A nerve that arises from the fifth, sixth, and seventh cervical nerves, descends the neck behind the brachial plexus, and is distributed to the anterior serratus muscle.

Whiplash injuries from motor vehicle accidents are very common. Brachial plexus traction injuries without any bone or joint lesion of the cervical spine have been reported before even in conjunction with paralysis of long thoracic nerve palsy and spinal accessory nerve at the same time. [2]. Winging of the scapula has three causes, each with different nerves and different clinical signs, one is caused by the long thoracic nerve and paralysis of serratus anterior. Camerota [3] described a patient who presented myoclonus in the left scapula 3 months after a traumatic lesion of the left long thoracic nerve. Myoclonic activity was recorded as pseudorhythmic electromyography bursts repeated at a frequency of 2 to 4 Hz, each lasting between 100 and 200 msec, in the left serratus-dorsalis muscle region, trapezius, and deltoid muscles. A combination of peripheral and central mechanisms may have induced the myoclonus in this case.

Brachial Plexus neuritis, often referred to as Parsonage-Turner syndrome, can be a vexing problem for both the patient and the physician. It is a common condition characterized by inflammation of a network of nerves that control and innervate the muscles of the chest, shoulders, and arms (brachial plexus). Individuals with the condition first experience a sudden onset of severe pain across the shoulder and upper arm. Within a few hours or days, the muscles of the involved shoulder may be affected by, weakness, wasting, and paralysis [4]

Winged scapula is defined as a prominence of the medial border of the scapula and it is the most common scapulothoracic disorder. The causes of this condition are well-known, and they include brachial plexus injury, isolated paralysis of the serratus anterior, fascioscapulohumeral muscular dystrophy or injury to the long thoracic nerve that occurs during resection of the first rib for decompression of thoracic outlet compression syndrome [5]

The cords are positioned lateral to the first rib within the axilla and are named for their relationship to the axillary artery. A number of nerves arise from the 3 cords. As the cords exit the axilla, they recombine into terminal branches.

As we can see below, absence of the musculocutaneous nerve with innervation of coracobrachialis, biceps brachii, brachialis and the lateral border of the forearm by branches from the lateral cord of the brachial plexus has been reported [6]

A variation of the brachial plexus characterized by the absence of the musculocutaneous nerve (MCN) on both sides was observed during the dissection of a 72 year-old female cadaver [7] Injuries on MCN have been informed on sportsmen [8] among other anatomical variation reported [9-12].

The long thoracic nerve included only the fibers from C5 and C6 on the left side. The musculocutaneous nerve was absent and two branches from the lateral cord innervated the coracobrachialis muscle. The median nerve innervated the biceps brachii and brachialis muscles in the arm and also gave off the lateral antebrachial cutaneous nerve. Additionally, a communicating branch was found from the median nerve to the ulnar nerve in the forearm. The knowledge of the anatomical variations of the peripheral nerve system can help give explanation when encountering an incomprehensible clinical sign.

As was before mentioned, brachial plexus innervates the upper limb. As it is the point of formation of many nerves, variations are common. Knowledge of these is important to anatomists, radiologists, anesthesiologists and surgeons. The presences of anatomical variations of the peripheral nervous system is often used to explain unexpected clinical signs and symptoms, and although these variations may not have affected the functioning of upper limb in some peoples, knowledge of such variations are also essential in evaluation of unexplained sensory and motor loss after trauma and surgical interventions to the upper limb [13].

Our findings about branches from medial cord can be seen on Figure 4. We concluded without doubt that the Medial cord is a division of the brachial plexus and gives rise to the following nerves: The median pectoral nerve, C8 and T1, to the pectoralis muscle; the medial brachial cutaneous nerve, T1; The medial antebrachial cutaneous nerve, C8 and T1; the median nerve, partly. The other part comes from the lateral cord. C7, C8 and T1 nerve roots. The first branch of the median nerve is to the pronator teres muscle, then the flexor carpi radialis, the palmaris longus and the flexor digitorum superficialis. The median nerve provides sensation to the anterior palm, the anterior thumb, index finger and middle finger. It is the nerve compressed in carpal tunnel syndrome. The ulnar nerve originates in nerve roots C7, C8 and T1. It provides sensation to the ring and pinky fingers. It innervates the flexor carpi ulnaris muscle, the flexor digitorum profundus muscle to the ring and pinky fingers, and the intrinsic muscles of the hand (the interosseous muscle, the lumbrical muscles and the flexor pollicus brevis muscle). This nerve traverses a groove on the elbow called the cubital tunnel, also known as the funny bone. Striking the nerve at this point produces an unpleasant sensation in the ring and little fingers.

Our findings from brachial plexus in the axilla and the cubital fossa are shown in the Figure 5 and 6 and no remarkable variations from those reported in the medical literature were found. Other findings related to median, ulnar, axillary, and radial nerves can be seen from Figure 7 to 10 and an appropriated comments made by us were published before [1] and not differences from another reports [13-20]were found

Figure 2

Figure 1. Brachial Plexus of the right side of 62 year old male cadaver (In Situ). Right axillary's region with long thoracic nerve supplying the serratus anterior muscle.(Dissection made by Dr. Milanes-Rodriguez G. MD MsC)

Figure 3

Figure 2. Right axilla with the branches of the lateral cord. (Dissection made by Dr. Milanes-Rodriguez. MD MsC)

Figure 4

Figure 3- Right arm. Musculocutaneous n traveling between biceps and brachialis m. (Dissection made by Dr. Milanes-Rodriguez. MD MsC)

Figure 5

Figure 4. Right axilla. Branches from the medial cord of the brachial plexus. (Dissection made by Dr. Milanes-Rodriguez. MD MsC)

Figure 6

Figure 5. Brachial plexus in the axilla. Main branches given forming an M. (Dissection made by Dr. Milanes-Rodriguez. MD MsC)

Figure 7

Figure 6. Picture of the cubital fossa in the right arm. (Dissection made by Dr. Milanes-Rodriguez. MD MsC)

Figure 8

Figure 7. Median nerve at the wrist, going through carpal tunnel into the hand. (Dissection made by Dr. Milanes-Rodriguez. MD MsC)

Figure 9

Figure 8. Right hand. Ulnar nerve superficial to the flexor retinaculum. (Dissection made by Dr. Milanes-Rodriguez. MD MsC)

Figure 10

Figure 9: Posterior view of the shoulder region. The quadrangular space with the axillary nerve around the surgical neck of the humerus, and the radial nerve in the spiral groove. (Dissection made by Dr. Milanes-Rodriguez. MD MsC)

Figure 11

Figure 10: Elbow region Radial nerve is branching in superficial and deep Branches. (Dissection made by Dr. Milanes-Rodriguez. MD MsC)