الفهرس 
Composition of the PlexusOnly 14 pages are availabe for public view
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Abstract
The brachial plexus is formed by the union of the ventral rami of the inferior four cervical (C5-C8) and first thoracic (T1) nerves. It supplies the upper limb and any injury at this level can lead to significant disability. from the cords arise the terminal branches including the musculocutaneous, median, ulnar, axillary, and radial nerves, ( Standring et al., 2008).
USGRA has given new life to the appreciation of clinical anatomy. The pattern recognition of normal sonographic landmarks is an important strategy in anatomical orientation and identification of nerves.The anesthesiologist should perform a pre-procedure scan of the perineural region for pathology detection in order to interpret any abnormal appearance, ( Bhatia, 2011).
Local anesthetics block the conduction of impulses in electrically excitable tissues. A comprehensive understanding of the mechanisms and the physiochemical properties of these agents would enable optimization of the therapeutic potential and avoid complications, ( Candido et al., 2010).
Accurate interpretation of US images, requires a basic understanding of the physical principles involved in US image generation. Many of the objects and artifacts seen in US images are due to the physical properties of ultrasonic beams, such as reflection, refraction, and attenuation, ( Hilda, 2011).
The ability of US to visualise nerves as well as structures (vessels, pleura) to be avoided, has resulted in increased confidence for anaesthesiologists performing regional anaesthetic techniques. US guided nerve blocks provide real time imaging of needle position and facilitate nerve location. The ability to now visualize directly the spread of local anaesthetic solution allows for immediate adjustments to needle location beside reducing the needed amount of local anaesthetic volume which in turn improves the block performance. Regional anaesthetic techniques such as the supraclavicular block approach that was considered high risk or challenging may now be undertaken with more ease,
( Brennan et al., 2011).
There are several positive significant impact of the USGRA technique including reduction in block-related complications, decreasing the incidence of systemic local anesthetic toxicity, increasing patient satisfaction during anesthesia due to the relatively painless procedure, especially when compared to other techniques. Patients with cardiovascular collapse from bupivacaine, ropivacaine, and levo-bupivacaine may be especially difficult to resuscitate; however intravenous lipid infusion is a promising new therapy. Furthermore, US can differentiate an intravascular from an extravascular injection based on the pattern of local anesthetic spread,
( Jeng et al., 2010).
The regional anesthesia techniques in children have been considered challenging due to:
(1) Targeting neural structures that often course very close to critical structures (e.g., nerves of the brachial plexus run close to the pleura as they traverse the supraclavicular region).
(2) The prerequisite for sedation or general anesthesia masking potential warning signs.
(3) The need for limiting the volume of local anesthetic solution below toxic levels.
By introducing US technology , many anesthesiologists who had previously abandoned regional techniques will be encouraged to resume their use of regional anesthesia in children, ( Hadzic et al., 2009).
US can be an important modality in those patients in whom the use of other nerve localization (i.e., nerve stimulation) techniques is impossible ( for example patient with femur fibula ulna syndrome,presenting with hypoplasia of the humerus), ( Neal et al., 2009).
The high cost of equipment is often the argument against USGRA techniques. A preliminary study suggests that the cost of using US and nerve stimulator techniques is similar based on the assumption that the average cost per ultrasound- guided block (machine, gel and noninsulated Tuohy needle) and the portable machine is used for 5000 procedures. Conceivably, price reduction with time may justify routine use of US in the future, ( Brown, 2009).
If US is to become an integral part of regional anesthesia, future guidelines and teaching curricula must be established for proper training. Also there is need for skill assessment and accreditation for individual anesthesiologists prior to clinical use of US imaging. A structured residency teaching curriculum will teach both the cognitive and manual component of the ultrasound-guided technique. USGRA is an evolving and exciting field that invites clinician participation and learning,