Cervical_Plexus.pptx
- 1. The Peripheral Nervous System (PNS)
- 2. Learning Objectives • Understand the formation and position of the cervical plexus. • Describe the cutaneous and motor branches of the cervical plexus and identify their areas of distribution.
- 3. Spinal Nerves • Thirty-one pairs of mixed nerves arise from the spinal cord and supply all parts of the body except the head • They are named according to their point of issue – 8 cervical (C1-C8) – 12 thoracic (T1-T12) – 5 Lumbar (L1-L5) – 5 Sacral (S1-S5) – 1 Coccygeal (CO1)
- 5. Spinal Nerves: Roots • Each spinal nerve connects to the spinal cord via two medial roots. • Each root forms a series of rootlets that attach to the spinal cord. • Ventral roots arise from the anterior horn and contain motor (efferent) fibers. • Dorsal roots arise from sensory neurons in the dorsal root ganglion and contain sensory (afferent) fibers.
- 7. Spinal Nerves: Rami • The short spinal nerves branch into three or four mixed, distal rami – Small dorsal ramus – Larger ventral ramus – Tiny meningeal branch – Rami communicantes at the base of the ventral rami in the thoracic region
- 9. Nerve Plexuses • All ventral rami except T2-T12 form interlacing nerve networks called plexuses. • Plexuses are found in the cervical, brachial, lumbar, and sacral regions. • Each resulting branch of a plexus contains fibers from several spinal nerves.
- 10. Nerve Plexuses • Fibers travel to the periphery via several different routes. • Each muscle receives a nerve supply from more than one spinal nerve. • Damage to one spinal segment cannot completely paralyze a muscle.
- 11. Cervical Plexus • The cervical plexus is formed by ventral rami of C1-C4. • Most branches are cutaneous nerves of the neck, ear, back of head, and shoulders. • The most important nerve of this plexus is the phrenic nerve. • The phrenic nerve is the major motor and sensory nerve of the diaphragm.
- 12. The cervical plexus is formed primarily by spinal nerves C1-C4 (C5 is not considered part of this plexus, even though it contributes some axons)
- 13. Characteristics and Branches of Cervical Plexus • From ventral rami of C1-4. • Sensory branches: Great auricular (C2-3). Lesser occipital (C2(3)): Ventral ramus of C2. Greater occipital is dorsal ramus of C2. Transverse cervical (C2-3). Supraclavicular (C3-4).
- 14. Cervical Plexus
- 15. Cervical Plexus
- 16. Characteristics and Branches of Cervical Plexus • Motor branches: To prevertebral muscles: To levator scapulae muscle. To scalene muscles. Ansa cervicalis: Supplies infrahyoid muscles. Phrenic nerve (C3,4,5).
- 17. Cervical Plexus & Brachial Plexus
- 18. Ansa Cervicalis • Nerve to geniohyoid: C1 via hypoglossal nerve. • Nerve to thyrohyoid. • Superior and inferior roots: Omohyoid. Sternothyroid. Sternohyoid.