Difference between human and sheep brain pons medulla relationship

Difference Between Human and Sheep Brain | Difference Between | Human vs Sheep Brain

difference between human and sheep brain pons medulla relationship

This is possible because the sheep brain and human brain are very similar. However, there are some key differences that should be kept in mind during. What is the difference between sheep and human brains when it comes to: 1. olfactory bulb 2. pons/medulla relationship 3. location of cranial. The cerebrum of humans is larger than that of sheep because the mental Describe the relationship between the optic nerve, optic chiasma, and optic tract. a bulging brainstem region between the midbrain and medulla oblongata area of the brain located between the diencephalon and pons that.

This space is called the cisterna magna. In the intact brain it is filled with cerebrospinal fluid. The meninges form another enclosed space at the anterior limit of the cerebellum called the superior cistern.

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Click on the image for an enlarged view. As discussed in the lecture and your textbook, the brain evolved from a primitive neural tube. As certain segments of the tube enlarged, the internal spaces in the tube followed suit. This resulted in the creation of large spaces in the interior of the brain called ventricles. The ventricles and their connecting passages are filled with the same CSF as that in the subarachnoid space.

Thus, the brain is cushioned by CSF that fills the ventricles within and the cisterns and subarachnoid space without. At the lateral junction of the cerebellum and the medulla notice the dark-brown, tufted material, the choroid plexus. This material is a capillary bed, which, along with other tissue, is involved in the production of CSF. We will see another choroid plexus in the lateral ventricles in Lab 3.

Difference Between Cerebellum and Cerebrum

Important structures or features of the dorsal surface of the brain. The dominant features of your sheep brain specimen are the two cerebral hemispheres and the exquisitely convoluted cerebellum. The cerebral hemispheres are divided into functional subsections called lobes or poles.

difference between human and sheep brain pons medulla relationship

To see the four lobes of neocortex of the sheep identified, follow the link. The lobes of the brain are separated from one another by sulci, or fissures.

Two important sulci can be found in the anterior regions of the two hemispheres. Together, these two sulci form a 'T. Don't be confused by this. The area anterior to the ansate sulcus is frontal lobe and the cortex posterior to the ansate sulcus is the parietal lobe.

The separation of the parietal lobe from the more posteriorly located occipital lobe is ill-defined. The temporal lobe in the sheep is very poorly developed in comparison to primates.

The temporal lobe sometimes called insula in the sheep is quite small as can be seen in the figure. Before you continue, stop and look at the mounted phylogenetic scale of brains and the preserved brains in jars that are available. Notice that the single-most distinctive feature of the phylogenetic sequence is the increase in the relative size of the cerebrum cerebral hemispheres. Notice that the frog's brain is distinguished from the codfish by a noticeable increase in cerebrum.

Compare the brain of the dog with that of the cat and rat. Now, look at the human brain specimen. Look at the dorsal aspect of the brain and the spinal cord that extends from it.

Have the instructor or lab assistant point this out to you. You should be able to see that the dorsal surface of the medulla, and the spinal cord, are marked by parallel, longitudinal striations formed by columns of fibers. The most medial pair of these columns is the fasciculus gracilis; the more lateral pair of columns is the fasciculus cuneatus.

Have the instructor or lab assistant point these out to you, if you are unclear about their locations.

difference between human and sheep brain pons medulla relationship

Collectively, these two fasciculi are also known as the dorsal columns. The axons in these columns are ascending sensory fibers, carrying for the most part, light touch sensations from the body and limbs.

difference between human and sheep brain pons medulla relationship

Click on the image at the left for an expanded view. Follow the dorsal columns rostrally until they just begin to disappear beneath the cerebellum; you will find two small mounds. These two swellings are the nucleus gracilis and the nucleus cuneatus. Remember from Lab 1 that nuclei are collections or clusters of cell bodies located within the CNS. The axons in the dorsal columns synapse on cells located in the nucleus gracilis and nucleus cuneatus.

  • Differences Between Human and Sheep Brains
  • When comparing human and sheep brains, you observe some profound differences between them.?

The axons of the cells residing in the two nuclei then exit the nucleus, decussate cross the midline and project to the contralateral thalamus where they synapse on cells in the ventroposterolateral nucleus VPL.

The axons of the cells located in VPL project to somatosensory cortex the post-central gyrus. Before you continue, stop to draw a schematic of the path that somatosensory information takes from spinal cord to postcentral gyrus. Include the nucleus gracilis, nucleus cuneatus, VPL and postcentral gyrus in your drawing.

Important features of the ventral surface. In Lab 1, you located a large fiber structure, the cerebral pedunclesjust anterior to the pons. The oculomotor nerves can be seen exiting from them. Recall that the cell bodies that give rise to the axons in the cerebral peduncles are found in motor cortex and that they are called pyramidal cells.

Difference Between Human and Sheep Brain

The fibers in the cerebral peduncles continue to the spinal cord. They can be seen on the ventral surface of the medulla, where they are known as the pyramidal tract. Stop, now, and mentally trace the pyramidal tract from cerebral cortex to spinal cord.

The pyramidal motor system, one of two major motor systems in the body is in control of fine, discrete and voluntary motor activities such as writing, typing, or playing the piano. Other motor systems are concerned with gross motor movements, such as, dancing, walking, or waving goodbye.

difference between human and sheep brain pons medulla relationship

This may be a good time to restate conventions concerning names of tracts in the CNS. If you keep the rule 'from-to' in mind, you will always be able to tell the site of origin and destination for a given tract. The first name in the title indicates the site of origin of the tract, while the second name indicates the tract's destination. The tract known as the corticospinal tract, according to the rule, originates from neurons whose cell bodies reside in the cortex and project their axons to the spinal cord.

The trapezoid body consists of fibers carrying information from the right ear to left auditory cortex and information from the left ear to right auditory cortex. The trapezoid body is to the auditory system what the optic chiasm is to the visual system. Unlike somatosensory cortex, the auditory and visual cortices receive bilateral input, that is, each projection site receives information from both ears or both eyes, respectively. If it has not been stripped away, you will find the VIII cranial nerve, the vestibulo-cochlear or auditory nerve at the most lateral extent of the trapezoid body.

The sheep brain is smaller, weighing around grams, or about one-tenth of the weight of an adult human brain, though it is still large enough to be easily dissected.

The cerebrum is more elongated in sheep than in humans, and the cerebellum and brain stem are located behind the cerebrum, instead of being tucked below it. This is because sheep, being four-legged animals, have a horizontal spine, while humans stand upright with their spines vertical.

Frontal Lobe A major difference is that the frontal lobe in the sheep brain is much smaller relative to the overall brain size, accounting for only a few percent by volume compared to about 25 percent in the human case.

The frontal lobe is connected with higher cognitive functions, such as abstract thinking and analysis.

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The relative size of the frontal lobe, as well as the number of ridges in the cortex, are indicators of species intelligence. Though the sheep has generally been regarded as an unintelligent animal, it is increasingly recognized that sheep are able to perform some advanced tasks, such as remembering the faces of other sheep and humans for two years or longer. Olfactory Bulb The sheep, like many mammals, has a more developed sense of smell, or olfaction, than humans do.

The olfactory bulb is the part of the brain located underneath the frontal lobe that is responsible for relaying sensory information from the nose to the rest of the brain. The olfactory bulb in sheep is two to three times the size of the human olfactory bulb, despite the sheep brain being much smaller overall.

Internal Structures and Safe Entry Zones of the Brainstem (3D Anaglyph)