The Eye -- Its Anatomy and Physiology III -- Lesson 263

-
In the recent post you have learned about the rods and cones.An optic nerve is the nerve of which light energy is focued on the retina, a chemical change occurred in the rods and cones initiating nerve impulseswhich travel from the eye to the brain via the optic nerve. The region in the eye where the optic nerve meets the retina is called retina is called the optic disk. This optic disk is otherwise called as the blind spot of the eye. A small oval which is called the macula is yellowish area to the side of the optic disk.

 A central depression which is called fovea centralis is also contained in it. which composed of largely of cones, and is the location of sharpest vision in the eye.  If fovea's portion or macula's portion is damaged, central vision blindness occurs and the vision is reduced. Through the opthalmoscope the fundus of th eye is the posterior and the inner part is visualized. 

The rods and cones in the retina synapse with neurons and leads to the optic nerve fibers. As the optic nerve fibers travel into the brain, the fibers located more medially cross in an area called the optic chiasm. From the right half of each retina nerve fibers form an optic tract, synapsing in the thalamus of the brain and ending in the right visual region of the cerebral cortex. In the same way, fibers from the left half of each retina merge to from the optic tract and pass from the thalamus to the left region of the cerebral cortex. 

The images are fused in the visual area of the cerebral cortex and a single visual sensation with a three-dimensional effect is experienced. This vision is called binocular vision. Loss of vision in the right visual field is caused due to the damage in the left cerebal cortex. This vision loss in the contralateral or opposite side of the visual field is called hemianopsia, in which hemi means half, an means without, opsia means vision.

In the next post we would learn the short definitions related to this topic.


To go to the prior post from here, please click the link below


To go to the first post from here, please click the link below


Comments

Post a Comment

Popular posts from this blog

HUMAN BONE STRUCTURE - LESSON 200

-
Now in this post we will learn about the structure of the bone. In our human body there are 206 bones of different types are there. The thigh, lower leg, and upper and lower arm consists of long bones. These bones have large surface areas for muscle attachment and are very strong, are broad at the ends where they join with other bones. There are five types of bones in the human body. The five types are long, short, flat, irregular, and sesamoid. 1. Long bones:- These bones are comprised mostly of compact bone and lower amounts marrow, which is located within the medullary cavity, and spongy bone and are characterized by a shaft, the diaphysis, that is much larger in length than breadth. These bones are mostly present in the limbs, including those of the fingers and toes are long bones. Except the wrist, ankle, and kneecap these long bones are located in most. 2. Short bones:- These short bones are generally cube shaped and having a thin layer of compact bone surrounding a...
Read more

IMPORTANT RADIOLOGY NUCLEAR MEDICINE TERMS-3-LESSON 148

-
1. Magnetic resonance imaging- A magnetic ground radio signals are used to outline sagittal, coronal, and axial pictures of the body. 2. Megavoltage- High-energy radiation engendered by means of an equipment and employed in restorative x-ray analysis intended for cancer. 3. Nuclear medicine- This is a medical speciality, which examines and employs of radioactive materials called radionuclides within identification and treatment of ailment. 4. Orthovoltage- Emission of low-energy radioactive waves that are employed in pain-killing radiation therapy and exterior skin cancer diseases. 5. Palliative- Means just soothing or painkilling, not curing completely that is not possible. 6. PET scan or positron emission tomography- Radioactive materials are administered using intravenous route and these substances give out positrons. They generate a cross-sectional picture of the metabolism of the body. These images symbolize local concentration of the radio...
Read more

The Longest Medical Word

-
Image
Today, we will know about an interesting medical term in medical language. This post is just to know about a different thing in the medical language, though this word is used very rarely in our day-to-day medical transcription work. The longest medical word is "Pneumonoultramicroscopicsilicovolcanoconiosis"!!!!!. Can you read at least Pneumonoultramicroscopicsilicovolcanoconiosis.  Now, we will see the meaning of this word.  To know the meaning shall we split the word by word. Okay.  1.  Pneumono 2.  Ultramicrosopic 3.  Silico 4.  Volcano 5.  Conosis. So, Pneumonoultramicroscopicsilicovolcanoconiosis comprises of 5 medical words and in combination, they give a meaning of a certain kind of disease condition related to lungs.  Now, we will see the meaning of each to get the combined understanding of the longest medical word. Pneumono means lungs, ultramicroscopic - means minute, silico means silicon, volc...
Read more