Brachial Plexus Injury and Related Anatomy
BP is most important anatomical structure in the Shoulder Girdle. Tangled and short plexus started from
Intervertebral Foramens and finishing in Axilla Pyramid. We divide the BP in six parts: Roots, Trunks, Divisions, Cords and Branches. Mnemonic is Rodger Tailor is Drums Composition Boss.
BP crosses five topographical areas: Scalenus Triangle, Posterior Neck Triangle, Costoclavicle Triangle, Subcoracoid – Retro
– Pectoralis Space, Axilla Pyramid. BP is more vulnerable than Lumbo – Sacral –Coccygeal nerve Plexus due to two reasons: Shoulder is muscle joint and is anatomically less stable and shoulder girdle has clavicle which acts as mechanical fulcrum for nerves and doubles BP Injury power. For that reason prognosis is different and can be divided in Supraclavicle, Retroclavicular and Infraclavicular.
From Microanatomy point of view a nerve consists of Axon, Myelin sheath, Basal lamina, Perineurium, Epineurium which is invisible on MRI. For that reason for treatment plan and for prognosis most important test is NCS in experienced specialist
hands. MRI and CT is useful only if we expecting changes of other structures than nerves. Relationship of vertebra and Root is different in spine.
Root comes from upper Intervertebral Foramen in a neck and from lower Intervertebral Foramen in a thoracic spine. Mnemonic is ‘ChiCken Bird and Thick Snake’.
Plexus consists of myelinated and unmyelinated fibres. Unmyelinated fibres are more fragile and more vulnerable with worse recovery prognosis. Usually they are responsible for pain transmission. Posterior Roothlets responsible for sensory
impulses and forward pull results in sensory deficit. Anterior Roothlets are motor and fall from high with violent hyper internal rotation and extension results in motor deficit. Violent direct fall down brings shoulder caudally and
comes with Erb-Dushen type lesion C5-6-7. Pull on arm in maximal abduction can result in Klumpke’s type paralysis C7-8-T1. And always PBI is partial due to ‘Up-Rooted Tree’ mechanism. Full paralysis due to full tear of all roots C5-6-7-8-T1 is rear and can be associated with Scapulothoracic Dissociation on X-ray and residual muscle atrophy and longstanding excruciate pain.
Inervertebral Foramina are mobile structures and can be compressed by over tight paraspinal muscles. It can cause ‘Vicious Circle’. C5-6-7-8-T1 Roots are located in Scalenus triangle. Scalene muscles can be tight. They can be reason for
brachial plexus or Subclavian artery compression. Long Thoracic nerve starts from C5-6-7 roots. The branches to Dorsal Scapular nerve and Phrenicus nerve starts in C5. Five roots connects together and form three trunks Upper, Middle
and Lower in Posterior triangle. Suprascapular nerve starts in Upper trunk.
Injury to Rami communicantes cases Horner Syndrome which is bad lower part of plexus prognosis indicator. Exploration of the Trunks can be achieved in Supraclavicular Posterior Triangle. Divisions can be vulnerable in CostoClavicle ‘scissors’. Cords can be explored by transaxillary approach. Trunks transformation through Divisions to Cords is RD complicated structure. Upper, Middle and Lower Trunks form Posterior Division and become Posterior Cord. Upper and Middle Trunks form Anterior Division and become Lateral Cord. Lower Trunk becomes Anterior Division and Later is called Medial Cord. Cords in SubCoracoid – Retro – Pectoral space are fixed around Subclavian artery. Musculocutaneus nerve starts from Lateral Cord.
Cords sink to dangerous anatomical Grater. Posterior wall of axilla Latissimus Dorsi muscle is inervated by Posterior Cord
Thoracodorsal Nerve. Anterior wall Pectoralis muscles are innerveted by Lateral and Medial Cords Lateral and Medial Pectoral Muscles. Lateral wall of the pyramid Teres Major and Subscapularis muscle are innervated by Lower Subscapular
and Upper Subscapular nerves. Medial Brachial and Antebrachial Cutaneal nerves start from Medial Cord. Axillary nerve starts from posterior cord and leaves Brachial plexus through Quadrilateral Space and innervates Deltoid muscle. Radial nerve runs through Triangular interval and innervates Triceps, Anconeus, Brachioradialis, ECRL, ECRB, EDC, EDM, ECU. Suprascapular nerve starts from Upper Trunk and goes through Suprascapular notch. It innervates Supraspinatus
goes through Spinoglenoid notch and finishes in Infraspinatus muscle.
Intervertebral Foramens and finishing in Axilla Pyramid. We divide the BP in six parts: Roots, Trunks, Divisions, Cords and Branches. Mnemonic is Rodger Tailor is Drums Composition Boss.
BP crosses five topographical areas: Scalenus Triangle, Posterior Neck Triangle, Costoclavicle Triangle, Subcoracoid – Retro
– Pectoralis Space, Axilla Pyramid. BP is more vulnerable than Lumbo – Sacral –Coccygeal nerve Plexus due to two reasons: Shoulder is muscle joint and is anatomically less stable and shoulder girdle has clavicle which acts as mechanical fulcrum for nerves and doubles BP Injury power. For that reason prognosis is different and can be divided in Supraclavicle, Retroclavicular and Infraclavicular.
From Microanatomy point of view a nerve consists of Axon, Myelin sheath, Basal lamina, Perineurium, Epineurium which is invisible on MRI. For that reason for treatment plan and for prognosis most important test is NCS in experienced specialist
hands. MRI and CT is useful only if we expecting changes of other structures than nerves. Relationship of vertebra and Root is different in spine.
Root comes from upper Intervertebral Foramen in a neck and from lower Intervertebral Foramen in a thoracic spine. Mnemonic is ‘ChiCken Bird and Thick Snake’.
Plexus consists of myelinated and unmyelinated fibres. Unmyelinated fibres are more fragile and more vulnerable with worse recovery prognosis. Usually they are responsible for pain transmission. Posterior Roothlets responsible for sensory
impulses and forward pull results in sensory deficit. Anterior Roothlets are motor and fall from high with violent hyper internal rotation and extension results in motor deficit. Violent direct fall down brings shoulder caudally and
comes with Erb-Dushen type lesion C5-6-7. Pull on arm in maximal abduction can result in Klumpke’s type paralysis C7-8-T1. And always PBI is partial due to ‘Up-Rooted Tree’ mechanism. Full paralysis due to full tear of all roots C5-6-7-8-T1 is rear and can be associated with Scapulothoracic Dissociation on X-ray and residual muscle atrophy and longstanding excruciate pain.
Inervertebral Foramina are mobile structures and can be compressed by over tight paraspinal muscles. It can cause ‘Vicious Circle’. C5-6-7-8-T1 Roots are located in Scalenus triangle. Scalene muscles can be tight. They can be reason for
brachial plexus or Subclavian artery compression. Long Thoracic nerve starts from C5-6-7 roots. The branches to Dorsal Scapular nerve and Phrenicus nerve starts in C5. Five roots connects together and form three trunks Upper, Middle
and Lower in Posterior triangle. Suprascapular nerve starts in Upper trunk.
Injury to Rami communicantes cases Horner Syndrome which is bad lower part of plexus prognosis indicator. Exploration of the Trunks can be achieved in Supraclavicular Posterior Triangle. Divisions can be vulnerable in CostoClavicle ‘scissors’. Cords can be explored by transaxillary approach. Trunks transformation through Divisions to Cords is RD complicated structure. Upper, Middle and Lower Trunks form Posterior Division and become Posterior Cord. Upper and Middle Trunks form Anterior Division and become Lateral Cord. Lower Trunk becomes Anterior Division and Later is called Medial Cord. Cords in SubCoracoid – Retro – Pectoral space are fixed around Subclavian artery. Musculocutaneus nerve starts from Lateral Cord.
Cords sink to dangerous anatomical Grater. Posterior wall of axilla Latissimus Dorsi muscle is inervated by Posterior Cord
Thoracodorsal Nerve. Anterior wall Pectoralis muscles are innerveted by Lateral and Medial Cords Lateral and Medial Pectoral Muscles. Lateral wall of the pyramid Teres Major and Subscapularis muscle are innervated by Lower Subscapular
and Upper Subscapular nerves. Medial Brachial and Antebrachial Cutaneal nerves start from Medial Cord. Axillary nerve starts from posterior cord and leaves Brachial plexus through Quadrilateral Space and innervates Deltoid muscle. Radial nerve runs through Triangular interval and innervates Triceps, Anconeus, Brachioradialis, ECRL, ECRB, EDC, EDM, ECU. Suprascapular nerve starts from Upper Trunk and goes through Suprascapular notch. It innervates Supraspinatus
goes through Spinoglenoid notch and finishes in Infraspinatus muscle.
