Brain Dissection Lab
Emily D, Chris F, Alaciel T, Megan W
The purpose of this lab was to dissect a sheep, cow, and pig brain as an introduction to
the nervous system. A thorough examination of the sheep brain promoted a familiarization
with the different structures of the brain before the other two brains were dissected. Once
familiar with this brain’s features, the pig and cow brains were dissected in order to identify
similarities and differences between the three different brains. This dissection encouraged an
exploration of the brain to become accustomed with its components and structure.
Guide through the Brain:
The cerebrum is the largest part of the brain and consists of four different lobes: the
frontal lobe, the parietal lobe, the occipital lobe, and the temporal lobe. These lobes control
anything from movement to speech to sensory input. The surface of the cerebrum as depicted
in the image consists of sulci, the crevices, and gyri, the bumps. These two aspects of the
cerebrum increase the surface area of the cerebrum which allows for more neurons within the
brain. Right below the cerebrum is the corpus collosum which holds together the two
hemispheres of the cerebrum with the assistance of axons. The corpus collosum helps to form
the lateral ventricle which holds CSF or cerebrospinal fluid that helps protect the neurons
within the brain.
Parietal Lobe
Corpus Collosum
Occipital Lobe
Temporal Lobe
(Behind corpus collosum)
Frontal Lobe
Gyri
Sulci
The pituitary gland is located underneath the hypothalamus and is attached to the
infundibulum, or the pituitary stalk. The pituitary gland consists of two parts, the anterior
pituitary and the posterior pituitary. As an endocrine gland, the pituitary gland secretes several
hormones like the growth hormone.
Pituitary Gland
Pituitary Stalk or
Infundibulum
(behind the gland)
THE PONS
The pons is one of the brain stem
structures surrounding the brain stem. It
relays signals from the cortex to assist in
the control of movement. The pons also
helps coordinate signals involved in
control of sleep and arousal.
THE MEDULLA OBLONGATA
The medulla oblongata sits at the bottom of the
brainstem on top of the spinal cord on top of the pons.
It is the structure which connects the brain and the
spinal cord. The medulla controls very primitive
functions of the central nervous systems: respiration
and blood pressure control.
THE HYPOTHALAMUS
The hypothalamus, sometimes called “the brain of the
brain,” is located right below the thalamus in the center of
the brain. It’s main function is the control of homeostasis
in the body. The hypothalamus works to manage
hormones, control blood pressure, body temperature, fluid
and electrolyte balance, and body weight.
THE THALAMUS
The thalamus is situated right above the
hypothalamus in the center of the brain. The
function of the thalamus is relaying and prioritizing of
signals, especially the sensory input signals. The
thalamus is part of the limbic system, which is
connected with emotions.
Spinal Cord: The spinal cord is a long bundle of nerve fibers that extends from the
brain downwards. It is enclosed by the vertebral column which contains and
protects it. The spinal cord is responsible for transmitting signals from the central
nervous system to the peripheral nervous system and vice versa. It also plays a large
role in generating reflex reactions.
Optic Chiasma: The optic chiasma is the location where the
optic nerves cross. It is located just below the hypothalamus.
Optic Nerve: The optic nerves are the nerves that relay sensory
information from the eyeballs to the brain. At the optic chiasma, these
nerves cross and send their information to opposite sides of the brain.
Meninges: The meninges is the name given to the membrane
that envelopes the brain. It is composed of three layers, the dura mater,
arachnoid mater, and pia mater. The function of this membrane, along
with the cerebrospinal fluid, is to protect and cushion the brain from
inury.
Cerebellum: The cerebellum is located beneath the
cerebral hemispheres and next to the pons. Its function is to
provide precise motor control to every action. It also plays a
role in attention and language, as well as some emotional
responses such as fear and pleasure.
Comparisons of Brain Structures:
Lateral ventricle, thalamus, parietal section of the cerebrum, and the arbor vitae
Cow Brain
Pig Brain
Sheep Brain
Sheep Brain
Thalamus
(sheep brain)
Lateral ventricle (sheep brain)
Parietal Lobe (sheep brain)
Arbor Vitae
(sheep brain)
Lateral Ventricle
Pig Brain
Parietal Lobe
Thalamus
Functions of Chosen Brain Structures:
1) Parietal Lobe of the Cerebrum: middle region of the cerebrum responsible
for processing sensory input and some language ability.
2) Thalamus: the sensory integration area of all parts of the nervous system to the
cerebrum.
3) Lateral Ventricle: (cavity) contains cerebrospinal fluid which protects and
cushions neurons.
4) Arbor Vitae: a gathering of white nerve tissue located within the cerebellum
Arbor Vitae
Cow Brain
Thalamus
Parietal Lobe
Lateral Ventricle
Arbor Vitae
Comparisons:
The Lateral Ventricle that is the most open is that from the sheep brain; and in the pig
brain, the cavity wasn’t as open but in the cow brain (the biggest of the three) the ventricle is a
little bit more open. Because the cavity in the sheep brain is the biggest, that means there
probably wasn’t as much fluid because there weren’t as many neurons to cushion and protect.
Therefore, it can be said that the pig and cow are smarter than the sheep. Also, the pig and cow
are smarter than the sheep because the brains displayed more gyri than the sheep, meaning
there are more contours in the brain of the pig and cow.
In the Parietal Lobe, it is significantly larger in the cow brain. And in the pig brain, that
part of the cerebrum has a noticeably softer texture than that of the sheep brain. However in
the sheep brain, there seems to be a thicker parietal lobe but there aren’t many gyri or
contours.
The thalamus is the most visible and distinguished in the cow brain because the circle is
defined. Compared to the cow brain, the other two brains’ thalamus is just known to be below
the corpus collosum and not easily visible.
And finally the Arbor Vitae in the cerebellum are the largest in the cow brain but just as
visible in the other two brains. Although it may look the thickest in the sheep brain, the arbor
vitae branches out to more places in the cerebellum of the pig brain and especially the cow’s.