. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. NERVOUS SYSTEM. (NERVE.) 594 the separation which takes place in the fat cells between the solid and the fluid elements of fat. As the combination of the primitive muscular fibres, in a common sheath, forms the muscle, so the union of the primitive nervous fibres, in a similar way, forms the nerve. And as the primitive fibre of muscle passes undivided from one point of the muscle to another, so the nerve tube exhibits no subdivision in its course. Brandling of' nerves.—The main trunk of a nerve breaks up into its compone
. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. NERVOUS SYSTEM. (NERVE.) 594 the separation which takes place in the fat cells between the solid and the fluid elements of fat. As the combination of the primitive muscular fibres, in a common sheath, forms the muscle, so the union of the primitive nervous fibres, in a similar way, forms the nerve. And as the primitive fibre of muscle passes undivided from one point of the muscle to another, so the nerve tube exhibits no subdivision in its course. Brandling of' nerves.—The main trunk of a nerve breaks up into its component bundles, as it passes from centre to periphery, yielding up branches to the various parts it is destined to connect with the nervous centre. These branches generally come off at acute angles, and soon plunge into the muscles and other parts to which they tend, dividing and subdividing as they pro- ceed. Such is the most common mode of sub- division, but there are many exceptions : some- times a branch separates from the parent trunk at an acute angle, and then turns to run in an op- posite direction, forming an arch, from the con- vexity of which several branches are given off. Such a nerve is said to be recurrent; the in- ferior laryngeal nerve takes this course. The anastomotic arches between the emerging spinal nerves, round the vertebral laminae, are also exceptions to the separation at acute angles. Before a branch separates, it often happens that the parent trunk presents an enlargement for some distance above the point of visible separation. This is due to the fact that the fibres which compose the future branch begin to loosen their connection with the trunk for some way before they actually leave it; and the con- necting areolar membrane becomes conse- quently looser and more abundant. Hence the trunk of the nerve appears enlarged, with- out any increase in the number of its nervous elements. This may be well seen in the auri- cular nerve of the neck, as it winds
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