What is a commissure in the brain?

Commissure. The most common usage of the term refers to the brain’s commissures, of which there are five. Such a commissure is a bundle of commissural fibers as a tract that crosses the midline at its level of origin or entry (as opposed to a decussation of fibers that cross obliquely).

Keeping this in view, what is the function of the posterior commissure?

The posterior commissure (also known as the epithalamic commissure) is a rounded band of white fibers crossing the middle line on the dorsal aspect of the upper end of the cerebral aqueduct. It is important in the bilateral pupillary light reflex.

Where is the anterior white commissure located?

The anterior white commissure (ventral white commissure) is a bundle of nerve fibers which cross the midline of the spinal cord just anterior (in front of) to the gray commissure (Rexed lamina X).

What is the function of the fornix in the brain?

The fornix (Latin: arch) is a C-shaped bundle of nerve fibers in the brain that acts as the major output tract of the hippocampus. The fornix also carries some afferent fibres to the hippocampus from structures in the diencephalon and basal forebrain. The fornix is part of the limbic system.

What is the commissure of the lip?

The commissure is the corner of the mouth, where the vermillion border of the superior labium (upper lip) meets that of the inferior labium (lower lip). The commissure is important in facial appearance, particularly during function such as smiling. As such it is of interest to dental surgeons.

What is a valve commissure?

3D interactive simulation of a normal mitral valve. Anatomy of the anterior and posterior commissure of the mitral valve.* The commissures define a distinct area where the anterior and posterior leaflets come together at their insertion into the annulus.

What is a Commissural fiber?

In contrast to commissural fibers, association fibers connect regions within the same hemisphere of the brain, and projection fibers connect each region to other parts of the brain or to the spinal cord.

What are projection fibers in the brain?

Projection fiber. The projection fibers consist of efferent and afferent fibers uniting the cortex with the lower parts of the brain and with the spinal cord.

What does the posterior commissure do?

The posterior commissure (also known as the epithalamic commissure) is a rounded band of white fibers crossing the middle line on the dorsal aspect of the upper end of the cerebral aqueduct. It is important in the bilateral pupillary light reflex.

What is an association fiber?

Association fibers are axons that connect cortical areas within the same cerebral hemisphere. In human neuroanatomy, axons within the brain, called fibers, can be categorized on the basis of their course and connection into association fibers, projection fibers, and commissural fibers.

Where is the arcuate fasciculus located?

The arcuate fasciculus (Latin: curved bundle) is a bundle of axons that forms part of the superior longitudinal fasciculus, an association fiber tract. The arcuate bidirectionally connects caudal temporal cortex and inferior parietal cortex to locations in the frontal lobe.

What is the function of the arachnoid villi?

The arachnoid granulations act as one-way valves. Normally the pressure of the CSF is higher than that of the venous system, so CSF flows through the villi and granulations into the blood. If the pressure is reversed for some reason, fluid will not pass back into the subarachnoid space.

What is the purpose of the arachnoid membrane?

It is interposed between the two other meninges, the more superficial and much thicker dura mater and the deeper pia mater, from which it is separated by the subarachnoid space. The delicate arachnoid layer is attached to the inside of the dura and surrounds the brain and spinal cord.

What does arachnoid granulation mean?

Arachnoid granulations, also known as a Pacchionian granulation, are projections of the arachnoid membrane (villi) into the dural sinuses that allow CSF entrance from the subarachnoid space into the venous system.

What makes CSF?

Cerebrospinal fluid (CSF) is a clear, colorless body fluid found in the brain and spinal cord. It is produced by the specialised ependymal cells in the choroid plexuses of the ventricles of the brain, and absorbed in the arachnoid granulations.

Where does CSF drain?

The circulation of CSF is aided by the pulsations of the choroid plexus and by the motion of the cilia of ependymal cells. CSF is absorbed across the arachnoid villi into the venous circulation and a significant amount probably also drains into lymphatic vessels around the cranial cavity and spinal canal.

What is the main purpose of the cerebrospinal fluid?

While the primary function of CSF is to cushion the brain within the skull and serve as a shock absorber for the central nervous system, CSF also circulates nutrients and chemicals filtered from the blood and removes waste products from the brain.

What is the purpose of the cerebrospinal fluid?

The central nervous system (CNS) consists of the brain and spinal cord. Cerebrospinal fluid (CSF) is a clear, colorless liquid that surrounds and protects the CNS. It bathes the brain and spine in nutrients and eliminates waste products. It also cushions them to help prevent injury in the event of trauma.

What are the three functions of the cerebrospinal fluid?

Cerebrospinal fluid has three main functions: CSF protects brain and spinal cord from trauma. CSF supplies nutrients to nervous system tissue. CSF removes waste products from cerebral metabolism.

How is the cerebrospinal fluid affected by meningitis?

Brain Infection Facts. Our brain, the spinal cord, and its surrounding structures can become infected by a large spectrum of germs. Meningitis is the inflammation of the meninges, the surrounding three-layered membranes of the brain and spinal cord, and the fluid it is bathed in, called cerebrospinal fluid (CSF).

What is the first sign of meningitis?

The first symptoms are usually fever, vomiting, headache and feeling unwell. Limb pain, pale skin, and cold hands and feet often appear earlier than the rash, neck stiffness, dislike of bright lights and confusion. Septicaemia can occur with or without meningitis.

Is meningitis is curable?

Early diagnosis and treatment will prevent brain damage and death. Bacterial meningitis is treated with intravenous antibiotics. There’s no specific antibiotic for bacterial meningitis. It depends on the bacteria involved.

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