Brachial Plexus (In-A-Nutshell)
A web like structure advancing from the cervical-spine is referred to as the Brachial Plexus. The anterior rami of the lower cervical nerves and first thoracic nerve C5–C8, T1,
Arrangement
The plexus pathways are divided into roots, trunks, divisions, cords, and branches. There are five "terminal" branches and numerous other "pre-terminal" or "collateral" branches that leave the plexus at various points along its length.
Roots Remember (Randy) when you think of Roots.
The five roots are the five anterior rami of the spinal nerves. Post allocation/termination to the muscles of the neck. The brachial plexus arises at five levels; C5, C6, C7, C8, and T1. In some cases C4 or T2.
Trunks Remember (Travis) when you think of Trunks.
Roots merge to form three trunks:
"superior or "upper" (C5-C6)
"middle" (C7)
"inferior" or "lower" (C8, T1)
Divisions Remember (Drinks) when you think of Divisions.
Each trunk then splits in two, to form six divisions:
anterior divisions of the upper, middle, and lower trunks
posterior divisions of the upper, middle, and lower trunks
Cords Remember (Cold) when you think of Cords.
Divisions eventually form three cords.
The posterior cord formed from the three posterior divisions of the trunks (C5-C8,T1)
The lateral cord is formed from the anterior divisions of the upper and middle trunks (C5-C7)
The medial cord is an extension of the anterior division of the lower trunk (C8,T1)
Branches Remember (Beer) when you think of Branches.
The branches are listed below. Most branch from the cords, but a few branch (indicated in italics) directly from earlier structures. The five on the left are considered "terminal branches". There have been several variations reported in the branching pattern but these are very rare.
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 (CN XI) and an area of skin near the axilla innervated by the intercostobrachial nerve.
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A web like structure advancing from the cervical-spine is referred to as the Brachial Plexus. The anterior rami of the lower cervical nerves and first thoracic nerve C5–C8, T1,
Arrangement
The plexus pathways are divided into roots, trunks, divisions, cords, and branches. There are five "terminal" branches and numerous other "pre-terminal" or "collateral" branches that leave the plexus at various points along its length.
Roots Remember (Randy) when you think of Roots.
The five roots are the five anterior rami of the spinal nerves. Post allocation/termination to the muscles of the neck. The brachial plexus arises at five levels; C5, C6, C7, C8, and T1. In some cases C4 or T2.
Trunks Remember (Travis) when you think of Trunks.
Roots merge to form three trunks:
"superior or "upper" (C5-C6)
"middle" (C7)
"inferior" or "lower" (C8, T1)
Divisions Remember (Drinks) when you think of Divisions.
Each trunk then splits in two, to form six divisions:
anterior divisions of the upper, middle, and lower trunks
posterior divisions of the upper, middle, and lower trunks
Cords Remember (Cold) when you think of Cords.
Divisions eventually form three cords.
The posterior cord formed from the three posterior divisions of the trunks (C5-C8,T1)
The lateral cord is formed from the anterior divisions of the upper and middle trunks (C5-C7)
The medial cord is an extension of the anterior division of the lower trunk (C8,T1)
Branches Remember (Beer) when you think of Branches.
The branches are listed below. Most branch from the cords, but a few branch (indicated in italics) directly from earlier structures. The five on the left are considered "terminal branches". There have been several variations reported in the branching pattern but these are very rare.
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 (CN XI) and an area of skin near the axilla innervated by the intercostobrachial nerve.
This is a file from the Wikimedia Commons. Information from its description page there is shown below.
Commons is a freely licensed media file repository