Peripheral Nerves: The Plexi
Learning Outcomes
At the end of this sessions you should be able to….
• Discuss the points at which the brachial and lumbosacral
plexi and their major branches are vulnerable
• Discuss the effects of mononeuropathy of the major nerves
• Explain the effects of damage to the brachial plexus trunks
• Discuss the difference between injury at the level of the
spinal nerve and at the level of the peripheral nerve
• Discuss reasons for relative frequency of injury to nerve
roots and peripheral nerves in the upper and lower limbs
Overview
• Review the anatomy of the cervical, brachial
and lumbosacral plexi
• Course of the plexi and nerves and sites of
vulnerability
• Distribution of the peripheral nerves and
effects of injury (case studies)
Some Terminology…
• Radiculopathy = result of damage to nerve
root
– May be little sensory loss due to overlap of
dermatomes
– Main symptom = perception of sharp, burning
pain in dermatomal distribution (‘shooting pains’)
• Mononeuropathy = result of damage to a
single peripheral nerve
– Signs and symptoms can include
paraesthesia/anaesthesia and paresis/paralysis
Cervical Plexus (ventral rami)
• Arises from the ventral rami of C1-C4 (some contribution
from C5)
• Lies deep to SCM, anterolateral to levator scapulae &
middle scalene
• Supplies skin and muscles of head, neck, shoulders, & chest
• Phrenic nerve (C3 -5) supplies motor and sensory fibers to
diaphragm
– Irritation phrenic nerve -> hiccups
– If both phrenic nerves severed, diaphragm paralyzed,
respiratory arrest
• Cervical plexus runs parallel to accessory and hypoglossal
nerves.
Cervical Plexus (continued)
• Lesser occipital n
• Great auricular n
• Transverse cervical n
• Supraclavicular n
• Phrenic n
• Other branches supply muscles of the neck
Cervical Plexus
Ref: Marieb & Hoehn , Human Anatomy & Physiology(7th edn)
Brachial Plexus
Ref: Drake et al (2005), Gray’s Anatomy for Students Flash Cards, Elsevier
Where/how might the brachial plexus be injured?
(think trunks, divisions, cords)
Vulnerable Sites for Upper Limb Nerves
Ref: Patten (1977) Neurological Differential Diagnosis
Vulnerable Sites for Lower Limb Nerves
Ref: Patten (1977) Neurological Differential Diagnosis
Clinical Considerations
• Key question when PPW neurological
symptoms is whether those symptoms are in
the territory of a single nerve root or the
territory of a single peripheral nerve or its
branches
• In upper limb, motor symptoms are more
reliable than sensory