This study aims to assess the longus colli muscle thickness by ultrasonography in order to guide stellate ganglion blocks

Stellate ganglion block is an interventional pain management procedure that is often performed for diagnostic and therapeutic purposes. It has long been performed with the guidance of fluoroscopy, and despite the increasing use of ultrasonography in recent years, fluoroscopy is still the gold standard method.

In traditional fluoroscopic method, the needle is directed to the transverse process of the C6 vertebra, after touching the anterior tubercle (Chassaignac's tubercule) the needle is slightly withdrawn and following a negative aspiration, injection is performed.

The ideal placement of the needle should be anterolateral to the longus colli muscle and deep to the prevertebral fascia. Further placement may cause intramuscular spread and superficial placement may cause injection in the carotid sheath or vascular structures. These are the most important reasons for clinical ineffectiveness. How far should the needle be withdrawn? Data is inconsistent in the literature.

The primary aim of this study is to determine the distance from transverse process to longus colli muscles anterior border and from transverse process to carotid sheath's posterior border. Secondary aim is to investigate the relationship between longus colli muscle thickness and age, gender, height, weight, BMI and neck circumference.

Inclusion Criteria:

• Age between 18 - 65 years,
• Giving informed consent for examination, ultrasonographic evaluation and study participation

Exclusion Criteria:

• Having a chronic neck pain for more than 6 months,
• Having any neurological or musculoskeletal conditions that may affect the anatomy of cervical region (cervical disc herniation, torticollis, severe scoliosis, vertebral malformation, spinal stenosis, myopathies, etc.)
• Having a history of surgery or radiation therapy in the cervical region

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