KINE 191- Neuroanatomy Lecture Notes

Introduction

• Neuroanatomy - Dr. Jerome Genz, B.Sc, DC

Lecture Outline

• CNS: Central Nervous System

  • Brain

  • Spinal Cord

• PNS: Peripheral Nervous System

  • Divisions of the PNS

  • Spinal nerves

  • Plexuses & associated nerves

    • Cervical

    • Brachial

    • Lumbar

    • Sacral

CNS and PNS Overview

Central Nervous System (CNS)

• is responsible for processing sensory information from the body and the environment, coordinating responses, and controlling various bodily functions. It serves as the main control center for the nervous system, integrating information, making decisions, and ensuring appropriate reactions to stimuli

• Functions:

  • Receives and integrates incoming sensory information (Afferent)

  • Sends outgoing motor command signals (Efferent)

• Components:

  • Brain and spinal cord

• Protection:

  • Vulnerable to compression ;therefore it is protected by bones (cranium and vertebrae)

Peripheral Nervous System (PNS)

• Functions:

  • Is a network of sensory receptors that detect internal and external environment, and nerves that transmits information to/from the CNS

• Components:

  • Cranial nerves (originate from the cranium)

  • Spinal nerves (originate from the spinal cord)

  • Ganglia, sensory receptors

• Protection:

  • Less vulnerable to compression; not protected by boney structures

Subdivisions of the PNS

1) Somatic Nervous System (SNS)

• Components:

  • Sensory neurons transmitting information from head, trunk, limbs to the CNS

  • Motor neurons conduct impulses from CNS to skeletal muscles

• Characteristics:

  • Includes spinal nerves

2) Autonomic Nervous System (ANS)

• Functions:

  • Sensory receptors that convey information from the visceral organs to CNS

  • Motor neurons that conducts impulses from CNS to smooth muscles via sympathetic (fight or flight) and parasympathetic divisions (rest and digest)

3) Enteric Nervous System

• Components:

  • Sensory receptor neurons that convey information from the GI tract

  • Motor neurons that contract the muscles of the intestines and propel food through the GI tract.

• Characteristics:

  • Often originates from the ANS

Spinal Nerves

Overview

• Generally belong to the Somatic Nervous System

• Components of CNS and PNS:

  • Somatic sensory receptors and neurons

  • Autonomic sensory receptors and neurons

  • Enteric sensory receptors and neurons

Number and Classification of Spinal Nerves

• Total: 31 pairs, serving specific regions of the body on each side

  • 8 Cervical (C1-C8)

  • 12 Thoracic (T1-T12)

  • 5 Lumbar (L1-L5)

  • 5 Sacral (S1-S5)

  • 1 Coccygeal (1Co)

Spinal Cord Structure

• Sections:

  • Cervical, Thoracic, Lumbar, Sacral, Coccygeal

• The spinal cord ends at the conus medullaris (between L1 and L2)

• Filum terminale: Connects the conus medulliaris to the coccyx, which stabilizes the distal ends of the spinal cord

• Cauda equina: Nerves extending from the end of the spinal cord within vertebral foramen

Plexuses

Major Plexuses of Anterior Rami

1. Cervical Plexus (C1-C5)

   • 2 Prominent Nerves:

     • Ansa cervicalis: Supplies the infrahyoid muscles

       • Function: depresses hyoid bone during swallowing

     • Phrenic nerve: Supplies the diaphragm

       • Function: Chief respiratory muscle

2. Brachial Plexus (C5-T1)

   • Prominent Nerves:

     • Musculocutaneous : Supplies to the anterior arm

       • Biceps brachii

       • Brachialis

       • Coracobrachialis

     • Axillary: Supplies both the

       • Deltoid

       • Teres minor

     • Median: Supplies all medial forearm muscles and most of the medial hand muscles

     • Radial: Supplies all arm and forearm muscles

     • Ulnar: Supplies medial forearm muscles (Flexor carpi ulnaris) and all medial hand muscles

3. Lumbar Plexus (L1-L4)

   • Prominent Nerves:

     • Obturator nerve (supplies all medial thigh muscles such as all the adductor muscles)

     • Femoral nerve (supplies all anterior thigh muscles, all the quadriceps muscles)

4. Sacral Plexus (L4-S4)

   • Prominent Nerves:

     • Superior gluteal nerve : supplies all of the lateral hip muscles (Abductors) like gluteus medius

     • Inferior gluteal nerve : supplies gluteus maximus muscle

     • Sciatic nerve : supplies all hamstrings muscles

     • Tibial nerve: supplies all posterior leg muscles such as gastrocnemius

     • Superficial fibular nerve: supplies the lateral leg muscles like fibularis longus and brevis

     • Deep fibular nerve : supplies all anterior leg muscles like Tibialis anterior, extensor digitorium longus

Conclusion