BIOLOGY 165 CENTRAL NERVOUS SYSTEM LAB MANUAL

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1 BIOLOGY 165 CENTRAL NERVOUS SYSTEM LAB MANUAL NOTE: You may be asked to identify any structure, cell, tissue, or organ labeled in the figures/pictures within this lab manual. In addition, you may be asked to name one function of each labeled item and one location within the human body where it can be found. You are only responsible for the specific information contained within this lab manual. Although the pictures in this packet show a particular model, you should look at all similar models we have in the lab; any model in lab can be used during the practical. INTRODUCTION The central nervous system consists of the brain and the spinal cord. The Brain 1. Brainstem with the following functional areas: a. Medulla oblongata. i. Contains all ascending and descending tracts that pass between the spinal cord and the brain. ii. Contains the decussation of the pyramids where motor tracts cross over to the opposite side of the central nervous system. iii. Contains the three vital reflex centers: 1. Cardiac center. 2. Respiratory center. 3. Vasomotor center. b. Pons with the following functional areas: i. Contains the nuclei of some of the cranial nerves. ii. Contains two vital reflex centers: 1. Pneumotaxic area and apneustic area: a. These two areas together define the limits of pulmonary ventilation (inhalation and exhalation). c. Midbrain with the following functional areas: i. Contains the cerebral peduncles that attach the brain stem to the cerebellum. ii. Contains the corpora quadrigemina with two specialized reflex areas: 1. Superior colliculi reflex center for visual stimuli. 2. Inferior colliculi reflex center for auditory stimuli. 2. Cerebellum the motor area of the brain that coordinates certain subconscious movements of skeletal muscles required for coordination of body movements, posture, and balance. 3. Diencephalon contains the following functional areas: a. Thalamus functions as a relay station for sensory stimuli between the cerebrum of the brain and the spinal cord. b. Hypothalamus with many functions including: i. Control and integration of the autonomic nervous system. ii. Control of secretion of hormones from various endocrine glands. iii. Control of body temperature. iv. Feelings of rage and aggression, food intake, thirst, and many more. c. Pituitary gland (attached to the hypothalamus by a stalk called the infundibulum) secretes many hormones. d. Pineal gland controls the onset of puberty and other biorhythms. 4. Cerebrum (composed of the left and right cerebral hemispheres) - with the following functional areas: a. Frontal contains the primary motor cortex (on the precentral gyrus), which is involved in the voluntary control of the skeletal muscles, among other things 1

2 b. Parietal contains the primary sensory cortex (on the postcentral gyrus) which is involved in the conscious perception of touch, pressure, pain, vibration, taste and temperature, among other things c. Temporal involved in the conscious perception of sound and smell, among other things d. Occipital involved in the conscious perception of visual stimuli, among other things e. Corpus callosum connects regions of one hemisphere of the cerebrum with the same regions on the other hemisphere of the cerebrum. Be able to identify the structures shown in the pictures below, using any similar model we have in lab. Parietal Frontal Temporal Occipital 2

3 Hypothalamus Superior colliculus of the corpora quadrigemina Inferior colliculus of the corpora quadrigemina 3

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5 Ventricles of the Brain The central nervous system contains chambers (ventricles) where cerebrospinal fluid (CSF) is produced. This fluid is produced by capillaries called the choroid plexus, found within the lateral, third, and fourth ventricles. 1. Lateral ventricles one is located in each cerebral hemisphere of the brain. Each contains a capillary bed called the choroid plexus that produces CSF. 2. Interventricular foramen drains the CSF from the two lateral ventricles into the third ventricle. 3. Third ventricle also contains a choroid plexus for the production of CSF. 4. Cerebral aqueduct drains the CSF from the third ventricle into the fourth ventricle. 5. Fourth ventricle also contains a choroid plexus for the production of CSF. 6. The CSF drains from the fourth ventricle into the central canal of the spinal cord and into the subarachnoid space around the brain and spinal cord. It is then reabsorbed into the blood. Seen below: Ventricles of the brain. Be able to identify the structures shown in the picture below, using any similar model we have in lab. Spinal Cord 1. Meninges three coverings of connective tissue that surround the brain and spinal cord: a. Dura mater the outer layer of the meninges, consisting of dense fibrous connective tissue. b. Arachnoid mater the middle layer of the meninges, composed of very delicate connective tissue. i. Beneath the arachnoid mater is the subarachnoid space, which contains CSF. c. Pia mater the inner layer of the meninges is composed of a delicate transparent fibrous membrane. It adheres tightly to the surface of the brain and spinal cord. It also forms the denticulate ligaments and filum terminale that holds the spinal cord in place. 2. Spinal cord structures: a. The dorsal roots contains the fibers of the incoming (afferent) sensory neurons. b. The ventral roots contains the fibers of the outgoing (efferent) motor neurons. c. The spinal nerves contains both sensory and motor fibers. d. The dorsal root ganglia contains the cell bodies of the sensory neurons. e. Gray matter contains the cell bodies of neurons. f. White matter contains the myelinated axons of motor and sensory neurons. 5

6 Be able to identify the structures shown in the pictures below, using any similar model we have in lab. Seen below: Model of the spinal cord within a cervical vertebra. Note: The three meninges and associated spaces are shown in a close-up view on the next page, and are named individually. Dorsal root ganglion Ventral root Dorsal root 6

7 Seen below: Meninges and spinal cord. Ventral horns Dorsal horns Arachnoid mater 7