Download - Anatomy of the Nervous System
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
The segmental innervation of anterior surface of trunk
PNS Throughout Life
• Embryonic muscles migrate to new locations
• Some skin dermatomes become displaced
• Muscles and skin always retain their original nerve supply
Spinal nerve plexus
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
The Cervical Plexus
(C5 -T1)
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
Lumbar Plexus
The Lumbar Plexus
Sacral Plexus
The Sacral Plexus
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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 surfaceSacral nerves – posterior surface
PosteriorMap of
Dermatomes
Anterior
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)
Sympathetic
Sympathetic
Sympathetic
Sympathetic
Parasympathetic
Parasympathetic