A&P Chapter 14: Brain and Cranial Nerves

Somatic sensory association area

Interprets inout to primary sensory cortex, for example, can tell you if a touch is light, cold, a person's touch, or a mosquito, so it recognizes sensations and helps sensory cortex respond to sensations.

Cranial meninges

Protect the brain from cranial trauma or impact to head and stabilize the brain in the cranial cavity by being continuous with the spinal meninges

Inferior colliculi

Receive AUDITORY info from medulla and pons and control reflex movements of the head, neck and truck in response to auditory stimulus like a loud noise.

Solitary nucleus

Receives VISCERAL SENSORY info in medulla oblongata nuclei

Superior colliculi

Receives VISUAL info from thalamus and controls reflex movements of head, neck and eyes in response to visual stimulus like bright light

Cardiovascular reflex center

Receives/gives input on the reflexes of heart rate and cardiac muscle contraction, while its vasomotor cortex manages blood flow, either vasodilating or vasoconstricting.

Respiratory rhythmicity center

Reflex center that sets the pace for respiratory movements (regulated by input from the pons)

Insula

Region of the brain deep in the cortex that you can see if you pull back the lateral sulcus

Nucleus gracilius and nucleus cuneatus

Relay SOMATIC SENSORY info like touch and pain to thalamus

Corpora quadrigemina

Two pairs of sensory nuclei in tectum of the midbrain and includes the superior and inferior colliculi

Third ventricle

Ventricle of the diencephalon (thalamus) that communicates with the lateral ventricles via the interventricular foramen

Fourth ventricle

Ventricle of the myelencephalon (medulla oblongata) that becomes continuous with the central canal of the spinal cord and connects with the third ventricle via the cerebral aqueduct

From top to bottom: 1. Telencephalon (cerebrum) 2. Diencephalon (thalamus to cerebrum connection) 3. Mesencephalon 4. Metencephalon ( cerebellum and pons) 5. Myelencephalon (Medulla oblongata)

What are the five SECONDARY brain vesicles during fetal development?

1. Cranial bones 2. Cranial meninges 3. Cerebrospinal fluid 4. Blood-brain barrier

What are the layers of protection for the brain?

From outside to inner layer: 1. Dura mater 2. Arachnoid mater 3. Pia mater

What are the layers of the cranial meninges?

1. Cerebrum 2. Cerebellum 3. Diencephalon 4. Mesencephalon 5. Pons 6. Medulla oblongata

What are the six regions of the brain?

From top to bottom of neural tube: 1. Prosencephalon 2. Mesencephalon 3. Rhombencephalon

What are the three PRIMARY brain vesicles?

Commissural fibers

White matter bands of fibers the connect two hemispheres and cross over, for example, the corpus callosum and the anterior commissure

Projection fibers

White matter fibers in the cerebrum that connect the cerebrum with lower areas. They pass through the diencephalon (thalamus) and link the brain with diencephalon, brain stem, cerebellum, and spinal cord. May run transverse, longitudinal, but connect superior and inferior parts is the important thing. Includes the internal capsule

Association fibers

White matter tracts of the cerebrum that do not cross over and make connections within the same hemisphere and include arcuate (short) fibers and longitudinal fasiculi

Lateral group of thalamic nuclei

group of thalamic nuclei that affects emotional states (limbic) and integrates sensory info

Posterior group of thalamic nuclei

group of thalamic nuclei that integrates sensory info to the cerebral cortex and includes the lateral geniculate nucleus and the medial geniculate nucleus

Ventral group of thalamic nuclei

group of thalamic nuclei that relay sensory info about touch, pressure, pain, temperature, and position to cerebral cortex

Olfactory cortex

In the insula lobe, receives info from odor receptors

Gustatory cortex

In the insula lobe, receives info from taste receptors

Visual cortex

In the occipital lobe, receives info from sight receptors

Auditory cortex

In the temporal lobe, receives info from sound receptors. If affected you can have Wernicke's which means you speak fine but can't process what you hear or Broca's which means you understand what's said but you can't say what you mean

Thalamus

In the walls of the diencephalon, it relays and processes sensory information, filtering ascending sensory info for primary sensory cortex and our conscious awareness, but it only passes a small amount through to the cerebrum. The third ventricle separates the left and right thalamus and each of those consists of a rounded mass of thalamic nuclei which have five groups: anterior, medial, ventral, posterior, and lateral.

Lentiform nucleus

Includes the putamen which, like the caudate nucleus, receives info from sensory, motor, and integrative areas of cortex and the globus pallidus where most of output leaves after processing to synapse with thalamus which then feeds back with the brain to alter motor commands.

Visual association area

Interprets activity in visual cortex, for example, helps you put letters into words

Infundibulum

Narrow stalk coming off hypothalamus that connects it to the pituitary gland

Somatic motor association area

Also known as the premotor cortex, it coordinates motor responses (learned movements), for example, picking up a glass or playing piano

Sensory areas of the cortex

Area of the cortex that includes the postcentral gyrus and the primary sensory cortex

Motor areas of the cortex

Area of the cortex that includes the precentral gyrus and the primary motor cortex

Integrative centers of the cerebrum

Areas located in lobes and cortex of both hemispheres that receive info from many association areas and direct very complex motor or analytical activities. Is concerned with speech, math, spatial relationships. For example, when you watch your dance teacher do a move and you analyze it before doing it to repeat it.

EEG/Electroencephalogram

Assesses brain activity by placing electrodes on skull and looking at patterns of electrical activity or brain waves

Reticular formation

Autonomic nuclei of the medulla oblongata that regulates vital autonomic functions and extends the length of the brain stem from the medulla oblongata to the midbrain. For example, the reticular formation relaxes the body when you go to sleep and alerts the start of body functions when you awaken. The reticular formation also contains reflex centers that receive messages from the cranial nerves, cerebral cortex, and brain stem to adjust peripheral systems that are categorized into two systems: the cardiovascular center and the respiratory rhythmicity center.

Blood-brain barrier

Barrier that allows things like oxygen into the CSF but blocks out other things that could harm the brain. The space between cells lining the blood vessels in the brain are very narrow and form tight junctions with astrocytes coating the outside of the vessels to allow only certain things to pass.

Tuberal area

Between the infundibulum and the mamillary bodies, this structure of the hypothalamus helps control the pituitary gland function

Pituitary gland

Connected to the hypothalamus by the infundibulum, it is a major endocrine gland responsible for integration of nervous and endocrine systems

Interventricular foramen

Connects lateral ventricles with third ventricle

Adult human brain

Contains 97% of body's neural tissue, weighs about 3 lbs, and its size doesn't correlate with intelligence. It has white matter under the superficial gray matter.

Caudate nucleus

Curving, slender tail of the basal nuclei where info arrives from sensory, motor, and integrative areas of cortex.

Fissures

Deep grooves of cerebral cortex

Medial longitudinal fissure

Divides cerebrum into left and right hemispheres and each hemisphere receives info from and sends info to the opposite side of the body.

Lobes

Divisions of cerebral cortex regions named after overlying bones of the skull: Frontal, Temporal, Occipital, Parietal, Insula

Neural tube

During fetal development, this is the origin of the brain that determines the organization of brain structures and enlarges into three primary brain vesicles: the prosencephalon, the mesencephalon, and the rhombencephalon.

Gyri

Elevated ridges of cerebral cortex that increase surface area

Hemispheric lateralization

Functional differences between the right and left hemispheres. Each hemisphere performs some functions that are not usually performed by the opposite. For example, in most people, the left controls: -Reading, writing, and math -Decision making -Speech and language For most people, the right controls: -Senses (touch, smell, sight, taste, feel) -Recognition (faces, voice inflections)

Medial group of thalamic nuclei

Group of thalamic nuclei that provide awareness of emotional states

Anterior group of thalamic nuclei

Group of thalamic nuclei that regulates emotions, motivation, and memory as part of the limbic system.

Two lateral ventricles in each cerebral hemisphere (larger ventricles) third ventricle in diencephalon, and fourth ventricle in myelencephalon in the medulla oblongata.

How many ventricles are there in the brain?

Cerebrum

Largest brain region that controls higher functioning, conscious thought, and intellectual functions. It also processes sensory and motor info and is divided into left and right hemispheres by the medial longitudinal fissure and contains the gray matter we call the neural or cerebral cortex.

Relay stations of the medulla oblongata

Located along the sensory and motor pathways of the brain stem and contain the solitary nucleus, the olivary nuclei (remember olives) and the nucleus gracilis and nucleus cuneatus and the tracts leaving all of these nuclei decussate, or cross to the opposite side of the spinal cord/brain before reaching their destination

Diencephalon

Located underneath the cerebrum and in front of the cerebellum, it links the cerebrum to the brain stem and integrates sensory info and motor commands. There is controversy about whether or not itself is included in the brain stem. It has three regions: the left thalamus, right thalamus, both of which are very important in connecting incoming signals to the brain, and the hypothalamus and also includes the epithalamus and pineal gland.

Longitudinal fasiculi

Long association fibers of the cerebrum that connect frontal lobe to other lobes in same hemisphere

Internal capsule

Longitudinal tracts on either side of longitudinal fissure carrying projection fibers

Olivary nuclei

Looking like olives, these nuclei relay info about SOMATIC MOTOR commands in medulla oblongata

Basal nuclei

Masses of gray matter in each hemisphere of the cerebrum deep to the floor of the lateral ventricle that direct subconscious activities like control of skeletal muscle tone and coordination of learned movements like walking and lifting, buried in white matter, the projection and commissural fibers travel around these nuclei. Does not initiate movement but provides the pattern and rhythym. For example, you forget you're wearing underwear after you put them on but that sensory info is still going into and out of the basal nuclei. If you're focusing on a puzzle there are still sensory info coming in and motor commands like move your foot happening on an unconscious level. Includes the caudate nucleus and lentiform nucleus.

Arachnoid mater

Middle layer of cranial meninges that covers the brain

Auditory association area

Monitors the auditory cortex, for example, makes word recognition when you hear sounds

Cerebral aqueduct

Narrow canal in the midbrain that connects the third and fourth ventricles

Hypothalamus

On the floor of the diencephalon, it is involved on hormone production, emotion, and autonomic function and includes the mamillary bodies, infundibulum, and tuberal area. Its eight functions include: 1. Autonomic function like heart rate, blood pressure, and digestion 2. Body temperature regulation by increasing or decreasing blood flow to the skin 3. Circadian rhythym 4. Coordination of voluntary and autonomic systems like when there's an emergency and heart rate and breathing go up 5. Emotions and behavioral drives including the feeding center for hunger and the thirst center 6. Endocrine and nervous system coordination to stimulate or inhibit production of hormones 7. Hormones- secretes ADH (antidiuretic hormone) and Oxytocin 8. Subconscious control of skeletal muscle like facial expressions that accompany rage

Midbrain/Mesencephalon

One of the first parts of the brain located in the brain stem to form from stem cells during fetal development, this part processes sight, sound, and their associated reflexes, for example, when you turn your head after hearing a loud noise. Its structures include the tectum and cerebral peduncles.

White matter of the cerebrum

Organized into various fibers like tracks running across the brain

Cerebellar cortex

Outer covering of the cerebellum

Dura mater

Outer most layer of cranial meninges that itself has two layers of fibrous material, an inner meningeal layer and an outer endosteal layer fused to the periosteum with venous sinuses between the two bringing the blood supply.

Medulla oblongata

Part of the brain stem that connects the brain to the spinal cord and also relays sensory info. It regulates autonomic reflexes and visceral functions like heart rate, blood pressure, and digestion (the part of the brain that still works even if you are "brain dead"). It includes three types of nuclei: reticular formation, sensory and motor neurons, and relay stations.

Pons

Part of the brain stem that connects the cerebellum to the brain stem and relays sensory info through tracts. The only structure with transverse fibers, it is involved in both somatic and visceral motor control (motor signals controlled here because we don't want signals traveling all the way up to cerebrum where we have to be conscious of everything). It is associated with sensory and motor nuclei of cranial nerves 5-8, which are involved with respiration rhythmicity center in medulla, processing and relaying info to/from the cerebellum. The pons contains transverse fibers that link the pons and the cerebellar peduncle.

Brain stem

Part of the brain that processes info between the spinal cord and cerebrum and/or cerebellum and includes the midbrain, pons, and medulla oblongata

Cerebral cortex

Part of the cerebrum also called the neural cortex that has folded surfaces for increased surface area like the elevated ridges of the gyri, the shallow depressions of the sulci, and the deep grooves of the fissures.

Precentral gyrus

Part of the frontal lobe that directs voluntary movements

Postcentral gyrus

Part of the parietal love that receives SOMATIC sensory info like touch, pressure, pain, vibration, taste, and temperature

Medial geniculate nucelus

Part of the posterior group of thalamic nuclei that relays auditory info from the ear to the cerebral cortex

Lateral geniculate nucleus

Part of the posterior group of thalamic nuclei that relays visual info from the optic tract to the cerebral cortex

Disorders of the cerebellum

Permanent damage to this area comes in the form of stroke or trauma, but temporary damage comes in the form of ataxia (or lack of order) caused by drug/alcohol intoxication that can cause a disturbance in muscle coordination and, if severe, someone can't walk or stand without help.

Cerebellum

Second largest brain region that coordinates repetitive body movements like bike riding, driving, walking, and other activities that become second nature. It is divided into two hemispheres and is covered by the cerebellar cortex. It is not directly connected to the cerebrum, rather it is connected to the pons. Its functions include adjusting postural muscles to coordinate rapid, automatic adjustments to balance and equilibrium and fine tuning conscious and subconscious movements to make them smooth. Its structures include the folia, anterior and posterior lobes, left and right hemispheres, arbor vitae, perkinje cells, and peduncles.

Sulci

Shallow depressions in cerebral cortex

Arcuate fibers

Short association fibers of the cerebrum that connect one gyrus to another

Folia

Structure of the cerebellum consisting of the highly folded neural cortex surface of the cerebellum (remember foliage is like leaves and the surface looks like the grooves in fern leaves).

Arbor vitae

Structure of the cerebellum that are highly branched internal white matter of the cerebellum in which the cerebellar nuclei are embedded and which helps relay info to the Purkinje cells

Primary fissure

Structure of the cerebellum that divides the anterior and posterior lobes

Vermis

Structure of the cerebellum that is a narrow band of cortex separating the cerebellar hemispheres

Pineal gland

Structure of the diencephalon that secretes melatonin which regulates day/night cycles and circadian rhythm

Tectum

Structure on the roof of the midbrain/mesencephalon (remember techo) that contains two pairs of sensory nuclei known as corpora quadrigemina

Penduncles

Structures of cerebellum that are tracts that link the cerebellum with the brain stem, cerebrum, and spinal cord. They can be superior, middle, and inferior and all help link the different brain stem sections with the cerebellum. They are the only way the cerebellum can connect to the brain stem and the cerebrum.

Purkinje cells

Structures of the cerebellum that are large branched cells in the superior cerebellar cortex that receive info from 200,000 synapses

Cerebellar hemispheres

Structures of the cerebellum that are separated at the midline by the vermis (a narrow band of cortex)

Anterior and posterior lobes

Structures of the cerebellum that are separated by the primary fissure

Mamillary bodies

Structures of the hypothalamus that process olfactory and other sensory info and control eating movements of chewing and swallowing

Cerebral peduncles

Structures of the midbrain that are nerve fiber bundles on the ventrilateral surfaces and contain descending fibers that carry VOLUNTARY MOTOR commands issued by cerebral hemispheres to the cerebellum and pons. For example, Parkinson's affects this area and causes shaky responses.

Central sulcus

Sulcus of the cerebral cortex that divides the frontal and parietal lobes, or the motor and sensory areas, and is the only one you can see in a real brain

Lateral sulcus

Sulcus of the cerebral cortex that divides the frontal and temporal lobes, difficult to see in a real brain

Parieto-occipital sulcus

Sulcus of the cerebral cortex that divides the parietal and occipital lobes, difficult to see in a real brain

Primary sensory cortex

Surface of the postcentral gyrus in the afferent division of the parietal lobe.

Astrocytes

TEST Type of glial cell critical for the integrity of the blood-brain barrier, adding an extra layer of protection and toughness as their webbed feet wrap around the blood vessels in the brain to protect and only allow certain substances to pass.

Origin of ventricles

The neural tube encases neurocoel, a fluid-filled internal cavity, which then expands to form the ventricles lined with ependyma cells

Primary motor cortex

The surface of the precentral gyrus in the efferent division of frontal lobe. Hands and facial movements take a large slice of this area.

Sensory and motor nuclei in the medulla oblongata/ cranial nerves

These are associated with 5 of the 12 cranial nerves and provide motor commands and delivery of sensory info. They are involved in many functions. Cranial nerve 8 is auditory and cranial nerves 9-12 command the neck, back, and tongue muscles.

Septum pellucidum

Thin tissue that separates the two lateral ventricles in the brain.