This composite educational resource details the anatomy and innervation of the brachial plexus. Panel (a) is a cadaveric dissection of the left axillary region. Key structures are labeled numerically: the median nerve (1), lateral and medial roots of the median nerve (2, 3), ulnar nerve (4), axillary artery (5), and axillary vein (6), alongside the medial cutaneous nerves of the arm (7) and forearm (8). In the supraclavicular region, the upper (9), middle (10), and lower (11) trunks are identified. Red and blue lines indicate proximal and distal bounds of a clinical lesion site. Panel (b) is a color-coded schematic diagram illustrating the brachial plexus architecture from roots (C5-T1) to terminal branches. It maps specific nerves to their target muscles, including the serratus anterior, deltoid, biceps brachii, and the intrinsic muscles of the hand. This content is designed for medical students and surgical residents to understand the relationship between neuroanatomical structures, their physiological territories, and the clinical correlation of axillary nerve injuries.

This composite educational graphic details the anatomy of the human brachial plexus (BP) through cadaveric dissections and a schematic diagram. (A) Cadaveric dissection of the cervical spine and axilla with the anterior scalene muscle removed, exposing the C5-T1 nerve roots emerging laterally to the middle scalene muscle (MS). (B) A structured schematic diagram illustrating the hierarchical organization of the BP from roots (C5-T1), trunks (Superior, Middle, Inferior), divisions (Anterior, Posterior), and cords (Lateral, Posterior, Medial) to terminal branches. (C) Dissection showing the roots in situ within the scalene triangle, formed between the anterior (AS) and middle scalene muscles, alongside major vessels including the subclavian artery (SCA) and internal jugular vein (IJV). The phrenic nerve (yellow arrowhead) is seen traversing the anterior scalene. (D) Detailed view of the infraclavicular and axillary regions showing terminal branches (1-8: suprascapular, musculocutaneous, axillary, radial, medial brachial cutaneous, median, ulnar, and intercostobrachial nerves) in relationship to the pectoralis minor (Pmi), pectoralis major (Pma), and subclavian vessels. This content provides essential topographical and clinical anatomy for understanding thoracic outlet syndrome and regional anesthesia.

This composite educational resource comprises three Magnetic Resonance Neurography (MRN) coronal views (a, b, c) and a correlating schematic anatomical diagram (d) illustrating a severe traumatic brachial plexus injury. The right side of the images displays normal brachial plexus anatomy, with continuous nerve structures including the upper trunk (1), middle trunk (2), C8 root (3), and Th1 root (4). In contrast, the left side demonstrates a total rupture of the brachial plexus (dashed arrows). This injury is characterized by the complete discontinuity of the neural trunks and cords, accompanied by a large axillary cavity hematoma (curved dashed arrows). The schematic (d) highlights the side-to-side difference, showing the organized right-sided roots (C5-Th1) and trunks versus the disorganized, hemorrhagic area on the left. This material is designed for advanced medical education in radiology and neurosurgery, focusing on diagnostic imaging features of high-grade nerve trauma, specifically Seddon grade 3-5 injuries (neurotmesis) and the identification of postganglionic plexopathy.

This anatomical diagram illustrates a common neuroanatomical variation of the brachial plexus in the upper limb, specifically the shoulder and proximal humerus region. The visual features the skeletal framework of the rib cage, clavicle, and humerus, with the coracobrachialis muscle (CB) highlighted in red. The neural structures are depicted in yellow, demonstrating the relationship between the musculocutaneous nerve (MC), median nerve (MN), and ulnar nerve (UN). A significant anatomical variant is shown: a communicating branch (C) originating from the musculocutaneous nerve distal to its exit from the coracobrachialis muscle. This branch travels medially and distally to join the median nerve. This illustration is an educational resource for medical students and clinicians to understand variations in peripheral nerve anatomy, which is critical for surgical planning in the axillary region and for interpreting unusual clinical presentations of peripheral nerve injuries.

This clinical photograph displays a posterior surgical dissection of the human shoulder, highlighting the neurovascular anatomy of the quadrangular space (1). The primary structure shown is the axillary nerve (2), which is visualized traversing the quadrangular space. The image demonstrates the branching patterns of the axillary nerve, specifically identifying the muscular branch to the deltoid muscle (3) and the muscular branch to the teres minor muscle (4). Additionally, an articular branch of the axillary nerve (5) is visible, showing its course toward the glenohumeral joint. The dissection reveals the spatial relationships between these neural structures and the surrounding musculature, including the deltoid and teres minor. This anatomical view is essential for understanding the distribution of the axillary nerve and its potential sites of compression or injury during posterior surgical approaches to the shoulder or in quadrangular space syndrome.

This dual-panel image displays an ultrasound-guided needle placement in the posterior shoulder region, specifically targeting the axillary nerve. The left panel shows a grayscale 2D ultrasound in a longitudinal view of the deltoid muscle and transverse view of the quadrangular space. A hyperechoic, straight line representing the needle is visible using an 'in-plane' technique, penetrating through the moderately echogenic, striated muscle layers. The right panel provides a corresponding color-coded anatomical illustration overlaid on the ultrasound scan to identify key structures: the deltoid and teres minor muscles (orange), the humerus cortical bone (white hyperechoic curve), the axillary artery (red), and the axillary nerve (yellow). The needle tip is precisely positioned adjacent to the yellow-coded axillary nerve, demonstrating the correct clinical procedure for percutaneous electrical nerve stimulation (PENS) or regional anesthesia while avoiding vascular puncture. This educational visual aids in understanding musculoskeletal ultrasound anatomy and needle-to-nerve proximity.

This clinical anatomical photograph displays a deep dissection of a left shoulder from a posterior-lateral perspective, illustrating the neurovascular supply to the deltoid muscle. The head of the humerus is visible superiorly (marked with an asterisk). The dissection reveals the axillary nerve and the posterior circumflex humeral artery (PCHA) emerging through the quadrangular space to traverse the medial surface of the deltoid. For educational clarity, the axillary nerve is color-coded yellow and sits superior to the PCHA, which is color-coded red. Both structures exhibit a horizontal branching pattern across the striated muscle fibers. Orientation indicators (SUP: superior, LAT: lateral, POST: posterior) are provided to establish the spatial context of the surgical neck region. This image serves as a high-fidelity anatomical reference for understanding the spatial relationships and branching density of neurovascular structures during orthopedic or surgical approaches to the humerus and shoulder joint.

This anatomical diagram presents an anterior view of a human skull overlaid with schematic arrows illustrating facial lymphatic drainage pathways. The illustration focuses on the primary drainage routes from two specific injection sites on the left side of the face (viewer's right). The supra-ocular pathway is shown as a superiorly arching arrow originating above the orbit and directing toward the pre-auricular lymph nodes. The para-nasal pathway originates near the nasal bridge and divides into three distinct directions: inferiorly toward the sub-mandibular lymph nodes, laterally toward the parotid lymph nodes, and superior-laterally toward the pre-auricular lymph nodes. This diagram is utilized in nuclear medicine and clinical anatomy to demonstrate typical patterns of lymphoscintigraphy tracer movement and to highlight the anatomical landmarks (orbit, nasal cavity, mandible) used to map lymphatic flow in patients with facial edema or lymphedema.

This diagnostic fluorescence image displays two patterns of subcutaneous lymphatic drainage pathways in the human breast, visualized using Indocyanine Green (ICG) fluorescence. Both images demonstrate a high-intensity fluorescent signal at the nipple/subareolar region, representing the injection site. From this origin, linear and slightly tortuous fluorescent streams—indicated by dashed arrows—course towards the axilla (axillary basin). The left image depicts a relatively direct and well-defined pathway, while the right image shows a more diffuse and wider lymphatic channel, potentially illustrating variations in individual anatomy or the merging of multiple lymphatic vessels. The clinical significance of this imagery is the real-time identification of sentinel lymph node drainage pathways, essential for oncological surgical planning and staging. These findings highlight the primary lymphatic flow from the mammary gland towards the axillary lymph nodes, which is a key concept in surgical oncology and breast cancer management.

This composite educational graphic illustrates four distinct patterns of axillary lymphatic drainage from the breast to sentinel lymph nodes (SLNs), using Contrast-Enhanced Ultrasound (CEUS) imaging and corresponding anatomical diagrams. The visual material is divided into four sets (A–D), each featuring a split-screen ultrasound image (CEUS and B-mode) alongside a schematic illustration. The primary components described are Lymphatic Channels (LC) and Sentinel Lymph Nodes (SLN). The four patterns shown are: (A) a single LC draining to a single SLN; (B) multiple LCs converging into a single SLN; (C) a single LC branching to multiple SLNs; and (D) multiple LCs draining to multiple separate SLNs. In the CEUS images, the LCs and SLNs are identified by high echogenicity (bright contrast enhancement) indicated by red arrows, facilitating real-time visualization of the drainage pathway. This content is intended for surgical oncology and radiology education, specifically regarding preoperative sentinel lymph node biopsy (SLNB) mapping in breast cancer staging. It demonstrates how CEUS can be used to identify complex lymphatic anatomy that may impact surgical planning.

This composite educational infographic illustrates the anatomy of the human breast, its cellular structure, and the molecular subtyping of breast cancer. Panel (a) presents an anatomical diagram of the whole breast in cross-section, labeling the pectoral muscle, ribs, adipose tissue, and the functional unit consisting of lobes and mammary ducts. Panel (b) depicts the cellular anatomy of a mammary duct in cross-section, showing the basement membrane, myoepithelium (basal layer), and luminal cells surrounding a central lumen. It highlights pathological progression from carcinoma in situ to invasive carcinoma, demonstrating the breach of basement membrane integrity. Panel (c) is a comparison chart of breast cancer molecular subtypes: Triple Negative, HER2+, Luminal B, Normal-like, and Luminal A. It correlates these subtypes with clinical and pathological features, including percentage of cases, prognosis (gradient from poor/red to good/green), and the expression levels of key biomarkers such as HER2, ER+/PR+, and Ki67. The visual is designed for medical education regarding oncology subtyping and pathophysiology.

This three-panel composite image displays diagnostic nuclear medicine imaging demonstrating aberrant lymphatic drainage in a patient with ipsilateral breast tumor recurrence (IBTR). Panel A is a planar lymphoscintigraphy image showing a large central area of radiotracer uptake at the injection site. Two secondary foci of uptake are visible: arrow 'a' indicates drainage to the contralateral axilla, and arrow 'b' indicates drainage to the ipsilateral internal mammary chain (IMC). Panels B and C show coronal SPECT/CT fusion images providing anatomical localization for these findings. Panel B demonstrates a 'hot spot' (focal radiotracer uptake) in the right axillary region adjacent to the thoracic wall. Panel C illustrates a 'hot spot' localized to the left internal mammary chain, situated lateral to the sternum. These images illustrate the utility of SPECT/CT in identifying sentinel lymph nodes in non-axillary or contralateral basins, which is clinically significant for staging and surgical planning in recurrent breast cancer cases where normal lymphatic pathways may be surgically disrupted.

This composite diagnostic image demonstrates sentinel lymph node (SLN) mapping in a 45-year-old female patient with Stage II invasive ductal breast carcinoma. Panel A presents planar lymphoscintigraphy in anterior (ANT), right lateral (RLAT), and right anterior oblique (RAO) views. These views show a high-intensity peritumoural injection site (blue arrow) and multiple smaller, discrete spots of radiotracer uptake representing SLNs (red arrows). Panel B displays fused SPECT/CT imaging in coronal and axial planes, providing anatomical localization of the tracer uptake. This diagnostic modality identifies a complex drainage pattern involving one SLN in the right axillary region and bilateral internal mammary involvement, specifically two nodes on the right and one on the left internal mammary chain. Panel C provides a 3D volumetric rendering, illustrating the spatial relationship between the primary injection site and the lymphatic nodes relative to the thoracic skeletal structures (ribs and sternum). The combination of these modalities highlights the utility of SPECT/CT in resolving complex or ambiguous drainage patterns seen on planar imaging, crucial for precise surgical staging and biopsy planning.

This composite diagnostic image demonstrates preoperative sentinel lymph node (SLN) mapping using 99mTc-nanocolloid SPECT/CT in a 63-year-old woman with breast cancer. Panel (a) shows planar lymphoscintigraphy with body contouring, revealing an intense area of tracer uptake at the intratumoral injection site in the left breast and weaker focal uptake indicating lymphatic drainage to the axillary, periclavicular, and internal mammary chains. Panel (b) presents a 3D surface volume rendering SPECT/CT, which provides a topographic view of the SLNs (bright orange foci) localized relative to the skin surface and skeletal structures. Lower panels (c-f) provide transaxial SPECT/CT and corresponding CT slices, allowing for precise anatomical correlation. These sections localize specific SLNs to the second intercostal space (internal mammary chain), level I of the left axilla, and the retroclavicular region, with yellow dashed circles highlighting the anatomical correlates on the CT images. The study illustrates the incremental value of SPECT/CT in providing high-resolution anatomical localization of sentinel nodes compared to planar scintigraphy.