Download NEURONS SPINAL CORD AND NERVE ROOTS

NEURONS
A typical neuron consists of a cell body or perikaryon with many small dendrites
coming off it and a long transmitting axon. Schwann cells (neurolemmocytes) in the
PNS and oligodendrocytes (in the CNS) produce a membranous wrapping of myelin that
surrounds the axon. The indentation or gap between each myelin bundle is the node of
Ranvier or neurofibril node. The axon branches at the distal end into axon terminals
with many small synaptic knobs. Internally the nucleus, Nissl bodies are prominently
visible.
SPINAL CORD AND NERVE ROOTS
When examining a transverse section of the spinal cord, you can see that it consists of an
inner “H” or butterfly shaped region of gray matter (that changes shape slightly from
cervical to lumbar regions) surrounded by white matter. Each side of the gray matter
contains three projections referred to as “horns”, creating the posterior gray horn,
lateral gray horn, and anterior gray horn. Connecting the two sides of the gray matter
is the gray commissure which contains the central canal. The white matter is divided
into the posterior white column (funiculus), lateral white column, and anterior white
column. A narrow groove on the dorsal side is the posterior median sulcus that
separates the two sides of the posterior white columns. A wider anterior median fissure
separates the anterior white columns on the ventral side.
Bio 230 Lab Materials
Page 1 of 21
The spinal nerve is formed from two roots going into or coming out of the dorsal gray
horn and ventral gray horn (respectively): the dorsal (posterior) root containing sensory
neurons and a dorsal (posterior) root ganglion which contains the cell bodies of these
sensory neurons, and the ventral (anterior) root containing motor neurons. Further out
the spinal nerve branches into the dorsal ramus, ventral ramus, and ramus
communicans (ANS nerves).
The meninges are the protective membranes that surround the spinal cord and consist of
the pia mater directly upon the spinal cord, with the outer arachnoid and dura mater.
When observing the longitudinal anatomy of the spinal cord, you will notice that there
are two thicker sections in the cervical area and lumber area, and are referred to as the
cervical and lumbar enlargements. The nervous tissue of the spinal cord ends between
first and second lumbar vertebrae as it forms the tapered conus medullaris. The spinal
cord continues as the connective tissue (from the meninges) filum terminale to the
coccyx. The lower spinal nerves attach to the spinal cord above the conus medullaris but
trail along side the filum terminale until each nerve exits at its specific vertebra. The
appearance of these nerves forms the cauda equina or horse’s tail.
Bio 230 Lab Materials
Page 2 of 21
SYMPATHETIC SYSTEM
Within the posterior portion of the abdominopelvic cavity lies the sympathetic chain
(trunk) that contains groups of cells bodies within their sympathetic (paravertebral)
ganglia.
Bio 230 Lab Materials
Page 3 of 21
SPINAL NERVES
The ventral rami of spinal nerves as they travel to the body’s organs do so directly or
form networks with other nerves forming plexuses. The cervical plexus forms primarily
from cervical nerves and contains the phrenic nerve going to the diaphragm. The
brachial plexus forms from the lower cervical nerves and thoracic nerves and forms the
radial nerve, median nerve, and ulnar nerve. The lumbar plexus gives rise to the large
femoral nerve while the sciatic nerve comes off the sacral plexus. The sciatic nerve
upon reaching the leg branches into the tibial nerve and common fibular (peroneal)
nerve.
Bio 230 Lab Materials
Page 4 of 21
Bio 230 Lab Materials
Page 5 of 21
Bio 230 Lab Materials
Page 6 of 21
BRAIN
EXTERNAL ANATOMY
The cerebrum consists of a left and right hemisphere divided into lobes corresponding to
the cranial bones above them. The anterior lobe is the frontal lobe followed by the
parietal lobe and then the occipital lobe. The temporal lobe is inferior and lateral to the
frontal and parietal lobes. The lobes contain many convolutions of gyri (ridges) and sulci
or fissures (grooves). The longitudinal fissure separates both hemispheres and the
transverse fissure is located between the occipital lobe and the cerebellum. The lateral
sulcus is a major groove that separates the temporal lobe from the lobes above it. The
central sulcus separates the frontal and parietal lobes. The ridge anterior to the central
sulcus is the precentral gyrus and the posterior ridge is the post central gyrus. Deep to
the temporal and parietal lobes is the insula.
Bio 230 Lab Materials
Page 7 of 21
The posterior portion of the brain is referred to as the cerebellum and contains two large
cerebellar hemispheres connected by the smaller vermis. Below the cerebrum is the
midbrain that contains four rounded processes referred to as the corpora quadrigemina.
It is consists of the two superior colliculi and two inferior colliculi. Below the midbrain
the swollen pons followed by the medulla oblongata.
Bio 230 Lab Materials
Page 8 of 21
INTERNAL ANATOMY
A midsagittal cut through the brain reveals the large corpus callosum that connects the
two cerebral hemispheres with white matter. Below this is the thin transparent septum
pellucidum that is the wall between the two lateral ventricles. An arch shaped fornix is
located below the septum pellucidum. Lateral to the mid cut are the two lobes of the oval
shaped thalamus that are connected by the intermediate mass (interthalamic
adhesion). Anterior and below the thalamus is the lateral hypothalamus that contains
many centers. One area, the mamillary body can be seen from the outside of the brain.
The infundibulum is a narrow stalk that connects the bulbous pituitary gland to the
hypothalamus. Posterior to the thalamus is the pineal gland.
Bio 230 Lab Materials
Page 9 of 21
VENTRICLES AND MENINGES
Cerebrospinal fluid is produced by the choroid plexuses located within the four
ventricles There are two horn-like lateral ventricles that are connected by the
interventricular foramina to the third ventricle that is medial to the thalamus and
hypothalamus. The aqueduct of midbrain connects the third ventricle to the fourth
ventricle and passes through the midbrain. Cerebrospinal fluid exits the fourth ventricle
through appetures that connect to the subarachnoid space. This fluid will then circulate
around the spinal cord and brain before draining into the superior sagittal sinus or
transverse sinus via the arachnoid granulations.
The meninges that contains three layers the dura mater, arachnoid, and pia mater
protect the brain. The falx cerebri, a wedge of dura mater, is found in the longitudinal
fissure separating the two cerebral hemispheres.
Bio 230 Lab Materials
Page 10 of 21
SHEEP BRAIN (Dissection)
Identify the following structures on the sheep brain.
Cerebrum
Longitudinal fissure
Cerebellum
Pons
Medulla oblongata
Transverse fissure
Superior colliculus
Inferior colliculus
Pineal gland
Olfactory bulb
Optic nerve and chiasma
Corpus callosum
Thalamus
Bio 230 Lab Materials
Page 11 of 21
CRANIAL NERVES
There are twelve pairs of cranial nerves that attach to the brain and can be seen
on the inferior surface of the cerebrum and brainstem. The following table
describes them. Nerve I is a long olfactory nerve that lies along the under side
of the frontal lobe. The optic nerves are number II that come together at the
optic chiasma before dividing into the optic tracts.
Nerve name
Number
Attachment point
Mnemonic
Olfactory
I
Cerebrum
Oh
Optic
II
Cerebrum
Oh
Oculomotor
III
Midbrain (medial)
Oh
Trochlear
IV
Midbrain (lateral)
To
Trigeminal
V
Pons (lateral and superior)
Touch
Abducens
VI
Pons (medial and inferior)
And
Facial
VII
Pons (middle and inferior)
Feel
Vestibulocochlear
VIII
Pons (lateral and inferior)
Very
Glossopharyngeal
IX
Medulla oblongata
(superior)
Green
Vagus
X
Medulla oblongata
(middle)
Vege’s
Accessory
XI
Medulla oblongata
(inferior)
A
Hypoglossal
XII
Medulla oblongata
(anterior)
H
Another acronym is: (Starting from I going to XII and used to determine function of the
cranial nerve)
Some Say Marry Money But My Brother Says it’s Bad Business to Marry Money
In this, S = sensory, M = Motor and B = Both (i.e. a mixed nerve)
Bio 230 Lab Materials
Page 12 of 21
EYE
The eyeballs are located within the bony orbits of the skull. The upper lateral area of the
eyeball contains the lacrimal gland that secretes fluid for lubrication. This fluid flows to
the lower medial corner where it drains into the lacrimal canals and sac and finally into
the nasal cavity.
There are six extrinsic eye muscles that are used to move the eyeball. They are the
superior rectus, inferior rectus, lateral rectus, medial rectus, superior oblique, and
inferior oblique muscles. The conjunctiva is a stratified squamous epithelium lining the
inner eyelids and covering the cornea and anterior portion of the sclera.
The anatomy of the eyeball consists of three layers. The outer layer contains the sclera or
white of the eye and the anterior transparent cornea. The middle layer is the pigmented
and vascular choroid coat. The anterior portion of the choroid enlarges into the ciliary
body that contains smooth muscle and ciliary processes that attach the suspensory
ligaments to the crystalline lens. The iris is a disk-like structure coming off the ciliary
body. The hole in its center is the pupil that lets light into the eye and onto the inner layer
or retina. The retina is the photosensitive layer containing rod and cone cells. An area on
the posterior part of the retina is referred to as the macula lutea and in its center is the
fovea centralis that is used for visual acuity. The neurons of the retina converge at the
optic disk before becoming the optic nerve.
Bio 230 Lab Materials
Page 13 of 21
The space behind the lens is the vitreous chamber and it contains a gel-like vitreous
body or humor. In front of the lens is a watery aqueous fluid that is produced by the
ciliary body. This fluid circulates in the posterior chamber located behind the iris,
through the pupil, and into the anterior chamber. The fluid is then reabsorbed into the
scleral venous sinus (canal of Schlemn), a small vein located within the sclera near the
cornea.
Bio 230 Lab Materials
Page 14 of 21
EAR
The external ear consists of the flexible pinna and the external auditory canal located
within the temporal bone. Sound is gathered by the pinna and sent down the canal to the
tympanic membrane or eardrum. The middle ear has a large tympanic cavity filled
with air and connected to the nasopharynx by the Eustachian (auditory) tube. The
middle ear also contains three ear ossicles or ear bones. The malleus (hammer) connects
to the tympanic membrane
followed by the incus (anvil), and
the stapes (stirup). The stapes rests
upon the oval window of the
vestibule.
Bio 230 Lab Materials
Page 15 of 21
The inner ear contains receptors for equilibrium and hearing. They are located within a
series of chambers and tubes. The outer part of the inner ear is the bony labyrinth and
consists of the vestibule, three semicircular canals and the cochlea. Within the bony
labyrinth lies the membranous labyrinth that contains the sense receptors and a fluid of
endolymph. Outside the membranous labyrinth and within the bony labyrinth is the
perilymph fluid.
The vestibule contains an oval window and round window. Within the vestibule are two
membranous chambers referred to as the utricle and saccule. They are involved with
static equilibrium. The three semicircular canals are the anterior, posterior and lateral
semicircular canals each with a bulbous ampulla. The semicircular canal contains a
semicircular duct also containing an ampulla. The three are used for dynamic
equilibrium.
The last part of the bony labyrinth is the coiled cochlea. The cochlear duct is the
membranous labyrinth located within the cochlea. On either side of the duct are the
perilymph filled vestibular duct (scala vestibuli) and tympanic duct (scala tympani).
The cochlear duct consists of the vestibular membrane near the vestibular duct and the
basilar membrane associated with the tympanic duct. The organ of Corti contains hair
cells and a tectorial membrane that acts as a roof over the hair cells.
Bio 230 Lab Materials
Page 16 of 21
Bio 230 Lab Materials
Page 17 of 21
HISTOLOGY
Slide # 1. Nerve cells, Ox spinal cord
Identify the neuron.
Slide #2. Nerve
Identify the epineurium, perineurium, endoneurium, neuron or nerve fiber, and the
fascicle (fasciculus) on the cross section of the nerve.
Slide # 3. Spinal cord
Identify the posterior gray horn, lateral gray horn, anterior gray horn, posterior
white column, anterior white column, lateral white column, and gray commissure.
Slide # 4. Spinal ganglion (Posterior root ganglion)
Identify the ganglion the sensory cell bodies, and the sensory axons.
Slide # 5. Cerebrum
Identify the slide.
Slide # 6. Cerebellum
Identify the cortex (gray matter), medulla (white matter), and the purkinje cells.
Slide # 7. Eye
Identify the sclera, cornea, conjunctiva, choroid coat, ciliary body, lens, iris, and
retina.
Slide # 8. Cochlea
Identify the vestibular duct (scala vestibuli), tympanic duct (scala tympani), cochlear
duct (scala media), vestibular membrane, basilar membrane, and the organ of Corti
with its tectorial membrane.
Slide # 9. Crista Ampullaris
Identify the crista ampullaris.
You may also simply use the internet for the slides… though make sure you are actually
getting what you searched for! Double check with your text.
Bio 230 Lab Materials
Page 18 of 21
List of anatomical structures for the nervous system
NEURONS
cell body
dendrites
axon
myelin
Node of Ranvier
synaptic knobs (bulbs)
SPINAL CORD AND NERVE ROOTS
Spinal cord
posterior (dorsal) gray horn
lateral gray horn
anterior (ventral) gray horn
gray commissure
central canal
White columns
posterior white column (funiculi)
lateral white column (funiculi)
anterior white column (funiculi)
anterior median fissure
posterior median sulcus
posterior medial septum
dorsal (posterior) root
dorsal (posterior) root ganglion
ventral (anterior) root
spinal nerve
denticulate ligaments
dorsal ramus (rami)
ventral ramus (rami)
ramus communicans
pia mater
arachnoid mater
dura mater
Sympathetic System
sympathetic chain (trunk)
sympathetic (paravertebral) ganglia
Bio 230 Lab Materials
Page 19 of 21
SPINAL NERVES
Cervical plexus nerves (C1-C5)
cervical enlargement
phrenic nerves
ansa cervicalis
supraclavicular nerve
greater auricular nerve
Brachial plexus (C4-T1)
Musculocutaneous nerve
Median nerve
Ulnar nerve
Radial nerve
Axillary nerve
Intercostal nerves
Lumbar plexus nerves (L1-L5)
Lumbar enlargement
Femoral nerve
Obturator nerve
Lateral femoral cutaneous nerve
Subcostal nerve
Iliohypogastric nerve
Ilioinguinal nerve
Sacral plexus nerves (S1-CO)
Sciatic nerve
Tibial nerve
Common fibular (peroneal) nerve
Deep fibular (peroneal) nerve
Superficial fibular (peroneal) nerve
Saphenous nerve
Sural nerve
Conus medullaris
Filum terminale
Cauda equina
BRAIN - EXTERNAL ANATOMY
Cerebrum
Left cerebral hemisphere
Right cerebral hemisphere
Cerebellum
Arbor vitae
vermis
longitudinal fissure
transverse fissure
Lobes
frontal lobe
parietal lobe
occipital lobe
temporal lobe
central sulcus
lateral sulcus
parieto-occipital sulcus
precentral gyrus (primary motor area)
post central gyrus (primary
somatosensory cortex)
somatosensory association area
Broca’s area
Prefrontal cortex
Wernicke’s area
insula
cerebellar peduncles
corpora quadrigemina
two superior colliculi
two inferior colliculi
brain stem
medulla oblongata
pons
midbrain
olfactory bulbs
olfactory tracts
optic chiasma
optic nerves
optic tracts
INTERNAL ANATOMY
corpus callosum
septum pellucidum
fornix
thalamus
intermediate mass (interthalamic
adhesion)
epithalamus
hypothalamus
mamillary body (bodies)
pituitary gland
infundibulum
pineal gland
central canal
VENTRICLES AND MENINGES
choroid plexuses
lateral ventricles
interventricular foramina
third ventricle
Cerebral aquaduct (aquaduct of midbrain)
fourth ventricle
median aperture
lateral aperture
superior sagittal sinus
transverse sinus
arachnoid granulations
tentorium cerebelli
meninges
dura mater
arachnoid
pia mater
falx cerebri
Bio 230 Lab Materials
Page 20 of 21
SHEEP BRAIN
Cerebrum
Longitudinal fissure
Cerebellum
Pons
Medulla oblongata
Transverse fissure
Superior colliculus
Inferior colliculus
Pineal gland
Olfactory bulb
Optic nerve and chiasma
Corpus callosum
Thalamus
CRANIAL NERVES
Olfactory
I
Optic
II
Oculomotor
III
Trochlear
IV
Trigeminal
V
Abducens
VI
Facial
VII
Vestibulocochlear
VIII
Glossopharyngeal
IX
Vagus
X
Accessory
XI
Hypoglossal
XII
EYE
lacrimal gland
Muscles
superior rectus muscle
inferior rectus muscle
lateral rectus muscle
medial rectus muscle
superior oblique muscle
inferior oblique muscle
conjunctiva
sclera
cornea
choroid coat
ciliary body
suspensory ligaments
lens
iris
pupil
retina
macula lutea
Bio 230 Lab Materials
Page 21 of 21
fovea centralis
optic disk
optic nerve
vitreous chamber
posterior chamber
anterior chamber
scleral venous sinus (canal of Schlemn)
EAR
external ear
pinna
external auditory canal
tympanic membrane
tympanic cavity
Eustachian (auditory) tube
malleus (hammer)
incus (anvil)
stapes (stirup)
endolymph
perilymph
vestibule
oval window
round window
utricle
saccule
anterior semicircular canals
posterior semicircular canals
lateral semicircular canals
ampulla
cochlea
cochlear duct
vestibular duct (scala vestibuli)
tympanic duct (scala tympani)
vestibular membrane
basilar membrane
organ of Corti
hair cells
tectorial membrane