Chapter 7: Nervous System Spinal Cord Chapter 7: Nervous System

Spinal Cord Approximately 17 inches long, pathway for both afferent and efferent impulses. About the size of a thumb in width Very well protected by the vertebrae and CSF.

Spinal Cord Humans have 31 pairs of spinal nerves that arise from the spine and exit from the vertebral column to serve the adjoining body Cauda equina- terminal end of the spinal nerves that travel through the vertebral canal Means Horse’s tail

7 cervical vertebrae 12 thoracic vertebrae 5 lumbar vertebrae Vertebral divisions 7 cervical vertebrae Atlas-C1-supports the skull Axis-C2-allows for rotation 12 thoracic vertebrae 5 lumbar vertebrae

Gray Matter in the Spinal Cord In the spinal cord, the posterior projections (dorsal horns) contain association neurons. Help interpret/translate sensory information The anterior projections (ventral horns) are made up of gray matter that are part of the somatic nervous system. These horns fuse together to form the spinal nerves.

White Matter Composed of fiber tracts, traveling to the higher cognition centers, and some traveling from the brain to the spinal cord. Some even communicate messages from one side of the spinal cord to the other. Divided into three sections Posterior, lateral and anterior columns. Each column contains a number of fiber tracts. Posterior column-sensory information to the brain. Lateral/anterior column- ascending and descending motor tracts (cause muscle action)

What is a nerve? Bundle of neurons, found outside of the CNS. Each nerve is comprised of neuron fibers or processes wrapped in connective tissue. Endoneurium-protective tissue sheath around a nerve. Perineurium-combine multiple nerves into a fascicle, or fiber bundle. Epineurium-a collection of fascicles, bound together by a fibrous sheath to form a cordlike nerve.

Cranial Nerves 12 pairs of cranial nerves Serve mainly the head and neck Vagus nerve only one that serves the thoracic and abdominal cavities Made up of mostly mixed nerves

Cranial Nerves Olfactory Optic Oculomotor Trochlear Trigeminal Abducens Facial Vestibulocochlear Glossopharyngeal Vagus Accessory Hypoglossal

Cranial Nerves Olfactory- Sense of smell-Pt is asked to identify an aroma Optic- vision-Pt’s vision is tested, eye chart Oculomotor-vision-PEARL, follow finger Trochlear-vision-mobility of eye, in conjunction with III

Cranial Nerves Trigeminal- facial sensations of pain, touch and temperature, also involved in jaw movement Abducens- lateral movement of the eye. Tested with III as well. Facial- Facial expression and salivary glands. Vestibulocochlear-hearing and balance. Sounds close to ear. Rombergs test.

Cranial Nerves Glossopharyngeal- ability to swallow Vagus- tested along with IX, open mouth wide Accessory- head rotation, resisted shoulder shrug Hypoglossal- stick out tongue, say “aahh”

Autonomic Nervous System Chapter 7.2

ANS Motor subdivision of the PNS Controls automatic body activities Regulate cardiac muscle, smooth muscle (inner lining of organs) Want to maintain homeostasis and a functional environment +/- Blood Pressure, heart rate, sweat glands, etc.

Sympathetic division Fight or flight Under extreme conditions the body will increase heart rate, blood pressure and blood glucose levels to assist in a higher level of functioning Not just under extreme conditions, but when your body is under physical stress, i.e. post- surgically

Parasympathetic division Rest and digest Most active when the body is at rest Promoting normal digestion, bowel function and conserving of body energy.

Nervous System Development Formed during the first month of embryonic development Any infection/disruption can lead to serious complications. Maternal measles-MMR- can lead to deafness Smoking- lack of oxygen to the neurons can lead to serious brain damage of the child Alcohol- can lead to FAS, causes developmental and emotional problems later on in child’s life.