These discs act as shock absorbers for the spinal bones. Ligaments attached to the vertebrae also serve as supportive structures. There are 31 pairs of spinal nerves and roots. Eight pairs of cervical nerves exit the cervical cord at each vertebral level. One member of the pair exits on the right side and the other exits on the left.
The first cervical root exits above the C1 vertebra. The second cervical root exits between the C1-C2 segment and the remaining roots exit just below the correspondingly numbered vertebra.
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The eighth nerve root exits between the C7 and T1 vertebra. There are 12 thoracic nerve pairs. The first nerve root exits between the T1 and T2 vertebrae. There are five lumbar nerve pairs. The first of these nerve roots exits between L1 and L2. There are five sacral nerve pairs. The first nerve root exits between S1 and S2. One pair of coccygeal Co1 nerves meets in the area of the tailbone.
By way of the peripheral nervous system PNS , nerve impulses travel to and from the brain through the spinal cord to a specific location in the body.
A Neurosurgeon’s Overview of the Anatomy of the Spine and Peripheral Nervous System
The PNS is a complex system of nerves that branch off from the spinal nerve roots. These nerves travel outside of the spinal canal to the upper extremities arms, hands and fingers , to the muscles of the trunk, to the upper and lower extremities arms, hands, fingers, legs, feet and toes and to the organs of the body. Any interruption of spinal cord function by disease or injury at a particular level may result in a loss of sensation and motor function below that level.
Depending on the severity of the disease or injury, the loss of function may be permanent. Did you know you can support education and research for neurosurgical conditions while you shop, at no extra cost to you? Register with AmazonSmile to designate the NREF as your charity, and a percentage of your purchase is donated automatically. Annulus fibrosus — The fibrous, ring-like outer portion of an intervertebral disc.
Arachnoiditis — Inflammation of the arachnoid membrane the middle of the three protective layers called the meninges ; most commonly seen around the spinal cord and cauda equina. Arthritis — Inflammation of a joint, usually accompanied by swelling, pain and restriction of motion.
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Bone spur — Bony growth or rough edge of bone. Cauda equina — The collection of nerves at the end of the spinal cord that resembles a horse's tail. The brain and spinal cord the CNS function as the control center. They receive data and feedback from the sensory organs and from nerves throughout the body, process the information, and send commands back out. Nerve pathways of the PNS carry the incoming and outgoing signals. Twelve pairs of cranial nerves connect the brain to eyes, ears, and other sensory organs and to head and neck muscles. Thirty-one pairs of spinal nerves branch out from the spinal cord to tissues of the thorax, abdomen, and limbs.
Each nerve is responsible for relaying sensory information, sending motor commands, or both. All nervous tissue, from the brain to the spinal cord to the furthest nerve branch, includes cells called neurons. Neurons are charged cells: they conduct electrical signals to pass information through the body. A typical neuron consists of a cell body, dendrites, and an axon with an axon terminal.
The dendrites receive signals from body tissues or other neurons and pass them into the cell body. If an outgoing signal is produced, it zips down the axon to the axon terminal and passes to the next neuron or target cell. This conductive capability sends information up and down nerve pathways and through the central nervous system at incredible speed.
Some billion neurons give the brain its awesome processing power.
A Reference for Patients
Nervous system messages travel through neurons as electrical signals. When these signals reach the end of a neuron, they stimulate the release of chemicals called neurotransmitters. Neurotransmitters travel across synapses , spaces between neurons or between neurons and other body tissues and cells. Bone necrosis is a complication of the bone that occurs in association with trauma and a wide range of medical conditions.
Osteoporosis is an important medical condition as it accounts for a large number of fractures, loss of independence in movement, and even death of individuals. Osteoporosis is a well-known consequence of glucocorticoid excess in humans, either in association with Cushing's syndrome or following long-term glucocorticoid therapy, notably in rheumatoid arthritis.
An increase in mineralized bone or osteoid can occur in a variety of different circumstances. The therapy-induced increases in bone mass and osteoid are also elaborated in this chapter. This chapter describes the principal drug-induced and spontaneous pathology found in the musculoskeletal system of laboratory animals and how this compares with lesions reported in humans.
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There is a discussion of the approach to the histological examination of bone and the evaluation of changes to bone mass and osteoid as well as the growth plate. Neoplasms of bone and cartilage are also described. Drug-induced changes to joints and cartilage are also analyzed, in particular degenerative alterations linked to quinolone antibiotics, corticosteroids and anticancer agents.
There is a detailed discussion of changes induced in skeletal muscle by treatment both by drugs given systematically such as the hypolipidemic drugs and therapies intended for administration by intramuscular injection. William S. Pietrzak, in Mechanical Testing of Orthopaedic Implants , The musculoskeletal system consists principally of bone, muscle, tendon, ligament, and articular cartilage tissue. These are arranged throughout the body to provide internal support and allow motion to occur. Their specific configuration, however, varies with the anatomic site by virtue of the types of loads these tissues experience and the movements that they are required to perform.
As such, while the musculoskeletal system is governed by a set of underlying principles, there is a great deal of local variance throughout.
Introduction to the Nervous System
This is why treatments for musculoskeletal injury and disease are divided into regions such as craniomaxillofacial, oral, shoulder and elbow, hand and wrist, hip and knee, foot and ankle, spine, and others. Leyla H. Computed tomography CT is useful in demonstrating paraspinal calcifications. Magnetic resonance imaging MRI is valuable for assessing paraspinal calcifications and their effect on neurologic structures, as well as for identifying areas of inflammatory myopathy.
High-resolution computed tomography HRCT is more sensitive than radiography in the assessment of early interstitial lung disease and is able to differentiate active inflammation from fibrosis. Enlargement occurs in pulmonary artery hypertension. Right heart catheterization optimally evaluates pulmonary arterial hypertension. Myocardial disease can be evaluated using radionuclide imaging, coronary angiography, or cardiac MRI. Nuclear scans can demonstrate decreased renal blood flow and glomerular filtration rate.
Barium swallow: Esophageal dilatation, diminished or absent peristalsis in the distal two thirds of the esophagus, and a patulous gastroesophageal junction are typical features. Stricture occurs secondary to chronic gastroesophageal reflux. Barium follow through: Delay in transit time with decreased motility, pseudodiverticula, and hidebound appearance.
Barium enemas are usually avoided because they may result in impaction. Scintigraphy: Delayed esophageal transit time and gastric emptying and gastroesophageal reflux are typical features. Delayed scans are useful for detection of pulmonary aspiration.