Intercostal nerves !
The intercostal nerves run along the underside of each rib; they supply the muscles between the ribs and feeling in bands around the trunk.
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What it is
The front branches of the thoracic nerves, running along the underside of each rib.
What it does
Supply the muscles between the ribs and feeling in bands around the chest and abdomen.
Key facts
- Roots
- Ventral rami of T1–T11 (T12: subcostal nerve); run in the costal groove below the vein and artery (VAN), between internal and innermost intercostals
- Moves
- Intercostal muscles, subcostales, transversus thoracis, serratus posterior; T7–T11: anterolateral abdominal wall muscles
- Feeling from
- Skin of chest and abdominal wall, parietal pleura and peritoneum; T2 intercostobrachial nerve to medial arm
Relations
- Course
- From the foramen it runs between the parietal pleura and the internal intercostal membrane, then in the costal groove between the internal and innermost intercostals; the lower nerves pass between transversus abdominis and internal oblique and pierce the rectus sheath
- Above
- The rib above, with the intercostal vein and artery above the nerve in the groove
- Deep
- Innermost intercostal muscle, endothoracic fascia and parietal pleura; near the spine only pleura, which is why intercostal and paravertebral blocks can cause a pneumothorax
- Superficial
- The internal and external intercostal muscles
How to find it
It cannot be felt. It is traced along the lower border of each rib; intercostal blocks are placed at the angle of the rib or in the posterior axillary line, just under the rib's lower edge, where the groove gives most cover.
On imaging
Not seen on radiographs; on ultrasound the nerve is found by its neighbours, in the groove under the rib with the intercostal vessels, between the internal and innermost intercostal muscles. Ultrasound guides intercostal and paravertebral blocks and a safe needle path just above the rib below. CT or MRI shows nerve sheath tumours as smooth masses along a rib or in the posterior mediastinum.
Clinical notes
- Intercostal and paravertebral blocks relieve the pain of rib fractures and chest surgery; absorption of local anaesthetic from the intercostal space is fast, so systemic toxicity is a known risk
- Post-thoracotomy pain: rib spreading and sutures around the rib crush the nerve, causing chronic burning pain along the scar
- Anterior cutaneous nerve entrapment syndrome: a branch trapped where it pierces the rectus sheath gives sharp local abdominal wall pain; Carnett sign (pain worse with the abdominal muscles tensed) points to the wall, not the viscera
Related conditions
Test yourself
Think of the answer, then tap the question to see it.
What is the order of the structures in the costal groove, from top to bottom?
Vein, artery, nerve (VAN): the intercostal nerve is lowest, between the internal and innermost intercostal muscles.
Why are chest drains placed just above the upper border of a rib?
The intercostal nerve and vessels run under the lower border of the rib above, so this avoids them.
What are the atypical intercostal nerves?
T1 joins the brachial plexus, T2 gives the intercostobrachial nerve to the medial arm, and T7–T11 continue into the abdominal wall.
What is Carnett sign, used in anterior cutaneous nerve entrapment syndrome?
Pain worse with the abdominal muscles tensed, pointing to the abdominal wall rather than the viscera.
Educational information, not medical advice. For any symptom, see a health professional.
Its names
- Official Latin (TA2)
- nervi intercostales TA2 6471
- Official Spanish (DeCS)
- Nervios intercostales DeCS D007367
- English (TA2)
- Intercostal nerves
Related
- Mid-back nerve roots
- Transversus abdominis
- Internal oblique
- External oblique
- Rectus abdominis
- Serratus posterior
Sources: Terminologia Anatomica (TA2); DeCS; Anatomy, Thorax, Intercostal Nerves; Anatomía humana (4.ª ed.), tomo 1, cap. 39: Ramos anteriores de los nervios espinales.
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Representative model, for educational purposes only.
