Anatomy Bones and Muscles · MU Pleven

163. Intercostal nerves.

Explains that the intercostal nerves are the ventral rami of the twelve thoracic spinal nerves, and describes their course between the pleura and the posterior intercostal membrane. It sets out the three branches each nerve gives off, including the collateral branch that supplies the intercostal muscles, parietal pleura and periosteum. It then separates typical nerves from atypical ones, noting the special features of the first, second and seventh to eleventh nerves, with two diagrams included.

Inside: 3 sections · 2 labelled pictures · 10 flashcards · 1 min

Topic 162 of 236 in the MU Pleven syllabus for Anatomy Bones and Muscles (Medicine, Year 2). The free AceMed note covers it in 3 sections, about 210 words (1 min of reading), with 10 flashcards.

In this note

  1. INTERCOSTAL NERVES
  2. Course :
  3. Typical Vs ATypical :

INTERCOSTAL NERVES

The intercostal nerves are the ventral rami of the 12 thoracic spinal nerves.

  • They innervate the intercostal muscles, skin & other structures.

Course :

  • Emerges from its intervertebral foramen to run between parietal pleura and post. intercostal membrane.
  • Gives 3 branches:
  1. 1. lateral cut. br. which divide into anterior br. / posterior br.
  2. 2. Anterior cut. br " " " Medial / lateral.
  3. 3. Collateral branch - they arise close to ribs & course along the superior border of the inferior rib to innervate the intercostal muscles, parietal pleura, & the periosteum. (motor br.)

Typical Vs ATypical :

  • Sometimes we divide the intercostal nerves into typical and atypical.

Typical - course only in their intercostal spaces.

  • (IC 3 - IC 6)

Atypical - go beyond the thoracic wall to supply other regions.

  • (IC1, IC2, IC7 - IC11)

- IC 1 nerve (special)

  • The ant. rami around the neck of the first rib bifurcate into superior & Inferior branches
  • the superior br. exits the thoracic cavity & joins the brachial plexus.
  • the inf. br. becomes the first intercostal nerve.
  • No lateral cutaneus branch.

- IC2 nerve

Has long lateral cutaneus br. supplies skin of floor of axilla. called (Intercostalbrachial n.)

- IC7 - IC11 :

They pass between diaphragmatic muscular bundles to reach the anterior abdominal wall.

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