From the Guidelines
The T2 intercostobrachial nerve originates from the second thoracic spinal nerve and follows a distinct anatomical course through the thoracic region into the upper limb. After emerging from the T2 spinal nerve, it travels along the inferior border of the second rib in the intercostal space. The nerve then pierces the intercostal muscles and external thoracic fascia near the mid-axillary line. Upon entering the axilla, the intercostobrachial nerve crosses the axillary region superficially and extends laterally into the medial aspect of the upper arm. Here, it provides sensory innervation to the skin of the medial and posterior aspects of the upper arm, as well as the axilla itself. The nerve typically communicates with the medial cutaneous nerve of the arm (from the brachial plexus), forming an anatomical network that ensures sensory coverage of the axillary and medial arm regions. This anatomical arrangement explains why procedures involving the axilla, such as lymph node dissections or certain surgical approaches, can result in sensory changes in the medial arm if the intercostobrachial nerve is damaged, as noted in studies related to axillary dissection 1. However, the provided evidence does not directly describe the anatomical course of the T2 intercostobrachial nerve, but based on general anatomical knowledge and the example provided, the description above holds. It's also worth noting that the intercostobrachial nerve's course and function are closely related to the brachial plexus, as discussed in the context of plexopathy 1 and thoracic outlet syndrome 1. The preservation of this nerve is desirable in surgical procedures to prevent sensory changes in the medial arm, as mentioned in guidelines for axillary dissection 1. Key points about the T2 intercostobrachial nerve's course include:
- Origin from the second thoracic spinal nerve
- Travel through the intercostal space along the second rib
- Piercing of intercostal muscles and external thoracic fascia
- Superficial crossing of the axillary region
- Extension into the medial aspect of the upper arm
- Sensory innervation of the medial and posterior upper arm and axilla
- Communication with the medial cutaneous nerve of the arm.
From the Research
Anatomical Course of T2 Intercostobrachial Nerve
The T2 intercostobrachial nerve originates from the second intercostal space, with possible contributions from the first and third intercostal nerves 2. The nerve's course can be described as follows:
- It arises from the lateral cutaneous branch of the second intercostal nerve, which is a constant finding in most cases 3.
- The nerve then courses through the axilla, where it may have a variable relationship with the lateral thoracic vein, either anterior, posterior, or wrapping around it 2.
- In the upper arm, the nerve lies in the subcutaneous fat and supplies at least the proximal half of the arm, with some cases reaching the level of the elbow joint 2.
- The nerve may also have connections to the medial cord of the brachial plexus in the axilla, as well as to the medial cutaneous nerve of the arm 2, 4.
Branching Patterns
The T2 intercostobrachial nerve can exhibit different branching patterns, including:
- A single trunk in approximately 47% of cases 3.
- A bifurcating pattern in around 42% of cases, with the bifurcation often being unequal 3.
- Connections to the brachial plexus, which occur in about 41% of cases 3.
- Contributions from other intercostal nerves, such as T1, T3, and T4, which can vary in their arrangement and frequency 5.
Clinical Relevance
Understanding the anatomical course and variations of the T2 intercostobrachial nerve is essential for surgeons to preserve the nerve during operative procedures, such as mastectomy and axillary lymph node dissection, to minimize the risk of postoperative sensory loss and neuropathic pain 3, 4.