Clerkship Years: Helpful Online Resources for Students

Nowadays books lag behind in updates (and sometimes forget they are addressing medical students not professors who understand everything about a topic) and reliable medical websites more than make up for it. The following are helpful every step of the way for students in their clerkship years (they include references and are reliable as sources to study from):

1. OSCE stop: One of the best resources for OSCE and DOCEE. It has many examination and history-taking checklists that we are not provided with for internal medicine, pediatrics and OBG especially - among many others.

2. Geeky Medics: Has not only OSCE checklists but also explanations for many subjects in surgery, medicine and emergency.

3. Learn Pediatrics: Many of us used this site for studying for the DOCEE. It tells you how to approach common pediatric problems by giving you the gist of things (as opposed to the endless blabber in many pediatrics reference books).

4. Dr. Smith's ECG Blog: This is not so much for studying purposes as learning and practicing ECG. Different interesting real patient cases are posted regularly with their ECG findings as well as any other investigation done.

Book Turned Movies: Yay or Nay?

In the past few years there has been an increasing number of movies that are based on books. I don't necessarily hate this, but the fact that each book I pick up ends up being made into a movie is just frustrating. 

Why you ask? Simply because I am all about imagination. Imagination is the most of the time the only thing many have to keep us going. 

The reason why I read stories is to escape from a world I despise, if only for a short-lived moment in between classes or an entire day of holiday. I can lose myself in a world I love where my problems are no longer mine but of the character I am impersonating for the time-being. On days when I am bored of life's quotidian patterns, I get to live adventures vicariously through this person developed out of someone else's imagination. For a while, I get to live an interesting life fighting crime, being a werewolf, falling in love with a faery prince, or being a wizard. For a while, I don't have to worry about grades, studying for tests, doing the chores, living up to parent's expectation, world hunger, world peace and everything humans do wrong. 

To me, books are also a special private sanctuary. No one around me usually knows about the books I read, their characters, the plot. Make it into a movie, and suddenly everyone in close proximity knows everything about the book. It is no longer that safe haven. (Still gotta get to reading that book by Nicholas Sparks. The imagination part is lost already because I have already seen the actors and will continue to imagine them as the characters when I read). I can no longer escape to the safety of the book alone with the characters. (Note the irony as book settings are anything but safe) It now feels like all of mankind is with me while reading the book and not just fellow readers. It's no longer our own private world (referring to the all the readers of the book). I used to feel a special camaraderie with other readers, but now that everyone knows the story, the feeling is no longer alive.

When I pick up a new book, I like having the choice of imagining details any way I fancy, twisting the descriptions around in my mind's eye to form images the way I desire. I don't care whether I have read a story once or five times. I like knowing that I have a stash of imagination food on my bookshelves that I can read over and over again whenever I wish to live the life of that character the way I imagine. I like modifying my imaginary world a little differently whenever I read the same book again. Stories aren't just nutrition for the imagination but your horizons, vocabulary, and thinking. It's also a proven stress-reliever I tell you!

Come ye media and movies, we are stripped of the joy of imagination. It is easy to say: well you are not forced to watch the movies. But darlings, it is hard to stay away from media in this day and age. I am alway encircled by it everywhere I go. I am bound to see a poster or a trailer of a book-made movie while walking on the street, in a mall, watching TV at home. Browsing the net I am bound to see 'so and so actor for the upcoming movie based on so and so book'. My friends would likely come to me with news about such stuff as everyone is in a media-frenzy this century. So how can I escape it? The answer is: I can't. 

Books are already beginning to lose readers to movies. I hear many people changing their minds about reading a book as soon as they see a movie coming up for it, not knowing the infinite joy of which they are depriving their imagination. There is no imagination is watching movies. Your eyes and ears feed your brain signals and that is all the stimulation you are getting: auditory and visual with no other cognitive processes. 

I can't blame hollywood, after all it is a business and businesses are all about making money. And what better way to make money, they realized, than using books that have already been read and loved by people and probably have a ginormous fan-base, instead of writing out new stories and living in fear of the movie being a flop. Or maybe it is simply that hollywood writers are running out of ideas and this proved to be their life jacket. But that simply could not be the answer because to me human minds are vast pools of imagination and do not run out of ideas. Perhaps the new minds of today are very savvy and sharp-witted that the previous movie ideas of hollywood simply do not entertain them and only through the stories of books being made into movies were they satisfied?

At the end of the day I think it is all about money, and supply and demand. Most people out there are more than eager to witness live-action versions of their most cherished stories. You get to see your favorite book come to life, hollywood makes money (not just money but MONEY), the author makes money, everyone's happy. But are they really - the readers that is?

Study Break: K-POP and Anime Meet Medicine

What do k-pop, anime and medicine have in common? A geeky med student's love for them. If you are a die-hard anime and k-pop fan and a med student you will find it hard not to find anime and k-pop references in everything you stumble upon. Many a time I had to hold in laughter in class so as to avoid looking like a guffawing buffoon amidst what could pass as a civil learning environment while the teachers explained or in an exam - I try to steer clear of the mental hospital.

1. You know when you first hear something, there is always one fleeting image or thought that comes upon the first impression? Well this was the image my neurons flashed me when I heard the term "Ghon focus" in a pathology class about TB:

2. If you're familiar with microbiology then you must have come across the BAP acronym. If like me you have not come across the acronym previously but the full name itself and were staring at your lecturer in bewilderment as the words "BAP" were displayed in the presentation and a picture of 5 handsome boys flashed in your mind, then you my friend are more k-pop-notized than you realize. 

This is exactly what happened to me as my microbiology lecturer was giving us a lesson on bacteria that cause meningites. She asked about the type of bacteria that can be cultured in a BAP. Instead of displaying an image of a scraped blood culture plate with disgusting colonies of bacteria, my brain screened a colony of guys with awesome hair.

Note to self: the medical 'BAP' means Blood Agar Plate.

Trigeminal Nerve - Cranial Nerve V/5

Introduction

• It is the largest cranial nerve.
• It divides into 3 nerve branches.

Functions in General (just to be oriented with the nerve. More detail below.):

• GSA (general sensory afferent/general somatic sensory):  sensory input from the head, ear and the dura mater.
• BE (branchial efferent AKA visceral motor AKA muscles derived from pharyngeal arches):  the muscles of mastication, the tensor tympani, the tensor veli palatini, the mylohyoid, and the anterior belly of the digastric.

Nuclei of Trigeminal Nerve in Brainstem

Nuclei of Trigeminal nerve are not confined to a specific part of the brainstem (such as only pons, or only the medulla) but are along the entire length of pons & medulla.

Figure 1: Trigeminal nerve nuclei approximate location in brainstem and relation to each other - longitudinal view

Figure 2: Location of Nuclei of Trigeminal Nerve in Brainstem and 
relation to each other - posterior view

Figure 3: Location of Nuclei of Trigeminal Nerve in Brainstem and 

relation to each other - longitudinal view

Sensory nuclei:

1. Main sensory nucleus: fibers carrying touch and pressure sensations end here.
2. Mesencephalic nucleus: fibers carrying proprioception from muscles supplied by the trigeminal nerve (muscles of mastication…etc.) end here.
3. Spinal nucleus: fibers carrying pain and temperature end here. 

Motor nuclei:

1. Motor nucleus: 
1. Receives corticonuclear(AKA corticobulbar) fibers from the precentral gyrus of the cerebral cortex of both hemispheres. 
2. Receives fibers from other brainstem nuclei.
3. Receives fibers from the mesencephalic nucleus thereby forming a reflex arc. 

Emerges from brainstem

• The trigeminal nerve has 2 roots that emerge together from the brainstem: one big sensory root and one small motor root. 
• These roots emerge from the anterior part of the pons. 

Figure 4: Trigeminal Nerve root emerging from brainstem - anterior view

Route

Figure 5: Trigeminal Nerve exit/entry from/to cranial cavity

1. After emerging from the pons, the roots continue anteriorly from the posterior cranial fossa to the middle cranial fossa by passing over the petrous temporal bone
2. The roots then reach the anterior part of the petrous temporal bone. 
1. At this point, the sensory root expands into the trigeminal ganglion. 
2. The motor root continues beside it without passing through the ganglion.
• Trigeminal ganglionWhat is it? The trigeminal ganglion is analogous to the spinal ganglion. It contains cell bodies for the sensory neurons of the trigeminal nerve.
  Where is it? It is located in a depression called the trigeminal depression on the anterior wall of the petrous bone.
  Note: the motor root of the trigeminal nerve is completely separate from the ganglion. It runs by the ganglion but does not pass through it as the trigeminal ganglion is purely for sensory neurons cell bodies.
3. Three nerve branches arise from the anterior border of the trigeminal ganglion: Ophthalmic branch, Maxillary branch and Mandibular branch.
1. Till here, these nerve branches are all sensory. 
2. What about the motor root that passed beside the ganglion? At this point, it continues as the motor root and is still separate from the 3 sensory roots. 

Opening in skull through which nerves pass

Nerve	Passes through Opening	To enter
Ophthalmic division (V1) of V	1.     Superior orbital fissure	Orbit
Maxillary division (V2) of V	2.     Foramen rotundum	Pterygopalatine fossa then inferior orbital fissure
Mandibular division (V3) of V	3.     Foramen ovale	Infratemporal fossa

Figure 6: Side view of internal cranial cavity showing openings in the skull through which Trigeminal nerve branches pass

Each branch passes through a different opening in the skull. 

1. V1: Ophthalmic branch passes through the cavernous sinus – in the lateral wall of the sinus above the maxillary nerve Fig. 7 – on its way to exit through the superior orbital fissure.

2. V2: Maxillary branch also passes through the cavernous sinus the most inferior structure in the lateral wall of the sinus Fig. 7 – on its way to exit through the foramen rotundum

Figure 7: Trigeminal Nerve location in cavernous sinus in relation to other structures

Figure 8: Cavernous sinus location inside skull

3. V3: Mandibular branch passes immediately through the foramen ovale.
4. Motor root: passes with the Mandibular branch through the foramen ovale. After exiting the foramen ovale it unites with the Mandibular nerve to form one nerve – still called Mandibular nerve. (Strange considering scientists love to name each part of a something differently especially when things merge together).

This means that the Mandibular nerve is the only trigeminal branch that has a motor component.

Figure 9: Side view of Trigeminal Nerve branches location and distribution

Figure 10: Trigeminal ganglion and relation to Trigeminal nerves

Thus:

1. 1. V1 – Ophthalmic branch: sensory fibers
2. 2. V2 – Maxillary branch: sensory fibers
3. 3. V3 – Mandibular branch: sensory fibers and motor fibers.

Branches

V1: Ophthalmic branch

Branches:

1. Lacrimal nerve:

Supplies?

• Lacrimal gland (for that time when we are watching The Notebook and we need tears to spill down)
• Sensory to conjunctiva and skin of upper eyelid
• Postganglionic parasympathetic secretomotor fibers: these fibers are from the Zygomaticotemporal nerve which is a branch of the Maxillary nerve. They are originally from the facial nerve though. (check Ptergopalatine ganglion post)

 NOTE: it is for this reason, in a lesion of the Ophthalmic nerve that you get loss of corneal reflex. The lacrimal nerve supplies the conjunctiva of the eye which if affected by an Ophthalmic nerve lesion would not convey the impulses when a cotton touches the eye. So a person would not blink when a cotton ball touches the eyeball.

2. Frontal:

Further branches?

These branches leave the orbital cavity to ascend to the forehead:

• supraorbital nerve
• supratrochlear nerve

Supplies?

• frontal air sinus
• skin of forehead and scalp

NOTE: thus a lesion of the Ophthalmic nerve would cause not only loss of corneal reflex but loss of upper facial sensation.

3. Nasociliary:

Where does it run?

• On the upper border of medial rectus muscle
• Enters anterior ethmoidal foramenenters cranial cavityexits through a slit beside the crista gallienters nasal cavity.
• Changes its name to anterior ethmoidal nerve as soon as it enters cranial cavity.

Branches in the eye and the supply of each branch?

• Sends sensory fibers to ciliary ganglion
• Long ciliary nerves  supply sympathetic to dilator pupillae muscle and sensory to cornea
• Infratrochlear nerve supplies sensory to skin of eyelids

Branches in ethmoid?

• Posterior ethmoidal nerve  supplies sensory to ethmoid and sphenoid sinuses

Branches in nose?

• Internal nasal branches
• External nasal branches  supplies sensory to skin of tip of nose

V2: Maxillary branch

It continues as the Infraorbital nerve as it passes through the infraorbital canal.

Figure 11: Branches of the maxillary nerve

Where does it run?

• Ganglionic branches: after entering pterygopalatine fossa it gives off branches to the pterygopalatine ganglion.
• Zygomatic branch: after entering inferior orbital fissure it gives off zygomatic nerve which divides into:
• Zygomaticotemporal nerve: supplies skin of face, transports parasympathetic secretomotor fibers of facial nerve to lacrimal gland
• Zygomaticofacial nerve: supplies skin of face
• Posterior superior, Middle superior and Anterior superior alveolar nerves from the infraorbital nerve: supplies middle region of face, nasal mucosa, maxillary sinus, palate, upper teeth & gums 

NOTE: thus a lesion of the Maxillary nerve causes loss of sensation from middle of face & upper jaw. 

V3: Mandibular branch

• Is the nerve of the 1^st pharyngeal (AKA branchial) arch.
• Divides into anterior and posterior divisions

Branches of main trunk (supply)?

• Meningeal branch: enters  through the foramen spinosuminto the middle cranial cavitysupplies the dura mater and mastoid cells
• Nerve to medial pterygoid muscle: supplies medial pterygoid muscle, tensor veli palatini

Branches of anterior division?

NOTE: all branches are motor except one – buccal nerve.

• Masseteric nerve: supplies masseter muscle
• Deep temporal nerves: supplies temporalis muscle
• Nerve to lateral pterygoid muscle: supplies lateral pterygoid muscle
• Buccal nerve: supplies sensory to mucous membranes of cheek

Branches of posterior division?

NOTE: all branches are sensory except one – the mylohoid nerve. “poSterior is Sensory”

• Auriculotemporal nerve (skin of auricle, external auditory meatus, temporomandibular joint, scalp, parasympathetic fibers to parotid salivary gland)
• Lingual nerve: 
• Joins fibers from the Chorda Tympani
• Its sensory supply is: 
• General sensation (general somatic afferent) from Lingual nerve fibers for the anterior 2/3 of tongue and floor of oral cavity.
• Fibers from the Chorda Tympani nerve (from the Facial nerve-CNVIII) carry:
• Special visceral afferent sensation carried is the taste from the anterior 2/3 of tongue. (do not pass through ganglion)
• Preganglionic parasympathetic secretomotor to the submandibular ganglion. These presynaptic fibers synapse with postganglionic parasympathetic fibers in the ganglion. The parasympathetic fibers then leave the ganglion to either:
• Supply the submandibular and sublingual glands straight away.
• Or re-enter the lingual nerve and from there are distributed to the submandibular and sublingual glands.
• Inferior alveolar nerve:
• Mylohyoid nerve: supplies the mylohyoid muscle
• Communicating branch: from inferior alveolar nerve to lingual nerve (of the anterior division)
• It then enters the Mandibular canal: supplies lower jaw and teeth
• Then it emerges from the mental foramen: supplies the skin of the chin

References

Drake, R., Vogl, A., & Mitchell, A. (2010). Chapter 8: Head and neck - orbit. Gray's anatomy for students (2nd ed., pp. 878-902). Philadelphia: USA: Elsevier: Churchill Livingstone.

Snell, R. (2010). The cranial nerve nuclei and their central connections and distribution. Clinical neuroanatomy (7th ed., pp. 331-370). Philadelphia: Lippincott Williams and Wilkins.

Snell, R. (2007). Chapter 18: The eye and the ear. Clinical anatomy by systems (pp. 657-685). Philadelphia: USA: Lippincott Williams & Wilkins.

Picture references

1. Done by me
2. By Gray696.png: User:mcstrother derivative work: Mcstrother (Gray696.png) [Public domain], via Wikimedia Commons / retouched from original
3. Brainstem Nuclei of Cranial Nerves
4. Done by me
5. CN V. Trigemninal Nerve fromm Stritch School of Medicine/retouched from original
6. Unknown (if you know source please message me so I can mention it) / retouched from original
7. Henry Gray (1918) Anatomy of the Human Body from Wikimedia Commons
8. By Anatomist90 (Own work) [CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons  / retouched from original
9. Struck on the face out of the blue from The Sunday Times
10. Done by me
11. Class presentation