pediagenosis

Thursday, August 20, 2026

Atrial Septal Defect (ASD): Types, Symptoms, Diagnosis and Treatment

pediagenosis August 20, 2026 Comment

ATRIAL SEPTAL DEFECTS

DEFECTS OF THE ATRIAL SEPTUM

The atrial septum normally consists of two overlapping, closely adjacent components. Each forms an incomplete partition. The right-side component, corresponding to the embryonic septum secundum, is muscular and firm and has a posteroinferior oval-shaped opening, the foramen ovale. The left-side component, derived from the embryonic septum primum, is fibrous and thin and has a somewhat round opening anterosuperiorly, the ostium secundum. Together, the two components act as a one-way flap valve, allowing the flow of blood from right to left (normal before birth) but not from left to right. After birth, with the establishment of pulmonary circulation, the increased amount of blood entering the left atrium elevates the pressure in that chamber, thereby closing the flap valve. In most cases, this functional closure is eventually followed by anatomic closure; that is, the two components of the septum fuse. In the minority of cases where fusion fails, an increase in the right atrial pressure due to congenital cardiac anomalies, or any other condition that elevates right ventricular and right atrial pressure, causes the right atrial blood to flow again into the left atrium. Such a probe-patent foramen ovale, however, should not be considered a form of atrial septal defect; it causes no hemodynamic abnormalities by itself. In ASD there is an abnormal opening in the atrial septum allowing blood to flow either way; a predominantly left-to-right shunt usually exists. With associated anomalies or other conditions tending to increase right atrial pressure, the shunt is always from right to left, as in tricuspid valve atresia, or an initially left-to-right shunt reverses, as occurs after pulmonary vascular changes with pulmonary hypertension.

Tuesday, August 18, 2026

Lymphatic Drainage of Internal Genitalia: Uterus, Ovary, Tube, Cervix & Vagina

pediagenosis August 18, 2026 Comment

LYMPHATIC DRAINAGE II—INTERNAL GENITALIA

The lymphatics of the uterus are contained within three main networks or plexuses one at the base of the endometrium, another in the myometrium, and a third subperitoneally. No lymphatics, surprisingly, have been detected in the superﬁcial parts of the endometrium. The principal collecting trunks pass outward at the isthmus along the course of the uterine vessels. Drainage from the uterine body and from the cervix is similar, except that, in the region of the fundus, lymphatics are more likely to pass directly along with the ovarian lymphatics to the periaortic nodes. Occasionally, also, lymphatics may extend along the inguinal ligament to the femoral nodes. The number of lymph nodes in the group of parauterine nodes is small; most frequently there is a single node immediately lateral to each side of the cervix and adjacent to the pelvic course of the ureter. Although anatomists frequently do not comment about the parauterine nodes, the group receives special attention in radical surgical operations to treat uterine or cervical malignancy. Primary drainage to this node originates in the vagina, cervix, and uterus. Secondary drainage from this node is to the internal iliac nodes on the same side of the pelvis.

Monday, August 17, 2026

Lymphatic Drainage of the External Genitalia: Inguinal Nodes & Cloquet Node

pediagenosis August 17, 2026

LYMPHATIC DRAINAGE—EXTERNAL GENITALIA

A network of lymphatic anastomoses drains the external genitalia, the lower third of the vagina, and the perineum. Bilateral or crossed extension and drainage is common. The superﬁcial femoral nodes are reached through the superﬁcial external pudendal lymphatic vessels, although the superﬁcial external epigastrics may also play a role. From the region of the clitoris, deeper lymphatic vessels may pass direct to the deep femoral nodes, particularly to Cloquet node in the femoral canal, or through the inguinal canal to the external iliac nodes. Cloquet node is thought to be the sentinel node between the superﬁcial and deep inguinal/obturator lymph nodes. Sometimes, intercalated nodes may be encountered in the prepubic area or at the external inguinal ring. The lowermost portion of the vagina, like the vulva, may drain to the femoral nodes. This complex network of lymph nodes is clinically important, for these are the nodes to which cutaneous and vulvovaginal gland malignancies may drain. Regional lymph node dissections are routinely performed in the surgical treatment of vulvar cancer as the status of regional lymph nodes is essential for therapeutic planning and overall prognosis. Superﬁcial nodes in the groin may also become enlarged when signiﬁcant inﬂammation is present in vulvar structures (e.g., Bartholin gland infections).

Nevus Lipomatosus Superficialis: Symptoms, Causes, Histology & Treatment

pediagenosis August 17, 2026 Comment

Nevus Lipomatosus Superficialis

Nevus lipomatosus superficialis is a not-uncommon benign skin growth that is considered to be a hamartomatous proliferation of adipose tissue located in the dermis. It was originally named nevus lipomatosus cutaneous superficialis of Hoffman-Zurhelle. There are no known systemic associations with this benign skin growth, and no inheritance pattern has been described.

Innervation of Genitalia and Perineum: Nerves, Scrotal Pain & Bulbospongiosus Reflex

pediagenosis August 17, 2026

Genital and perineal innervation anatomy showing pudendal and genitofemoral nerves

Innervation of Genitalia II and of Perineum

The nerves supplying the anterior scrotal wall are the ilioinguinal and the external spermatic branch of the genitofemoral branch of the lumbar nerves. The superﬁcial perineal branches of the internal pudendal nerve, along with branches from the posterior cutaneous nerves of the thigh, innervate the posterior scrotal wall. The unstriated muscle in the dartos fascia is innervated by ﬁne autonomic ﬁbers that arise from the hypogastric plexus and reach the scrotum along with the blood vessels. Because of this complex innervation from various sources, the entire scrotum is difﬁcult to anesthetize with local anesthesia, unlike the spermatic cord and testicles.

Sunday, August 16, 2026

Connective Tissue: Types, Functions, Cells, and Extracellular Matrix

pediagenosis August 16, 2026

Connective or Supportive Tissue.

Connective or supportive tissue is the most abundant tissue in the body. As its name suggests, it connects and binds or supports the various tissues. Connective tissue is unique in that its cells produce the extracellular matrix that supports and holds tissues together. The capsules that surround organs of the body are composed of connective tissue. Bone, adipose tissue, and cartilage are specialized types of connective tissue that function to support the soft tissues of the body and store fat. The proximity of the extracellular matrix to blood vessels allows it to function as an exchange medium through which nutrients and metabolic wastes pass.

Sporotrichosis: Causes, Symptoms, Diagnosis, Histology and Treatment

pediagenosis August 16, 2026 Comment

Plate 6-24

SPOROTRICHOSIS

Sporothrix schenckii is an environmental fungus that is capable of causing human disease after direct inoculation into the skin. Inoculation is the cause of cutaneous sporotrichosis, which is considered to be a subcutaneous mycosis. Unusual cases of inhalation sporotrichosis have been described in the literature, as have cases of central nervous system disease. These cases occur almost exclusively in immunosuppressed hosts. Sporotrichosis has classically been associated with inoculation after the prick from a rose plant. This is well reported; the fungus can be isolated from rose plants but is also found on many other plants and in soil environments.

Friday, August 14, 2026

Vocal Cord Dysfunction (VCD): Symptoms, Diagnosis, Causes and Treatment

pediagenosis August 14, 2026

VOCAL CORD DYSFUNCTION

Vocal cord dysfunction (VCD), also known as paradoxical vocal cord motion (PVCM), is a relatively poorly understood laryngeal disorder manifest by inappropriate adduction, or closing, of the vocal cords during inspiration. This is in contrast to the normal respiratory cycle, in which the vocal cords are abducted, or open, during inspiration and only begin to adduct toward the end of exhalation or with the onset of phonation. Physiologically, partial adduction of the vocal cords at the end of the expiratory phase maintains alveolar patency by generating positive end-expiratory pressure. Full adduction of the vocal cords occurs normally during phonation. As air expelled from the lungs encounters a closed glottis, subglottic air pressure increases, which in turn provides the force necessary to vibrate the vocal cords and produce voice. In contrast, paradoxical adduction of the vocal cords during inspiration in patients with VCD results in acute, intermittent episodes of functional airway obstruction.

Uterus and Adnexa Anatomy: Uterus, Cervix, Fallopian Tubes and Ovaries

pediagenosis August 14, 2026 Comment

UTERUS AND ADNEXA

The uterus is a pear-shaped, thick-walled, hollow, muscular organ situated between the bladder and rectum. The fundus is the dome-shaped portion above the level of entrance of the fallopian tubes. The body, or corpus, lies below this and is separated from the cervix by a slight constriction, termed the isthmus. The cavity of the uterine body is a ﬂattened potential space, triangular in shape. The uterine tubes open into its basal angles. Its apex is continuous with the cervical canal at the internal os. The uterine wall is composed of an outer serosal layer (peritoneum); a ﬁrm, thick, intermediate coat of smooth muscle (myometrium); and an inner mucosal lining (endometrium).

Friday, August 7, 2026

Phenylketonuria (PKU): Symptoms, Causes, Diagnosis, Treatment & Low-Phenylalanine Diet Guide

pediagenosis August 07, 2026

NORMAL AND ABNORMAL METABOLISM OF PHENYLALANINE

PHENYLKETONURIA

Phenylalanine is an essential amino acid that serves as a substrate for many different biochemical pathways. Two end products that use phenylalanine as their precursors are melanin and epinephrine. Under normal physiological and biochemical environments, any excess amount of phenylalanine is converted into tyrosine by the liver and used for a host of biochemical processes including protein synthesis. In patients with phenylketonuria, the enzyme in the liver that converts phenylalanine into tyrosine is completely absent. This inborn error of metabolism is one of the most thoroughly researched disease states. With early detection and therapy, the severe sequelae of phenylketonuria can be avoided. Screening is performed soon after birth for all children in the United States and in most of the world. Children born in regions with poor medical infrastructure and no testing are at risk for the disease. Once the disease symptoms have appeared, therapy usually cannot reverse the damage that has been done. Phenyl-ketonuria is inherited in an autosomal recessive manner, but many genotypes have been described, and many mutations in the responsible gene have been reported. The defect is located on the long arm of chromosome 12, where the PAH gene encodes the protein, phenylalanine hydroxylase.