Intercostal Space
The anatomic space between two ribs, used as a reference point for needle decompression, chest tube placement, and other procedures involving the chest wall.
In the Field
The intercostal space is the anatomic landmark you have to find correctly to perform needle decompression. Wrong space, wrong outcome. The procedure depends on inserting the needle through a precisely located gap between ribs, into the pleural space, while avoiding the vessels and nerves that run along the lower edge of each rib. Knowing how to count the intercostal spaces by feel, in low light, on a moving patient, is the kind of skill that separates trained tactical paramedics from people who have read about the procedure. The fundamentals matter.
Common Mistake
Misidentifying the intercostal space during needle decompression, resulting in needle insertion at the wrong level or in a location that increases the risk of injury to vessels or nerves.
Technical Detail
The intercostal spaces are the anatomic spaces between adjacent ribs. The human thorax has 11 intercostal spaces on each side, numbered by the rib superior to the space (so the second intercostal space is between the second and third ribs).
Anatomy. Each intercostal space contains:
Three intercostal muscles in layers (external, internal, and innermost intercostal muscles), which provide structural support to the chest wall and assist with respiration.
The intercostal neurovascular bundle, running along the lower edge of the rib above the space. The bundle includes the intercostal vein (most superior), intercostal artery (middle), and intercostal nerve (most inferior). The classic anatomic mnemonic is VAN (Vein, Artery, Nerve) from superior to inferior.
The pleural cavity lies deep to the inner surface of the intercostal muscles.
Procedural significance. The intercostal space is the anatomic gap through which several thoracic procedures access the pleural space:
Needle decompression of tension pneumothorax. The needle is inserted through an intercostal space to release pressurized air from the pleural space. CoTCCC currently recognizes two acceptable insertion sites:
Fifth intercostal space, anterior axillary line (current preferred site under CoTCCC guidance).
Second intercostal space, midclavicular line (traditional site, still acceptable but with higher failure rate in larger patients).
See the Needle Decompression entry.
Chest tube (thoracostomy) placement. Performed at higher levels of care for ongoing pneumothorax, hemothorax, or other thoracic conditions. Typically inserted in the fourth or fifth intercostal space, anterior or mid axillary line.
Thoracentesis. Removal of fluid or air from the pleural space, performed at intercostal sites selected based on the location of the abnormal accumulation.
Counting intercostal spaces. Field providers must be able to identify specific intercostal spaces by palpation. Standard counting methods:
The Angle of Louis (sternal angle) is a palpable ridge on the upper sternum at the level of the second rib. Counting downward from this landmark identifies subsequent ribs and spaces.
The clavicle attaches at approximately the level of the first rib. Counting downward from the clavicle is an alternative landmark approach.
Counting by palpating each rib in sequence and identifying the space below each.
In tactical conditions (low light, moving patient, gloves, body armor), reliable counting requires practice and familiarity with the anatomic landmarks.
Insertion technique principles. When inserting a needle or other instrument through an intercostal space, the technique aims to:
Insert just superior to the lower rib of the space, avoiding the neurovascular bundle that runs along the lower edge of the upper rib.
Maintain perpendicular orientation to the chest wall to avoid lateral deflection.
Advance with controlled pressure, recognizing the resistance change as the needle passes through the parietal pleura into the pleural space.
Avoid excessive depth that could injure the underlying lung tissue.
Provider scope. Procedures using intercostal space access are provider-level skills. Needle decompression is taught at the Combat Lifesaver and provider levels and is within the scope of practice for tactical paramedics with appropriate medical director authorization. Chest tube placement is a higher-level skill typically restricted to physicians, advanced practice clinicians, and selected paramedic protocols.
For non-medical procurement officers, understanding the intercostal space concept matters when reviewing aid bag specifications, training course content, and protocol documents that reference these procedures. The terminology appears in equipment specifications (specifically for needle decompression catheter length and gauge requirements), in training course descriptions, and in scope-of-practice documents.
Anatomy. Each intercostal space contains:
Three intercostal muscles in layers (external, internal, and innermost intercostal muscles), which provide structural support to the chest wall and assist with respiration.
The intercostal neurovascular bundle, running along the lower edge of the rib above the space. The bundle includes the intercostal vein (most superior), intercostal artery (middle), and intercostal nerve (most inferior). The classic anatomic mnemonic is VAN (Vein, Artery, Nerve) from superior to inferior.
The pleural cavity lies deep to the inner surface of the intercostal muscles.
Procedural significance. The intercostal space is the anatomic gap through which several thoracic procedures access the pleural space:
Needle decompression of tension pneumothorax. The needle is inserted through an intercostal space to release pressurized air from the pleural space. CoTCCC currently recognizes two acceptable insertion sites:
Fifth intercostal space, anterior axillary line (current preferred site under CoTCCC guidance).
Second intercostal space, midclavicular line (traditional site, still acceptable but with higher failure rate in larger patients).
See the Needle Decompression entry.
Chest tube (thoracostomy) placement. Performed at higher levels of care for ongoing pneumothorax, hemothorax, or other thoracic conditions. Typically inserted in the fourth or fifth intercostal space, anterior or mid axillary line.
Thoracentesis. Removal of fluid or air from the pleural space, performed at intercostal sites selected based on the location of the abnormal accumulation.
Counting intercostal spaces. Field providers must be able to identify specific intercostal spaces by palpation. Standard counting methods:
The Angle of Louis (sternal angle) is a palpable ridge on the upper sternum at the level of the second rib. Counting downward from this landmark identifies subsequent ribs and spaces.
The clavicle attaches at approximately the level of the first rib. Counting downward from the clavicle is an alternative landmark approach.
Counting by palpating each rib in sequence and identifying the space below each.
In tactical conditions (low light, moving patient, gloves, body armor), reliable counting requires practice and familiarity with the anatomic landmarks.
Insertion technique principles. When inserting a needle or other instrument through an intercostal space, the technique aims to:
Insert just superior to the lower rib of the space, avoiding the neurovascular bundle that runs along the lower edge of the upper rib.
Maintain perpendicular orientation to the chest wall to avoid lateral deflection.
Advance with controlled pressure, recognizing the resistance change as the needle passes through the parietal pleura into the pleural space.
Avoid excessive depth that could injure the underlying lung tissue.
Provider scope. Procedures using intercostal space access are provider-level skills. Needle decompression is taught at the Combat Lifesaver and provider levels and is within the scope of practice for tactical paramedics with appropriate medical director authorization. Chest tube placement is a higher-level skill typically restricted to physicians, advanced practice clinicians, and selected paramedic protocols.
For non-medical procurement officers, understanding the intercostal space concept matters when reviewing aid bag specifications, training course content, and protocol documents that reference these procedures. The terminology appears in equipment specifications (specifically for needle decompression catheter length and gauge requirements), in training course descriptions, and in scope-of-practice documents.