The plexus extends toward the armpit axilla. The lumbar plexus is formed by the ventral rami of L1—L5 spinal nerves with a contribution of T12 form the lumbar plexus. This plexus lies within the psoas major muscle. The sacral plexus is formed by the ventral rami of L4-S3, with parts of the L4 and S4 spinal nerves. It is located on the posterior wall of the pelvic cavity.
The coccygeal plexus serves a small region over the coccyx and originates from S4, S5, and Co1 spinal nerves. It is interconnected with the lower part of sacral plexus. Brachial plexus : Cervical C5—C8 and thoracic T1 nerves comprise the brachial plexus, which is a nerve plexus that provides sensory and motor function to the shoulders and upper limbs. They can be classified as sensory nerves, motor nerves, or a combination of both, meaning that the axons in these nerves originate out of sensory ganglia external to the cranium or motor nuclei within the brain stem.
Sensory axons enter the brain to synapse in a nucleus. Motor axons connect to skeletal muscles of the head or neck. Three of the nerves are solely composed of sensory fibers; five are strictly motor; and the remaining four are mixed nerves. Learning the cranial nerves is a tradition in anatomy courses, and students have always used mnemonic devices to remember the nerve names.
The names of the nerves have changed over the years to reflect current usage and more accurate naming. An exercise to help learn this sort of information is to generate a mnemonic using words that have personal significance. The names of the cranial nerves are listed in Table They are listed here with a brief explanation of each nerve Figure The olfactory nerve and optic nerve are responsible for the sense of smell and vision, respectively.
The oculomotor nerve is responsible for eye movements by controlling four of the extraocular muscles. It is also responsible for lifting the upper eyelid when the eyes point up, and for pupillary constriction. The trochlear nerve and the abducens nerve are both responsible for eye movement, but do so by controlling different extraocular muscles.
The trigeminal nerve is responsible for cutaneous sensations of the face and controlling the muscles of mastication. The facial nerve is responsible for the muscles involved in facial expressions, as well as part of the sense of taste and the production of saliva. The vestibulocochlear nerve is responsible for the senses of hearing and balance. The glossopharyngeal nerve is responsible for controlling muscles in the oral cavity and upper throat, as well as part of the sense of taste and the production of saliva.
The vagus nerve is responsible for contributing to homeostatic control of the organs of the thoracic and upper abdominal cavities. The spinal accessory nerve is responsible for controlling the muscles of the neck, along with cervical spinal nerves.
The hypoglossal nerve is responsible for controlling the muscles of the lower throat and tongue. Three of the cranial nerves also contain autonomic fibers, and a fourth is almost purely a component of the autonomic system. The oculomotor, facial, and glossopharyngeal nerves contain fibers that contact autonomic ganglia.
The oculomotor fibers initiate pupillary constriction, whereas the facial and glossopharyngeal fibers both initiate salivation. The vagus nerve primarily targets autonomic ganglia in the thoracic and upper abdominal cavities. Visit this site to read about a man who wakes with a headache and a loss of vision. His regular doctor sent him to an ophthalmologist to address the vision loss.
The ophthalmologist recognizes a greater problem and immediately sends him to the emergency room. Once there, the patient undergoes a large battery of tests, but a definite cause cannot be found.
A specialist recognizes the problem as meningitis, but the question is what caused it originally. How can that be cured? The loss of vision comes from swelling around the optic nerve, which probably presented as a bulge on the inside of the eye. They are the intercostal nerves, which are located between the ribs. An accident that pulls the arm or severely bends the arm at the shoulder may damage the brachial plexus located near the shoulder.
In newborns, the brachial plexus can be damaged during birth if the delivery requires pulling or other maneuvers. A fall can injure the lumbosacral plexus located near the hip. A cancer growing in the breast or upper part of the lung can invade and destroy the brachial plexus.
Cancer of the intestine, bladder, or prostate can invade the lumbosacral plexus. Other masses, such as a noncancerous benign tumor, an abscess, or a pocket of blood hematoma , may cause plexus disorders by putting pressure on a plexus. Diabetes or radiation therapy for breast cancer, which can damage nerves throughout the body, may also damage nerves in a plexus. Acute brachial neuritis Parsonage-Turner syndrome, or neuralgic amyotrophy is sudden malfunction of the brachial plexus due to inflammation rather than injury or cancer.
It is probably caused by an autoimmune reaction Autoimmune Disorders An autoimmune disorder is a malfunction of the body's immune system that causes the body to attack its own tissues.
What triggers autoimmune disorders is not known. Symptoms vary depending on This disorder occurs primarily in men. It typically occurs in young adults but can occur at any age.
Malfunction of the brachial plexus causes pain, weakness, and loss of sensation in an arm. All or part of the arm such as the forearm or biceps may be affected.
If the cause is an injury, recovery tends to occur slowly, over several months. Some severe injuries cause permanent weakness. Acute brachial neuritis causes severe pain in the upper arms and shoulders. Usually, the arm becomes weak and reflexes are impaired as the pain resolves. Weakness develops within 3 to 10 days. Then people typically regain their strength over the next few months. Malfunction of the lumbosacral plexus causes pain in the lower back and leg as well as weakness and loss of sensation in all or part of a leg such as the foot or calf.
Recovery depends on the cause. Doctors suspect that a plexus is involved when symptoms are located in a part of the body supplied by a specific plexus.
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