the car park background. The image tells it all.