Adrenal Glands: Anatomy
Overview Location There are 2 adrenal glands in the body and each gland is in close association with a kidney. The adrenal glands are: Borders/anatomic relations Development Gross Anatomy General structure The adrenal glands are composed of 2 functionally separate layers: the adrenal cortex and the adrenal medulla. Each layer has its own embryologic origins, […]
Thyroid Gland: Anatomy
Development Embryologic origins Medial thyroid anlage Lateral thyroid anlage Gross Anatomy Characteristics Location Borders, attachments, and associated anatomy Microscopic Anatomy and Function Thyroid follicles Thyroid follicles are the structural and functional units of the thyroid glands. Thyroid follicles are composed of a simple epithelial layer that encloses a colloid-filled cavity. C cells Also known as […]
Pituitary Gland: Anatomy
Overview The pituitary gland is known as the “master endocrine gland.” This gland receives stimulatory input from the hypothalamus and secretes multiple different hormones, which target multiple different end organs and have wide-ranging effects throughout the body. Location General structure The pituitary gland is divided into 2 primary components: The 2 halves function independently, as […]
Parathyroid Glands: Anatomy
Development The parathyroid glands are derived from pharyngeal pouches, which originate in the mesoderm. The parathyroid glands develop by the 7th week of gestation. The 3rd pharyngeal pouch gives rise to inferior parathyroid glands. The 4th pharyngeal pouch gives rise to superior parathyroid glands. Gross Anatomy and Neurovasculature Gross anatomy Structure: Total of 4 parathyroid […]
Vagina, Vulva, and Pelvic Floor: Anatomy
Development Embryology timeline Weeks 1–6: Embryo is sexually indifferent/nonbinary. Embryo possesses the following primordial sexual organs: Mesonephric ducts (wolffian ducts) Paramesonephric ducts (müllerian ducts) Urogenital sinus Genital tubercle Urogenital fold Labioscrotal swelling Week 7: Sexual differentiation begins with the development of the gonads. The genes present at fertilization determine if the developing, bipotent gonads differentiate […]
Ventricular System: Anatomy
Topography and Relations of the Ventricular System The ventricular system consists of 4 ventricles with an aqueduct connecting the 3rd and 4th ventricles. Cerebrospinal fluid (CSF) flows through the ventricles before entering the subarachnoid space of the brain and spinal cord from the 4th ventricle: Choroid Plexus and Cerebrospinal Fluid Choroid plexus Cerebrospinal Fluid Subarachnoid […]
Facial Muscles: Anatomy
Muscles of the Cranium The muscles of the cranium assist with actions of facial expression. These muscles receive nerve supply from the facial nerve (cranial nerve (CN) VII). Table: Muscles of the cranium Muscle Origin Insertion Nerve supply Function Occipitofrontalis Frontal belly (frontalis): galea aponeurotica (epicranial aponeurosis) Skin of the eyebrow Temporal branch of the […]
The 12 Cranial Nerves: Overview and Functions
General Features Table: Overview of the 12 cranial nerves (CNs) Nerve CN Function Type Olfactory I Olfaction (smell) Sensory Optic II Vision Sensory Oculomotor III Eye movement Pupillary constriction Accommodation Eyelid opening Motor Trochlear IV Eye movement (superior oblique muscle) Motor Trigeminal V Facial sensation Mastication Both Abducens VI Eye movement (lateral rectus muscle) Motor […]
Paranasal Sinuses: Anatomy
Maxillary Sinuses Overview Relations Neurovasculature Frontal Sinuses Overview Relations Neurovasculature Ethmoid Sinuses Overview Relations Neurovasculature Sphenoidal Sinuses Overview Relations Neurovasculature Clinical Relevance References
Lymphatic Drainage System: Anatomy
Overview Immune system The immune system provides defense (immunity) against invading pathogens, ranging from viruses to parasites, and its components are interconnected by blood and the lymphatic circulation. 2 lines of defense (which overlap): Innate immunity (which is nonspecific) involves the following cells: Natural killer cells Monocytes/macrophages Dendritic cells Neutrophils, basophils, eosinophils Tissue mast cells […]