The Theory of General Relativity

The Theory of General Relativity

"The Newtonian Disability"

"General Relativity"

Whenever a person in this universe says that word, the history of modern physics prevails itself. From the starting of the era where human mind wondered the aspects of this elegant universe, few intriguing questions came along. Newton discovered gravity and called it to be a force. for more than two centuries the equations given by him proved to be true. But when our minds started to imagine even higher some difficulties with the Newtonian mechanics came along. These questions were answered by Einstein himself. And when he did, Everything changed!

The problem with Newtonian Theory

 Newton stated gravity to be a force of attraction that acts at a distance. Through his understanding of gravitational force he successfully explained the motion of the moon around the earth and the motion of other planets around the solar system. He said that moon like any free falling body falls towards the earth, but it does not crashes on earth to create a planetary catastrophe because it also moves along the direction of its velocity in the space. Consequently, it moves 38 miles forward and 16 feet towards the earth. 

    

Newtonian Laws explained that light is not affected by the gravity of any mass M. He also stated that the change in Massive M is felt through out the cosmos instantly because of the denudation of that objects gravitational pull. But through SR we know that the speed of light (c) is the cosmic speed limit so no physical entity can exceed this limit. We can imagine this as we are supposed to cross a very fragile and old wood bridge that can diminish instantly. If we cross the bridge cautiously, the bridge will survive but if we cross the bridge at a robust speed the bridge tends to fall. And so does the spacetime. Through SR we know at speed of light the Mass of the object increases beyond our imagination and so does the energy it releases. This results in spacetime Distortion. 

    

      So, how can the change of loosing that mass M can be felt instantly. For example, light from the sun takes 8 minutes to reach us so, how can impact of loosing the sun can be felt instantly. This mystery was solved by Einstein through his theory of General Relativity. 

  

Introduction to theory in next post!

Anatomy of "Magic Wands"

Anatomy of "Magic Wands" 

Part-3

In this part of the series the topic of discussion will be one of the most interesting topics of  human anatomy- neurology. We are going to explore the nervous paradigm of hand and arm to get a deeper understanding that how those strong muscles that we talked about earlier move and co-ordinate. The significance of nervous paradigm of a working arm and hand is that it not only receipts the orders from brain but also transmits the first stimuli from the fore limbs. 

   

 The Musculocutaneous Nerve

 The main nerves of the fore limb are musculocutaneous nerves from the cervical and the thorax of the the spinal chord. It obliquely passes between the biceps brachii and brachialis. It is almost hidden and rarely gets damaged. It is the main supplier for the interior compartment of the hand muscles. It also branches along the interior compartment. The medical conditions for this nerve are also very rare because of the fact that it is covered by the exterior compartment. But some damage may occurs due to hypertrophy or stress of localized muscle tissue.  

The Radial Nerve 

Radial nerve supplies to the posterior portion of the upper limb controlling the 12  muscles of the posterior oestofascial compartment and the dorsal muscles. It is one of the major nerves of the upper limb and is subdivided into many branches. It passes through the inter muscular gaps near the triceps brachii and enters the grove of humerus to the fore arm. In the fore arm the nerve divides into

Muscle Supplied by Radial nerve

superficial branches of upper set  which is the sensory set and deep set  which is primarily the motor set. The deep branches of the radius nerve induces the supinator muscles and upper, the nail bead and some finger sections including middle, index fingers.

    

      The radial nerve being one of the most important nerves is also prone to serious medical conditions and injuries. Any kind damage in the radial nerve can lead to loss of sensation in the fore arm, weakness, loss of supinator control and eventually a complete motor failure while using radial induced muscle sets.

 

The Median Nerve

Median Nerve

The median nerve is one of the main nerves originating from the brachial plexus. It passes through the carpel tunnel into the hand. The median nerve has no voluntary function in the brachium. It basically induces the flexor groups of the fore arm including flexors like- 

• digitorum superfacialis,

•  flexor digitorum profundus

 It also supplies to the Superficial groups like-

• Pronator treres

• flexor carpi radialis

• Palmaris longus

The most common disorder with the median nerve is the carpal tunnel syndrome about which I have already discussed in my earlier posts.

The Ulnar Nerve

The ulnar nerve is called so because it runs really close to the ulna bone. The interesting thing about this nerve is that it passes between the medial epicondyle and the skin over that. Sometimes if we are struck over that spot a sensation of a electric shock passing through the fore arm is felt. This point is called funny point. 

 Muscles supplied

• Flexor Carpi Ulnaris

• Flerxor Digitorum Profundus

• Opponens digiti mini

• Dorsal and Palmar interossei.

     

Anatomy of "Magic Wands"

Anatomy of "Magic Wands" 

Part-2

In the second part of this series we are going to discuss about the muscle anatomy of the fore limbs.The muscle system in the arm and hand consists of both large and small muscles. We can also find exceptional amount of tendon tissue all over the fore limb.

     

        The interesting thing about arm is that the muscle groups are divided into two fascial layers namely lateral and medial inter muscular septa. These layers divide the muscle groups into two different compartments. The important thing about limbs is that they are responsible for flexion and extension of themselves that helps us to carry out almost every movement that takes place by limbs.

The basic naming involving muscle is carries out on the character of the muscle and is place. For example the brachioradialis is the big strapped muscle that we observe to pop out while flexion near the elbow joint. This muscle is named so because it is found at the brachial side of the radius bone.

 

The list of Muscle Involved in following movements-

Flexion of fore arm-                                                             

• Brachialis
• Biceps Brachii
•  Brachioradialis

The Supination of forearm-

• Bicep Brachii

The extension-

• Triceps brachii

The extensor muscles-

• Triceps Brachii (Posterior)
• Carpi Ulnaris (Posterior)
•  Extensor Digitorum (Posterior)

Flexion Muscles

• Flexor Carpi Radialis
• Flexor Digitorum Suerficialis

Carpal tunnel

The flexor and extensor muscles pass through a narrow tunnel at our wrists called carpal tunnel. The tendons of these muscles pass through the tunnel to connect with the phalanges and other bones in the hand. Some time due to incorrect posture or over work a strong inflammation occurs in the carpel tunnel due to extensive stress on median nerve by localized swelling of tendons or muscles.This causes numbness and inability to do griping work. This is called Carpel tunnel syndrome.