1. Peripheral Nerves: The Plexi

2. 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

3. 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)

4. 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

5. 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.

6. Cervical Plexus (continued) Lesser occipital n Great auricular n Transverse cervical n Supraclavicular n Phrenic n Other branches supply muscles of the neck

7. Cervical Plexus Ref: Marieb & Hoehn, Human Anatomy & Physiology(7 th edn)

8. Brachial Plexus Ref: Drake et al (2005), Gray’s Anatomy for Students Flash Cards, Elsevier

9. Where/how might the brachial plexus be injured? (think trunks, divisions, cords)

10. Vulnerable Sites for Upper Limb Nerves Ref: Patten (1977) Neurological Differential Diagnosis

11. Vulnerable Sites for Lower Limb Nerves Ref: Patten (1977) Neurological Differential Diagnosis

12. 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