CH13.1-13.9(EXAM3) Flashcards
The Brain is Composed of 4 Major Regions:
Cerebrum, Diencephalon, Brainstem, and Cerebellum.
The Cerebrum is Divided into Two Halves, Called The:
left and right cerebral hemispheres; Each hemisphere may be further subdivided into five functional areas called lobes.
Our skull volume limits the size of:
the brain, so the outer brain tissue of the cerebrum is folded on itself so that more neurons can fit within the cranium.
These folds of brain tissue are called
Gyri.
Gyri
Elevated fold of cerebral cortex.
The shallow depressions between those folds are called
sulci
Sulci
Groove or furrow; e.g., on the surface of the brain.
the deeper grooves are named
fissures
Fissures
Deep furrow, cleft, or slit
The cerebellum is
inferior to the cerebrum
The brainstem has three regions:
the midbrain, pons, and medulla oblongata
The diencephalon is organized into the
epithalamus, thalamus, and hypothalamus
Twelve pairs of cranial nerves extend from
the brain
What two directional terms are often used to describe relative positions of brain anatomy ?
Anterior is synonymous with rostral (meaning “toward the nose”), and posterior is synonymous with caudal (meaning “toward the tail”)
The formation of nervous tissue begins in the
embryo during the third week of development with a thickening of a portion of the ectoderm
This portion of the ectoderm specifically overlies the
notochord, which is a tightly packed group of mesoderm cells positioned on the developing embryo midline
The thickened ectoderm is called the
neural plate
The neural plate is induced by the
underlying notochord to form a neural tube, which begins the process called neurulation
Neurulation
Formation of the neural plate and its closure to form the neural tube.
Neurulation ultimately forms all
nervous tissue structures
The initial process of neurulation is
1.) The neural plate develops a central longitudinal indentation called the Neural Groove. As this is occurring, cells along the lateral margins of the neural plate proliferate, becoming the thickened neural folds. The tips of the neural folds form neural crest cells (or simply, the neural crest).
The initial process of neurulation is (STEP2)
2.) The neural folds elevate and approach one another as the neural groove continues to deepen. The neural crest cells are now at the very highest point of the neural groove.
The initial process of neurulation is (STEP3)
3.)The neural crest cells begin to pinch off from the neural folds and form other structures
The initial process of neurulation is(STEP4)
4.)By the end of the third week, the neural folds have met and fused at the midline as the neural groove starts to form a neural tube, which has an internal space called the neural canal. The neural tube initially fuses at its midline, and later the portions of the neural folds slightly superior and inferior to this midline fuse as well. Thus, the neural tube forms as the neural folds “zip” together both superiorly and inferiorly.
For a short time, the neural tube is open at
both its ends. These openings, called neuropores, close during the end of the fourth week.
The opening closest to the future head is the
cranial neuropore
the opening closest to the future buttocks region is the
caudal neuropore
If these openings do not close, the developing human will have a
neural tube defect
The developing neural tube forms the
central nervous system
the cranial part of the neural tube expands to form
the brain
the caudal part of the neural tube expands to form the
spinal cord
The brain develops from the
cranial part of the neural tube in the human embryo. The neural tube undergoes disproportionate growth rates in different regions.
This growth has formed
three primary brain vesicles by the late fourth week of development, which eventually give rise to all the different regions of the adult brain
The names of two of these vesicles describe their relative positions in the developing head:
The forebrain is called the prosencephalon, the midbrain is called the mesencephalon, the hindbrain is called the rhombencephalon.
By the fifth week of development, the three primary vesicles further develop into a total of
five secondary brain vesicles
The telencephalon arises from the
prosencephalon and eventually forms the cerebrum.
The diencephalon also derives from the
prosencephalon, and it eventually forms the thalamus, hypothalamus, and epithalamus.
The mesencephalon is the only
primary vesicle that does not form a new secondary vesicle. It becomes the midbrain.
The metencephalon arises from the
rhombencephalon and eventually forms the pons and cerebellum.
The myelencephalon also derives from the
rhombencephalon, and it eventually forms the medulla oblongata.
