Methods | Statistics | Clinical | Educational | Industrial | Professional items | World psychology |
Biological: Behavioural genetics · Evolutionary psychology · Neuroanatomy · Neurochemistry · Neuroendocrinology · Neuroscience · Psychoneuroimmunology · Physiological Psychology · Psychopharmacology (Index, Outline)
|Nerve: Brachial plexus|
|The right brachial plexus with its short branches, viewed from in front.|
|Gray's||subject #210 930|
The brachial plexus is responsible for cutaneous and muscular innervation of the entire upper limb, with two exceptions: the trapezius muscle innervated by the spinal accessory nerve and an area of skin near the axilla innervated by the intercostobrachialis nerve.
Therefore, lesions of the plexus can lead to severe functional impairment.
One can remember the order of brachial plexus elements by way of the mnemonic, "Randy Travis Drinks Cold Beer" - Roots, Trunks, Divisions, Cords, Branches
- The five roots are the five anterior rami of the spinal nerves, after they have given off their segmental supply to the muscles of the neck.
- These roots merge to form three trunks:
- Each trunk then splits in two, to form six divisions:
- These six divisions will regroup to become the three cords. The cords are named by their position in respect to the axillary artery.
- The branches are listed below. Most branch off of the cords, but a few branch (indicated in italics) directly off of earlier structures. The five in bold are considered "terminal branches".
|roots||dorsal scapular nerve||C5||rhomboid muscles and levator scapulae||-|
|roots||long thoracic nerve||C5, C6, C7||serratus anterior||-|
|superior trunk||nerve to the subclavius||C5, C6||subclavius muscle||-|
|superior trunk||suprascapular nerve||C5, C6||supraspinatus and infraspinatus||-|
|lateral cord||lateral pectoral nerve||C5, C6, C7||pectoralis major and pectoralis minor (by communicating with the medial pectoral nerve)||-|
|lateral cord||musculocutaneous nerve||C5, C6, C7||coracobrachialis, brachialis and biceps brachii||becomes the lateral cutaneous nerve of the forearm|
|lateral cord||lateral root of the median nerve||C5, C6, C7||fibres to the median nerve||-|
|posterior cord||upper subscapular nerve||C5, C6||subscapularis (upper part)||-|
|posterior cord||thoracodorsal nerve||C6, C7, C8||latissimus dorsi||-|
|posterior cord||lower subscapular nerve||C5, C6||lower part of subscapularis and teres major||-|
|posterior cord||axillary nerve||C5, C6|| anterior branch: deltoid and a small area of overlying skin|
posterior branch: teres minor and deltoid muscles
|posterior branch becomes upper lateral cutaneous nerve of the arm|
|posterior cord||radial nerve||C5, C6, C7, C8, T1||triceps brachii, anconeus, the extensor muscles of the forearm, and brachioradialis||skin of the posterior arm as the posterior cutaneous nerve of the arm|
|medial cord||medial pectoral nerve||C8, T1||pectoralis major and pectoralis minor||-|
|medial cord||medial root of the median nerve||C8, T1||fibres to the median nerve||portions of hand not served by ulnar or radial|
|medial cord||medial cutaneous nerve of the arm||C8, T1||-||front and medial skin of the arm|
|medial cord||medial cutaneous nerve of the forearm||C8, T1||-||medial skin of the forearm|
|medial cord||ulnar nerve||C8, T1||flexor carpi ulnaris, the medial 2 bellies of flexor digitorum profundus, most of the small muscles of the hand||the skin of the medial side of the hand and medial one and a half fingers on the palmar side and medial two and a half fingers on the dorsal side|
Brachial plexus lesions are classified as traumautic or obstetric. These typically result from excessive stretching and avulsion injury. Traumatic injuries are often caused by high-velocity motor vehicle accidents, especially in motorcyclists. Injury from a direct blow to the lateral side of the scapula is also possible.
Most commonly, forceps delivery or falling on the neck at an angle causes upper plexus lesions (Erb's Palsy). This type of injury produces a very characteristic sign called Waiter's tip deformity due to loss of the lateral rotators of the shoulder, arm flexors, and hand extensor muscles.
Much less frequently, sudden upward pulling on an abducted arm (as when someone breaks a fall by grasping a tree branch) produces a lower plexus injury. This results in the sign known as clawed hand due to loss of function of the ulnar nerve and the intrinsic muscles of the hand it supplies.
The cardinal signs of brachial plexus avulsion are:
In most cases the nerve roots are stretched or torn from their origin, since the meningeal coverings of the nerve roots are thinner than the sheaths enclosing the peripheral nerves. The epineurium of the peripheral nerve is contiguous with the dural mater, providing extra support to the peripheral nerves. In cases where the nerve roots have been torn, recovery is unlikely without invasive experimental surgical techniques [How to reference and link to summary or text].
Brachial Plexus Palsy, also referred to as Erb's Palsy, is a condition that affects the nerves that control the muscles in the arm and hand.Possible Symptoms:-a limp or paralyzed arm-lack of muscle control in the arm-a decrease of sensation in the arm or handTypes of Brachial Plexus InjuriesThe injury may involve one or more nerves of the brachial plexus. The Brachial Plexus is located on the right and left side of your neck, between the neck and shoulder area.It is a group of nerves that run from the spinal cord through the arm to the wrist and hand.
Q. What is a Brachial Plexus Injury?
A. A brachial plexus injury is an injury to the nerves that supply the muscles of the arm. Injury to nerves of the brachial plexus can result in complete to partial paralysis to the shoulder, upper arm, elbow, forearm, wrist, hand, or fingers.
Q. Are there various degrees of severity with a Brachial Plexus Injury?
A. There are four basic types of nerve injuries. Some people only have one type while others have a combination of two or more types. � Avulsion- the nerve is detached from the spinal cord. � Rupture- the nerve is separated from itself, but not at the juncture of the nerve and the spinal cord. There may be one or more ruptures in a single nerve. � Praxis or Traction- the nerve is typically overstretched and damaged, but not detached from itself or the spinal cord. � Neuroma- scar tissue has surrounded the injured nerve and excessive pressure is now placed on the nerve. Therefore, the nerve has trouble getting all the signals to the muscle to be able to perform a movement.
Q. How do Brachial Plexus Injuries occur?
A. Brachial plexus injuries occur when there is excessive stretching, tearing, or other trauma to the brachial plexus network. Injuries can be sustained during delivery of a baby. This is known as Obstetrical Brachial Plexus. Traumatic Brachial Plexus is seen when injuries are sustained secondary to vehicular accidents such as automobiles, motorcycles, or boats, sports injuries particularly football, gunshot wounds, or surgeries. Traumatic BPI's have also been noted with animal bites or puncture wounds.
Q. What are some symptoms associated with Brachial Plexus Injuries?
A. There are several degrees of symptoms that can be seen with BPI. Here are some of the most typical examples: � Limited active range of motion of the entire arm or any part of the arm. � Sensation changes in the involved arm. � Weakness of specific muscle groups. � Poor ability to perform typical midline activities. � Poor ability to weight bear through the arm. � Neglect of the affected arm. � Posturing of the arm in atypical positions. � Developmental Delay � Torticollis- a shortened muscle of the neck, so the head tilts to one side.
Q. How often do obstetrical brachial plexus injuries occur?
A. The current research suggests that brachial plexus injuries are seen 1-3 in every 1000 live births.
Q. What are the treatments?
A. Treatments include but are not limited to the following: Physical therapy, occupational therapy, aquatic therapy, surgical interventions, splinting, casting, electrical stimulation.
Q. When should I initiate treatments?
A. It is essential that a person suffering from a brachial plexus injury initiate treatments as soon as possible. Typically, a person suffering from an obstetrical brachial plexus injury sees a physical therapist or occupational therapist in the first two weeks of life. The goal of the therapist is to assist the family in Range of motion exercises, assess for muscle contractions even when movement is not seen, address positioning, make adaptive equipment, reduce the infant's tendencies toward neglect, and avoid atypical movement patterns, avoid tightening of muscles, and assist with weight bearing activities even in the newborn stage.
- ↑ Mnemonic at medicalmnemonics.com 18 2741
- ↑ Dorlands/Elsevier t_20/12826113
- ↑ Dorlands/Elsevier t_20/12826075
- ↑ Dorlands/Elsevier t_20/12826025
- ↑ Dorlands/Elsevier d_26/12310223
- ↑ Dorlands/Elsevier d_26/12310244
|Nerves of upper limbs (primarily): the brachial plexus|
| supraclavicular: dorsal scapular - suprascapular - to the subclavius - long thoracic
posterior cord: subscapular (upper, lower) - thoracodorsal - axillary (superior lateral cutaneous of arm) - radial (muscular, inferior lateral cutaneous of arm, posterior cutaneous of arm, posterior cutaneous of forearm, superficial branch, deep branch, posterior interosseous)
Nerves: spinal nerves