Ch. 7 Text Notes
Anatomical References:
 anterior: (or rostral) top or front – in a rat, the part of the brain pointing to the NOSTRAL
 posterior: (or caudal) bottom or back – in a rat, the part of the brain pointing to the tail.
 dorsal: the back (like the fin)
e.g., the dorsal vs. ventral roots in the spinal cord; dorsal carry information
 ventral: the front
into the cord (senses), ventral carry information away (muscle control)
 midline: the invisible line running down the center of the nervous system
 medial: structures closer to the midline
 lateral: structures farther from the midline
 ipsilateral: structures that are on the same side are ipsilateral (e.g., your right ear and right eye)
 contralateral: structures that are on different sides are contralateral (e.g., your right and left eye)
 midsagittal plane: the cross section of the brain formed by running a plane rostral to caudal through the
center of the brain (i.e., dividing the hemispheres)
 sagittal plane: any cross section of the brain the runs rostral to caudal and is perpendicual to the ground.
 horizontal plane: any cross section of the brain that runs rostral to caudal and is parallel to the ground
(would contain both eyes and both ears)
 coronal plane: any cross section of the brain that is perpendicual to the midsagittal plane as well as the
horizontal plane (would contain both eyes or both ears but not both at the same time)
Organization of the Nervous System
 central nervous system (CNS): the part of the nervous system which lies on the midline – consists of the
brain and spinal cord.
 spinal cord: encased in the bony vertical column of vertebrae; attached to brain stem; major conduit of
information from the skin, joints, and muscles to the brain, and vice versa.
 brain: encased in the skull; all mammillian brains consist of these three parts:
o cerebrum: rostral-most and largest part of brain; split into two halve by the sagittal fissure.
Responsible for reception and interpretation of sensation.
o cerebellum: (“little brain”) the caudal-most part of the brain; responsible largely for movement
control.
o brain stem: forms the stalk from which the cerebrum and cerebellum sprout; serves to relay info
from cerebrum to cerebellum and spinal cord; also regulation of vital functions (e.g., breathing,
consciousness, body temp, etc.).
 cerebral hemispheres: the cerebellum is divided in half by the sagittal fissure; the left side of cerebellum
receives sensory input from the right side of body and vice versa.
 spinal nerve: spinal cord communicates with body via spinal nerves which enter through the dorsal and
ventral roots (depending upon origin of spinal nerve)
o dorsal root: spinal nerves that enter into the spinal cord on its dorsal (back) side; these carry
information from the body into the spinal cord.
o dorsal root ganglia: clusters of somatic sensory nerve cell bodies; lie outside the spinal cord;
there is a dorsal root ganglion for each spinal nerve.
o ventral root: spinal nerves that enter into the spinal cord on its ventral (front) side; carry info
from the spinal cord to the body.
 peripheral nervous system (PNS): all parts of the nervous system besides the brain and spinal cord. Has
TWO parts:
o somatic PNS: all spinal nerves that innervate the skin, the joints, and the muscles that are under
voluntary control.
o autonomic nervous system (ANS): consists of neurons that innervate the internal organs, blood
vessels, and glands; the controls and monitors the involuntary parts of the body (e.g., pressure
and oxygen content of blood).
 afferent: axons that carry sensory information to the CNS (“carry to”)
 efferent: axons that innerate the muscles and glands—come from the CNS (“carry from”)
 cranial nerve: there are 12 pairs of cranial nerves, which arise from the brain stem and innervate
(mostly) the head; have vaired purposes and are parts of different systems.
 meninges: protective membranes that surround the brain and spinal cord
o dura mater: (“hard mother”) though, non-elastic bag; outermost casing
o arachnoid membrane: under the dura mater, appearance and consistency of a spider web –
usually no space b/w dura and arachnoid, but if ruptured blood vessle, then subdural hematoma
o pia mater: (“soft mother”) adheres closely to brain surface; seperated from arachnoid by a fluidfilled space (subarachnoid space), which is filled with CSF.
 cerebrospinal fluid (CSF): salty, clear liquid that surrounds the brain and spinal cord as protective
cushion; is produced in the ventricles by the choroid plexis; is reabsorbed into the blood after being
circuluated through ventricular system.
 ventricular system: The fluid-filled (CSF) caverns and canals inside the brain; production and circulation
of CSF.
 Imaging Techniques:
o CT (Computed Tomography): 1979 by Hounsfields and Cormack; generates image of slice of
Excellent for
brain. Created by rotating x-ray source around the head. First to reveal gray and white matter,
detecting
swelling and
ventricles in the living brain.
other structural
o
MRI (Magnetic Resonence Imaging): yeilds more detailed map of brain than CT, no X-rays,
changes.
slices can be made in any plan desired.
o
PET (Positron Emission Tomography): detect changes in blood flow by detecting radioactive
Able to detect
changes in
material injected into blood.
actual brain
o
fMRI (functional MRI): detects changes in blood flow by measuring ratio of oxyhemoglobin to
activity.
deoxyhemoglobin.