The Structure of the Brachial Plexus in Selected Representatives of the Caniformia Suborder

Abstract

Like most structures, the brachial plexus is subject to species variation. Analysing this structure over a wide spectrum of species, we can obtain a complex view of the changes-in a given group of animals. The aim of this study was to describe the brachial plexus anatomy of species from two families of Caniformia. We analysed the brachial plexus structure of five species from two families of Caniformia: Canidae and Mustelidae. The cadavers were obtained from breeders and hunters. All were fixed by being kept in a 10% formaldehyde solution for two weeks. This study allows us to present the similarities as well as the differences between species and families. Our study reveals different trends in the course of the individual nerves and innervations of the thoracic limb. A species-specific feature is the extent of the brachial plexus, as each species has a specific number of ventral branches of the spinal nerves in the brachial plexus. However, a characteristic of the family Mustelidae is the course of the median nerve through the epicondylar foramen. Within the Canidae, two species are characterised by a very long branch for the coracobrachialis muscle. The general conclusion is that the brachial plexus of species belonging to the Caniformia is subject to variation within families and species, as well as individual variation while maintaining a general schematic for the group.

Keywords: American mink; European pine marten; common raccoon dog; comparative anatomy; neuroanatomy; red fox.

Figure 1

Innervation of the left arm of the common raccoon dog (Nyctereutes procyonoides). 1—Radial nerve; 2—Deep branch of the radial nerve; 3—Superficial branch of the radial nerve; 4—Branch of the radial nerve to lateral head of the triceps muscle of the arm; 5—Branch of the radial nerve to anconeus muscle; 6—Branch of the radial nerve to brachioradialis muscle; 7—Lateral branch of the superficial branch; 8—Lateral antebrachial cutaneous nerve; 9—Medial branch of the superficial branch.

Figure 2

Structure of the right brachial plexus of the red fox (Vulpes vulpes). 1—Brachiocephalic nerve; 2—Suprascapular nerve; 3—Branch of the musculocutaneus nerve to coracobrachialis muscle; 4—Branch of the musculocutaneus nerve to biceps muscle of the arm; 5—Radial nerve; 6—Musculocutaneus nerve; 7—Medial nerve; 8—Ulnar nerve; 9—Part of the caudal antebrachial cutaneus nerve; 10—Lateral thoracic nerve; 11,11′,11′′—Caudal pectoral nerves; 12—Thoracodorsal nerve; 13—Axillary nerve; 14—Cranial pectoral nerve.

Figure 3

Structure of the left brachial plexus of the American mink (Mustela vison). 1—Brachiocephalic nerve; 2—Suprascapular nerve; 3,—Subscapular nerve; 4—Axillar nerve; 5—Musculocutaneus nerve; 6—Radial nerve; 7—Medial antebrachial cutaneous nerve; 8—Median nerve; 9—Ulnar nerve; 10—Thoracodorsal nerve; 11—Lateral thoracic nerve; 12—Caudal pectoral nerve; 13—Cranial pectoral nerve; 14—Long thoracic nerve.

Figure 4

Course of the ulnar nerve at the forearm level in the European badger (Meles meles). 1—Median nerve; 2—Ulnar nerve; 3—Part of the caudal antebrachial cutaneus nerve; 4—Brach of the ulnar nerve to ulnar head of the flexor carpi ulnaris muscle; 5—Branch of the ulnar nerve to humeral head of the flexor digitorum profundus muscle; 6—Branch of the ulnar nerve to humeral head of the flexor carpi ulnaris muscle; 7—Dorsal branch of the ulnar nerve; 8—Superficial branch of the palmar branch of the ulnar nerve; 9—Deep branch of the palmar branch of the ulnar nerve.

Figure 5

Structure of the left brachial plexus of the European pine marten (Martes martes). 1—Brachiocephalic nerve; 2—Suprascapular nerve; 3,3′—Subscapular nerve; 4—Musculocutaneus nerve; 5—Axillar nerve; 6—Radial nerve; 7—Medial antebrachial cutaneous nerve; 8—Median nerve; 9—Ulnar nerve; 10—Branch to tensor fasciae antebrachii; 11—Thoracodorsal nerve; 12—Lateral thoracic nerve; 13—Caudal pectoral nerve; 14—Cranial pectoral nerve.