MCAT Biology › Brain and Central Nervous System
The central nervous system consists of the brain and the spinal cord. In general, tracts allow for the brain to communicate up and down with the spinal cord. The commissures allow for the two hemispheres of the brain to communicate with each other. One of the most important commissures is the corpus callosum. The association fibers allow for the anterior regions of the brain to communicate with the posterior regions. One of the evolved routes from the spinal cord to the brain is via the dorsal column pathway. This route allows for fine touch, vibration, proprioception and 2 points discrimination. This pathway is much faster than the pain route. From the lower limbs, the signal ascends to the brain via a region called the gracile fasciculus. From the upper limbs, the signal ascends via the cuneate fasciculus region in the spinal cord.
Which of the following sentences correctly explains what happens when a person steps on a pin?
I. Transmit to the brain rapidly
II. Will utilize the gracile fasciculus region in the spinal cord
III. Will utilize the cuneate fasciculus region in the spinal cord
The brain is a very delicate structure with little room to move around. Surrounding the brain and the spinal cord are three protective layers in addition to the skull and the vertebral column. Directly surrounding the brain and spinal cord is the pia mater. Following the pia mater is the arachnoid mater. Between the pia mater and the arachnoid mater is the sub-arachnoid space where the cerebrospinal fluid circulates. Finally, the protective layer is the dura mater is loosely attached to the arachnoid mater but is strongly associated with the skull bone.
Depending on the type of injury, a certain type of vein and/or artery are more susceptible to injury. For example, the meningeal artery and vein run through the foramen spinosum and travel between the two layers making up the dura mater. As the artery and the vein are traveling in between the dura mater, there is a vulnerable region at the temple. A strike to the temple region could rupture these vessels and result in a epidural hematoma.
Traveling from the cerebral cortex to the venous dural sinus (located at certain regions between the two layers of the dura mater) is the cerebral vein. When an injury results in the dura mater shifting away from the arachnoid mater, the cerebral vein could rupture and lead to a subdural hematoma.
When a physician performs a lumbar puncture, he/she is extracting cerebrospinal fluid. Through which of the follow structure(s) must the needle pass?
I. Dura mater
II. Arachnoid mater
III. Pia mater
Which section of the brain is responsible for regulating temperature?
An individual presents to his physician with a complaint of "uncoordinated muscle movements." After running proper tests, the physician suspects that this individual has some degree of brain injury. Which portion of the brain is most likely to be injured?
The central nervous system consists of the brain and the spinal cord. In general, tracts allow for the brain to communicate up and down with the spinal cord. The commissures allow for the two hemispheres of the brain to communicate with each other. One of the most important commissures is the corpus callosum. The association fibers allow for the anterior regions of the brain to communicate with the posterior regions. One of the evolved routes from the spinal cord to the brain is via the dorsal column pathway. This route allows for fine touch, vibration, proprioception and 2 points discrimination. This pathway is much faster than the pain route. From the lower limbs, the signal ascends to the brain via a region called the gracile fasciculus. From the upper limbs, the signal ascends via the cuneate fasciculus region in the spinal cord.
Patient A has a tumor in his spinal cord. He is able to feel fine touch below the waist. Above the waist, he is unable to feel fine touch on either side. Where is the tumor most likely located?
I. All levels of the spinal cord
II. In the gracile fasciculus region
III. In the cuneate fasciculus region
Which of the following activities would you expect to be controlled by the cerebral cortex?
The central nervous system consists of the brain and the spinal cord. In general, tracts allow for the brain to communicate up and down with the spinal cord. The commissures allow for the two hemispheres of the brain to communicate with each other. One of the most important commissures is the corpus callosum. The association fibers allow for the anterior regions of the brain to communicate with the posterior regions. One of the evolved routes from the spinal cord to the brain is via the dorsal column pathway. This route allows for fine touch, vibration, proprioception and 2 points discrimination. This pathway is much faster than the pain route. From the lower limbs, the signal ascends to the brain via a region called the gracile fasciculus. From the upper limbs, the signal ascends via the cuneate fasciculus region in the spinal cord.
Patient A has a tumor in his spinal cord. He is able to feel fine touch above the waist. Below the waist he is unable to feel fine touch on either side. Where is the tumor most likely located?
I. All levels of the spinal cord
II. In the gracile fasciculus region
III. In the cuneate fasciculus region
Which is the correct order of sequences during the knee-jerk reflex?
A lesion to which brain region would result in a lack of coordinated movement?
Which of the following is part of the hindbrain?