. Biology of the vertebrates : a comparative study of man and his animal allies. Vertebrates; Vertebrates -- Anatomy; Anatomy, Comparative. 68o Biology of the Vertebrates the skull and the first cervical vertebra, or atlas, and so, having no vertebra in front of it, takes its name from the vertebra immediately behind it. This method of nomenclature is followed throughout the cervical series, leaving the eighth pair of nerves without any cervical, vertebral godfather standing behind it, and accordingly it is called the eighth pair, although mammals have only seven neck vertebrae. The next pair
. Biology of the vertebrates : a comparative study of man and his animal allies. Vertebrates; Vertebrates -- Anatomy; Anatomy, Comparative. 68o Biology of the Vertebrates the skull and the first cervical vertebra, or atlas, and so, having no vertebra in front of it, takes its name from the vertebra immediately behind it. This method of nomenclature is followed throughout the cervical series, leaving the eighth pair of nerves without any cervical, vertebral godfather standing behind it, and accordingly it is called the eighth pair, although mammals have only seven neck vertebrae. The next pair of nerves plainly belongs to the trunk, and so begins a new series as the first thoracic pair, taking its name from the vertebra behind which it emerges (Fig. 607). 3nium| m m CXI m m m £E S : Ist thoracic Fig. 607. Diagram showing the relation of the cervical nerves to the cervi- cal Fig. 608. Cross section of the central and peripheral nervous systems in man. 1, dorsal fissure and septum of nerve cord; 2, ventral fissure; 3, dorsal root of spinal nerve; 4, dor- sal ganglion; 5, spinal nerve; 6, dorsal branch of the nerve; 7, ventral branch; 8, autonomic branch; 9, meningeal branch; 10, sympa- thetic chain ganglion; 11, ventral root; 12, cutaneous branch. (After Rauber.) The size of the spinal nerves is dependent upon the relative area of the body which they supply, the largest in man being the first sacral pair that goes to the legs. The general distribution of every spinal nerve in connection with the region which it supplies is indicated in Figure 608. The relation between the spinal nerves and the metameric embryonic muscles is very regular and constant, but the rearrangement and migration of these muscles in the adult organism brings about apparent irregularities. A nerve once associated with a muscle, however, remains faithful to it. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - c
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