Tuesday of this week we expanding on the Cranial and Spinal nerves. First we re-capped that the vetebral canal is where the spinal cord passes thorough the veterbral column. We looked at the break-down on different vertebrae: Cervical has 7, thoracic 12, lumbar 5 and sacrum 5. There are 31 spinal nerve pairs. It was interesting to learn that the cranial nerves come out superiorly from the vertebrea whereas the spinal nerves emerge inferiorly. We touched on the meninges, the spinal cord only has one layer whereas the brain has two. It's important to know anatomical names and positions we reviewed that anterior and ventral both mean the front and posterior and dorsal refers to the back. Sensory and motor neurons travel in opposite directions like a highway. Sensory output leaves posteriorly as motor output leaves anteriorly. The ascending tracts head toward the brain and carry sensory impulses. They are found on each side of the posterior fissure. They relay infor about proprioreception. The Gracius Fasiculos provides info from the lower legs to the brain while the Cuneanus fasiculu realys info from the upper extremities. The descending tracts travel down the spinal cord and carry motor impulses. The spinothalamic tract is so named that it tells you the impulse gets on at the spinal region and off at teh thalmus. It relays sensory of pain and temperature. The anterior corticospinal and lateral corticospinal tracts realy every impulse out to the entire body.
After reviewing and learning this information we were sent home with a take-home quiz. I spent every moment working on that, to the point that I was second-guessing my answers. There came a point when I just had to set the quiz down and walk away. Thursday we returned to lecture, went over some information about the cranial nerves that we hadn't yet learned and hesitantly passed in the quiz. Thursday we started talking about the parasympathetic and sympathetic nervous systems. I think it's easiest to remember that the sympathetic takes your body away from it's baseline while the Parasympathetic returns you to baseline. The Parasympathetic is also nick-named the "feed/breed" or rest/digest system with the Sympathetic is known for its "fight or flight" responses. We also talked about the muscles of the eye. The radial muscles are controlled by the SNS and they cause pupillary dilation. The circular muscles of the eye are controlled by the PNS and constrict the pupil.
Learning about all the cranial nerves reminded me of something. When I was much younger I had to have lower mandibular surgery. I remember my surgeon talking about the mandibular nerve. Even though I was young he took out the model of a skull and explained to me how my surgery would go, where the incisions were, the cutting of the mandible and where the nerve is in the jaw. He said that if it was damaged I could have permanent damage. In my case that didnt' happen but as I read stories from blotched surgies online it's unfortunate that so many people have to suffer through this. This goes to show how important every part of our bodies are and that we need to take charge of our own health an well being. We live in this body yet many of us know (or even care) about it. This A&P class has been so interesting because I have learned so much about my body. It's an amazing piece of work.
Saturday, February 21, 2009
Saturday, February 7, 2009
Cranial and Spinal Nerves
I survived last weeks quiz, I'm glad to report. But that doesn't mean they don't still scare me to death. There is so much information. I was thankful that on Tuesday we mostly reviewed material. We talked again about the anatomy of the brain, lobes and functions, arterial blood flow, the limbic system and CSF circulation. Thursday was a new topic and a new Prof. Mr Haskell. Mr Haskell had the task of teaching about the Cranial and Spinal nerves. A whole lot of info packed in one lecture. We started learning that the spinal cord and CSF (dorsal cavity) is called the Conus medullaies, this separates into the Cauda equina which further branches off in the sacral area of Filium equina. Confused yet? Yeah, that's just the beginning. Looking at a cross section of the spinal cord we can see it's shaped like a white circle with an gray "H" inside. The area of the spinal cord that is white appears so because it's myelinated and the gray mater is unmyelinated and appears darker. The dorsal root is sensory as the ventral root is motor. The white commisure are tracts that are coming from the brain (like a highway). The horns have three areas, the posterior, lateral and anterior. The lateral gray horn is only found in the thoracic region and is where sympathetic nerves exit the spinal cord.
We learned that some nerves are weaved together in a plexus and that they branch off in many areas. The lumbar-sacral region is not as mingling or complex as the brachial plexus. We referred to a lot of diagrams in the text and the PowerPoint to see how the nerves are situated in and throughout the human body. We highlighted the 12 cranial nerves and looked at their points on entrance/exit in the human skull. I am still learning what all the nerves do and the labeling of the skull. There is another quiz on Tuesday so I still have to spend a lot of time learning the brain/blood flow and nerves.
We learned that some nerves are weaved together in a plexus and that they branch off in many areas. The lumbar-sacral region is not as mingling or complex as the brachial plexus. We referred to a lot of diagrams in the text and the PowerPoint to see how the nerves are situated in and throughout the human body. We highlighted the 12 cranial nerves and looked at their points on entrance/exit in the human skull. I am still learning what all the nerves do and the labeling of the skull. There is another quiz on Tuesday so I still have to spend a lot of time learning the brain/blood flow and nerves.
Sunday, February 1, 2009
The Brain
We started this week with an exam. I'm going to wait until I receive my exam back before I post any comments. The second half of the week we started to focus on the brain. We reviewed the three Primary Regions of the brain: Prosencephalon, Mesencephalon and Rhombencephalon. Then at week 8 of development we now have the Telencephalon (which as an adult becomes the cerebral hemispheres) the Diencephalon (becomes the Thalmus, hypothalmus), the Mesencephalon becomes the Midbrain (corpora quadrigemina), the Metencephalon in the adult brain develops the Pons and Cerebullum while the Myencephalon becomes the medulla oblongata.
We focused on the midbrain region. The Corpora Quadrigemina which has the superior colliculi (the relay system for vision impulses) and the inferior colliculi (relay system for auditory impulses). The tectum is the "roof" or dorsal surface of the midbrain. One thing that makes learning the human body so difficult is the vocabulary. Many words are spelled similarly but have a very different meaning, or there are multiple names for the same thing. We see this with the cerebral aqueduct which is the same as the aqueduct of Sylvius. Very confusing. We then took a quick overlook of the midbrain that extends inferiorly into the Pons and more inferiorly the medulla oblongota. If somebody is talking about the hindbrain they are referring to the Pons and the Medulla, but the term brain stem includes the midbrain, pons, and medulla. Just the beginning of this topic seems confusing with a lot of details. However, we move right along to the protective coverings of the brain (and spinal cord) the meninges. Of these there are three layers. The outermost consists of a thick, white, dense irregular connective tissue called the Dura Mater. Within this layer there are major blood vessels. The area above the Dura Mater is called the Epidural Space whereas the area below it is the sub-dural space. The dura mater around the brain is 2 layers thick, in contrast to only being one layer thick around the spinal cord. The middlemost layer is the Arachnoid Mater, this is web-like, contains no blood vessels and is found next to the sub-arachnoid space where CSF is and diffusions through CSF allows nutrients between these two layers. The third and innermost layer of meninges is the Pia Mater. It's structure is capillary network.
We took a closer look at the Dura Mater which is two layers. The Periosteal layer is closest to the skull and the meningeal layer is the inner layer. These two layers adhere tightly together however in some places spaces do form between the layers. One such space is the Superior Sagittal Sinus (where venous blood collects between the right and left cerebral hemispheres).
Next we turned to the blood flow of the brain. For this we referred to page 774 in our Primary textbook. It was pointed out that the falx cerebri was the region of dura mater between the cerebral hemisphers.
We followed the path of venous drainage: Superior sagittal sinus>Right transverse sinus>inferior sagittal sinus>left transverse sinus>Sigmoid sinus>internal jugular>right branchiocephal>Superior vena cava>heart.
Then we turned to page 757 and 758 and looked at Arterial Blood Circulation: Oxygenated blood from the lungs to the heart.
Blood enters the Left Atrium>(bicuspid/mitral valve) Left Ventricle>Semilunar valve>ascending Aorta>Aortic Arch>Descending Aorta>Thoracic Aorta>Abdominal Aorta
Focus was given to the three vessels which come off the Aortic Arch 1)Right branchiocephalic artery -right subclavian and right common carotid ....2) Left common carotid-external and internal 3) left subclavian Both internal carotids go through the neck; feed blood into the Circle of Willis.
These are the notes I took in class. I have to re-read over the material and study each of these components. A&P II has proven to be a lot different from A&P I. It's a challenge to comprehend everything you think you need to know and bringing the information from lecture and the four textbooks together.
We focused on the midbrain region. The Corpora Quadrigemina which has the superior colliculi (the relay system for vision impulses) and the inferior colliculi (relay system for auditory impulses). The tectum is the "roof" or dorsal surface of the midbrain. One thing that makes learning the human body so difficult is the vocabulary. Many words are spelled similarly but have a very different meaning, or there are multiple names for the same thing. We see this with the cerebral aqueduct which is the same as the aqueduct of Sylvius. Very confusing. We then took a quick overlook of the midbrain that extends inferiorly into the Pons and more inferiorly the medulla oblongota. If somebody is talking about the hindbrain they are referring to the Pons and the Medulla, but the term brain stem includes the midbrain, pons, and medulla. Just the beginning of this topic seems confusing with a lot of details. However, we move right along to the protective coverings of the brain (and spinal cord) the meninges. Of these there are three layers. The outermost consists of a thick, white, dense irregular connective tissue called the Dura Mater. Within this layer there are major blood vessels. The area above the Dura Mater is called the Epidural Space whereas the area below it is the sub-dural space. The dura mater around the brain is 2 layers thick, in contrast to only being one layer thick around the spinal cord. The middlemost layer is the Arachnoid Mater, this is web-like, contains no blood vessels and is found next to the sub-arachnoid space where CSF is and diffusions through CSF allows nutrients between these two layers. The third and innermost layer of meninges is the Pia Mater. It's structure is capillary network.
We took a closer look at the Dura Mater which is two layers. The Periosteal layer is closest to the skull and the meningeal layer is the inner layer. These two layers adhere tightly together however in some places spaces do form between the layers. One such space is the Superior Sagittal Sinus (where venous blood collects between the right and left cerebral hemispheres).
Next we turned to the blood flow of the brain. For this we referred to page 774 in our Primary textbook. It was pointed out that the falx cerebri was the region of dura mater between the cerebral hemisphers.
We followed the path of venous drainage: Superior sagittal sinus>Right transverse sinus>inferior sagittal sinus>left transverse sinus>Sigmoid sinus>internal jugular>right branchiocephal>Superior vena cava>heart.
Then we turned to page 757 and 758 and looked at Arterial Blood Circulation: Oxygenated blood from the lungs to the heart.
Blood enters the Left Atrium>(bicuspid/mitral valve) Left Ventricle>Semilunar valve>ascending Aorta>Aortic Arch>Descending Aorta>Thoracic Aorta>Abdominal Aorta
Focus was given to the three vessels which come off the Aortic Arch 1)Right branchiocephalic artery -right subclavian and right common carotid ....2) Left common carotid-external and internal 3) left subclavian Both internal carotids go through the neck; feed blood into the Circle of Willis.
These are the notes I took in class. I have to re-read over the material and study each of these components. A&P II has proven to be a lot different from A&P I. It's a challenge to comprehend everything you think you need to know and bringing the information from lecture and the four textbooks together.
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