Anatomical Diagram: This axial cross-section of a human cadaver illustrates the musculoskeletal anatomy of the ischiofemoral space, a key region in the diagnosis of ischiofemoral impingement syndrome (IIS). The image identifies the medial boundary formed by the ischial tuberosity (IT) and the lateral boundary formed by the lesser trochanter (LT) of the femur. Centrally, the quadratus femoris muscle (QF) is shown spanning the distance between these two bony landmarks, with the obturator externus muscle (OE) situated deep to it. The adductor muscle group—including the adductor longus (ADL), adductor brevis (ADB), and adductor magnus (ADM)—is positioned medially and anteriorly. Posterior to the ischial tuberosity, the tendons of the semitendinosus (ST) and semimembranosus (SM) are visible, emerging from their proximal attachments. The gluteus maximus (GMA) provides the most superficial posterior layer. This clinical imaging resource provides essential context for understanding the spatial relationships and narrowing of the ischiofemoral and quadratus femoris spaces in pelvic pathology.

This medical anatomical diagram illustrates a transverse section of the neck at the C6 vertebral level, detailing the layers of the deep cervical fascia and the potential spaces they define. The illustration categorizes the fascia into three layers: superficial (yellow), middle (light blue), and deep (dark blue). Key anatomical structures labeled include the superficial fascia (SF), the superficial layer of deep cervical fascia (SLDCF), and the pretracheal fascia (PTF) enclosing the visceral compartment. Centrally, the diagram highlights the alar fascia (marked with an asterisk), which is situated between the retropharyngeal fascia (RF) anteriorly and the prevertebral fascia (PVF) posteriorly. This arrangement delineates two critical clinical spaces: the retropharyngeal space (RS), located between the RF and the alar fascia, and the 'danger space' (DS), situated between the alar fascia and the PVF. The carotid sheath (CS) is shown laterally. This visualization is essential for understanding the pathways of infection spread between the neck and the mediastinum, as well as providing anatomical guidance for surgical procedures in the prevertebral region.

This composite educational graphic illustrates the cross-sectional anatomy of the anterior neck, focusing on the left thyroid lobe through three modalities: (a) a 3D anatomical diagram, (b) an optoacoustic image, and (c) a correlative ultrasound with Directional Power Doppler. The 3D diagram establishes the spatial orientation of the common carotid artery, jugular vein, trachea, and thyroid lobe. The optoacoustic cross-section (b) displays high-sensitivity vascular mapping, identifying the sternocleidomastoid (s) and infrahyoid (m) muscles, the carotid artery (C), and the trachea (Tr). Intraglandular vascularity (3) and superficial vessels (1, 2) are highlighted in a high-contrast heatmap. The corresponding ultrasound image (c) provides structural grayscale context with superimposed Doppler signals (red and blue) indicating blood flow direction. This multimodal comparison demonstrates how optoacoustic imaging provides superior visualization of microvascular networks within the thyroid gland (T) compared to standard Doppler ultrasound, while maintaining consistent anatomical landmarks such as the trachea's medial position and the lateral placement of the carotid artery.

**Modality:** Axial Computed Tomography (CT) scan of the neck. **Anatomical Region:** Mid-cervical level (suprahyoid/infrahyoid junction), displaying the cervical vertebrae, airway, and surrounding soft tissue structures. **Description:** This is an educational anatomical diagram utilizing digital color-coding to delineate the deep cervical fascia compartments on the left side of a normal neck. The image serves as a reference for the topographic anatomy of potential neck spaces. **Key Landmarks and Color-Coded Spaces:** * **Visceral Space (Blue):** Encompasses the midline structures including the trachea, esophagus, and thyroid gland. * **Anterior Cervical Space (Orange):** Located anterior to the carotid space. * **Carotid Space (Green):** Contains the carotid artery, internal jugular vein, and cranial nerves IX–XII. * **Retropharyngeal Space (Yellow):** Positioned between the visceral fascia and the prevertebral fascia. * **Perivertebral Space (Red):** Surrounds the cervical vertebra and paraspinal muscles. * **Posterior Cervical Space (Purple):** Located posterior and lateral to the carotid space, deep to the sternocleidomastoid muscle. **Clinical Significance:** Essential for localizing pathology, such as abscesses or neoplasms, and predicting the spread of infection along fascial planes.

This diagnostic image is a sagittal view of a computerized tomography (CT) scan of the neck and upper thorax. The image demonstrates a large retropharyngeal abscess, characterized by a well-defined hypodense (darker) fluid collection. Black arrows indicate the longitudinal extent of the collection as it occupies the retropharyngeal space, located anterior to the cervical vertebrae and posterior to the pharynx and esophagus. Notably, the abscess tracks caudally from the cervical region, crossing the thoracic inlet and extending into the posterior mediastinum. The surrounding soft tissues show significant edema and displacement. Anatomical landmarks visible include the oral cavity, nasal passages, cervical spine, and superior mediastinal structures. This clinical finding is of high significance due to the risk of descending necrotizing mediastinitis. The image is intended for medical education regarding deep neck space infections and their potential routes of anatomical spread.

This diagnostic image is an axial CT scan of the head and neck with intravenous contrast. The scan shows a well-defined, low-density fluid collection in the retropharyngeal space, characteristic of a retropharyngeal abscess. The primary lesion is centrally located, measuring approximately 3.7 x 1.5 cm, and exhibits peripheral rim enhancement. Two smaller adjacent satellite collections are visible, suggesting multi-loculated fluid or local spread of infection. Anatomical landmarks include the nasal cavity and maxillary sinuses anteriorly, the oropharynx, and the cervical vertebrae (C1/C2 level) posteriorly. The surrounding soft tissues show evidence of edema and inflammatory changes, manifesting as increased mottled density and obliteration of normal tissue planes. The image is clinically significant for diagnosing deep neck space infections and evaluating potential complications such as airway compromise or posterior extension into the 'danger space' and epidural space. This material is suitable for intermediate to advanced medical learners focusing on radiology, otolaryngology, and emergency medicine.

This diagnostic image is a sagittal computed tomography (CT) scan of the head, neck, and upper chest, highlighting a large retropharyngeal abscess. The visual reveals a significant, hypodense, and heterogeneously textured collection in the retropharyngeal space, marked by white arrows. The abscess originates at the level of the cervical spine and extends inferiorly through the deep neck spaces into the superior mediastinum. The mass effect is clinically significant, showing marked anterior displacement and compression of the trachea, along with narrowing of the glottic and subglottic airway regions. The cervical vertebrae are visible posterior to the collection, with some hyperdense artifacts suggesting possible spinal hardware. This image illustrates the critical pathophysiology of descending necrotizing mediastinitis and the acute risk of airway obstruction associated with deep neck space infections. It is a vital educational resource for identifying radiological signs of abscess progression and secondary mass effects on vital aerodigestive structures.

**Modality:** Axial Computed Tomography (CT) of the neck with contrast. **Anatomic Region:** Deep neck spaces at the level of the hypopharynx and cervical vertebrae. **Pathology:** Extensive emphysema/gas collection within the retropharyngeal and "danger" spaces. **Visual Features:** - **Distribution:** Large, confluent pockets of low-attenuation gas (black) occupy the retropharyngeal space. - **Landmarks:** The gas collection is positioned posterior to the pharyngeal constrictor muscles and anterior to the prevertebral fascia. - **Extension:** The gas extends across the midline, indicating potential involvement of the "danger space" (the potential space between the alar and prevertebral fascia). - **Secondary Findings:** There is visible soft tissue swelling and displacement of adjacent vascular and airway structures. Scattered small gas bubbles are also visible in the right lateral soft tissues. **Diagnostic Significance:** This radiologic pattern is characteristic of a deep neck space infection (e.g., retropharyngeal abscess with gas-forming organisms) or traumatic pneumomediastinum/neck emphysema. Cross-midline extension in this anatomical plane is a key feature for identifying potential pathways for descending mediastinitis.

This diagnostic image is an axial contrast-enhanced CT scan of the submandibular and floor-of-mouth region. The image demonstrates a characteristic presentation of Ludwig's angina, an aggressive cellulitis of the submandibular space. Significant pathology includes bilateral hypodense areas within the floor of the mouth (indicated by black arrows), representing the formation of bilateral abscesses. These collections are associated with diffuse soft tissue swelling and a noticeable mass effect on the surrounding structures. Key anatomical landmarks visible include the mandible, the cervical spine, and the oropharyngeal airway, the latter of which shows significant narrowing (stenosis) due to the posterior displacement and swelling of the tongue and sublingual tissues. The pathology originates from the mandibular molar region, highlighting the odontogenic nature of the infection. This image is used in medical education to illustrate life-threatening airway compromise and the diagnostic imaging findings associated with deep neck space infections and maxillofacial emergencies.

This clinical photograph displays an inferior-to-superior view of a patient's neck and submental region, demonstrating significant, diffuse soft tissue swelling characteristic of Ludwig's angina. The swelling involves the bilateral submandibular and sublingual spaces, resulting in a firm, 'woody' induration that obscures normal anatomical contours. The skin surface appears taut, stretched, and erythematous, indicating underlying acute inflammation. Visible skin wrinkling and grey facial hair suggest an older adult patient. The clinical presentation is highly suggestive of a rapidly spreading cellulitis of the submandibular space, often secondary to odontogenic infections, which poses a severe risk of airway obstruction. This image serves as an educational tool for identifying the external manifestations of floor-of-mouth infections and the necessity for urgent surgical decompression and airway management.

This clinical photograph displays a six-month-old female infant with a severe presentation of Ludwig's angina. The image shows significant, diffuse swelling (cellulitis) involving the submandibular and submental regions, extending toward the right side of the face and neck. Notable skin findings include prominent ecchymosis and dark purple discoloration on the right side of the neck, suggesting vascular congestion or tissue ischemia. Linear abrasions and skin lesions are visible on the left lateral aspect of the face near the ear. The infant's face appears flushed, indicating acute inflammation. This case represents a rare pediatric manifestation of Ludwig's angina, which is typically characterized by rapidly spreading cellulitis of the floor of the mouth and submandibular space. The image highlights the critical need for monitoring airway patency in pediatric patients with progressive submandibular swelling.