Nerve Anatomy

Peripheral Nerves

Illustration of the cervical plexus

Anatomy of brachial plexus

Dermatomes of the upper extremity

Illustration of the lumbosacral plexus

Occipital Nerves

• Greater Occipital Nerve
• Lesser Occipital Nerve
• Third Occipital Nerve
• Suboccipital Nerve

Cervical Plexus

• Motor
  • Phrenic Nerve
  • Nerve to Thyrohyoid
  • Ansa Cervicalis
• Sensory
  • Greater Auricular Nerve
  • Transverse Cervical Nerve
  • Lesser Occipital Nerve
  • Supraclavicular Nerve

Upper Extremity: Brachial Plexus

• Branch Nerves from the brachial plexus
  • Suprascapular Nerve
  • Spinal Accessory Nerve
  • Dorsal Scapular Nerve
  • Lateral Pectoral Nerve
  • Medial Pectoral Nerve
  • Subscapular Nerves
  • Nerve to Subclavius
  • Medial Cutaneous Nerve of Forearm
  • Medial Cutaneous Nerve of Arm
  • Long Thoracic Nerve
• Axillary Nerve
  • Superior Lateral Cutaneous Nerve of the Arm
• Musculocutaneous Nerve
  • Lateral Cutaneous Nerve of the Forearm
• Radial Nerve
  • Posterior Cutaneous Nerve of the Arm
  • Inferior Lateral Cutaneous Nerve of the Arm
  • Posterior Interosseous Nerve
  • Superficial Branch of the Radial Nerve
  • Posterior Cutaneous Branch of the Forearm
• Ulnar Nerve
  • Superficial Branch of the Ulnar Nerve
  • Deep Branch of the Ulnar Nerve
  • Dorsal Cutaneous Branch of the Ulnar Nerve
• Median Nerve
  • Anterior Interosseous Nerve
  • Recurrent Branch of Median Nerve
  • Palmar Digital Nerves
  • Palmar Cutaneous Branch of the Median Nerve

Thoracic

• Brachial Plexus
  • Thoracodorsal Nerve
  • Long Thoracic Nerve
• Intercostal Nerves
  • Intercostal Brachial Nerve
• Subcostal Nerve
• Lumbar Plexus
  • Iliohypogastric Nerve
  • Ilioinguinal Nerve
  • Genitofemoral Nerve
  • Lateral Cutaneous Nerve of the Thigh
  • Femoral Nerve
• Sacral Plexus
  • Pudendal Nerve
  • Posterior Femoral Cutaneous Nerve

Lower Extremity: Lumbosacral Plexus

• Lumbar Plexus
  • Iliohypogastric Nerve
  • Ilioinguinal Nerve
  • Genitofemoral Nerve
  • Lateral Cutaneous Nerve of the Thigh
  • Obturator Nerve
  • Femoral Nerve
    • Saphenous Nerve
  • Obturator Nerve
• Sacral Plexus
  • Superior Gluteal Nerve
  • Inferior Gluteal Nerve
  • Sciatic Nerve
    • Tibial Nerve
      • Sural Nerve, Medial Plantar Nerve, Lateral Plantar Nerve, Calcaneal Nerve
    • Common Peroneal Nerve
      • Superficial Peroneal Nerve, Deep Peroneal Nerve
  • Posterior Femoral Cutaneous Nerve
  • Pudendal Nerve
  • Nerve to Obturator Internus
  • Nerve to Quadratus Femoris
  • Perforating Cutaneous Nerve
• Other
  • Geniculate Nerves
  • Anococcygeal Nerve

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Spinal Cord

Anatomy of the spinal cord

General

• Tubular bundle of nervous tissue extending from the brainstem to the lumbar vertebrae
• When combined with the brain, forms the central nervous system

Gross Anatomy

• Cylindrical structure, grey-white in color
• Arises as a continuation of the medulla (inferior part of the brain stem))
• Travels inferiorly within the vertebral canal
• Protected/ surrounded by meninges which contain cerebrospinal fluid
• At approximately L2, the cord tapers off forming conus medullaris
• The spinal nerves bundled together at the end of the conus are known as cauda equina
• Cervical enlargement: located at C4-T1, represents origin of brachial plexus
• Lumbar enlargement: located at T11-L1, represents origin of lumbosacral plexus

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Cranial Nerves

Anatomy of cranial nerves. a Pathways of cranial nerves to various innervated tissues of the body

• Olfactory nerve (I)
• Optic nerve (II)
• Oculomotor nerve (III)
• Trochlear nerve (IV)
• Trigeminal nerve (V)
• Abducens nerve (VI)
• Facial nerve (VII)
• Vestibulocochlear nerve (VIII)
• Glossopharyngeal nerve (IX)
• Vagus nerve (X)
• Accessory nerve (XI)
• Hypoglossal nerve (XII)

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Brain

Anatomic cross section of human brain in sagittal plane

General

• Central organ of the nervous system
• Combined with spinal cord, comprises the central nervous system
• Brain consists of cerebrum, brainstem, cerebellum
• Controls the activities of the body
• Processes, receives and integrate the signals it receives from the sensory nervous system
• Delegates instructions to the rest of the body

Cerebrum

• Largest part of the human brain, divided into two hemispheres
• Inner later of white matter, outer layer of grey matter
• Divided into four lobes (frontal, parietal, temporal, occipital)
• Frontal: executive functions including self control, planning, reasoning, abstract thought
• Occipital: vision
• Left cerebrum specializes in language
• Right cerebrum specializes in visual-spatial ability
• Hemispheres connected by commissural nerve tracts such as the corpus callosum

Brainstem

• Lies beneath the cerebrum in the back part of the skull
• Consists of midbrain, pons, medulla oblongata
• 10/12 cranial nerves originate directly from the brainstem

Other

• Cerebrum contains the 4 ventricles where CSF is produced

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Cellular Anatomy

Anatomy and physiology of a nerve

Terminology

• Nerve: enclosed, cable-like bundle of nerve fibers in the peripheral nervous system
• Neuron: single individual nerve, considered the basic unit of the nervous system
• Axon: extension of an individual neuron
• Schwann cell: coats the axon in myelin
• Fascicle: bundle of axons
• Endoneurium: layer of connective tissue that surrounds each axon
• Perineurium: layer of connective tissue that surrounds each fasciclee
• Epineurium: layer of connective tissue that wraps around the entire nerve
• Nerves are either classified as sensory or motor

Action

• Provides an electrochemical impulse called an action potential
• This is transmitted along the axon to peripheral organs or to the central nervous system

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See Also

• Neurology Main
• Neuropathies Main
• Anatomy Main

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