Brachial plexus

The brachial plexus (Latin for " Armgeflecht ") is a network of the ventral branches of the spinal nerves of the last four cervical and the first thoracic segment ( C5 - Th1). In humans, even smaller bundles of the fourth cervical vertebra segment ( C4 ) and the second thoracic vertebra segment ( Th2) in the formation of the brachial plexus are involved. In some mammals, it only begins with the sixth cervical nerves and extends to the second thoracic nerve (C6 - Th2). Armgeflecht the part of the peripheral nervous system.

These spinal nerves unite after passing through the Musculi scaleni to three main stems ( trunks, more specifically, upper trunk, middle trunk and the inferior trunk ) and then to multiple, interconnected strands ( fasciculi, lateral cord, medial cord and posterior cord ). These strands occur along the subclavian artery and axillary artery in the axilla. From these, in turn, form the nerves that through the exchange fiber plexus now always hold Shares of several (2-3) spinal nerves. These nerves innervate the entire upper (front in animals ) and extremity portions of the chest wall. The same principle shows the leg braid ( lumbosacral plexus ).

Brachial plexus in humans

The brachial plexus of man is formed from the spinal cord segments C5 to T1 and divides into an above the collarbone ( supraclavicular ) and one located below the collarbone ( infraclaviculären ) part. The actual braid for the supply of the arm thereby forming the infraclaviculäre, pulling with the axillary artery part.

Supraclavicular branches are:

Infraclaviculäre branches:

Brachial plexus in pets

In domestic animals, the plexus behaves very similar. The medial cutaneous nerve brachii is not formed and the medial antebrachial cutaneous nerve does not leave the plexus itself, but from the musculocutaneous nerve forth. The thoracic nerves run in more strands and Nervi pectorales referred to as cranial and caudal. Also the subscapularis nerve consists of several branches ( Nervi subscapular ). In addition, isolated a thoracic nerve lateralis, which is the fuselage skin muscle (musculus cutaneous trunci ) innervation and efferent limb for the Pannikulusreflex.

Clinical significance of the brachial plexus

About an anesthetic block of the plexus can be temporarily switched off and thus a complete freedom from pain in the arm can be achieved. Common methods are the interscalene blockade that supraclavikuläre plexus, the infraclavicular brachial plexus and the axillary block.

For a demolition of the brachial plexus, it comes to a complete paralysis ( paralysis ) of the muscles of the upper / front limb and a total failure of sensitivity. In part breaks (or other damage ) of individual fascicles produces a characteristic partial failures of the arm.

The passage of the brachial plexus by the so-called posterior scalene in the neck area can be narrowed, it then develops under certain circumstances a so-called Skalenussyndrom. Here, the ulnar (small finger ) shows side of the lower arm and hand painful and affected by paresthesia, which is reinforced with arm hanging. Since the arm supplying artery ( subclavian artery ) passes through the scalene, cyanosis develop simultaneously ( bluish discoloration due to lack of oxygen) and edema ( swelling caused by impaired blood backflow ). The Adson's test is positive.

Lesions of the brachial plexus with painful conditions are grouped under the collective term brachialgia.

As birth traumatic plexus palsy refers to paralysis ( paralysis ) of the arm, caused by train at the brachial plexus during birth. Due to an unfavorable size ratio between the child and the birth canal it comes to the so-called shoulder dystocia. A distinction strain, demolition and avulsion ( Avulsionsverletzungen ). There is also the division into

• Upper plexus type Erb - Duchenne (cervical nerves 4-6 (C4 -6) affected). There will be a flaccid arm paresis ( however, the movement of the hand is possible) and to a Phrenicusparese.
• Lower plexus type Klumpke ( cervical nerve 7 to thoracic nerve 1 (C7 - Th1) affected). The symptoms here are hand paralysis (obstetrician ) and Horner 's syndrome. The prognosis is worse than that of the upper brachial plexus.

Most injuries recover very well by itself. In severe injury ( tear or avulsion ) may be a direct operation to restore the brachial plexus sense. A direct operation is meaningful only within the first nine months of life. Therefore, early referral to a center for birth traumatic Armplexusparese makes sense. Later solutions can be achieved by tendons and ligaments still a further improvement in displacement.

The neuralgic Schulteramyotrophie is an immune-mediated inflammation of the brachial plexus.