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I'm Dr. Banumathy, Anatomist
from Tamil Nadu, India.
Today, we will discuss
the brachial plexus and
nerves of the upper limb.
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The brachial plexus is a
plexus of nerves the branches
from which supply the structures
in the upper extremities.
The brachial plexus is situated
in the root of the neck,
extending deep to the clavicle,
and then into the axilla.
The part of the plexus
above the clavicle
is the supraclavicular part.
The part below the clavicle
is the infraclavicular part.
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The brachial plexus is
studied in five stages.
Roots stage, trunks
stage, divisions stage,
cords stage, and branches stage.
The roots stage and the trunks
stage are supraclavicular,
and the cords stage
and the branches stage
are infraclavicular.
The divisions stage is
situated deep to the clavicle.
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Roots stage.
The roots are contributed by
the anterior primary rami of C5,
C6, C7, C8, and
T1 spinal nerves.
What is an anterior
primary ramus?
Each spinal nerve is attached
to the spinal cord by two roots.
The anterior spinal root and
the posterior spinal root.
The anterior root is
motor in function,
and the posterior
root is sensory.
The two roots unite to
form the spinal nerve.
Each spinal nerve divides
into two divisions
- the anterior primary ramus
and the posterior primary ramus.
The anterior primary
ramus supplies
the structures in the
anterior aspect of the body.
The posterior primary ramus
supplies the structures
in the posterior
aspect of the body.
The limb bud develops from the
anterior aspect of the trunk.
Hence, the limbs
are supplied by the
anterior primary rami.
Hence, the anterior primary rami
contribute to the
roots of the plexus.
Trunks stage.
Three trunks are formed.
Upper trunk, middle
trunk, and lower trunk.
Divisions stage.
Each trunk divides into
an anterior and a
posterior division.
Cords stage.
The divisions unite
to form three cords.
Lateral, medial, and
posterior cords.
Branches stage.
The cords give off branches
at the termination
at the lateral border
of the pectoralis minor
called terminal branches,
and proximal to termination
called collateral branches.
Scheme of the brachial plexus.
