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Brain
Anterior view
Brain
Superior view
Brain
Inferior view
Brain
Posterior view
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1 Spinal cord
2 Medulla oblongata
3 Pons
4 Cerebellum
5 Fourth ventricle
6 Midbrain
7 Inferior colliculus
Sagittal section of the brain
Medial view
As the spinal cord ascends through the foramen magnum to enter the skull, the
cranial central nervous system gradually expands in size to form the large central
processing circuitry we call the brain. The increasing size of the brain results from
Brain Regions
8 Superior colliculus
9 Thalamus of diencephalon
10 Hypothalamus of diencephalon
11 Interthalamic adhesion
12 Pineal gland
13 Mammillary body
14 Optic tract
the addition of more and more gray processing centers to the basic cord-like brain stem. The caudal part of the brain, called
the brain stem, consists of the medulla oblongata, pons, and midbrain. Though all of these structural regions exhibit their
own specializations, they have certain fi ber tracts in common and all have nuclei for the cranial nerves. Added to the brain
stem are the more rostral portions of the brain — the cerebellum, diencephalon, and cerebral hemispheres. These large processing centers greatly increase the size of the brain. The images on the facing page show the principal parts of the brain.
15 Frontal lobe of cerebrum
16 Parietal lobe of cerebrum
17 Occipital lobe of cerebrum
18 Temporal lobe of cerebrum
19 Corpus callosum
20 Lateral ventricle
21 Fornix
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Medulla oblongata Pons
Cerebellum
Cerebrum
Midbrain
Diencephalon – epithalamus, thalamus, hypothalamus
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1 Central sulcus
2 Precentral gyrus
3 Postcentral gyrus
4 Precentral sulcus
5 Postcentral sulcus
6 Parieto-occipital sulcus
7 Transverse occipital sulcus
Brain dissection revealing insular lobe
Lateral view
The cerebrum, by far the largest part of the human brain, consists of the cerebral hemispheres
and the basal nuclei. The large, obvious cerebrum is divided into two halves, the right and left
cerebral hemispheres. Each cerebral hemisphere has an outer layer of gray matter, the cereCerebrum
8 Calcarine sulcus
9 Superior temporal gyrus
10 Middle temporal gyrus
11 Inferior temporal gyrus
12 Inferior frontal gyrus
13 Middle frontal gyrus
14 Superior frontal gyrus
bral cortex, covering deeper networks of interconnecting white tracts that connect different areas of the cortex with one
another and with lower brain centers. The amount of cortex is greatly increased by a complex folding of the cerebral surface.
The folds produce hills, gyri (singular gyrus), and depressions, sulci (singular sulcus). This cortical surface forms the highest
level of processing circuitry in the brain. The two hemispheres are connected to each other by the corpus callosum, a thick
band consisting of an estimated 300 million neuronal axons traversing between the two hemispheres. Located deep within
the cerebrum is another region of gray matter, the basal nuclei, which form key integration centers between the cortex and
lower brain centers.
15 Short gyri
16 Long gyrus
17 Limen
18 Pons
19 Cerebellum
20 Medulla oblongata
21 Spinal cord
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Frontal lobe Parietal lobe
Occipital lobe Temporal lobe
Insular lobe
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1 Folia of cerebellum
2 Anterior lobe of cerebellum
3 Posterior lobe of cerebellum
4 Superior vermis
5 Inferior vermis
6 Postlunate fissure
7 Posterior cerebellar notch
8 Tonsil
9 Quadrangular lobe of anterior
Immediately above the medulla oblongata the central nervous system expands dorsally
to form the cerebellum, which means little brain. The cerebellum, like the cerebrum, has
a highly folded surface that greatly increases the surface area of its outer gray matter
Cerebellum
10 Primary fissure
11 Flocculus
12 Lingula
13 Central lobule
14 Culmen
15 Declive
16 Folium
17 Tuber
18 Pyramid
cortex. It is estimated that the cerebellum has in the neighborhood of 10 billion neurons, which have a variety of functional
roles. The cerebellum processes input received from the cerebral cortex, various brain stem nuclei, and peripheral sensory
receptors to smooth and coordinate complex, skilled movements. It plays an important role in posture and balance and
functions in cognition and language processing.
Cerebellum
Posterior view
Cerebellum
Lateral view
Sagittal section of cerebellum
Medial view
19 Uvula
20 Nodulus
21 Midbrain
22 Superior medullary velum
23 Fourth ventricle
24 Median aperture
25 Cerebral aqueduct
26 Pons
27 Medulla oblongata
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1 Infundibulum
2 Anterior perforated substance
3 Tuber cinereum
4 Mammillary body
5 Posterior perforated substance
6 Pulvinar of thalamus
7 Pineal gland
8 Superior colliculus
9 Inferior colliculus
10 Medial geniculate ganglion
11 Pons
12 Superior cerebellar peduncle
13 Middle cerebellar peduncle
14 Inferior cerebellar peduncle
The diencephalon, rostral to the midbrain
and almost completely surrounded by the
cerebral hemispheres, consists of four
Diencephalon and Brainstem
major parts — the thalamus, subthalamus, epithalamus, and hypothalamus. Projecting from the hypothalamus is the
hypophysis, or pituitary gland. The brainstem consists of the medulla oblongata, pons, and midbrain. The medulla resembles the
spinal cord in many ways. Like the cord it gives rise to many nerve roots; however, these are the roots of cranial nerves
rather than spinal nerves. The pons is the bridge between the two cerebellar hemispheres. The ventral portion of the pons
forms a large synaptic relay station consisting of scattered gray centers called the pontine nuclei. The dorsal portion of the
pons is more like the other regions of the brainstem, the medulla and midbrain. The midbrain sits just above the pons and
is obscured by the large, overlapping cerebral hemispheres. It contains nuclei for cranial nerves III and IV, as well as
ascending and descending fi ber tracts from the cerebrum.
Brainstem
Ventral view
Brainstem
Posterior view
15 Medial eminence
16 Facial colliculus
17 Locus ceruleus
18 Trigeminal tubercle
19 Hypoglossal tubercle
20 Vestibular area
21 Sulcus limitans
22 Lateral recess
23 Obex
24 Olive
25 Pyramid
26 Third ventricle
27 Fourth ventricle
28 Cerebral crus
29 Superior medullary vellum
30 Flocculus of cerebellum
31 Caudate nucleus
32 Optic tract
33 Optic chiasm
34 Optic nerve
35 Oculomotor nerve
36 Trochlear nerve
37 Abducens nerve
38 Trigeminal nerve
39 Facial nerve
40 Vestibulocochlear nerve
41 Glossopharyngeal nerve
42 Vagus nerve
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44 Hypoglossal nerve
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