Www Barnard

Telencephalon cerebral cortex basal ganglia

Diencephalon thalamus pineal hypothalamus posterior pituitary retina

Mesencephalon tectum tegmentum

Metencephalon pons cerebellum

Myelencephalon medulla oblongata

Spinal cord cephalic flexure pontine flexure cervical flexure

third ventricle cerebral aqueduct fourth ventricle

FIGURE 2 Growth and folding of the rostral portion of the neural tube. Human embryos at the three-vesicle stage at about 28 days (A) and the five-vesicle stage at about 38 days (B). Dorsal views of the unfolded embryos show the expansion of the neural tissue during development. Lateral views of the embryos show the three bends or flexures that occur as the embryo develops. The organization of the adult brain (C) reveals the ultimate fate of the three embryonic areas shown in differing shades of blue and gray. Brains are not drawn to scale.

third ventricle cerebral aqueduct fourth ventricle

FIGURE 2 Growth and folding of the rostral portion of the neural tube. Human embryos at the three-vesicle stage at about 28 days (A) and the five-vesicle stage at about 38 days (B). Dorsal views of the unfolded embryos show the expansion of the neural tissue during development. Lateral views of the embryos show the three bends or flexures that occur as the embryo develops. The organization of the adult brain (C) reveals the ultimate fate of the three embryonic areas shown in differing shades of blue and gray. Brains are not drawn to scale.

A. 2 months

lateral ventricles third ventricle cerebral aqueduct fourth ventricle central canal

48. Organization of the Nervous System B. 5 months lateral ventricle anterior horn inferior horn body

C. 9 months lateral ventricles cerebral aqueduct fourth ventricle

choroid plexus

posterior horn

posterior horn

D. Circulation of cerebral spinal fluid

- arachnoid granulations reabsorbing cerebral spinal fluid -venous blood drainage cerebral spinal fluid in the sub arachnoid space choroid plexus producing cerebral spinal fluid

Arachnoid Granulations

FIGURE 3 Development of the ventricles, choroid plexus, and circulation of the cerebral spinal fluid, as well as the ventricles and choroid plexus. Shades of blue and gray of the spaces correspond to the shades of the surrounding neural tissue in Fig. 1A. Cerebral spinal fluid is formed by the choroid plexus located in the two lateral, third, and fourth ventricles. It flows through the cerebral aqueduct and out three holes in the fourth ventricle into the subarachnoid space, bathing the entire brain and spinal cord. Cerebral spinal fluid is reabsorbed by the arachnoid granulations and returned to the venous blood.

FIGURE 3 Development of the ventricles, choroid plexus, and circulation of the cerebral spinal fluid, as well as the ventricles and choroid plexus. Shades of blue and gray of the spaces correspond to the shades of the surrounding neural tissue in Fig. 1A. Cerebral spinal fluid is formed by the choroid plexus located in the two lateral, third, and fourth ventricles. It flows through the cerebral aqueduct and out three holes in the fourth ventricle into the subarachnoid space, bathing the entire brain and spinal cord. Cerebral spinal fluid is reabsorbed by the arachnoid granulations and returned to the venous blood.

sensory nerve sensory nerve

FIGURE 4 Organization of the peripheral nervous system. Sensory information (afferent neurons) from all parts of the body enters the dorsal part of the spinal cord; motor information (efferent neurons) exits the ventral part of the spinal cord. Primary sensory cell bodies are located in the dorsal root ganglia, and their axons project via the dorsal root to the dorsal horn gray matter (and on to higher centers in brain, not shown). Cell bodies of somatic motor neurons are located in the gray matter of the anterior horn, and their axons pass via the ventral root directly to somatic muscles. Autonomic motor neurons also exit the ventral root but synapse in autonomic ganglia, and postganglionic neurons then contact target tissue. The example on the left illustrates the autonomic (sympathetic) neurons that speed the heart. Cell bodies and synaptic connections between neurons are located in areas indicated in blue.

FIGURE 4 Organization of the peripheral nervous system. Sensory information (afferent neurons) from all parts of the body enters the dorsal part of the spinal cord; motor information (efferent neurons) exits the ventral part of the spinal cord. Primary sensory cell bodies are located in the dorsal root ganglia, and their axons project via the dorsal root to the dorsal horn gray matter (and on to higher centers in brain, not shown). Cell bodies of somatic motor neurons are located in the gray matter of the anterior horn, and their axons pass via the ventral root directly to somatic muscles. Autonomic motor neurons also exit the ventral root but synapse in autonomic ganglia, and postganglionic neurons then contact target tissue. The example on the left illustrates the autonomic (sympathetic) neurons that speed the heart. Cell bodies and synaptic connections between neurons are located in areas indicated in blue.

neurons. Their cell bodies remain in the spinal ganglia, a distal process projects to the tissue to be innervated, and a proximal process projects into the appropriate level of the dorsal aspect of the spinal cord. Other groups of neural crest cells migrate to equivalent positions along the medulla and pons, where they form sensory ganglia associated with the cranial nerves, and still other groups form motor ganglia associated with both sympathetic and parasympathetic components of the autonomic nervous system (Fig. 4).

Peripheral Neuropathy Natural Treatment Options

Peripheral Neuropathy Natural Treatment Options

This guide will help millions of people understand this condition so that they can take control of their lives and make informed decisions. The ebook covers information on a vast number of different types of neuropathy. In addition, it will be a useful resource for their families, caregivers, and health care providers.

Get My Free Ebook


Post a comment