Brachial plexus Flashcards
outline the various components of the brachial plexus
roots
trunks
divisions
cords
branches
what are the spinal nerves part of
the peripheral nerve system
how many pairs of spinal nerves
31 pairs
where of spinal nerves arise from
dorsal and ventral roots
what fibres are from the dorsal root
afferent sensory fibres (body -> brain)
what fibres are from the ventral root
efferent motor fibres (brain -> muscle)
what do dorsal and ventral roots merge into
single spinal nerve
containing sensory and motor fibres (mixed nerve)
what do the spinal nerves exit via
intervertebral foramen
what does the intervertebral formed divide into
dorsal / posterior ramus
venture / anterior ramus
what forms a plexus
some rami (ramus) from different spinal nerves will anastomose into a plexus ( e.g brachial plexus )
what is a plexus
a network of intersecting nerves or vessels (arteries)
what is a nerve plexus
a network of intersecting nerve fibres from different spinal nerves that serve the sam part of the body
terminate distally as individual nerves
what spinal nerves form brachial plexus
Anterior rami
spinal nerve C5 -T1
what are dermatomes
an area of skin in which sensory peripheral nerves derive from a single spinal nerve root
each spinal nerve relays sensation form a particular region of the skin to the brain
cervical nerves
C1-C8
carry sensation from cevical dermatomes (C2-C8)
head neck majority of arm and hand
how come there are only 30 dermatomes but 31 pairs of spinal nerves
C1 spinal nerve does not have a dorsal root so does not carry sensory information from the skin
thoracic nerves
T1-T12
carry sensation from thoracic dermatomes
(torso , inner part of arm )
lumbar nerves
L1-L5
carry sensation from lumbar dermatomes
(groin area, majority of lower limbs)
sacral nerves
S1-S5
carry sensation from sacral dermatomes
(minority of lower limbs, perianal region, genitals)
coccygeal nerve
C0
Carry sensation from coccyx (Co1)
(coccygeal region - around the tailbone)
what are myotomes
muscle innervated by a single spinal nerve
each spinal nerve relays motor information to a particular set of muscles
most muscle = more than one myotomes - receive innervation from more than one spinal nerve
brachial plexus
a complex intercommunicating network of nerves
provides sensory and motor innervation to upper extremity
areas supplied by branchial plexus - Sensory innervation
upper limb except area of the skin near the axilla
areas supplied by branchial plexus - motor innervation
muscles of upper limb
should girdle except trapezius muscle