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1 Frontal lobe
2 Parietal lobe
3 Temporal lobe
4 Insular lobe
5 Lateral ventricle
6 Third ventricle
7 Cerebral aqueduct
8 Fourth ventricle
9 Septum pellucidum
10 Falx cerebri
11 Tentorium cerebelli
12 Anterior lobe of cerebellum
13 Posterior lobe of cerebellum
Frontal section of head at anterior aspect of auricle
Anterior view
The brain sections on this and the following page depict aspects of brain anatomy
that are not evident on the external views of the brain, and the association of the
brain with surrounding structures of the head. Each section is approximately 2
Brain Sections
14 Flocculus
15 Superior vermis
16 Superior cerebellar peduncle
17 Cerebral peduncle
18 Pituitary gland
19 Pons
20 Olive
21 Corpus callosum
22 Caudate nucleus
23 Internal capsule
24 Putamen
25 External capsule
26 Body of fornix
27 Globus pallidus
28 Medial thalamic nucleus
29 Lateral thalamic nucleus
30 Dentate gyrus
31 Circular gyrus
32 Optic chiasm
33 Facial nerve
34 Vestibulocochlear nerve
35 Vertebral artery
36 Middle cerebral artery
37 Internal carotid artery
38 Anterior cerebral artery
39 Superior sagittal sinus
centimeters thick and is an anterior view of three sections in succession. The fi rst section begins at the anterior aspect of
the ear and the last section is just posterior to the ear.
40 Sigmoid sinus
41 Internal jugular vein
42 Tympanic cavity
43 Cochlea
44 Sphenoid sinus
45 Mastoid air cells
46 Mandibular condyle
47 Occipital condyle
48 Atlas
49 Axis
50 Lateral pterygoid muscle
51 Medial pterygoid muscle
52 Sternocleidomastoid muscle
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Frontal section of head through
middle of auricle
Anterior view
Frontal section of head just postrior to auricle
Anterior view
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Sagittal section of braining revealing the ventricular system
Medial view, arrows show path of cerebrospinal fluid
Developmentally the entire central nervous system forms from the
hollow neural tube. As development proceeds and the wall of the
neural tube becomes increasingly thicker, the hollow lumen of the tube
Ventricular System
undergoes changes in relative size and shape throughout different regions of the changing central nervous system. As a
result of this developmental history, there remains a hollow interconnected center throughout the entire central nervous
system. This hollow core forms the ventricular system. Beginning within the cerebral hemispheres are the large paired lateral
ventricles. Each lateral ventricle has a C-shape like its corresponding hemisphere. The lateral ventricles communicate via
the interventricular foramina with a midline cavity, the third ventricle. The third ventricle sits within the core of the diencephalon where the right and left thalamus form its lateral walls. From the third ventricle a narrow channel, the aqueduct of the
midbrain or cerebral aqueduct, passes through the core of the midbrain. This narrow channel expands in the region of the
pons and cerebellum to form the fourth ventricle. The fourth ventricle tapers through the medulla to enter the spinal cord as
the central canal. Within the four ventricles of the brain convoluted aggregations of capillaries, called a choroid plexus, project into the cavity of the ventricle. These capillary projections are the principal site for the production of cerebrospinal fl uid.
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1 Lateral ventricle
2 Interventricular foramen
3 Third ventricle
4 Cerebral aqueduct
5 Fourth ventricle
6 Median aperture
7 Choroid plexus
8 Corpus callosum
9 Caudate nucleus
10 Septum pellucidum
11 Fornix
12 Frontal lobe
13 Parietal lobe
14 Occipital lobe
15 Temporal lobe
16 Cingulate gyrus
17 Hypothalamus
18 Thalamus
19 Pineal gland
20 Midbrain
21 Superior colliculus
22 Inferior colliculus
23 Pons
24 Medulla oblongata
Floor of lateral ventricles
Superior view
Roof of lateral ventricles
Inferior view
Fourth ventricle
Posterolateral view
25 Cerebellum
26 Falx cerebri
27 Internal carotid artery
28 Middle cerebellar peduncle
29 Trochlear nerve
30 Vestibulocochlear nerve
31 Vagus nerve
32 Accessory nerve
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Dissection of cranial and spinal dura mater
Posterior view
Dura removed to expose leptomeninges
Posterior view
Within the cranium and vertebral column, the meninges form a protective encasement for the
tissue of the brain and spinal cord. There are three meningeal membranes, the tough outer
connective tissue pachymenix, the dura mater, and the epithelial inner leptomeninges, the
Meninges
arachnoid mater and pia mater. Between the leptomeningeal layers there is a fl uid compartment called the subarachnoid
space. Cerebrospinal fl uid, secreted from the choroid plexuses of the ventricles, exits the ventricles to fi ll this compartment.
The cerebrospinal fl uid forms a hydraulic shock absorber and suspension system for the brain and spinal cord. In addition
to protecting the central nervous system, the meninges support many of the blood vessels that are associated with the brain.
Within the cranium the subdivisions of the dura mater split to form large venous channels, the dural venous sinuses, which
drain all the tissues of the cranial vault, and these splits also form strong, fi brous septa that separate different parts of the brain.
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Dural sac (above), Leptomeninges (below)
Lateral views
1 Cranial dura mater
2 Spinal dura mater
3 Dural venous sinus
4 Cranial leptomeninges - arachnoid is superficial to and covering pia mater
5 Spinal leptomeninges - arachnoid is superficial to and covering pia mater
6 Middle meningeal artery and branches in dura mater
7 Superficial middle cerebral vein and tributaries in subarachnoid space
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1 Falx cerebri
2 Tentorium cerebelli (cut)
3 Superior sagittal sinus
4 Straight sinus
5 Transverse sinus
6 Lateral ventricle
7 Septum pellucidum
8 Third ventricle
9 Fourth ventricle
10 Cerebrum
11 Cerebellum
12 Corpus callosum
13 Choroid plexus
14 Optic chiasm
15 Trigeminal nerve
Head frontal section revealing dural septa
Anterior view
Dissection of cranium
Superoposterior view
Dissection of cranium
Superoposterior view
Meninges
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15 Endocrine System
Like the nervous
system, the endocrine system is a control system within the
body. Th e nervous system administers its control over the
body tissues via long wirelike cells that originate form
complex circuits in the central nervous system. Th is
circuitry receives sensory input, processes this input,
and generates regulatory output. Endocrine control
works in a much diff erent fashion. Th e endocrine
system consists of a number of diff erent glands
that function like radio transmitting stations.
Just as different radio stations send radio
signals of diff erent wavelengths into the air,
endocrine glands distribute diff erent types of
small molecules called hormones throughout
the body via the circulatory system. Th ese
small molecules travel through the blood
stream and are detected by eff ector organs in
diff erent parts of the body, much like radio
waves are detected by radios in diff erent
parts of a city. Eff ector organs have receptor
sites that are specifi c to specifi c hormones.
Th is results in a “lock and key” function at the
eff ector cell. When the hormone binds to the
receptor site, it initiates a regulatory eff ect on
the cell.
Because the hormones are distributed by the
circulatory system, the speed of endocrine
regulation is slower than that of nervous regulation, many minutes compared to milliseconds.
Also, because of the distribution of the hormones
via the circulatory system, endocrine eff ects can
be experienced anywhere there are cells with the
appropriate receptor site. In comparison to the
nervous system, endocrine distribution is potentially
very widespread. Because the hormone can lock into
the receptor site and not be degraded instantly, the
duration can be longer lasting than that initiated by a single
nervous impulse.
Find more information
about the endocrine
system in
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REAL ANATOMY
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1 Hypothalamus
2 Pineal gland
3 Frontal lobe of cerebrum
4 Parietal lobe of cerebrum
5 Occipital lobe of cerebrum
6 Temporal lobe of cerebrum
7 Corpus callosum
8 Thalamus
Sagittal section of brain
Medial view
The hypothalamus occupies the area of the brain
between the third ventricle and the subthalamus. It is
a major intersection between the thalamus, cerebral
Hypothalamus
cortex, and ascending fi ber systems from the spinal cord and brainstem. It is the control center
of the autonomic nervous system and regulates the function of numerous endocrine glands. The
posterior pituitary gland, or neurohypophysis, is an outgrowth of the hypothalamus. Many
factors infl uence the hypothalamus and dictate its controlling infl uence over tissues in the body.
These factors include the nervous input that enters it, temperature, osmotic pressure, and levels
of hormones in the circulating blood that pass through its capillaries.
9 Midbrain
10 Pons
11 Cerebellum
12 Medulla oblongata
13 Lateral ventricle
14 Fourth ventricle
15 Mammilary body
16 Spinal cord
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Photomicrograph of anterior pituitary
200x
1 Pituitary gland
2 Infundibulum
3 Adenohypophysis
4 Neurohypophysis
5 Parenchyma consisting of
acidophils, basophils, and
chromophobes
6 Capillary with red blood cells
7 Parenchyma consisting of
axons and pituicytes
8 Hypothalamus
9 Cerebrum
10 Falx cerebri
11 Midbrain
12 Pons
13 Cerebellum
14 Medulla oblongata
15 Spinal cord
16 Nasal septum
17 Soft palate
18 Tongue
19 Epiglottis
20 Atlas
21 Axis
22 Intervertebral disc
23 Sphenoid sinus
24 Occipital bone
Sagittal section of head and neck with enlarged callout of pituitary gland
Medial view
The pituitary gland, or hypophysis, “hangs” from the base
of the brain via a connecting stalk, the infundibulum,
which connects it to the hypothalamus. The infundibulum
Pituitary Gland
contains numerous nerve fi bers that relay from the hypothalamus to the posterior portion of the pituitary
gland. In addition to this nervous pathway between the hypothalamus and the pituitary, numerous
small blood vessels pass between the two organs. The pituitary gland has two anatomically and functionally distinct lobes, the neurohypophysis (posterior lobe) and the adenohypophysis (anterior lobe).
The posterior lobe arises as an outgrowth of the embryonic brain. It is composed of nervous tissue and
forms a neural link with the hypothalamus through the infundibulum. The anterior lobe arises from the
epithelial lining of the embryonic pharynx. It consists of glandular epithelial tissue and forms a vascular
link with the hypothalamus via the small blood vessels that pass between the two regions.
Photomicrograph of posterior pituitary
200x
Photomicrograph of posterior pituitary
200x
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