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Anatomy of the Nervous System. Central nervous system (CNS) Brain Spinal cord Peripheral nervous system (PNS) Nerve outside the brain and spinal cord. The 12 pairs of cranial nerves. Spinal Nerves 31 pairs. Spinal Nerves. Dorsal ramus. Ventral ramus.
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Anatomy of the Nervous System • Central nervous system (CNS) • Brain • Spinal cord • Peripheral nervous system (PNS) • Nerve outside the brain and spinal cord
PNS Throughout Life • Embryonic muscles migrate to new locations • Some skin dermatomes become displaced • Muscles and skin always retain their original nerve supply
The Cervical Plexus • Deep in the neck under the sternocleidomastoid muscle. • Formed by ventral rami of first 4 cervical nerves (C1 – C4) • Most are cutaneous nerves • Phrenic nerve – major nerve
Brachial plexus main branches • Axillary:shoulder (Deltoid) • Musculocutaneous:Flexors in arm • Radial: Extensors in arm and forearm • Median:Flexors in forearm • Ulnar:Flexors in forearm and hand
The Sacral Plexus c c c
Innervation of the Skin: Dermatomes • Dermatome – an area of skin • Innervated by cutaneous branches of a single spinal nerve • Upper limb – skin is supplied by nerves of the brachial plexus • Lower limb: Lumbar nerves – anterior surface Sacral nerves – posterior surface
Posterior Anterior Map of Dermatomes
Autonomic Nervous System • General visceral motor part of the PNS • Has 2 divisions (with opposite effects): - Parasympathetic: ‘housekeeping’ activities (rest and digest) - Sympathetic: extreme situations (fight or flight)
