Contains about 90 billion neurons and about 100 billion neuroglia which has a mass of about 1300 g (almost 3 lb) in adults. On average, each neuron forms 1000 synapses with other neurons. Thus, the total number of synapses, about a thousand trillion or 10¹⁵, is larger than the number of stars in our galaxy. This structure is the control center for registering sensations, correlating them with one another and with stored information, making decisions, and taking actions. It also is the center for the intellect, emotions, behavior, and memory.

During fetal development, the brain and spinal cord develop from the ectodermal _______________.

During development, the anterior (front) part of the neural tube expands forward and the begins constriction (breaking apart into segments) into three regions called __________________.

Which of the following is not one of the three regions that develop immediately after the ectodermal neural tube grows from its anterior side?

Which of the three region primary brain vesicles continue to divide in the next stage into secondary brain vesicles?

The prosencephalon is also known as the ___________.

The rhombencephalon is also known as the ____________.

The prosencephalon (forebrain) and the rhombencephalon (hindbrain) further subdivide into two additional structures each. Match the structures that the forebrain or hindbrain develop into:

Match each of the following structures with the structure that they develop into after:

The telencephalon (from the forebrain) develops into which of the following?

The diencephalon (from the forebrain) develops into which of the following?

The mesencephalon (not from the hindbrain or forebrain) develops into which of the following?

The metencephalon (from the hindbrain) develops into which of the following?

The myelencephalon (from the hindbrain) develops into which of the following?

The walls of these brain regions develop into nervous tissue, while the hollow interior of the tube is transformed into its various ventricles (fluid-filled spaces). The expanded neural crest tissue becomes prominent in head development. Most of the protective structures of the brain—that is, most of the bones of the skull, associated connective tissues, and meningeal membranes—arise from this expanded neural crest tissue (posterior neural tube).

Group each of the following:

The brain consists of four major parts. Which of the following is not one of those four?

The diencephalon (originating from the forebrain) is also classified as one of the 4 major parts of the brain.

The telencephalon (originating from the forebrain) is also classified as one of the 4 major parts of the brain.

The _____________ is the largest part of the brain.

The soft protective cover of the brain is called the _______________.

The hard protective cover of the brain is called the _______________.

Which of the following is not one of the layers of the cranial meninges:

The cranial meninges have the same number of layers as the spinal meninges.

Write the two cranial dura layers using the word "and" to combine them. Don't use the word layer. 

The periosteal and meningeal layers are part of the cranial __________ mater. 

Like the spinal cord, there is an epidural space. 

Blood flows to the brain mainly via the internal carotid and vertebral arteries. The dural venous sinuses drain into the _____________ veins to return blood from the head to the heart.

Even though the brain makes up only 2% of the total body mass, it consumes _____% of the total energy, glucose and oxygen -- even at rest.

Neurons synthesize ATP almost exclusively from glucose via reactions that use oxygen. Therefore, the brain is very oxygen and glucose dependent; Moreso than many other bodily systems. When an area of the brain is seeing increased brain activity, the neurons and neuroglia are supplied with increased blood flow.

The brain is so sensitive to oxygen and blood flow that a brief slowing of brain blood flow may cause disorientation or a lack of consciousness, such as when you stand up too quickly after sitting for a long period of time.

Permanent brain injury requires loss of blood blow for how many minutes?

Glucose is stored within the cell body of the neurons within the brain.

Because virtually no glucose is stored in the brain, the supply of glucose also must be continuous. If blood entering the brain has a low level of glucose, mental confusion, dizziness, convulsions, and loss of consciousness may occur. People with diabetes must be vigilant about their blood sugar levels because these levels can drop quickly, leading to diabetic shock, which is characterized by seizure, coma, and possibly death.

The _______________ consists mainly of tight junctions that seal together the endothelial cells of brain blood capillaries and a thick basement membrane that surrounds the capillaries. Astrocytes are one type of neuroglia; the processes of many astrocytes press up against the capillaries secrete chemicals that maintain the “tightness” of the tight junctions.

The blood brain barrier allows very few selective substances to pass through based on select criteria.  Lipid-soluble substances (including O2, CO2, steroid hormones, alcohol, barbiturates, nicotine, and caffeine) and water molecules cannot cross the endothelial cells of the BBB.

Only a few water-soluble substances can cross the BBB, and they require facilitation through facilitated diffusion. These include the water-soluble substances such as glucose. All others are facilitated much more slowly. Therefore, when designing drugs that target the brain, it is better to make then water soluble than lipid soluble.

Since most proteins and most antibiotics are not lipid soluble, they can cross the blood brain barrier.

Trauma, certain toxins, and inflammation can cause a breakdown of the BBB.

______________________ a clear, colorless liquid composed primarily of water that protects the brain and spinal cord from chemical and physical injuries. It also carries small amounts of oxygen, glucose, and other needed chemicals from the blood to neurons and neuroglia. CSF continuously circulates through cavities in the brain and spinal cord and around the brain and spinal cord in the subarachnoid space

The total volume of CSF is 80 to 150 mL (3 to 5 oz) in an adult. CSF contains small amounts of glucose, proteins, lactic acid, urea, cations (Na+, K+, Ca2+, Mg2+), and anions (Cl− and HCO3−); it also contains some white blood cells.

CSF circulates throughout cavities called _______________ within the cranial cavity.

The brain is separated into two hemispheres. On each hemisphere CSF circulate in two ventricles -- specifically in the cerebrum. These ventricles are called the ______________ ventricles. 

The _________ ventricle is a narrow, slit-like cavity along the midline superior to the hypothalamus and between the right and left halves of the thalamus.

The _____________ ventricle lies between the pons and medulla anteriorly and the cerebellum posteriorly.

CSF serves as a shock-absorbing medium that protects the delicate tissues of the brain and spinal cord from jolts that would otherwise cause them to hit the bony walls of the cranial cavity and vertebral canal. The fluid also buoys the brain so that it “floats” in the cranial cavity.

CSF provides an optimal chemical environment for accurate neuronal signaling. Even slight changes in the ionic composition of CSF within the brain can seriously disrupt production of action potentials and postsynaptic potentials.

CSF is a medium for minor exchange of nutrients and waste products between the blood and adjacent nervous tissue.

The majority of CSF production is from the ___________________, networks of blood capillaries in the walls of the lateral ventricles. The ependymal cells of the ________________ filter out water from the blood capillaries. This blood–cerebrospinal fluid barrier permits certain substances to enter the CSF but excludes others, protecting the brain and spinal cord from potentially harmful blood-borne substances.

In contrast to the blood–brain barrier, which is formed mainly by tight junctions of brain capillary ________________ cells, the blood–cerebrospinal fluid barrier is formed by tight junctions of ependymal cells.

The CSF formed in the choroid plexuses of each lateral ventricle flows into the third ventricle through two narrow, oval openings called ______________.

The CSF fluid flows from the third vesicles through the ______________ which then passes through the midbrain into the fourth ventricle. The choroid plexus of the fourth ventricle contributes more fluid.

CSF enters the subarachnoid space through three openings in the roof of the fourth ventricle: a single median aperture and paired lateral apertures, one on each side. CSF then circulates in the central canal of the spinal cord and in the subarachnoid space around the surface of the brain and spinal cord.

CSF is gradually reabsorbed into the blood through _______________, fingerlike (cilia-like) extensions of the arachnoid mater that project into the dural venous sinuses, especially the superior sagittal sinus.

The volume of CSF remains constant, produced and removed at the same rate.

The _____________ is the part of the brain between the spinal cord and the diencephalon. It consists of three structures: (1) medulla oblongata, (2) pons, and (3) midbrain. Extending through the brainstem is the reticular formation, a netlike region of interspersed gray and white matter.

_________________ is continuous with the superior part of the spinal cord; it forms the inferior part of the brainstem. ________________ begins at the foramen magnum and extends to a distance of about 3 cm. Its white matter contains all sensory (ascending) tracts and motor (descending) tracts that extend between the spinal cord and other parts of the brain.

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Just superior to (above/before) the junction of the medulla with the spinal cord, a crossing occurs where 90% of the axons in the left pyramid cross to the right side, and 90% of the axons in the right pyramid cross to the left side. This crossing is known as the ___________ of pyramids. This cross over explains why each side of the brain controls movements (voluntary) on opposite sides of the body. 

Recall that a nucleus is a collection of neuronal cell bodies at one center within the CNS. The medulla oblongata contains some of those centers. While there are several, two very important such centers are the cardiovascular center and the medullary respiratory center. What is the function of the cv center?

The medulla also contains the vomiting center which controls:

The medulla also contains the deglutition center which controls:

Which of the following does the medulla not have a center for:

Another nucleus called the inferior olivary nucleus, or red nucleus of the midbrain/spinal cord, is in a close by structure within the medulla that is responsible for controlling all the neurons in the cerebellum. The cerebellum is location for learning new motor functions and muscle activity. What structure contains this red nucleus?

One of the most important nuclei found in the medulla is the nuclei for sensations such as touch, pressure, vibration, and conscious proprioception (awareness of the position of your body/presence). Postsynaptic neurons relay the sensory information to the thalamus on the opposite side of the brain. Which of the following is the nucleus responsible for that?

Postsynaptic neurons then relay the sensory information to the thalamus on the opposite side of the brain. The axons ascend to the thalamus in a band of white matter called the __________________ which extends through the medulla, pons, and midbrain. The tracts of the posterior funiculi and the axons of the medial lemniscus are collectively known as the posterior column–medial lemniscus pathway.

The _____________ nucleus of the medulla is part of the gustatory pathway from the tongue to the brain; it receives gustatory input from the taste buds of the tongue.

The _______________ nuclei of the medulla are part of the auditory pathway from the inner ear to the brain; they receive auditory input from the cochlea of the inner ear.

The _____________ nuclei of the medulla and pons are components of the equilibrium pathway from the inner ear to the brain; they receive sensory information associated with equilibrium from proprioceptors (receptors that provide information regarding body position and movements) in the vestibular apparatus of the inner ear.

Match the following medulla nerves with their nuclei purposes:

This structure is directly superior to the medulla and anterior to the cerebellum and is about 2.5 cm (1 in.) long.  Like the medulla, it consists of both nuclei and tracts. As its name implies in Latin, it is a bridge that connects parts of the brain with one another. These connections are provided by bundles of axons. Some axons connect the right and left sides of the cerebellum. Others are part of ascending sensory tracts and descending motor tracts. In other words, it is a focal bridge between the left and right hemispheres as well as to the medulla.

How many major structural components make up the pons?

The ventral region and the dorsal region are the two major components of the pons.

Which of the major components of the pons contains pontine nuclei?

The ______________ nuclei of the pons contain numerous white matter tracts, each connecting different sides of the cerebral hemisphere and that of the opposite hemisphere of the cerebellum. This complex circuitry plays an essential role in coordinating and maximizing the efficiency of voluntary motor output throughout the body.

The dorsal region of the pons is more like the other regions of the brainstem, the medulla and midbrain. It contains ascending and descending tracts along with the nuclei of cranial nerves.

Also, within the pons is the ____________ respiratory group. Together with the medullary respiratory center, the pontine respiratory group helps control breathing.

Match the following pons nerves with their nuclei purposes:

Match the following nerves with the correct brainstem structure:

The ________________ extends from the pons to the diencephalon (see Figures 14.1, 14.5) and is about 2.5 cm (1 in.) long.  Like the medulla and the pons, the ____________ contains both nuclei and tracts.

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Having said that the anterior part is the cerebral peduncle, the posterior part of the midbrain is called _________________. It contains four rounded "bumps" or elevations. 

___________________ nerves contain nuclei in the midbrains which provide motor impulses that control movements of the eyeball, while accessory oculomotor nuclei provide motor control to the smooth muscles that regulate constriction of the pupil and changes in shape of the lens via the oculomotor nerves.

Trochlear (IV) nerves. Nuclei in the midbrain provide motor impulses that control movements of the eyeball via the trochlear nerves.

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A netlike arrangement of both white and gray matter that extends from the superior part of the spinal cord up through the brainstem, and into the inferior part of the diencephalon. Neurons within it have both ascending (sensory) and descending (motor) functions. 

The upward (sensory) signal portion of the reticular formation is called __________________. It consists of sensory axons that project to the cerebral cortex, both directly and through the thalamus. 

Among the many reticular activating system signals are visual and auditory stimuli; mental activities; stimuli from pain, touch, and pressure receptors; and receptors in our limbs and head that keep us aware of the position of our body parts.

The most important function of the reticular activating system (RAS) is consciousness or awakening from sleep. 

Which of the following is not a function of the reticular activating system:

Drugs such as melatonin affect the RAS by helping to induce sleep, and general anesthetics turn off consciousness via the RAS.

The descending portion of the RAS has connections to the cerebellum and spinal cord and helps regulate _________________, the slight degree of involuntary contraction in normal resting skeletal muscles. This portion of the RAS also assists in the regulation of heart rate, blood pressure, and respiratory rate.

The ___________ is the second largest structure after the cerebrum by size. It occupies the inferior and posterior aspects of the cranial cavity. Like the cerebrum, it contains a lot of folded area which serves the purpose of increasing the surface area despite the area that it occupies. For instance, a larger paper has more surface area than a smaller paper. But if the larger paper is crumpled then it occupies less space while still having a larger surface area due to folding. 

The large surface area of the cerebellum has the downside of it having less neurons.

The folded (crumpled) surface area of the cerebellum allows for it to have more place area for neurons to exit thus having a much higher number of neurons than otherwise possible. This allows it to have half of all neurons in the brain despite only being 10% of the size of the brain. 

Both folded (crumpled) parts of the brain are right next to each other: cerebrum and cerebellum. However, they are separated transversely by a deep groove called the _____________________.

Both folded (crumpled) parts of the brain are right next to each other: cerebrum and cerebellum. However, they are separated at the posterior by a deep groove called the _____________________.

The ___________________ are regions of gray matter that give rise to axons carrying impulses from the cerebellum to other brain centers.

The cerebellum is attached to the brainstem by three paired ________________. This structure contains white matter that have similar functions to the cerebellar nuclei.

Match each of the following as appropriate for the three cerebral peduncles:

The primary function of the cerebellum is to evaluate how well movements initiated by motor areas in the cerebrum are actually being carried out. When movements initiated by the cerebral motor areas are not being carried out correctly, the cerebellum detects the discrepancies. It then sends feedback signals to motor areas of the cerebral cortex, via its connections to the thalamus. Therefore, it is also responsible for posture and balance.

Match the following structures of the cerebellum to their function:

Label the following image: https://www.purposegames.com/game/midsaggital-section-of-brain-stem-and-cerebellum-game

_______________ is the central core of brain tissue superior to midbrain. Almost completely surrounded by the cerebral hemispheres and contains numerous nuclei involved in a wide variety of sensory and motor processing between higher and lower brain centers.

The diencephalon extends from the brainstem to the cerebrum and surrounds the third ventricle. Which of the following is not part of the diencephalon:

From the hypothalamus is a projection which is called the _______________.

The optic tracts carrying neurons from the retina enter the diencephalon.

Makes up 80% of the diencephalon, consists of paired oval masses of gray matter organized into nuclei with interspersed tracts of white matter

Complete the following quizzes: https://www.purposegames.com/game/ipap-15-2-special-senses-thalamic-nuclei-game and https://www.purposegames.com/game/thalamus-pt2

The bridge of gray matter that connects the right and left half of the thalamus in 70% of human brains is called the __________________.