Biology 211 Anatomy & Physiology I The Brain

Biology 211Anatomy & Physiology I

The Brain

Human Central Nervous System

Starts as a hollow tube in the embryo;Remains hollow & fluid-filled throughout life;These spaces form the ventricles of the brain and the central canal of the spinal cord.

Cranial end of this hollow tube enlarges & folds to form brain and its various parts

Caudal end of this hollow tube does not enlarge or fold;Develops into spinal cord

Embryology of nervous system

From lab, you should understand what adult structures form from the myelencephalon metenchephalon mesencephalon diencephalon telencephalon

Prosencephalon

Rhombencephalon

More terms you need to know for brain and spinal cord

Nervous tissue of the CNS consisting of neuron cell bodies, their supporting glia, and unmyelinated axons & dendrites.

Nervous tissue of the CNS consisting of myelinated axons & dendrites and their supporting glia

A region of gray matter on the surface of the brain (found only on the cerebrum and cerebellum) A deeper region of gray mattter, surrounded by white matter

Coronal Section of Brain

Cross Section of Spinal Cord

The brain has seven major (and many minor) regions: Cerebrum Thalamus Hypothalamus Midbrain Pons Cerebellum Medulla Oblongata

Let’s discuss each of these briefly.

Thalamus develops from diencephalon

Most nuclei are relay centers:Receive sensory information from spinal cord, other regions of brain, eyes, ears, tongue, nasal epithelium. Relay that to sensory regions of cerebral cortex

Some nuclei relay motor information from cerebral cortex to other regions of brain

Some nuclei regulate sleep/wakefulness

Hypothalamus develops from diencephalon

Some nuclei regulate body temperature, blood pressure, hunger, thirst, fatigue.

Some nuclei regulate endocrine (hormone) functions by controlling activity of pituitary gland (to which it is connected)

Midbrain develops from mesencephalon Often still called that.

Some nuclei regulate eye movement & visual reflexes.

Large tracts of white matter (myelinated axons) pass through, carrying motor information from cerebral motor cortex toward other parts of brain and spinal cord.Some nuclei modify that information to regulate motor functions.

Large tracts of white matter pass through, carrying sensory information from spinal cord toward thalamus.

Pons develops from metencephalon

Some nuclei relay signals between cerebrum and cerebellum.

Some nuclei help regulate sleep, respiration, swallowing, taste, hearing, bladder control, equilibrium, eye movement, facial expressions, facial sensation, and posture.

Motor information from cerebral cortex (white matter) continues toward medulla oblongata and spinal cord; sensory information continues from the medulla oblongata and spinal cord toward the thalamus and toward the cerebellum.

Cerebellum develops from metencephalon

Nuclei and cortex receive both motor information (from cerebral cortex and nuclei of other parts of brain) and sensory information spinal cord and other parts of the brain. Uses that information to coordinate and fine-tune movement, particularly timing and precision.

White matter carries that information to and from nuclei and cortex.

Medulla Oblongata develops from myelencephalon

Some nuclei help regulate respiration, heart rate, blood pressure, blood distribution.

Other nuclei regulate vomiting, coughing, sneezing, swallowing.

White matter carries motor information from other regions of brain to spinal cord, and sensory information from spinal cord to other regions of brain.

Cerebrum

Arises from the telencephalon

Consists of right and left hemispheres separated from each other by the

Each hemisphere is hollow, containing a which is lined by ependyma and filled with cerebrospinal fluid

Cerebrum

Each hemisphere Includes both white matter and gray matter:

Coronal Section

Cerebral Cortex

Gray Matter2 - 4 mm thickFolded into ridges, or (singular: ) separated by shallow grooves, or (singular = )Different parts of brain separated by deep

Lobes of Cerebral Cortex

Cerebral Cortex

Each gyrus, sulcus, and fissure has a name (more than 50 gyri & sulci)

Cerebral Cortex

Each gyrus, sulcus, and fissure has a name You don't need to know all of them

You will need to know the following:

Central SulcusPrecentral GyrusPostcentral Gyrus

Longitudinal Fissure

Parietooccipital SulcusLateral Fissure/Sulcus

Cerebral Cortex

Different regions of the cortex have specific functions

Three types of functional areas: Motor Sensory Association

Cerebral Cortex

Different regions of the cortex have specific functions

From your reading and lab exercises, you should know the functions of the following areas and where they are located: Primary somatosensory area Somatosensory association area Primary motor area Motor association area Primary visual area Visual association cortex Primary auditory area Auditory association area

Questions on these may be on lecture and/or lab exams

Cerebral Cortex

Different regions of the cortex have specific functions

Two regions of cortex important in language:

deals with formation of speech

deals with recognition and interpretation of speech

Both located primarily onjust one hemisphere(usually the left).Similar regions on other hemisphere control emotional content of speech.

Cerebrum

Recall::Gray matter forms both: Cortex

Basal Nuclei

Coronal Section

Cerebral Nuclei

Basal or Deep or Cerebral Nuclei

Not shown:

From your reading and lab exercises, you should also know the locations of the

- Lateral ventricles - Interventricular foramen - Third ventricle - Fourth ventricle - Mesencephalic aquaduct - Median aperture - Lateral apertures

Questions on these may be on lecture and/or lab exams

Brain is surrounded by three layers of connective tissue:

Mater

Mater

Mater

(Skull)

Space

Space

Space

The brain is protected in three ways:

1)

2)

3) Floats in

Cerebrospinal fluid produced within ventricles by specialized tissue called

Flows toward fourth ventricle

Exits from fourth ventricle through three openings (apertures or foramina) into the subarachnoid space.

Two

Surrounds brain & spinal cord.

Reabsorbed into blood through arachnoid villi on surface of brain