The Brain Meninges The brain and spinal cord
�The Brain - Meninges The brain and spinal cord are surrounded by membranes called meninges that lie between the bone and the soft tissues.
dura mater Outermost meninx is made up of tough, white dense connective tissue, contains many blood vessels In some areas, the dura mater forms partitions between lobes of the brain, and in others, it forms dural sinuses. The sheath around the spinal cord is separated from the vertebrae by an epidural space. (where the epidural is placed when having a child)
Dura mater intact
arachnoid mater (spider web appearance) The middle meninx, the arachnoid mater, is thin and lacks blood vessels. It does not follow the convolutions of the brain. Between the arachnoid and pia maters is a subarachnoid space containing cerebrospinal fluid.
Brain, whole; Right hemisphere has arachnoid mater intact {CNS}
pia mater The innermost pia mater is thin and contains many blood vessels and nerves. It is attached to the surface of the brain and spinal cord and follows their contours.
Brain--Cerebrum Conscious thought, intellectual functions, memory storage & processing, regulation of motor patterns
Lobes (Cerebrum) Frontal- voluntary control of skeletal muscles Parietal- perception of touch, pressure, vibration, pain, temp, taste Occipital- perception of visual stimuli Temporal- perception of olfactory and auditory stimuli All lobes have association areas where sensory data is integrated & processes
Cerebrum is divided into 2 hemispheres-separated by a deep longitudinal fissure and connected by a thick band of axons called the corpus callosum. Left controls right side Right controls left side
Corpus callosum
Cerebellum Inferior & posterior to cerebrum Coordinates adjustments that maintain balance and equilibrium Fine tunes voluntary & involuntary movements to ensure smooth movements.
Thalamus Atop brain stem Relays and processes sensory info
Hypothalamus Inferior to thalamus Controls emotions, autonomic functions, hormone production
Midbrain Processing of visual and auditory data Generation of involuntary motor responses Maintenance of consciousness
Pons Relays sensory info to cerebellum & thalamus Involuntary motor center
Medulla Oblongata Relays sensory info to thalamus Autonomic centers for regulation of cardiovascular, respiratory, & digestive activities
Spinal Cord The spinal cord begins at the base of the brain and extends as a slender cord to the level of the intervertebral disk between the first and second lumbar vertebrae.
The spinal cord consists of 31 segments, each of which gives rise to a pair of spinal nerves. A cervical enlargement gives rise to nerves leading to the upper limbs, and a lumbar enlargement gives rise to those innervating the lower limbs.
1. Cervical enlargement 2. Lumbar enlargement 3. Ventral rami of spinal nerves
Two deep longitudinal grooves (anterior median fissure and posterior median sulcus) divide the cord into right and left halves.
White matter, made up of bundles of myelinated nerve fibers (nerve tracts), surrounds a butterfly-shaped core of gray matter housing interneurons.
A central canal contains cerebrospinal fluid.
The spinal cord has two major functions: to transmit impulses to and from the brain, and to house spinal reflexes.
Tracts carrying sensory information to the brain are called ascending tracts; descending tracts carry motor information from the brain.
The names that identify nerve tracts identify the origin and termination of the fibers in the tract. Many spinal reflexes also pass through the spinal cord.
Spinal Nerves 1. Thirty-one pairs of mixed nerves make up the spinal nerves.
2. Spinal nerves are grouped according to the level from which they arise and are numbered in sequence, beginning with those in the cervical region.
3. Each spinal nerve arises from two roots: a dorsal, or sensory, root, and a ventral, or motor, root. 4. The main branches of some spinal nerves form plexuses.
Cervical Plexuses a. The cervical plexuses lie on either side of the neck and supply muscles and skin of the neck.
Brachial Plexuses a. The brachial plexuses arise from lower cervical and upper thoracic nerves and lead to the upper limbs.
Lumbosacral Plexuses a. The lumbosacral plexuses arise from the lower spinal cord and lead to the lower abdomen, external genitalia, buttocks, and legs.
Observe the Brain…. when they get in. . .
Cranial Nerves 1. Twelve pairs of cranial nerves arise from the underside of the brain, most of which are mixed nerves.
Cranial nerves 2. The 12 pairs are designated by number and name and include the: olfactory, optic, oculomotor, trochlear, trigenimal, abducens, facial, vestibulocochlear, glossopharyngeal, vagus, accessory, and hypoglossal nerves.
5 senses and organs
HEARING AND BALANCE 1. The EAR is really TWO Sense Organs in ONE. It not only detects Sound Waves, it also senses the Position of the HEAD, whether it is STILL, MOVING IN A STRAIGHT LINE, OR ROTATING.
2. Sound is nothing more than Vibrations in the Air around us. 3. Deep LOW-PITCHED Sounds result from slow vibrations. HIGH-PITCHED Sounds are caused from faster Vibrations.
4. In addition to Pitch, sounds differ by their Loudness or Volume. 5. The Sense Organ that can distinguish BOTH PITCH AND LOUDNESS of SOUNDS are the EARS.
6. The External Ear consists of the visible fleshy part helps to COLLECT Sounds and FUNNEL them into the AUDITORY CANAL. The Auditory Canal connects the External Ear with the TYMPANIC MEMBRANE, also called the Eardrum.
7. The Auditory Canal contains small Hairs and WAX Producing GLANDS that PREVENT Foreign objects from entering the ear.
8. The Auditory Canal extends into the bone of the head, but stops at the EARDRUM OR TYMPANIC MEMBRANE. 9. The Eardrum is the beginning of the MIDDLE EAR.
10. Sound Vibrations STRIKE the EARDRUM and are Transmitted through THREE TINY BONES: THE MALLEUS (HAMMER), INCUS (ANVIL), AND STAPES (STIRRUP).
11. The Stirrup transfers the Vibrations to a thin membrane covering an opening called the OVAL WINDOW. 12. This Membrane transmits the vibrations to the COCHLEA, which begins the INNER EAR.
13. The COCHLEA is SNAIL SHAPED, consisting of Three FLUID FILLED Chambers that are separated by membranes.
14. The Middle Chamber contains the ORGAN OF CORTI, which is the organ of Hearing. 15. When the Fluid Vibrates, tiny Hair Cells lining the Cochlea are PUSHED back and forth, providing Stimulation that is turned into NERVE IMPULSES.
16. These Nerve Impulses are carried to the Brain by the AUDITORY OR ACOUSTIC NERVE. 17. The EARS also contain structures for DETECTING STIMULI that make us aware of our MOVEMENTS and allow us to maintain our BALANCE.
18. Located within the INNER EAR just above the Cochlea are three tiny canals that lie at right angles to each other. 19. They are called the SEMICIRCULAR CANALS BECAUSE THEY EACH MAKE HALF A CIRCLE.
20. The Semicircular Canals and the TWO Tiny Sacs located behind them help us to SENSE BALANCE OR EQUILIBRIUM. 21. Both the Canals and the Sacs are filled with Fluid and Lined with Hair Cells (Mechanoreceptors).
22. There also Tiny Grains of Calcium Carbonate and Protein called OTOLITHS, Otoliths roll back and forth in response to gravity, acceleration, and deceleration.
23. The Movement of Fluid and Otoliths bend the hair on the Hair Cells, and in turn sends the impulses to the Brain that enable it to determine BODY MOTION AND POSITION.
VISION 1. The Sense Organ we use to sense Light is the EYES. (Figure 50 -13)
2. The EYE is composed of THREE LAYERS: A. The OUTER Layer consists of the SCLERA AND CORNEA.
B. The MIDDLE Layer contains the CHOROID, CILIARY BODY, AND IRIS.
C. The INNER Layer consists of the RETINA.
3. The SCLERA (WHITE OF THE EYE) consist of tough white connective tissue. The Sclera helps MAINTAIN the SHAPE OF EYE, and also provides a means of ATTACHMENT for the MUSCLES THAT MOVE THE EYE.
4. IN THE FRONT OF THE EYE, THE SCLERA FORMS A TRANSPARENT LAYER CALLED THE CORNEA. 5. The CORNEA is the part of the eye through which LIGHT ENTERS.
6. Just inside the Cornea is a small chamber filled with FLUID known as the AQUEOUS HUMOR. 7. At the BACK of this chamber, the PIGMENTED CHOROID, WHICH CONTAINS THE BLOOD VESSELS OF THE EYE, BECOMES a disk-like structure called the IRIS.
8. The IRIS (A DIAPHRAGM) is the portion of the eye that gives your eye its COLOR. The Iris controls the amount of Light entering the eye by altering the Diameter of the Pupil. 9. In the MIDDLE of the Iris is a small opening called the PUPIL, through which LIGHT ENTERS THE EYE.
11. In DIM LIGHT the Pupil OPENS to INCREASE the amount of Light, In BRIGHT LIGHT the Pupil CLOSES to DECREASE the amount of Light entering the Eye.
12. Behind the Iris is the LENS. Light is Focused by the Lens, which changes shape when pulled by muscles around its edges. 13. The CELLS that form the Lens contain a special PROTEIN called CRYSTALIN is almost transparent and allows light to pass through.
14. Small Muscles attached to the Lens cause it to bend, this enables the eye to FOCUS on close and distant objects.
15. Behind the Lens is a Large Chamber called the VITREAL CHAMBER filled with a transparent Jellylike Fluid called VITREOUS HUMOR.
16. Special Light Sensitive RECEPTOR CELLS, or PHOTORECEPTORS, are arranged in a layer in the RETINA, at the BACK of the EYE. 17. The PHOTORECEPTORS CONVERT LIGHT ENERGY INTO IMPULSES THAT ARE CARRIED TO THE CNS.
18. THERE ARE TWO TYPES OF PHOTORECEPTORS: RODS AND CONES. We have about 125 million RODS and 7 million CONES on a single Retina.
19. Photoreceptors contain a PIGMENT called RHODOPSIN, that can respond to most wavelengths of light. 20. RODS are extremely sensitive to ALL COLORS of LIGHT, but DO NOT DISTINGUISH DIFFERENT COLORS.
21. CONES are less sensitive than RODS, but they DO RESPOND DIFFERENTLY TO LIGHT OF DIFFERENT COLORS, PRODUCING COLOR VISION.
22. Humans have three kinds of cones. Each type of cone contains a pigment that absorbs different wavelengths of light. When the signals from these three kinds of cone are integrated, a person is able to see all the colors in the visible spectrum.
23. In DIM Light, when only RODS are activated, you may see objects clearly, but not their colors. 24. As the amount of Light INCREASE, the CONES are stimulated and the colors become clear.
25. The Impulses leave the Eye by way of the OPTIC NERVE, and CARRIED to the part of BRAIN Known as the OPTIC LOBE OR OCCIPITAL LOBE. Here the Brain Interprets the visual images and provides information about the external world.
SMELL 1. The Sense of Smell is a CHEMICAL SENSE, the Cells responsible for smell are Specialized Chemoreceptors called OLFACTORY RECEPTORS. 2. These Cells are located in the Upper Part of the Nasal Cavity.
3. Chemoreceptors contain Cilia that extend into the air passageways of the nose and react to Chemicals in the Air. Chemicals that come into contact with the Chemoreceptors Stimulate them, causing Impulses to be sent to the Brain by the OLFACTORY NERVE
TASTE 1. The Sense of Taste is a Chemical Sense. 2. The Cells that are Stimulated by the Chemicals are called CHEMORECEPTORS
CHEMORECEPTORS. 3. The Sense Organ that detects Taste are the TASTE BUDS. NOT THE TONGUE! 4. Most of the 10, 000 Taste Buds are embedded between bumps called PAPILLAE on the tongue, but can also be found on the roof of the mouth, on the lips, and in the throat.
5. Humans can detect FOUR main kinds of TASTE: SWEET, SALTY, SOUR, AND BITTER.
6. Each Taste Bud shows a particular Sensitivity to one of these taste. The Sense of Taste is converted to Nerve Impulses in the Taste Buds and transmitted to the Brain by TWO Nerves - The FACIAL NERVE AND GLOSSOPHARYNGEAL NERVES.
7. Many of the Sensation associated with taste are actually SMELL Sensations, You depend on both Senses to detect Flavors in Food. 8. That is why when you have a Cold and Your Smell Receptors are blocked, food seems to have little or no taste.
Eye Dissection. .
Reliability of Vision Lab
Smell, Hearing, Equilibrium, taste, labs……
Study Guide
Test…
- Slides: 88