what is paracentral disk protrusion and extrusion?
540940
It's usually a degenerative process.  Normally, your spine is made up of blocks called vertebrae.  They are cushioned by a gell-like material called disks.  When you get older (in some people it starts in the 30s), they can get smashed and push out against some nerves.  It normally doesn't bother people until the nerve becomes inflamed.  It can be aggravated by injury.  It usually gets better with pain medicine and rest.  It sometimes gets better with surgery.\n\nBut if you look at all the people with back pain and all the people with abnormal disks on MRIs,  you'll see a lot of people with pain where the MRI is normal, and a whole bunch of people with abnormal MRIs without pain.
86333
thorasic, lumbar and cervical
780246
It is something like solar eclipse.It depends on how close to the eye you hold it.It can be anything total,annular or partial.\nIt will be partial if the axis of the disc deviates slightly from the line of view.
189232
For many uniform configurations, the centroid is the center of gravity or the center of mass.  As I recall, I believe that the two may differ under certain circumstances where motion and acceleration is involved.  See the source for uniform materials and origin of the term.
440362
I would guess it is made from rapid prototyping:- Fused-deposition modeling.  It technique is call Extrusion of melted plastic. there is more information that you can find. Just keep looking..
7798
an accretion disk is a disk of matter from the smaller star that is being sucked into the other star by gravity.
175138
The shape of the articular surfaces of the vertebrae give good clues as to the types of movements that they allow. \nFish have amphicelous vertebrae, that is, with both surfaces concave. Fishes have primarily lateral movements of the body axis. \nIn tetrapods, in addition to the main articular surfaces, there are apophyses that restrict dorsoventral movements between adjacent vertebrae. They are called zygapophyses and are situated anterodorsally and posterodorsally in each vertebra.\nIn tetrapods the vertebrae may have one convex surface and one concave surface (complementary), or other shapes. If they have anterior concavity they're called procoelous, and if the concavity is in the posterior surface they're opisthocelous. Amphibians and reptiles have procoelous, opisthocoelous or amphicoelous vertebrae. These type of joints permit much lateral movement (except in frogs that have a shortened vertebrate column, and no tail).\nThe neck vertebrae of birds are heterocoelous: their articular surfaces have the shape of a horse saddle and this allows greater mobility (some birds are able to rotate their heads 180º). \nIn mammals the vertebrae are amphiplatyan, with both surfaces flat; mammals do not move their column laterally, but there is dorsoventral undulation when running. The xenarthrans (armadillos, sloths and giant anteaters) have special additional articulations that make their lumbar area more rigid when they stand on their hindlegs.
956612
There is a difference. a bulging disc means that the disc material is still intact inside of the disc. There is a weakening to the disc wall. A slipped disc is another way if referring to a herniated disc. This occurs when the disc material leaks out of the disc eliminating the cushion you have between the vertebral space. You can have either problem with or without symptoms. The only time you should consider having this repaired is if you are in pain. Either problem can be caused by trauma or by doing something as simple as sneezing.
911487
The equations of motion for the angular displacement of each disk are given by:\n\nDisk A: R1(t) = (1/2)*alpha1*t² + w1*t +Ri1\nDisk B: R2(t) = (1/2)*alpha2*t² + w2*t +Ri2\n\nFor part (a), we're looking for the time, T, for which R1(T) = R2(T)\n\n(1/2)*alpha1*T² + w1*T +Ri1 = (1/2)*alpha2*T² + w2*T +Ri2\n\nFrom the problem statement, we obtain the following information:\n\nRi1 = Ri2\nalpha1 = 0\nw1 = 9.5 rad/s\nalpha2 = 2.2 rad/s²\nw2 = 0\n\nSubstituting these values and simplifying, we obtain:\n\nw1*T= (1/2)*alpha2*T²\n\nw1= (1/2)*alpha2*T\n\nT = 2*w1 / (alpha2)\n\nT = 2(9.5 rad/s) / (2.2 rad/s²)\n\nT = 8.64 s\n\nTechnically, part (b) is impossible to say without knowing how the reference line is defined, but I'll give it a whirl. If the reference line is measured from the center of each disk to its outer edge, then yes.\n\nHowever, if the reference line is placed across the diameter of the disk, then no. In this case, the reference lines will be aligned when the angular displacement of Disk A is 180° or pi radians ahead of Disk B. To solve for this time, simply add pi to Disk B's equation of motion:\n\n(1/2)*alpha1*T² + w1*T +Ri1 = (1/2)*alpha2*T² + w2*T +Ri2 + pi\n\nSubstituting out known values again leads us to:\n\nw1*T= (1/2)*alpha2*T² + pi\n\nor:\n\n(1/2)*alpha2*T² - w1*T + pi = 0\n\n1.1*T² - 9.5*T + pi = 0\n\nUsing the quadratic formula, we find that \n\nT = .344 seconds or 8.292 seconds\n\nThus, if the reference line is directed across the entire disk, then they are momentarily aligned twice before having the same angular displacement.\n\n(This added after a while)\n{BTW, monohan47130 - no I didn't. Please read what I wrote. If the reference lines are defined along the radius only, then you are correct - there is only one point at which the disks have the same angular displacement. But, reference lines are typically made along the entire circle (diameter). This means that they will be aligned 3 times total in 8.64 seconds :) }
771017
Bulging lumbar discs are usually associated with decreased pain with walking and increased pain with prolonged and improper sitting.  There is up to 200 times the normal pressure in a disc when we remain seated.  Getting up and walking reverses the curve in our spine that occurs with sitting...allowing the disc to resume a more neutral position.  \n\nIf you already have a documented back condition, I suggest following up with a physical therapist who will perform an evaluation as to which exercises are the most appropriate for YOU (rather than guessing which ones MIGHT be good)!  \n\n...but keep up the walking if it decreases the pain...and limit your time sitting to 20 minutes at a time.
360937
I hope that this has nothing to do with computer hardware.\n\nYour spine, the bone that runs from your head all the way down to your bum has segments (vertebrae) which are loosely called 'discs'.  Due to a fall, accident or injury, they slip causing severe pain by pushing against the spinal cord that runs through the spine.  They can sometimes he returned to their proper position by manipulation by a doctor or chiropractor.
42476
A small outgrowth of the ventral wall of the embryonic brain from which the pars nervosa (the posterior lobe of the pituitary gland) develops is called the infundibulum.\n\nMore generally it refers to any number of funnel-shaped bodily passages, openings, structures, or parts which include the stalk of the pituitary gland, the calyx of a kidney or the ovarian opening of a fallopian tube.\n\nWho exactly thought it was an aneurysm?
513263
Spiral, lenticular, elliptical and irregular\n\nSee the link
641595
The term is oblate spheroid I believe. Get that extra credit!
619061
It means "around" the vertebrae.  For example the paravertebral muscles are the two long muscle groups that run down your back on either side of the midline.  A paravertebral tumor is one that lies around or adjacent to the spinal column.
657371
The posterior projection of a single vertebra is known as the spinous process. It is an attachment for various ligaments and muscles.
612539
The inner portion of the disk between vertebrae is called the nucleus propulsus.  This area is heavily laden with proteogylcans - a type of molecule that holds onto water.  The effect is to keep this area well hydrated - hence, allowing for better shock absorbance.  As you age, or after an injury the biochemical composition of the nucleus propulsus changes slightly.  It no longer holds water quite as well - hence the appearance on MRI (and MRI helps show differences in density or water content - the difference in water content of various body structures is what makes them stand out on the scan).  \n\nThere is no good way to repair the damage.  Some experts will tell you to keep well hydrated - this may keep the area as full of water as possible.   You likely are already seeing an orthopedic surgeon - they can offer surgical corrections- but surgical management is generally reserved for severe cases.  \n\nI generally don't recommend alternative medicine, but chiropractic (osteopathic manipulation) can actually be very helpful with chronic back/neck pain.  There is a new technology allowing serial decompressions using low impact that many chiropractors in my area are using - it may be of benefit to you.  Make sure to find a highly qualified professional - these are generally willing to use several different techniques depending on your issues (high-velocity or "back cracking" techniques MAY make cervical compression worse)