Comprehensive Review: Special Senses, Cardiovascular System, and Neuroendocrine Anatomy

A set of 100 comprehensive vocabulary flashcards covering the anatomy and physiology of the special senses, cardiovascular system, and neuroendocrine systems.

External Ear

The outer division of the auditory system consisting of the auricle (pinna) and the external auditory meatus.

Middle Ear (Tympanic Cavity)

An air-containing cavity situated in the petrous part of the temporal bone lined with mucous membrane that houses the auditory ossicles to transmit vibrations from the tympanic membrane to the perilymph of the internal ear.

Internal Ear (Labyrinth)

The deep division of the auditory apparatus located in the petrous temporal bone containing the essential sensory organs for hearing and balance.

External Auditory Meatus

An S-shaped canal that conducts sound waves from the auricle to the tympanic membrane, composed of elastic cartilage in its outer third and bone formed by the tympanic plate in its inner two thirds.

Ceruminous Glands

Modified sweat glands located in the outer third of the external auditory meatus that secrete a yellowish-brown wax to form a sticky barrier against foreign bodies.

Tegmen Tympani

A thin plate of bone forming the roof of the middle ear that separates the tympanic cavity from the middle cranial fossa.

Aditus to the Mastoid Antrum

A large, irregular aperture situated in the upper portion of the posterior wall of the middle ear that opens into the mastoid antrum.

Pyramid (Middle Ear)

A small, hollow conical bony projection on the posterior wall of the middle ear from whose apex emerges the tendon of the stapedius muscle.

Malleus

The largest auditory ossicle, possessing a handle attached firmly to the inner surface of the tympanic membrane.

Incudomalleolar Joint

A saddle-shaped diarthrotic synovial joint enclosed by an articular capsule connecting the incus and the malleus.

Incudostapedial Joint

An enarthrodial (ball-and-socket) synovial joint surrounded by an articular capsule that articulates the incus with the head of the stapes.

Tensor Tympani Muscle

A middle ear muscle originating from the auditory tube and its bony canal, inserting into the handle of the malleus, innervated by the mandibular nerve ($V_3$), that dampens tympanic membrane vibrations.

Stapedius Muscle

A middle ear muscle originating inside the pyramid, inserting into the neck of the stapes, innervated by the facial nerve (CN VII), that dampens vibrations of the stapes.

Auditory (Eustachian) Tube

A channel linking the nasopharynx to the middle ear cavity, measuring approximately $35\,\text{mm}$ in adults, that equalizes air pressure across the tympanic membrane.

Bony Labyrinth

A series of dense bony cavities situated in the petrous temporal bone (vestibule, semicircular canals, and cochlea) lined by endosteum and containing perilymph.

Membranous Labyrinth

A continuous system of communicating membranous ducts and sacs (utricle, saccule, semicircular ducts, and cochlear duct) lodged within the bony labyrinth and filled with endolymph.

Septal Cartilage

A quadrilateral-shaped cartilage that forms the whole of the nasal septum between the anterior parts of the nasal cavity.

Nasal Conchae

Three curved bony projections (superior, middle, and inferior) along the lateral wall of the nasal cavity that create underlying pathways termed meatuses.

Oropharyngeal Isthmus (Isthmus of the Fauces)

The junctional opening between the mouth cavity proper and the oropharynx, bounded superiorly by the soft palate, laterally by the palatoglossal arches, and inferiorly by the tongue.

Lingual Nerve

A sensory branch of the mandibular division of the trigeminal nerve ($V_3$) providing general sensation to the anterior two thirds of the tongue.

Chorda Tympani

A branch of the facial nerve (CN VII) that passes through the middle ear to join the lingual nerve, supplying taste sensation to the anterior two thirds of the tongue.

Enamel

The hardest, white outer layer of a tooth, composed predominantly of the rock-hard mineral calcium phosphate.

Dentin

The mineralized living layer of a tooth directly beneath the enamel, formed by cells that secrete a hard mineral substance.

Dental Pulp

The soft, living central connective tissue core of a tooth that houses blood vessels and nerves.

Cementum

A layer of connective tissue that binds the roots of the teeth firmly to the periodontal ligament, gums, and jawbone.

Deciduous Teeth

The set of $20$ primary teeth ($4$ incisors, $2$ canines, and $4$ molars per jaw) that begin erupting at approximately $6$ months after birth and completely emerge by $2$ years.

Permanent Teeth

The set of $32$ secondary teeth ($4$ incisors, $2$ canines, $4$ premolars, and $6$ molars per jaw) that begin erupting at $6$ years of age.

Tarsal (Meibomian) Glands

Modified sebaceous glands embedded within the tarsal plates of the eyelids that secrete a lipid layer to prevent tear overflow and slow evaporation.

Conjunctiva

A thin, transparent mucous membrane extending from the eyelid margins (palpebral conjunctiva), reflecting into fornices, and covering the anterior sclera (bulbar conjunctiva) up to the cornea.

Nasolacrimal Duct

A membranous canal approximately $18\,\text{mm}$ long extending from the lacrimal sac down to drain tears into the inferior meatus of the nose.

Mediastinum

The central thoracic compartment extending from the sternum to the vertebral column between the two pleural cavities that contains the heart, great vessels, and pericardium.

Base of the Heart

The broad, posterosuperior aspect of the heart directed posteriorly, superiorly, and to the right.

Apex of the Heart

The pointed inferolateral extremity of the heart, directed anteriorly, inferiorly, and to the left.

Fibrous Pericardium

The tough, unyielding outer connective tissue sac enclosing the heart that prevents over-stretching and anchors the heart within the mediastinum.

Serous Pericardium

A closed, double-layered serous sac within the fibrous pericardium consisting of a parietal layer adhering to the fibrous sac and a visceral layer (epicardium) adhering to the myocardium.

Pericardial Fluid

Serous lubricating fluid (normally around $50\,\text{ml}$) located within the pericardial cavity between parietal and visceral serous layers that minimizes friction during cardiac contractions.

Pectinate Muscles

Parallel muscular ridges lining the anterior internal walls of the right and left cardiac atria.

Fossa Ovalis

An oval depression on the interatrial septum representing the closed postnatal remnant of the fetal foramen ovale.

Trabeculae Carneae

Muscular ridges and columns formed by specialized cardiac muscle fibers that project from the internal surfaces of the ventricular walls.

Papillary Muscles

Cone-shaped projections of the trabeculae carneae that attach to the chordae tendineae to anchor the atrioventricular valve leaflets during ventricular systole.

Tricuspid Valve

The right atrioventricular inlet valve consisting of three cusps situated between the right atrium and the right ventricle.

Mitral (Bicuspid) Valve

The left atrioventricular inlet valve composed of two cusps situated between the left atrium and the left ventricle.

Auscultation of Heart Valves

The clinical procedure of listening to valve sounds at specific thoracic locations: Aortic at the right $2\text{nd}$ ICS PSL, Pulmonic at the left $2\text{nd}$ ICS PSL, Tricuspid at the left $4\text{th}$ ICS PSL, and Mitral at the left $5\text{th}$ ICS MCL.

Intercalated Discs

Transverse cell boundaries separating individual cardiac myocytes that contain permeable gap junctions facilitating rapid, unhindered diffusion of ions across the functional syncytium.

First Heart Sound ($S_1$)

The 'Lubb' sound produced by the closure of the atrioventricular (tricuspid and mitral) valves at the onset of ventricular systole, characterized as louder, longer, and lower-pitched.

Second Heart Sound ($S_2$)

The 'Dub' sound produced by the closure of the semilunar (aortic and pulmonic) valves at the end of ventricular systole, characterized as shorter and higher-pitched.

Third Heart Sound ($S_3$)

A low-frequency sound occurring during the rapid filling phase of the ventricles in early diastole; pathologically indicates congestive heart failure (ventricular gallop).

Fourth Heart Sound ($S_4$)

An abnormal heart sound generated during atrial systole due to blood being forced into a stiff, non-compliant ventricle; pathologically associated with myocardial infarction and hypertension (atrial gallop).

Sinoatrial (SA) Node

The primary cardiac pacemaker ('Node of Keith and Flack') located in the superior septal wall of the right atrium lateral to the SVC opening, generating spontaneous autorhythmic action potentials.

Atrioventricular (AV) Node

The junctional conduction tissue ('Node of Kent and Tawara') located behind the tricuspid valve that delays impulse propagation and represents the most common site of heart block.

Purkinje Fibers

Specialized, large-diameter cardiac conduction cells with few myofibrils and numerous gap junctions that rapidly transmit impulses throughout the ventricular myocardium.

Conducting System of the Heart

Specialized cardiac muscle tissue pathway comprising the SA node, AV node, AV bundle of His, right and left bundle branches, and Purkinje fibers that coordinates heart contractions.

Left Anterior Descending Artery (LADA)

A major branch of the left coronary artery traveling down the anterior interventricular sulcus to supply the anterior wall and apex of the left ventricle.

Circumflex Artery

A branch of the left coronary artery that courses around the coronary sulcus to supply the lateral and inferior walls of the left ventricle.

Cardiac Action Potential

The electrical cycle of ventricular myocytes featuring rapid Phase 0 depolarization ($\text{Na}^+$ influx), Phase 1 initial repolarization, Phase 2 plateau ($\text{Ca}^{2+}$ influx), and Phase 3 repolarization ($\text{K}^+$ efflux).

Frank-Starling Law

The physiologic principle stating that the critical factor controlling stroke volume is the preload or degree of stretch of cardiac muscle cells before contraction.

Preload

The internal load and stretch placed on the ventricular myocardial fibers at the end of diastole immediately prior to contraction.

Afterload

The arterial pressure or resistance ($8\,\text{mmHg}$ in the pulmonary trunk, $80\,\text{mmHg}$ in the aorta) that must be exceeded by the ventricles to open the semilunar valves and eject blood.

Isovolumic Contraction

The early phase of ventricular systole where intraventricular pressure rises sharply while all four cardiac valves remain closed, resulting in no change in blood volume.

Arterioles

The smallest arterial branches, featuring heavily innervated smooth muscle walls that serve as control conduits and represent the site of highest vascular resistance in the circulatory system.

Stressed Volume

The portion of circulating blood volume maintained under high pressure within the systemic arterial network.

Unstressed Volume

The large portion of circulating blood volume contained under low pressure within the highly distensible systemic venous system.

Poiseuille's Law

The hemodynamic principle stating that blood flow is directly proportional to the fourth power of the vessel radius, meaning slight changes in luminal diameter drastically alter resistance.

Hematocrit

The percentage of whole blood volume occupied by red blood cells; its elevation dramatically increases blood viscosity and vascular resistance.

Mean Arterial Pressure (MAP)

The average arterial pressure across a complete cardiac cycle, calculated as $\text{Diastolic BP} + \frac{1}{3}(\text{Systolic BP} - \text{Diastolic BP})$.

Neuroglia

The non-excitable supporting cellular tissue of the nervous system, comprising astrocytes, oligodendrocytes, microglia, and ependymal cells in the CNS, and Schwann and satellite cells in the PNS.

Primary Divisions of the Developing Brain

The three embryonic brain vesicles (Prosencephalon, Mesencephalon, and Rhombencephalon) that differentiate into secondary subdivisions and give rise to adult cerebral structures.

Precentral Gyrus

The primary motor cortex located immediately anterior to the central sulcus, arranged somatotopically with inverted representation to control voluntary movement on the opposite side of the body.

Postcentral Gyrus

The primary somatosensory cortex situated immediately posterior to the central sulcus that receives and interprets pain, temperature, touch, and pressure from the opposite side of the body.

Broca's Area

The motor speech area located just above the lateral sulcus in the inferior frontal gyrus, typically dominant in the left cerebral hemisphere of right-handed persons.

Superior Temporal Gyrus

The convolution situated immediately below the lateral sulcus whose middle region serves as the primary auditory area for acoustic perception and interpretation.

Hippocampus

A seahorse-shaped structure in the temporal lobe limbic system essential for memory consolidation and converting short-term experiences into long-term memory.

Amygdala

An almond-shaped limbic nuclear complex located in the temporal lobe that plays a central role in emotional behavior, arousal, and aversion.

Cerebellar Peduncles

Three pairs of heavy fiber bundles (superior connecting to midbrain, middle connecting to pons, and inferior connecting to medulla oblongata) linking the cerebellum to the brainstem.

Dura Mater

The thick, tough, fibrous outermost meningeal layer that protects underlying neural tissue and provides protective sheaths for exiting cranial and spinal nerves.

Arachnoid Mater

A thin, avascular, impermeable meningeal membrane situated between the dura mater and the pia mater that loosely covers the brain and spinal cord.

Pia Mater

A delicate, highly vascular inner meningeal membrane that closely invests and adheres to the gyri and sulci of the brain and spinal cord.

Interventricular Foramina (of Monro)

The bilateral channels through which cerebrospinal fluid flows from the lateral ventricles in the cerebral hemispheres into the third ventricle.

Cerebral Aqueduct (Aqueduct of Sylvius)

A narrow channel traversing the midbrain that conveys cerebrospinal fluid from the third ventricle to the fourth ventricle.

Conus Medullaris

The tapered lower extremity of the spinal cord terminating at the level of the first or second lumbar vertebra ($\text{L1}\text{--}\text{L2}$).

Cauda Equina

The collection of descending lumbar, sacral, and coccygeal nerve roots within the subarachnoid space below the conus medullaris resembling a horse's tail.

Filum Terminale

A slender thread-like extension of the pia mater extending from the apex of the conus medullaris to anchor the spinal cord to the coccyx.

Phrenic Nerve

A vital motor and sensory branch arising from the cervical plexus ($\text{C3}\text{--}\text{C5}$) that provides primary motor innervation to the diaphragm.

Sciatic Nerve

The largest nerve of the sacral plexus, comprising the combined tibial and common peroneal nerves to innervate the posterior thigh, leg, and foot.

Dermatome

A specific cutaneous area of skin whose sensory innervation is derived from the dorsal roots of a single spinal nerve.

Parasympathetic Division

The craniosacral division of the autonomic nervous system that mediates restful, vegetative states and releases acetylcholine from its terminal postganglionic fibers.

Sympathetic Division

The thoracolumbar division of the autonomic nervous system that governs fight-or-flight responses, featuring sympathetic chain ganglia and releasing primarily norepinephrine at terminal organs.

Adenohypophysis

The anterior glandular lobe of the pituitary gland that secretes ACTH, TSH, GH, LH, FSH, ICSH, MSH, and prolactin.

Neurohypophysis

The posterior lobe of the pituitary gland connected to the hypothalamus that stores and releases oxytocin and antidiuretic hormone (ADH).

Pineal Gland

A small pinecone-shaped endocrine gland situated between the superior colliculi in the groove where the thalamic bodies join, functioning as the primary timing center for circadian rhythms.

Melatonin

A hormone derived from serotonin produced by the pineal gland, secreted at night and inhibited by light, that modulates sleep/wake cycles and inhibits early sexual development.

Thyroid Gland

A vascular endocrine organ weighing $15\text{--}20\,\text{g}$ located in the anterior lower neck below the larynx whose right and left lobes are linked across the $2\text{nd}\text{--}4\text{th}$ tracheal rings by an isthmus.

Calcitonin

A hormone secreted by the thyroid gland that acts directly to lower blood calcium concentration.

Parathyroid Hormone (PTH)

A polypeptide hormone secreted by the four parathyroid glands that increases blood calcium concentration.

Islets of Langerhans

Endocrine micro-organs scattered throughout the pancreas responsible for systemic glucose homeostasis.

Insulin

A hormone produced by centrally located beta cells in the pancreatic islets that lowers blood glucose levels and enhances cellular glucose metabolism.

Glucagon

A hormone produced by peripheral alpha cells of the pancreatic islets that stimulates glycogenolysis and gluconeogenesis to raise blood glucose levels.

Aldosterone

A mineralocorticoid synthesized by the adrenal cortex that promotes renal reabsorption of $\text{Na}^+$ and urinary excretion of $\text{K}^+$.

Cortisol

A glucocorticoid secreted by the adrenal cortex that promotes gluconeogenesis, stimulates liver glycogen accumulation, and antagonizes the effects of insulin.

Hypoglossal Nerve (CN XII)

The twelfth cranial nerve, which emerges from the medulla between the pyramid and olive and exits via the hypoglossal canal to supply motor control to all intrinsic and extrinsic tongue muscles except the palatoglossus.