214 Introduction to Anatomy and Physiology
Ventral (anterior)
horn of gray matter
Lateral horn of
gray matter
Dorsal (posterior)
horn of gray matter
Pia mater
Arachnoid
mater
Dura mater
Central canal
White matter
Dorsal root
of spinal nerve
Spinal nerve
Dorsal root
ganglion
Ventral root of
spinal nerve
neural connections involved in refl ex arcs. Like
the brain, the spine is surrounded and protected
by the three meninges and cerebrospinal fl uid.
When viewed in cross section, the exterior of
the spinal cord is myelinated white matter, with
butterfl y-shaped gray matter, composed of
neuron cell bodies and interneurons (inter-NOO-
rahnz), located centrally (Figure 6.15). The
regions of the white and gray matter in the spinal
cord are named after their locations—ventral
(anterior), lateral, or dorsal (posterior). The
dorsal columns of white matter carry sensory
impulses to the brain, while the lateral and
ventral columns transmit both sensory and
motor impulses. The dorsal, lateral, and ventral
projections of gray matter are called horns.
Figure 6.15 also shows the formations of the
spinal nerves. These will be discussed in the next
lesson.
1. Name the three structures that make
up the diencephalon and state their
functions.
2. Name the three structures that make up
the brain stem and state the function of
each.
3. Where is the cerebellum located and
what is its function?
4. What are the three regions of white and
gray matter in the spinal cord?
Check Your Understanding
Figure 6.15 Layers and regions of the spinal cord. Which is shaped like a butterfly—the layers and regions of
the spinal cord, the gray matter, or the white matter?