Week 2 The Brain - Grp 2 answers Flashcards
Describe the flow of cerebral spinal fluid.
The ventricular system provides the pathway of circulation for the cerebral spinal fluid. It is composed of four fluid filled cavities which include the left and right lateral ventricles, the third ventricle, and the 4th ventricle. The lateral ventricles are composed of a frontal lateral horn, temporal horn, and a occipital horn.
cerebral spinal fluid. Where is this fluid normally found?
The spinal fluid is found within the sub-arachonoid space.
Where is CSF produced
Choroid plexus: produces the CSF in the posterior horns of the lateral ventricle
CSF where does it flow and where does it leave the subarachnoid space
It flows from the L and R lateral ventricles into the 3rd ventricle through the interventricular foramen, it then exits the 3rd ventricle through the cerebral aqueduct( aqueduct of sylvius) into the 4th ventricle. The CSF exits the ventricular system through the foramina inside the fourth ventricle, this exit route is called the median aperture( foramen of Magendie). It is located in the posterior wall of the 4th ventricle. The CSF then continues into the spinal cord through the central canal.
Discuss the basal ganglia and their general function. Name these, describe their location and surrounding/separating white matter tracks
The basal ganglia are a group of nuclei located deep within the cerebral hemispheres of the brain. They play a crucial role in various motor functions, cognition, and emotion regulation. Although traditionally associated with motor control, research has shown their involvement in a wide range of functions, including procedural learning, routine behaviors, and even some aspects of cognition and emotion.
Caudate nucleus- a C-shaped structure located within the basal ganglia, a collection of nuclei deep within the cerebral hemispheres of the brain. It is situated adjacent to the lateral ventricles, which are fluid-filled spaces within the brain, and it extends from the frontal lobe to the occipital lobe.
lentiform nucleus- the putamen and globus pallidus form the lentiform nucleus, which is situated between the caudate nucleus and the internal capsule. The lentiform nucleus, along with the caudate nucleus and the subthalamic nucleus, plays a crucial role in the regulation of motor function and the integration of motor signals within the basal ganglia circuitry.The lentiform nucleus is a lens-shaped structure located within the basal ganglia of the brain. It consists of two main components
Putamen: The putamen is a large, rounded structure situated lateral to the internal capsule. It is involved in motor control and receives input from the cerebral cortex, particularly motor areas.
Globus pallidus: The globus pallidus lies medial to the putamen and is divided into two segments: the external globus pallidus (GPe) and the internal globus pallidus (GPi). The GPe serves as a major inhibitory output nucleus of the basal ganglia, while the GPi serves as a major output nucleus projecting to the thalamus.
claustrum-a thin, irregular sheet of gray matter located deep within the brain, underneath the neocortex. It is situated between the insular cortex and the putamen of the basal ganglia. The claustrum is divided into two segments:
External claustrum: This portion of the claustrum is located closer to the cortex and is involved in receiving sensory information from various cortical regions.
Internal claustrum: This segment lies deeper within the brain and is thought to be involved in integrating and processing sensory information before relaying it to other brain regions.
The basal ganglia are surrounded and separated by white matter tracts, including:
Internal capsule: This dense bundle of white matter fibers separates the caudate nucleus and putamen from the thalamus and other structures of the brain.
External capsule: It surrounds the putamen and separates it from the claustrum and other nearby structures.
Corona radiata: These are the fan-shaped white matter fibers that radiate from the internal capsule throughout the cerebral cortex, connecting the basal ganglia with various cortical regions.
Describe the route of arterial blood from the internal carotid arteries through the Circle of Willis. Name the arterial structures/branches in the order blood will flow
The Route of Blood from Internal Carotid arteries through the Circle of Willis:
Internal Carotid Arteries (ICA): The major arteries that supply blood to the brain, then enter the skull through the carotid canal.
Anterior Cerebral Arteries (ACA): After entering the skull, the arteries travel along the midline of the brain and supply blood to frontal lobes and partially the parietal lobes as well.
Anterior Communicating Artery( ACoA): The ACA are connected by the ACoA and form part of the Circle of Willis.
Posterior Communicating Arteries (PCoA):The internal carotid arteries go to the posterior communicating arteries, which connect with branches of the basilar artery.
Posterior Cerebral Arteries (PCA):The posterior communicating arteries lead into the posterior cerebral arteries, which supply blood to the occipital lobes.
Basilar Artery:The basilar artery is formed when two vertebral arteries fuse at the base of the brainstem. It provides blood supply to structures in the brainstem and cerebellum.
Vertebral Arteries:The vertebral arteries arise from the subclavian arteries and ascend through openings in the cervical vertebrae and enter the skull.
Superior Cerebellar Arteries (SCA) and Posterior Inferior Cerebellar Arteries (PICA): Branches of both vertebral arteries contribute to supplying blood to different parts of the cerebellum.
Circle of Willis:The Circle of Willis connects major arterial structures at the base of the brain from both internal carotid and vertebrobasilar systems.
Describe the route of venous blood return from the brain to the internal jugular veins. Only include the venous structures discussed in the lecture, but describe what makes up the sinuses and the route venous blood will flow to the internal jugular veins.
All of the veins in our brain flow into the dural sinuses ,which lead to the internal jugular veins in the neck. These venous sinuses do not have a valve, so they have bidirectional flow.
Superior sagittal sinus: Blood return starts in the superior sagittal sinus. The blood is collected from the cerebral veins that are going to the confluence of sinuses. This sinus in superior to the falx cerebri.
Inferior sagittal sinus: The inferior sagittal sinus is superior to the corpus callosum. This sinus connects with the great cerebral vein, forming the straight sinus.
Straight sinus: Inferior to cerebrum, superior to the cerebellum. The straight sinus drains the fluid from the inferior sagittal sinus into the confluence of sinuses.
Confluence of sinuses: The mechanism of venous return, this sinus is an intersection consisting of the superior sagittal, transverse, and straight sinuses.
Bilateral right and left transverse sinus: Bilaterally located in the tentorium cerebelli. It is responsible for transporting the blood from the confluence of sinuses into the left and right sigmoid sinus.
Sigmoid sinus: Sigmoid sinuses connect in the posterior cranial fossa to join the internal jugular veins.
Cavernous sinus: Collection of venous blood inferior to the Circle of Willis.
Discuss the brainstem and its general function. Name the structures, describe their location and the structures that surround each
The brainstem is made up of 3 different areas: Midbrain, Pons, and Medulla Oblongata. It is packed with motor and sensory nuclei making it vital for normal brain function. These areas act as a channel between the cerebral cortex, cerebellum, and spinal cord.
Midbrain: Is located above the pons and is the smallest portion of the brainstem. It is composed of massive bundles of nerve fiber tracts. It is responsible for assisting visual reflexes, auditory relay to the thalamus, melanin and dopamine production as well as pain and temperature information to the brain..
Pons: Is a distinct bulge on the brainstem inferior to the midbrain, superior to the medulla oblongata, and anterior to the cerebellum. This structure is a bridge for signals between the spinal cord and cerebral and cerebellar cortices.
Medulla Oblongata: Is located below the pons and extends to into the spinal cord. It can be divided into 2 symmetrical halves the anterior and posterior median fissures. Each half of the brain control the opposite half of the body. It contains all fiber tracts and acts as a relay structure between brain and spinal cord.These fibers contribute to voluntary and motor control. The olive is a structure on the lateral surface of the Medulla Oblongata which is responsible for coordination, balance, and regulation of inner ear sound impulses
