Sheep brain-dissection and labelBy Leslie Young

Section 63

Sheep brain-dissected and shown olfactory bulb and optic nerve.

The olfactory bulb is a structure of the vertebrate forebrain involved in olfaction, the perception of odors

The optic nerve, also known as cranial nerve 2, transmits visual information from the retina to the brain.

Sheep brain-dissected optic chiasm and pons

The optic chiasm or optic chiasma (Greek χίασμα, "crossing", from the Greek χιάζω 'to mark with an X', after the Greek letter 'Χ', chi) is the part of the brain where the optic nerves (CN II) partially cross. The optic chiasm is located at the bottom of the brain immediately below the hypothalamus.

The pons (pronounced /ˈpɔnz/) is a structure located on the brain stemIt iscranial to the medulla oblongata, caudal to the midbrain, and ventral to the cerebellum.

Sheep Brain-dissected medulla oblongata

The medulla oblongata is the lower half of the brainstem. The medulla contains the cardiac, respiratory, vomiting and vasomotor centers and deals with autonomic, involuntary functions, such as breathing, heart rate and blood pressure.

Sheep Brain-dissected longitudinal fissure

The great longitudinal fissure (or longitudinal cerebral fissure, or longitudinal fissure, or interhemispheric fissure) is the deep groove that separates the two hemispheres of the vertebrate brain.

Sheep brain-dissected frontal lobe

The frontal lobe is an area in the brain of mammals, located at the front of each cerebral hemisphere and positioned anterior to (in front of) the parietal lobe and superior and anterior to the temporal lobes. It is separated from the parietal lobe by a space between tissues called the central sulcus, and from the temporal lobe by a deep fold called the lateral (Sylvian) sulcus. The precentralgyrus, forming the posterior border of the frontal lobe, contains the primary motor cortex, which controls voluntary movements of specific body parts.The frontal lobe contains most of the dopamine-sensitive neurons in the cerebral cortex. The dopamine system is associated with reward, attention, short-term memory tasks, planning, and motivation. Dopamine tends to limit and select sensory information arriving from the thalamus to the fore-brain. A report from the National Institute of Mental Health says a gene variant that reduces dopamine activity in the prefrontal cortex is related to poorer performance and inefficient functioning of that brain region during working memory tasks, and to slightly increased risk for schizophrenia.

Sheep brain-dissected cerebellum

The cerebellum (Latin for little brain) is a region of the brain that plays an important role in motor control.

Sheep brain-dissected parietal and temporal lobe.

The parietal lobe is a part of the brain positioned above (superior to) the occipital lobe and behind (posterior to) the frontal lobe.The parietal lobe integrates sensory information from different modalities, particularly determining spatial sense and navigation.The temporal lobe is a region of the cerebral cortex that is located beneath the lateral fissure on both cerebral hemispheres of the mammalian brain.[3]

The temporal lobes are involved in the retention of visual memories, processing sensory input, comprehending language, storing new memories, emotion, and deriving meaning.[

Sheep brain-dissected occipital lobe.

The occipital lobe is the visual processing center of the mammalian brain containing most of the anatomical region of the visual cortex.[

Sheep brain-dissected infundibulum

An infundibulum (Latin for funnel; plural, infundibula) is a funnel-shaped cavity or organ.

Sheep brain-dissected corpus callosum

The corpus callosum (Latin: tough body), also known as the colossal commissure, is a wide, flat bundle of neural fibers beneath the cortex in the eutherian brain at the longitudinal fissure. It connects the left and right cerebral hemispheres and facilitates interhemispheric communication. It is the largest white matter structure in the brain, consisting of 200–250 million contralateral axonal projections.

Sheep brain-dissected cerebrum

The cerebrum, or telencephalon, together with the diencephalon, constitutes the prosencephalon during embryonic development.With the assistance of the cerebellum, the cerebrum controls all voluntary actions in the body.

Sheep brain-dissection of the PiaMater.

Pia mater (pron.: /ˈpaɪ.ə ˈmeɪtər/ or pron.: /ˈpiˈ.ə ˈmɑˈtər/[1]) often referred to as simply the pia, is the delicate innermost layer of the meninges, the membranes surrounding the brain and spinal cord.

Sheep Brain-dissection of the Thalamus and hypothalamus.

The thalamus (from Greek θάλαμος, "inner chamber")[1] is a midline symmetrical structure within the brains of vertebrates including humans, situated between the cerebral cortex and midbrain. Its function includes relaying sensory and motor signals to the cerebral cortex,[2][3] along with the regulation of consciousness, sleep, and alertness.

The hypothalamus (from Greek ὑπό = under and θάλαμος = room, chamber) is a portion of the brain that contains a number of small nuclei with a variety of functions. One of the most important functions of the hypothalamus is to link the nervous system to the endocrine system via the pituitary gland (hypophysis).

Sheep brain-dissected arbor vitae

The arbor vitae /ˈɑrbɔr ˈvaɪtiˈ/ (Latin for "Tree of Life") is the cerebellar white matter, so called for its branched, tree-like appearance. In some ways it more resembles a fern and is present in both cerebellar hemispheres.[1] It brings sensory and motor information to and from the cerebellum. The arbor vitae is located deep in the cerebellum. Situated within the arbor vitae are the deep cerebellar and the fastigial nuclei. It also contains the emboliform-globose and dentate nuclei. These four different structures lead to the efferent projections of the cerebellum.[

Sheep brain-dissected septum pellucidum

The septum pellucidum (also called the septum lucidum), and not to be confused with the medial septum, is a thin, triangular, vertical membrane separating the anterior horns of the left and rightlateral ventricles of the brain. It runs as a sheet from the corpus callosum down to the fornix.

Sheep brain

The brain is the center of the nervous system in all vertebrate and most invertebrate animals—only a few invertebrates such as sponges, jellyfish, adult sea squirts and starfish do not have one, even if diffuse neural tissue is present. It is located in the head, usually close to the primary sensory organs for such senses as vision, hearing, balance, taste, and smell. The brain of a vertebrate is the most complex organ of its body. In a typical human the cerebral cortex (the largest part) is estimated to contain 15–33 billion neurons,[1] each connected by synapses to several thousand other neurons. These neurons communicate with one another by means of long protoplasmic fibers called axons, which carry trains of signal pulses called action potentials to distant parts of the brain or body targeting specific recipient cells.

Physiologically, the function of the brain is to exert centralized control over the other organs of the body. The brain acts on the rest of the body both by generating patterns of muscle activity and by driving secretion of chemicals called hormones. This centralized control allows rapid and coordinated responses to changes in the environment. Some basic types of responsiveness such as reflexes can be mediated by the spinal cord or peripheral ganglia, but sophisticated purposeful control of behavior based on complex sensory input requires the information-integrating capabilities of a centralized brain.