Neuroanatomy of Nerves

Plexus and Nerve Innervation

General Overview of Plexuses

• Plexus Types:
  • Cervical Plexus
  • Lumbar Plexus
  • Sacral Plexus

Cervical Plexus and the Phrenic Nerve

• Phrenic Nerve:

  • The significant nerve from the cervical plexus
  • Role: Innervates the diaphragm
  • Clinical Note:
  • Irritation of the phrenic nerve can lead to hiccups.
  • Hiccups can be triggered by:
    • Swallowing air while eating quickly
    • Resulting in the stomach bulging with air, leading to irritation of the diaphragm.

• Case Study:

  • Observed hiccups in laryngeal cancer patients due to nerve involvement rather than receptor activation - akin to phantom limb pain principles.

Brachial Plexus

• Axillary Nerve and Musculocutaneous Nerve:

  • Key nerves arising from the brachial plexus
  • Example Muscle:
  • Biceps Brachii: Innervated by musculocutaneous nerve.

• Ulnar Nerve:

  • Located on the ulnar (medial) side of the forearm.
  • Associated Muscle:
  • Flexor Carpi Ulnaris
  • Function:
  • Innervates muscles that perform flexion of the wrist and fingers.

Lumbar Plexus and Its Branches

• Lumber Plexus Overview:

  • Splits into two main branches: tibial nerve and common fibular nerve.

• Tibial Nerve:

  • Associated with the medial side of the leg (tibialis posterior).

• Common Fibular Nerve:

  • Innervates the anterior aspect of the leg (including tibialis anterior).
  • Key Point: The distinction is made between these two nerves based on their anatomical locations around the medial and lateral bones of the leg.

Understanding Muscular Innervation

• Flexors:

  • Muscles responsible for flexion, contributing to movement patterns in the limbs.

• Anatomical Position Importance:

  • Nerve pathways and functions are based on maintaining anatomical positioning for accurate identification and study.

Summary of Plexus Functions

• Knowledge of neck and limb plexuses vital for understanding muscular and sensory function, clinical diagnosis, and neurological assessments.