Page 222 - Anatomy and Physiology of Farm Animals, 8th Edition

Anatomy of the Nervous System / 207

Table 10-2. Nerves of Brachial Plexus
VetBooks.ir Nerve Muscles Innervated Cutaneous Distribution
No sensory fibers
Supraspinatus and infraspinatus
Suprascapular
Pectorals Superficial, deep pectoral No sensory fibers
Subscapular Subscapularis No sensory fibers
Musculocutaneous Biceps brachii Medial aspect of antebrachium,
Coracobrachialis carpus;
Brachialis craniomedial aspect of metacarpus
Axillary Teres minor et major Shoulder region
Deltoid
Radial Triceps brachii Craniolateral aspect of
Anconeus antebrachium
Extensor carpi radialis
Common and lateral digital extensors
Ulnaris lateralis
Extensor carpi obliquus
Supinator
Ulnar Flexor carpi ulnaris Caudal aspect of antebrachium,
Deep digital flexor craniolateral aspect of metacarpus,
pastern/foot
Intrinsic millimetre of digit (when
present)
Median Flexor carpi radialis Caudal metacarpus, pastern/foot
Superficial and deep digital flexor
Pronator teres (when present)
Thoracodorsal Latissimus dorsi No sensory fibers
Lateral thoracic Cutaneous trunci No sensory fibers

of the peripheral nervous system ignores series of two neurons (Fig. 10‐19). The
the facts that (1) sensory fibers from vis- first has its cell body in the CNS, and its
cera make up a large proportion of the fib- axon extends into the periphery, where it
ers in autonomic nerves and (2) some CNS synapses on the cell body of a second neu-
tracts and nuclei integrate and control vis- ron. It is the axon of the second neuron
ceral activity. Nonetheless, for purposes of that contacts the visceral target. Because
this introduction, we consider only the of this two neuron arrangement, auto-
peripheral motor components of the ANS. nomic nerves are characterized by the
These are the nerves that influence activity presence of autonomic ganglia, periph-
in smooth muscle, cardiac muscle, and eral collections of the cell bodies of the
glands. second neurons. Using the autonomic
In the somatic motor system (the vol- ganglion as a point of reference, the first
untary muscle system), the cell bodies of neuron is called preganglionic, and the
neurons directly innervating the target are second, postganglionic.
found in the gray matter of the CNS, and The motor output of the ANS is con-
the telodendria of these neurons make cerned with homeokinesis, the dynamic
direct contact with the target. Motor process of regulating the internal environ-
nerves of the ANS, in contrast, consist of a ment to meet the needs of the organism.