Veterinary Nervous System
Terms
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- Nervous System
- is the body's control center
- Central Nervous System (CNS)
- the brain, spinal cord, and their associated structures
- Peripheral Nervous System (PNS)
- nerves traveling from the brain or spinal cord to target organs and back
- Voluntary (Somatic)
- carries out concious activities (walking eating etc)
- Involuntary (Autonomic)
- performs activites that do not require concious thought (breathing, heart rate, blood pressure)
- Neuron (Nerve Cell)
- basic structural and functional unit of the nervous system.Carry signals to various areas of the body.
- Sensory Neuron
- carries signals of touch, taste, etc to the brain.
- Motor Neurons
- carry instructions from the brain to the muscles causing them to move.
- Interneurons
- carry signals between neurons
- Cell Body
- central portion of the neuron where the neucleus is located
- Perikaryon
- the cytoplasm within the cell body.
- Axon
- cylindrical projection extending from the cell body usually opposite from the dendrites. transmits signals from the cell body to other neurons or to target organs.
- Dendrites
- highly branched cell receptors that sense the environment or recieve signals from other neurons.
- Synaptic Knob
- disk shaped bulb at the end of an axon
- Synapse
- the junction of the synaptic knobs of one neuron with the dendrites or cell body of the adjacent neuron.
- Schwann Cells
- surround the axons and dendrites and provide structural and metabolic support to the neurons.
- Myelin Sheath
- made up by the Schwann cells as a protective covering over the axon to improve transmission speed of the electric impulse through the axon.
- Node of Ranvier
- where the myelin sheath thins.
- non-mylelinated neurons
- are not wrapped in a myelin sheath.
- Membrane Potential
- difference between the electrical charges on either side of the neuron cell membrane.
- Selectively Permeable
- some ions can come in and some cannot.
- Active Transport
- acheived by molecules embedded on the cell membrane.
- Sodium-potassium Pump
- molecules that are embedded in the cell membrane. Transports sodium out of the cell and potassium into the cell.
- polarity
- electrical potential
- depolarization
- loss of electrical potential between the two sides of the membrane
- repolarization
- when potassium quickly diffuses across the channel
- action potential
- the process of depolarization and repolarization
- saltatory conduction
- the method at which electrical signals travel along myelinated axons
- neurotransmitters
- contents of the synaptic vesicles which get released into the synaptic cleft.
- gray matter
- CNS tissue, composed of aggregates of brain neuron cell bodies.
- white matter
- CNS tissue, composed of axons and dendrites of brain neurons.
- meninges
- external coverings (connective tissue)
- Pia Mater
- layer of the meninges that covers the surface of the brain or spinal cord tissue
- Arachnoid
- the middle layer of the meninges
- Dura Mater
- the outermost layer of the meninges
- subdural space
- space that lies between the arachnoid and the dura mater which is filled with a minute amount of fluid under normal conditions.
- epidural space
- space that lies between the dura and the vertebrae in the spinal cord and is filled with fibrous tissue fat tissue and veins.
- Cerebrum (cerebral cortex)
- shaped like a half sphere, comprises the bulk of the brain.
- Cerebellum
- roughly spherical bundle of brain tissue with a very convoluted surface. Maintains balance and coordination.
- Diencephalon
- acts as a passageway between the brain stem and the cerebrum. Has three major components, thalamus, hypothalamus, and pituitary.
- thalamus
- one of the major components of the diencephalon.
- hypothalamus
- one of the major components of the diencephalon.
- pituitary
- one of the major components of the diencephalon.
- Brain Stem
- forms the connection between the brain and the spinal cord and is composed of three anatomic areas. Midbrain, pons, and medulla oblongata.
- spinal nerves
- branch away from the spinal cord at regular intervals. Part of the PNS. Generally exit from the spinal cord in the spaces between the vertebrae.
- Cranial Nerves
- located in or near the head, most of them enter or exit the brain stem.
- sensory pathway
- carries signals regarding touch, pain, temperature, stretch and so on to the CNS.
- Motor Pathway
- carries signals from the CNS to muscles.
- dorsal root ganglion
- a cluster of sensory neuron cell bodies that lie next to the spinal cord.
- brachial plexus
- medial to the scapula on each side of the body, controls the thoracic limbs.
- axillary nerve
- exits the brachial plexus and supplies the muscles that flex the shoulder and the skin over the cranial surface of the elbow.
- radial nerve
- is the larges brachial plexus nerve and supplies the lateral surface of the humerous and the cranial-lateral surface of the foreleg and foot.
- median nerve
- exits the brachial plexus and supplies the medial surface of the foreleg and the palmar surface of the foot.
- ulnar nerve
- exits the brachial plexus and supplies the caudal surface of the foreleg and palmar surface of the foot. (overlapping with the median nerve)
- lumbosacral plexus
- gives nerve supply to the pelvic limbs and has three major nerves, femoral, obturator, and ischiatic.
- femoral nerve
- comes from the lumbosacral plexus and supplies the cranial muscles of the femur and sensory nerves to the medial surface of the thigh and foreleg.
- obturator nerve
- comes from the lumbosacral plexus and supplies primarily the muscles of the medial thigh.
- ischiatic nerve (sciatic)
- the larges lumbosacral nerve, passes over the hip joint and travels down the caudal-lateral surface of the thigh supplying the caudal thigh muscles.
- olfactory nerve
- cranial nerve that carries signals to the brain regarding the sense of smell.
- optic nerve
- cranial nerve that originates in the retina of the eye and carries visual signals to the brain from the eye.
- oculomotor nerve
- cranial nerve that controls the movement of the eye and pupil.
- trochlear nerve
- fourth cranial nerve that carries nerve fibers to a single muscle around the eye that causes the eye to rotate medially.
- trigeminal nerve
- largest cranial nerve, carries signals to the muscles involved with chewing.
- abducent nerve
- rotates the eye laterally or retract the eyeball deeper into the socket.
- facial nerve
- performs motor functions involving facial muscles controlling facial expressions, muscles of the eye, tear glands, some of the salivary glands, and nasal glands and tongue.
- vestibulocochlear nerve
- carries signals regarding hearing and motion and balance.
- glossopharyngeal nerve
- controls the muscles of the soft palate and pharynx, and secretion from some of the salvary glands.
- vagus nerve
- connect organs within the thorax and abdomen, and control the muscles of the pharynx, larynx, and esophagus.
- spinal accessory nerve
- carries only motor nerves that control certain muscles of the neck and thoracic limbs.
- hypoglossal nerve
- controls muscles of the tounge and some muscles of the neck.
- motor neuclei
- located in the cerebral cortex the basal ganglia and the brain stem. Place where signals are initiated to move the body.
- primary motor cortex
- signals travel from here to the spinal cord segment that sends out spinal nerves to the muscle of interest
- premotor area
- a motor area in the cortex
- innervated
- supplied with nerves
- norepinephrine
- secreted by the adrenal medulla
- ganglion
- collection of neuron cell bodies
- Sulcus (sulci)
- indentation in the brain tissue
- gyri
- raised tissue between the indentations in the brain.