Figure 43-5. Diagram of the brachial plexus: the components of the plexus have been separated and drawn out of scale. Note that peripheral nerves arise from various components of the plexus: roots (indicated by cervical roots 5, 6, 7, 8, and thoracic root 1); trunks (upper, middle, lower); divisions (anterior and posterior); and cords (lateral, posterior, and medial). The median nerve arises from the heads of the lateral and medial cords. (From Haymaker and Woodhall, Peripheral Nerve Injuries, 2nd ed. Philadelphia, Saunders, 1953, by permission.)
L12345LumbosacraltrunkPudendal n.Perineal n.Dorsal n. ofpenisSuperior gluteal n.Lumbosacral trunkInferior gluteal n.Posterior cutaneous n.of thighSciatic n.Inferiorhemorrhoidal n.34Obturator n.Femoral n.Genitofemoral n.Ilioinguinal n.Iliohypogastric n.Lateral cutaneous n.of thighL1234
Figure 43-6. Diagram of the lumbar plexus (left) and the sacral plexus (right). The lumbosacral trunk is the liaison between the lumbar and the sacral plexuses. (From Haymaker and Woodhall, Peripheral Nerve Injuries, 2nd ed. Philadelphia, Saunders, 1953, by permission.)
Chapter  43    Diseases of the Peripheral Nerves
Dorsal scapular n.Subclavian n.RootsTrunksCordsSub-div.56712Suprascapular n.Subscapular n’s.Axillary n.Radial n.Median n.Med. cut. n. of forearmMed. cut. n. of armThoracodorsal n.(n. to latissimus dorsi)Lat. & med. anteriorthoracic n’s.Long thoracic n.(n. to serratus ant.)Ulnar n.Musculo-cutaneous n.UPPERLOWER18765APAPMIDDLEPOST.LAT.MED.APUPPERLOWERAPMIDDLEPOSTLATMEDAPP
Diseases of the Cranial Nerves
The cranial nerves occupy a special place in neurology because examination of their function and dysfunction can provide critical information localizing lesions to the brainstem or skull base. Certain of the cranial nerves and their disorders have already been discussed: namely, disorders of olfaction in Chap. 11; of vision and extraocular muscles in Chaps. 12 and 13; of cochlear and vestibular function in Chap. 14; and craniofacial pain in Chap. 9. There remain to be described the disorders of the facial (VII) nerve and of the lower cranial nerves (IX to XII), as well as certain diseases that affect the trigeminal (V) nerve. These are considered here.
The Fifth, or Trigeminal, Nerve