Study Notes
Study Notes 2217
Study Notes
ANHB2217 1
Study Notes 2217
Development of the Central Nervous System Embryonic origins
Abnormalities
Brain regions throughout development
The development of the eye
Shape of the brain - origins The spinal cord The Lumbar Cistern Resulting structures from the Neural Crest 2
The environment of a cell plus its gene and developmental history determine what a cell will become. The inner cell mass within the developing blastocyst becomes the embryo and the outer cell mass becomes the placenta. The neural plate, neural groove and the neural tube form in succession; often in the first 4 weeks of gestation. From the neural tube the central nervous system is formed. The front end becomes the brain and the back end becomes the spinal cord and canal. If the anterior pore (or the tube at the front) does not close properly anencephaly is resultant (little or no forebrain). If the chordal end of the tube doesn’t close spina bifida is resultant. There are varying degrees of severity from hairs over the base of the spine to total paralysis below that point. Lissencephaly – occurs when there is no sulcus. Cells do not migrate so formation of the cortex is incomplete. Intellect is significantly compromised in affected individuals. Prosencephalon →forebrain → telecephalon. Cerebral hemispheres, cortex, basal ganglia, lateral ventricles. Diencephalon → thalamus, hypothalamus and the epithalamus. Mesencephalon → midbrain; cephalic flexure (flexure = bend). Rhombencephalon → pontine and cervical flexures. Metencephalon (pons and cerebellum) and myelencephalon (medulla). The retina derives from the vesicle on the ventral side of the diencephalon. It is a part of the central nervous system. It grows until contact is made with the outside of the embryo.
Sulci and gyri originate from the need to minimise volume whilst maximising surface area of the cortex. The ‘C’ shape of the forebrain occurs because of the ‘dragging’ of the fore brain area during the pattern of growth. Cells in the nervous system are born in plates in the spinal cord; 2 dorsal plates (also known as alar plates) with dorsal horns. These are for sensory input. Also 2 ventral plates (also known as basal plates) with ventral horns. These are for motor input. The space at the base of the vertebral column, as the vertebrae grows the spinal cord grows at a slower rate, stopping at L3 at birth and L2 at adulthood. The resultant space between the terminal of the spinal cord and the ending vertebrae is called the lumbar cistern. This space is used for epidural anaesthesia. All other neural tissues, outside of the central nervous system, derive from the neural crest. Essentially forms the autonomic nervous system. Produces neurons in the gut and ganglia.
Study Notes
ANHB2217 1
Study Notes 2217
Development of the Central Nervous System Embryonic origins
Abnormalities
Brain regions throughout development
The development of the eye
Shape of the brain - origins The spinal cord The Lumbar Cistern Resulting structures from the Neural Crest 2
The environment of a cell plus its gene and developmental history determine what a cell will become. The inner cell mass within the developing blastocyst becomes the embryo and the outer cell mass becomes the placenta. The neural plate, neural groove and the neural tube form in succession; often in the first 4 weeks of gestation. From the neural tube the central nervous system is formed. The front end becomes the brain and the back end becomes the spinal cord and canal. If the anterior pore (or the tube at the front) does not close properly anencephaly is resultant (little or no forebrain). If the chordal end of the tube doesn’t close spina bifida is resultant. There are varying degrees of severity from hairs over the base of the spine to total paralysis below that point. Lissencephaly – occurs when there is no sulcus. Cells do not migrate so formation of the cortex is incomplete. Intellect is significantly compromised in affected individuals. Prosencephalon →forebrain → telecephalon. Cerebral hemispheres, cortex, basal ganglia, lateral ventricles. Diencephalon → thalamus, hypothalamus and the epithalamus. Mesencephalon → midbrain; cephalic flexure (flexure = bend). Rhombencephalon → pontine and cervical flexures. Metencephalon (pons and cerebellum) and myelencephalon (medulla). The retina derives from the vesicle on the ventral side of the diencephalon. It is a part of the central nervous system. It grows until contact is made with the outside of the embryo.
Sulci and gyri originate from the need to minimise volume whilst maximising surface area of the cortex. The ‘C’ shape of the forebrain occurs because of the ‘dragging’ of the fore brain area during the pattern of growth. Cells in the nervous system are born in plates in the spinal cord; 2 dorsal plates (also known as alar plates) with dorsal horns. These are for sensory input. Also 2 ventral plates (also known as basal plates) with ventral horns. These are for motor input. The space at the base of the vertebral column, as the vertebrae grows the spinal cord grows at a slower rate, stopping at L3 at birth and L2 at adulthood. The resultant space between the terminal of the spinal cord and the ending vertebrae is called the lumbar cistern. This space is used for epidural anaesthesia. All other neural tissues, outside of the central nervous system, derive from the neural crest. Essentially forms the autonomic nervous system. Produces neurons in the gut and ganglia.
