Anatomy · MU Sofia

PNS · 181. Somatic and autonomic (vegetative) nerves. Regional and segmental nerve supply of the skin and muscles.

Covers the structure and development of peripheral nerves, from neural crest origin through myelination and fascicle formation with perineurium. Describes dermatomes and myotomes with their overlap and axial lines, then Head's zones listing the segmental levels of referred pain or tenderness for internal organs such as the heart, stomach, liver, intestines and pelvic organs.

Inside: 4 sections · 4 labelled pictures · 10 flashcards · 3 min

Topic 165 of 264 in the MU Sofia syllabus for Anatomy (Dental Medicine, Year 2). The free AceMed note covers it in 4 sections, about 369 words (3 min of reading), with 10 flashcards.

In this note

  1. PERIPHERAL NERVES
  2. Development of PN:
  3. Regional Innervation:
  4. Head’s Zone:

PERIPHERAL NERVES

  • A peripheral nerve is a bundle of nerve fibers (axons) held together by connective tissue.

Development of PN:

  • Peripheral nerves originate from neural crest cells.
  1. 1. Neural Crest cells (NCS) seperate from the neural tube, and migrate to various regions of the embry, where they differentiate into different cell types, including neurons & glial cells of the PNS.
  2. 2. Differentiated neurons extend axons & dentrites to establish connections with target cells, forming the basis of PN.
  3. 3. Schwan cells wrap around axons to form myelin seaths, wich increase the speed & efficiency of nerve impulse conduction.
  4. 4. Multiple nerve fibers bundle together to form nerve fascicles, which are surrounded by connective tissue layers called perineurium.
  5. 5. Perineurial cells secrete extracellular matrix components that provide structural support and organization to nerve fascicles.

Regional Innervation:

  • Peripheral nerves have a different distribution pattern compared to spinal nerves.

Dermatomes

  1. 1. Definition:
  • A dermatome is an area of skin supplied by sensory fibers from a specific spinal nerve.
  1. 2. Dermatome Maps:
  • These maps show the approximate areas of skin supplied by each spinal nerve.
  • There is considerable overlap between adjacent dermatomes.
  1. 3. Axial Lines:
  • Areas where there is little overlap between the skin areas served by non-contiguous spinal nerves.

181 cont.

Myotomes

  1. 1. Definition:
  • A myotome is a group of muscles innervated by the motor fibers of a particular spinal nerve.
  1. 2. Functionality:
  • These muscles are usually functionally related and responsible for specific patterns of movement.

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