PNS · 190. Intercostal nerves · Anatomy · MU Sofia

PNS · 190. Intercostal nerves.

Covers the origin of the intercostal nerves as the ventral rami of the twelve thoracic spinal nerves and their course between the parietal pleura and the posterior intercostal membrane. It then sets out the three branches, namely the lateral, anterior and collateral (motor) branches, and the division of intercostal nerves into typical and atypical groups. Notes on the first, second and seventh to eleventh nerves, including the first nerve's link to the brachial plexus and the second nerve's lateral cutaneous branch, are included.

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

Topic 174 of 264 in the MU Sofia syllabus for Anatomy (Dental Medicine, Year 2). The free AceMed note covers it in 3 sections, about 208 words (1 min of reading), with 10 flashcards.

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. lateral br. wich divide into anterior br. / posterior br. (cut.)
2. Anterior br. (cut.) " " " Medial / lateral.
3. Collateral branch (motor br.) - they arise close to ribs & course along the superior border of the inferior rib to innervate the intercostal muscles, parietal pleura, & the periosteum.

Typical Vs ATypical :

Sometimes we divide the intercostal nerves into typical and atypical.

Typical - course only in their intercostal spaces.

(IC3 - IC6)

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 diaphramatic muscular bundles to reach the anterior abdominal wall.