pyramidal cell: Definition and Much More from Answers.com

Wikipedia: pyramidal cell

Pyramidal cell
A human neocortical pyramidal neuron stained via Golgi technique. Notice the apical dendrite extending vertically above the soma and the numerous basal dendrites radiating laterally from the base of the cell body.
Location	Cortex esp. Layers III and V
Function	excitatory projection neuron
Neurotransmitter	Glutamate
Morphology	Multipolar Pyramidal
Presynaptic connections	Superficial cortical layers
Postsynaptic connections	Varies (see text)
Gray's	subject #183 722

A pyramidal cell (or pyramidal neuron, or projection neuron) is a multipolar neuron located in the hippocampus and cerebral cortex. These cells have a triangularly shaped soma, or cell body, a single apical dendrite extending towards the pial surface, multiple basal dendrites, and a single axon. Pyramidal neurons compose approximately 80% of the neurons of the cortex, and release glutamate as their neurotransmitter, making them the major excitatory component of the cortex (see synapse).

In the primary motor cortex, layer V pyramidal cells are extremely large. These cells are called Betz cells. Their cell bodies can be as large as 100 micrometers in humans. Typical human pyramidal cell bodies range from 10 to 50 micrometers. Also, any pyramidal cell that faces the opposite direction of a Betz cell (i.e. its longest dendrite faces the opposite direction of all of the other Betz cells) is known as a Martinotti cell.

Pyramidal cells are tall and conical, triangular in tissue sections. Their apex points toward the brain surface and has a thick dendrite with many branches, and small, knobby dendritic spines. The base gives rise to horizontally oriented dendrites, and an axon that passes into the white matter. Pyramidal cells are the output neurons of the cerebrum. They transmit signals to other parts of the CNS. Their axons have collaterals that synapse with other neurons in the cortex or in deeper regions of the brain.

See also

• Cerebral cortex
• Pyramidal tract

External links

• Diagram
• Image
• Diagram (as part of slideshow)
• BrainMaps at UCDavis pyramidal neuron

Histology: nervous tissue
Neurons (gray matter)	soma, axon (axon hillock, axoplasm, axolemma, neurofibril/neurofilament), dendrite (Nissl body, dendritic spine) types (bipolar, pseudounipolar, multipolar, pyramidal, Purkinje, granule)
Afferent nerve/Sensory nerve/Sensory neuron	GSA, GVA, SSA, SVA, fibers Ia, Ib or Golgi, II or Aβ, III or Aδ or fast pain, IV or C or slow pain
Efferent nerve/Motor nerve/Motor neuron	GSE, GVE, SVE, Upper motor neuron, Lower motor neuron (Aα motorneuron, Aγ motorneuron) - Gamma motoneuron
Synapses	neuropil, synaptic vesicle, neuromuscular junction, electrical synapse - Interneuron (Renshaw)
Sensory receptors	Free nerve ending, Meissner's corpuscle, Merkel nerve ending, Muscle spindle, Pacinian corpuscle, Ruffini ending, Olfactory receptor neuron, Photoreceptor cell, Hair cell, Taste bud
Glial cells	astrocyte, oligodendrocyte, ependymal cells, microglia, radial glia
Myelination (white matter)	Schwann cell, oligodendrocyte, nodes of Ranvier, internode, Schmidt-Lanterman incisures, neurolemma
Related connective tissues	epineurium, perineurium, endoneurium, nerve fascicle, meninges