The brachial plexus is a complex network of nerves that innervates the upper limbs, originating from the cervical and thoracic vertebrae. This article details the anatomical structure and surgical exposure techniques for the brachial plexus in a neonatal piglet model.
The brachial plexus is a network of nerves present around the neck and the shoulder region that supplies the upper limbs. The plexus roots originate above the fifth to seventh cervical vertebrae and the first thoracic vertebra. These roots unite to form the superior, middle, and inferior trunks.
Each of these trunks diverges into anterior and posterior divisions. These divisions proceed towards the axillary region or the armpit, where they recombine to form three cords: the posterior, lateral, and medial cords. The cords travel laterally toward the arm, finally terminating in the nerve branches, namely the musculocutaneous, axillary, radial, median, and ulnar nerves.
To expose the brachial plexus, begin by taking an anesthetized neonatal piglet with the forelimb stretched to expose the axilla. Make a midline incision from the sternum towards the tracheal opening. Extend the top part of this cut towards the forelimb at the level of the third cervical vertebra.
At the base of the midline incision, cut the skin at the third thoracic vertebra level and extend it towards the forelimb. Remove the superficial skin and muscle layers to locate the lower three cervical and first thoracic vertebrae and identify the brachial plexus. Examine the intactness of the exposed brachial plexus before further testing.
After confirming a lack of palpebral and withdrawal reflexes, place the anesthetized pig in the supine position on the operating table, with the upper limb in abduction to expose the axillary region. Place a drape over the animal, and use a #10 scalpel blade to make incisions over the marked skin.
Midline incision is overlying the trachea down to the upper third of the sternum, exposing the brachial plexus complex on both sides of the spine. To expose one side of the animal's brachial plexus, a superior incision is made from the upper end of the midline incision, corresponding to C3 to the upper arm, and an inferior incision is made from the lower end of the midline incision corresponding to T3 to the upper arm.
Use forceps on each side of the incision to separate tissue from the suprasternal notch along the edge of the clavicle to the upper arm, while sparing the cephalic and basilic veins. Using scissors, forceps, and blunt dissection, release the superior flap to access the cervical region of the brachial plexus, and the inferior flap to access the thoracic region of the brachial plexus.
Perform blunt dissection on superficial muscles to expose the brachial plexus, then, examine the plexus carefully to locate bifurcations of the divisions, and identify the brachial plexus regions below the bifurcations closer to the arm as the cord and the nerve and the regions above the bifurcations closer to the spine as the root or trunk.
繁體中文
