. Anatomy, descriptive and applied. Anatomy. 1026 THE NERVE SYSTEM communicate with the spinal accessory nerve, in the substance of the Sterno- mastoid muscle, in the posterior triangle, and beneath the Trapezius. Muscular branches are distributed to the Sternomastoid, Trapezius, Levator anguli scapulae, and Scalenus medius. The branch for the Sternomastoid is derived frojn the second cervical; the Trapezius and Levator anguli scapulae receive branches from the third and fourth. The branch for the Scalenus medius is derived sometimes from the third, sometimes from the fourth, and occasionally
. Anatomy, descriptive and applied. Anatomy. 1026 THE NERVE SYSTEM communicate with the spinal accessory nerve, in the substance of the Sterno- mastoid muscle, in the posterior triangle, and beneath the Trapezius. Muscular branches are distributed to the Sternomastoid, Trapezius, Levator anguli scapulae, and Scalenus medius. The branch for the Sternomastoid is derived frojn the second cervical; the Trapezius and Levator anguli scapulae receive branches from the third and fourth. The branch for the Scalenus medius is derived sometimes from the third, sometimes from the fourth, and occasionally from both SCULO SPIRAL Fig. 765.—Plan of the brachial plexus. (Gerrish.) Applied Anatomy.—The cervical plexus may be damaged by wounds or contusions, which may or may not be associated with fracture of the clavicle. Paralysis ensues, the extent depend- ing on the degree of damage. After a contusion the paralysis is apt to be temporary and to be followed by pain and muscular spasm in the arm. Paralysis of the arm due to plexus injury may be partial or complete. In some cases there is complete motor palsy and partial sensor palsy, the sensor impulses passing along undamaged collaterals. In certain spasmodic diffi- culties the surgeon occasionally stretches the cervical plexus. It is reached by an incision at the posterior margin of the Sternomastoid muscle. This incision begins t\vo inches below the level of the tip of the mastoid and is carried downward for three inches. THE BRACHIAL PLEXUS (PLEXUS BRACHIALIS) (Figs. 763, 764). The brachial plexus is formed by the union of the anterior primary divisions of the lower four ce^^'^cal nerves and the greater part of the first thoracic nerve, receiving usually a fasciculus from the fourth cervical nerve, and frequently one from the second thoracic nerve. It extends from the lower part of the side of the neck to the axilla. It is very broad, and presents little of a plexiform arrangement at its commencement. It is narrow o
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectanatomy, bookyear1913
