## 1 Introduction  
Bacterial infections and abscess are frequently occurring diseases in the head and neck. Deep neck infection (DNI) can be caused by odontogenic infection, pharyngitis, salivary gland infection, trauma, or lodged foreign bodies. Deep neck abscesses have a fulminant evolution. The respiratory tract is compromised at an early stage, followed by rapid extension of the infection toward the mediastum. The stages of a diagnostic (clinical and imaging) and therapeutic algorithm are essential. The neck has two states of cervical fascia that cover its contents and form the potential spaces of the head and neck. These facial planes constitute important anatomical limitations to the spread of an infection, as well as to its targeting once their natural resistance to this spread is overcome. Therefore, anatomical considerations are essential in the treatment of deep cervical sup-urations, especially when planning treatment strategies and guarding against potential complications [1]. The neck contains several cavities and fascial recesses, including the retropharyngeal, peritonsillar, masseteric, pterygopalatine maxillary, parapharyngeal, and submandibular spaces, all of which are interconnected and filled with soft connective tissue, adipose tissue, muscles, blood vessels, and nerves [2]. DNIs can spread to several of these tissue sites along interconnected soft tissues, potentially resulting in severe symptoms and poor health outcomes [2] (Figure 1). The spread of the infection is limited by the fascial planes, but it is also directed by them when their natural resistance is exceeded. The superficial cervical fascia includes the superficial musculoaponeurotic system, facial muscles, platysma muscle, superficial blood vessels (external jugular vein), and adipose tissue. There are three important deep spaces between the layers of the deep fascia. The shape of the parapharyngeal space resembles an inverted pyramid, with boundaries between the petrous apex at the base of the skull and the greater horn of the hyoid bone. It is delimited medially by the buccopharyngeal fascia, laterally by the superficial layer of the deep cervical fascia, posteriorly by the prevertebral fascia, and anteriorly by the pterygomandibular raphe and the medial pterygoid muscle. The cervical space is segmented by superficial and deep cervical fascia. The alar fascia extending from the base of the skull to the T2 vertebra is positioned between the prevertebral fascia and retropharyngeal space. The danger space lies behind the alar fascia and stretches down to the diaphragm [1]. Due to their close anatomical relationship, an infection in the cervical space can spread to the mediastum. There are three pathways through which an abscess can spread along the fascial planes to the mediastum: the pretracheal route, leading to the anterior mediastum; the lateral pharyngeal route, leading to the middle mediastum; and the retropharyngeal route, leading to the posterior mediastum [3]. The danger space is named so because of the potential for the rapid spread of infection to the posterior mediastum through the lax arealor tissue. It is a potential space between the alar and the prevertebral fascia of the deep layer of the deep cervical fascia [3]. The \"danger space\" extends from the base of the skull to the diaphragm [4]. It is bounded anteriorly by the alar fascia, posteriorly by the prevertebral fascia, and laterally by the transverse processes [4]. The danger space lies posterior to the retropharyngeal space and anterior to the perivtebral space [4]. Infections in this space result indirectly from the spread of retropharyngeal, parapharyngeal, and prevertebral abscesses [4]. The danger space also contains fat. The \"danger\" is the tendency for infections to spread inferiorly into the mediastum and thorax, because the loose arealor contents offer little resistance, leading to complications such as mediastitis, empyema, and sepsis.