Pigs. 109 and no. Nerve-Supply of the Muscles of the Upper Extre- 

 mity, according to their Segmental (Spinal) Origin. 



The segments are given partly according to WICHMANN and BOLK, partly after ZIEHEN. 



In the text, Arabic figures represent the Cen'ical Segments, the first Dorsal is indicated by n 



Roman I. Coloiin as in Figs. loy and 108. 



The ventral muscles of the superficial layer of the shoulder-girdle are the Sterno- 

 Mastoid and Pectoralis Major; those of the deep layer the Subclavius and Pectoralis Minor. 



That portion of the Spinal Accessory Nerve which supplies the Stemo-Mastoid 

 Muscle contains 2. C. and 3. C. The Anterior Thoracic Nerves divide into several branches; 

 the upper segments are for the Pectoralis Major 5. C, 6. C, 7. C. (Clavicular portion 5. C), 

 the lower segments are for the Pectoralis Minor 7. C, 8. C. ; 8. C. in some cases also supplies 

 the lowest fibres of the Pectoralis Major. 



The Nerve to the Subclavius Muscle is composed uf fibres derived from 5. C. and 6. C. 



The superficial layer of the Extensor Muscles of the Shoulder-Girdle is composed 

 of the Trapezius and Latissimus Dorsi ; in the majorit\- of cases the Spinal Accessor)' 

 Nerve to the Trapezius Muscle contains 2., 3. and 4. C, the long Subscapular Nerve to 

 the Latissimus Dorsi Muscle 6., 7. and 8. C. The other Subscapular Nerves to the Teres 

 Major Muscle 5., 6. (and 7.) C. ; to the Subscapularis Muscle 5. and 6. C, the Supra- 

 scapular Nerve to the Supraspinatus Muscle 5. C, to the Infraspinatus Muscle 5. and 6. C. 



The deep layer is composed of the Serratus Magnus with Bell's Nerve 5., 6. 

 and 7. C. ; Levator Scapulae (3.) 4. and 5. C. and the Rhomboid Muscles 5. C, possibly 

 further fibres from 4. C. to the Rhomboideus Minor Muscle. 



Of the mixed nerves, the Median contains fibres derived from each segment, 5., 6., 

 7., 8. C. and I. D. — (though 5. C. probably contains Sensory fibres only). — The motor 

 part of the Musculo-Cutaneous Nerve contains fibres from 5., 6. and 7. C. ; the Ulnar 

 Nerve usually 7. and 8. C. and I. D. or 8. C. and L D. only. The motor part of the 

 Circumflex 5. and 6. C. The motor part of the Musculo-Spiral (5. C.) 6., 7. and 8. C. 



Musculo-Cutaneous Nerve: Coraco-Brachialis Muscle 6. and 7. C; Biceps 

 Muscle 5. and 6. C. ; Brachialis Anticus Muscle 5. and 0. C. This last named muscle 

 has a double Nerve-supply as it also recei\'es fibres from the Musculo-Spiral Nerve 

 (derived from the same segments). 



Median Nerve: Pronator Radii Teres Muscle 6. and 7. C. ; Flexor Carpi 

 Radialis 6. and 7. (and 8.) C. ; Palmaris Longus 7. and 8. C. and L D. ; Flexor Sublimis 

 Digitorum 7. and 8. C. and I. D. ; Flexor Longus Pollicis 6., 7. (and 8.) C. ; Pronator 

 Quadratus (6.) 7. and 8. C. and L D. ; Muscles of the Thenar Eminence 6. and 7. C. 

 The two outer Lumbrical Muscles are usually considered to be supplied from 8. C. and 

 L D. segments. 



Ulnar Nerve: Flexor Carpi Ulnaris Muscle (7.) 8. C. and I. D. ; the outer 

 (radial) portion may also be supplied b\' the Median Nerve (Frohse) thus having a 

 double Nerve-supply, like the following muscle; Flexor Profundus Digitorum (Ulnar and 

 Median) 7., 8. C. and I. D. The deep portion of the Ulnar contains 8. C. and I. D., 

 but chiefly 8. C. ; at the Hypothenar Eminence even the 7. C. may take part (Bolk). 



For the Motor Anastomosis between the Ulnar and Median Nerves cf. Figs. 84 and 96. 



The Circumflex Nerve contains fibres from the 5th and 6th Cervical Segments. The 

 small area of Deltoid Muscle coloured green denotes the probabilit}', as evidenced by 

 clinical observations, that fibres from 4. C. supply this portion (Ziehen). The Anterior 

 part of the Deltoid mav be supplied by the Anterior Thoracic Nerves (Anastomosis with the 

 Circumflex, Frohse). The nerve to the Teres Minor Muscle usually only contains 5. C. 



I for Long Head of Triceps 6., 7. and 8. C. 

 for Outer Head of Triceps 6., 7. (and 8.) C. 

 for Inner Head of Triceps (6.), 7. and 8. C. 

 for Anconeus 7. and 8. C. 



Brachio- Radialis (Supinator Longus) 5. and 6. C. Extensor Carpi Radialis Longior 

 and Brevior (5.) 6. and 7. C. Supinator Brevis 5., 6. (and 7.) C. Extensor Communis 

 Digitorum and Extensor Minimi Digiti 6., and 7. and 8. C. 



Extensor Primi Intemodii Pollicis 6., 7. (and 8.) C. Extensor Indicis 6., 7. and 

 8. C. Extensor Secundi Internodii Pollicis 6., 7. (and 8.) C. (in Bolk's case 7. C. only) 



