OSPE Master Study Guide: CNS, MSK, and Cardiorespiratory Anatomy

Comprehensive vocabulary flashcards covering central nervous system structures, musculoskeletal anatomy and joint mechanics, and cardiorespiratory anatomy and physiology based on the OSPE master study document.

Dura Mater

The most superficial layer of the brain coverings (meninges), composed of two distinct layers: the periosteal layer and the meningeal layer.

Arachnoid Mater

The thin, smooth, spiderweb-like middle layer of the meninges, separated from adjacent layers by the arachnoid space.

Pia Mater

The deepest layer of the meninges that directly covers and adheres to the brain surface; highly vascularized by a network of fine blood vessels.

Frontal Lobe

Cerebral lobe responsible for behavioural functions, including thoughts, cognition, emotion, and action.

Parietal Lobe

Cerebral lobe responsible for processing sensory modalities of touch, pain, and limb position, as well as visuospatial awareness.

Temporal Lobe

Cerebral lobe responsible for sensory functions (especially auditory processing), memory, and emotion; contains Wernicke's area on the superior temporal gyrus.

Wernicke's Area

Specialized cortical region located on the superior temporal gyrus that mediates the processing and understanding of speech.

Occipital Lobe

Cerebral lobe dedicated to vision; contains the calcarine sulcus, which is only visible in a medial view.

Insula

Cortical structure buried within the lateral fissure/sulcus that functions as a bridge between sensory input and emotional responses (such as disgust and cravings) and regulates autonomic functions.

Precentral Gyrus

Gyrus in the frontal lobe situated rostral/anterior to the central sulcus; serves as the primary motor cortex and controls mechanical actions of movement.

Postcentral Gyrus

Gyrus in the parietal lobe situated caudal/posterior to the central sulcus; functions as the primary somatic sensory cortex for initial processing of sensory information.

Central Sulcus

Prominent cerebral sulcus that physically separates the frontal lobe from the parietal lobe.

Lateral (Sylvian) Fissure

Deep fissure separating the frontal, parietal, and temporal lobes; deep within it lies the insula.

Parieto-occipital Sulcus

Sulcus best visualized from the medial view that demarcates the boundary between the occipital lobe and the parietal lobe.

Calcarine Sulcus

Sulcus within the occipital lobe whose depths contain the primary visual cortex responsible for initial visual processing.

Thalamus

Diencephalic structure located superior/dorsal to the midbrain; visible in medial view and acts as the central sensory gateway transmitting information to cortical areas.

Hypothalamus

Diencephalic structure located ventral and rostral to the thalamus; regulates endocrine release from the pituitary gland and governs overall autonomic nervous system (ANS) function.

Epithalamus

Diencephalic structure positioned ventral and caudal to the thalamus; contains the pineal gland, connects the limbic system to other regions, and manages the sleep-wake cycle.

Corpus Callosum

Major commissural structure connecting the two cerebral hemispheres, consisting of axons that interconnect corresponding cortical regions on both sides.

Lateral Ventricles

Paired C-shaped cavities (one in each hemisphere) consisting of an anterior/frontal horn, body, inferior horn, and posterior horn; drain directly into the third ventricle.

Third Ventricle

Midline ventricle situated ventral/inferior to the frontal horn of the lateral ventricles and dorsal/superior to the inferior horn; drains into the cerebral aqueduct.

Cerebral Aqueduct

Narrow conduit running through the midbrain that connects the third ventricle to the fourth ventricle.

Fourth Ventricle

Tent- or inverted 'v'-shaped ventricle positioned between the brainstem and cerebellum that drains into the central canal of the spinal cord.

Ventricular Flow of CSF

The sequential pathway of cerebrospinal fluid: Lateral ventricles $\rightarrow$ Third ventricle $\rightarrow$ Cerebral aqueduct $\rightarrow$ Fourth ventricle $\rightarrow$ Central canal of spinal cord.

Midbrain

Most dorsal portion of the brainstem, positioned rostral to the cerebellum; regulates vision, hearing, motor control, alertness, and temperature.

Cerebral Peduncles

Lateral structures of the midbrain composed of nerve fiber bundles connecting the cerebrum to the brainstem; transmit voluntary motor signals, aid coordination, and modulate sleep-wake, alertness, and sensory processing.

Pons

Middle brainstem division positioned ventral to the midbrain and dorsal to the medulla; mediates signal relay to the PNS, respiration, alertness, and postural/movement control during sleep.

Medulla Oblongata

Most ventral segment of the brainstem; controls vital autonomic reflexes including breathing, heart rate, and blood pressure, and serves as the crossover site for descending motor tracts via decussation.

Medullary Pyramids

Paired motor tracts running along the ventral/anterior surface of the medulla oblongata that control voluntary muscle movement.

Pyramidal Decussation

The morphological crossing of motor fibers between the medullary pyramids, enabling motor signals from one hemisphere to control the contralateral side of the body.

Cerebellum

The most caudal portion of the brain; coordinates ocular and limb movements, maintains balance and posture, and contributes to cognition, language, and emotion.

Conus Medullaris

The tapered, conical terminal lower end of the spinal cord proper (distinct from the spinal nerves).

Cauda Equina

A bundle of lumbar and sacral spinal nerve roots resembling a horse's tail that originates at the conus medullaris.

Filum Terminale

A slender, delicate fibrous strand of connective tissue extending from the conus medullaris to anchor the spinal cord to the coccyx.

Dorsal (Posterior) Root

Nerve root attached to the posterior spinal cord via rootlets that conveys sensory (afferent) impulses into the CNS; features a distinct swelling called the dorsal root ganglion.

Ventral (Anterior) Root

Nerve root attached to the anterior spinal cord via rootlets that transmits motor (efferent) signals away from the CNS.

DAVE Mnemonic

An anatomical mnemonic summarizing spinal root functions: Dorsal Afferent, Ventral Efferent.

Dorsal Root Ganglion (DRG)

An aggregation of sensory neuron cell bodies located just outside the spinal cord along the dorsal root; critical for initial sensory signal relay and reflex arcs.

Spinal Nerve

Mixed nerve formed by the confluence of dorsal and ventral roots; $31$ pairs exist (8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal) that branch into dorsal and ventral rami.

Dorsal Ramus

Smaller posterior branch of a spinal nerve providing motor and sensory innervation to deep back musculature and the overlying skin of the back and posterior neck.

Ventral Ramus

Larger anterior division of a spinal nerve supplying the anterolateral trunk and limbs; forms intercostal nerves in the thorax and nerve plexuses elsewhere.

Sympathetic Ganglion

Paravertebral autonomic structure arranged in bead-like chains anterior and slightly medial to spinal nerves; functions as a relay hub for sympathetic output.

First-Order Sensory Neuron

Primary afferent neuron that detects stimuli at peripheral receptors, has its soma in the dorsal root ganglion, and projects into the spinal cord or brainstem.

Second-Order Sensory Neuron

Ascending neuron located within the spinal cord or brainstem that acts as a gatekeeper, decussates across the midline, and projects to the thalamus.

Third-Order Sensory Neuron

Sensory relay neuron with its soma in the thalamus that projects axons to the primary somatosensory cortex for conscious awareness.

Upper Motor Neuron (UMN)

Motor neuron entirely confined to the central nervous system that originates in higher centers to initiate, regulate, and direct lower motor neurons.

Lower Motor Neuron (LMN)

Efferent motor neuron extending from the brainstem/spinal cord into the peripheral nervous system to terminate at the neuromuscular junction of skeletal muscle.

Interneuron

Centrally located neuron within the spinal cord or brain that synapses locally between afferent and efferent neurons.

Reflex Arc Components

The five functional components of a somatic reflex: 1. Receptor (stimulus), 2. Sensory/afferent neuron, 3. Integration center (interneurons in gray matter), 4. Motor/efferent neuron, 5. Effector (response).

Monosynaptic Reflex

A simple reflex circuit involving only one central synapse directly between an afferent and efferent neuron; demonstrated by the patellar reflex.

Polysynaptic Reflex

A reflex circuit containing two or more synapses and at least one interneuron interposed between sensory and motor neurons; exemplified by the withdrawal reflex.

Babinski Sign

An abnormal neurological reflex where stimulation of the sole causes dorsiflexion/extension of the hallux (big toe); diagnostic of an upper motor neuron lesion.

Broca's Aphasia

Expressive language impairment caused by damage to the motor speech area (typically the left frontal lobe in right-handed individuals), characterized by preserved comprehension but impaired speech production.

Hemianopia

Visual deficit marked by blindness in one half of the visual field across both eyes, typically secondary to occipital lobe damage.

Contralateral Hemiplegia

Unilateral motor paralysis or weakness affecting the face, arm, and leg on the side of the body opposite to a primary motor cortex lesion.

Hemispatial Neglect

Neuropsychological condition where an individual behaves as if one side of space does not exist; caused by injury to the non-dominant (typically right) parietal lobe.

Standard Anatomic Position

Universal reference posture: standing upright, facing directly forward with eyes and toes forward, upper limbs resting at the sides, and palms supinated.

Proximal vs. Distal

Proximal describes a position closer to the trunk or point of limb attachment; distal denotes a point farther along an extremity toward the free end.

Ipsilateral vs. Contralateral

Ipsilateral refers to structures located on the same side of the body; contralateral denotes structures on opposite sides of the body.

Coronal (Frontal) Plane

Vertical anatomical plane resembling a crown that bisects the body into anterior (front) and posterior (back) halves.

Transverse (Horizontal) Plane

Horizontal anatomical plane dividing the body or structure into superior (top) and inferior (bottom) sections.

Sagittal Plane

Vertical anatomical plane that divides the body or specimen longitudinally into right and left halves (called midsagittal when exactly on the midline).

True, False, and Floating Ribs

The $12$ pairs of ribs classified as: True ribs (pairs $1\text{--}7$, $7$ total), False ribs (pairs $8\text{--}10$, $3$ total), and Floating ribs (pairs $11\text{--}12$, $2$ total).

Tendons

Dense, cord-like bands of fibrous connective tissue composed of parallel collagen fibers that connect muscle to bone to transmit contractile forces.

Ligaments

Strong, slightly elastic fibrous bands of dense connective tissue that connect bone to bone, stabilize articular joints, and anchor visceral organs.

Hinge Joint

Uniaxial synovial joint permitting movement exclusively in one plane (flexion and extension); seen in the elbow, knee, and interphalangeal joints.

Saddle Joint

Biaxial joint where articulating surfaces possess reciprocal concave and convex contours; allows multi-directional movement without axial rotation (e.g., base of the thumb).

Plane (Gliding) Joint

Synovial joint characterized by flat or nearly flat articular facets that slide across each other (e.g., carpal bones of the wrist, tarsal bones of the ankle).

Ball-and-Socket Joint

Multiaxial joint where a spherical bone head articulates with a cup-like socket, providing rotational movement across all anatomical planes (e.g., shoulder, hip).

Condyloid Joint

Biaxial 'egg in cup' joint featuring an oval convex surface received by an elliptical concavity; permits flexion, extension, abduction, and adduction without rotation (e.g., radiocarpal wrist joint, knuckles).

Pivot Joint

Uniaxial synovial joint designed exclusively for rotational movement about a single central axis (e.g., the atlantoaxial joint between atlas and axis).

Pronation & Supination

Forearm-specific movements: supination rotates the radius so the palm faces upward or forward; pronation rotates it so the palm faces downward or backward.

Dorsiflexion & Plantarflexion

Ankle-specific motions: dorsiflexion raises the dorsal foot so toes point superiorly toward the shin; plantarflexion pushes the foot downward toward the ground.

Inversion & Eversion

Foot/ankle movements: inversion angles the plantar surface (sole) medially toward the opposite foot; eversion tilts the sole laterally away from the midline.

Agonist vs. Antagonist

An agonist is the prime mover that contracts to drive a specific joint movement; an antagonist relaxes and lengthens to oppose, brake, and stabilize the motion.

Tricuspid Valve

Right atrioventricular (AV) valve consisting of three fibrous cusps that prevents blood regurgitation from the right ventricle into the right atrium during systole.

Mitral (Bicuspid) Valve

Left atrioventricular (AV) valve featuring two broad cusps that separates the left atrium from the left ventricle, closing under systolic ventricular pressure.

Chordae Tendineae

Fibrous cords ('heart strings') anchoring the margins of AV valve cusps to papillary muscles, preventing valve eversion into the atria during ventricular contraction.

Papillary Muscles

Specialized muscular projections arising from ventricular walls that contract synchronously with systole to tether the chordae tendineae and brace the AV valves.

Pulmonary Valve

Right semilunar valve located at the base of the pulmonary trunk composed of three crescent-shaped cusps that prevent retrograde flow into the right ventricle.

Aortic Valve

Left semilunar valve positioned at the outflow tract of the left ventricle; prevents arterial blood in the aorta from re-entering the relaxing left ventricle.

Pulmonary Circulation

The pathway of deoxygenated blood: Venae cavae $\rightarrow$ Right atrium $\rightarrow$ Tricuspid valve $\rightarrow$ Right ventricle $\rightarrow$ Pulmonary valve $\rightarrow$ Pulmonary trunk/arteries $\rightarrow$ Lungs.

Systemic Circulation

The pathway of oxygenated blood: Pulmonary veins $\rightarrow$ Left atrium $\rightarrow$ Bicuspid/mitral valve $\rightarrow$ Left ventricle $\rightarrow$ Aortic valve $\rightarrow$ Aorta $\rightarrow$ Body tissues.

Right Lung vs. Left Lung Lobes

The right lung possesses three lobes (superior, middle, inferior) divided by horizontal and oblique fissures; the left lung possesses two lobes (superior, inferior) divided by an oblique fissure.

Pleural Cavity

The potential space between visceral pleura (covering lung tissue) and parietal pleura (lining the thoracic cage), containing pleural fluid that eliminates friction and maintains negative pressure.

Diaphragm

Primary inspiratory skeletal muscle separating the thorax and abdomen; upon contraction, it flattens and descends, increasing thoracic volume and decreasing intrapulmonary pressure.

External vs. Internal Intercostal Muscles

External intercostals elevate the ribs during inspiration (expanding thoracic volume); internal intercostals depress the ribs during forced expiration (reducing thoracic volume).

Sinoatrial (SA) Node

The primary physiological cardiac pacemaker situated in the posterior wall of the right atrium near the superior vena cava entrance; initiates action potentials at a rate of $60\text{--}100\,\text{beats/min}$.

Atrioventricular (AV) Node

Specialized nodal tissue in the lower interatrial septum that introduces an intrinsic delay of $0.1\,\text{second}$, ensuring the atria complete emptying before ventricular contraction begins.

Purkinje Fibres

Specialized subendocardial conduction network branching from bundle branches that rapidly sweeps impulses upward through ventricular myocardium from the apex.

Cardiac Output (CO)

The volume of blood pumped by the heart per unit of time, mathematically defined by: $\text{CO} = \text{HR} \times \text{SV}$.

Tidal Volume (TV)

The specific volume of air inhaled or exhaled during an unforced, quiet, restful respiratory cycle.

Inspiratory Reserve Volume (IRV)

The maximal additional volume of air that can be voluntarily inspired beyond a normal resting tidal inhalation.

Expiratory Reserve Volume (ERV)

The additional volume of air that can be actively and forcefully exhaled following the conclusion of a normal tidal expiration.

Residual Volume (RV)

The non-expellable volume of gas remaining inside the alveoli and airways following a maximal forced expiration, preventing pulmonary atelectasis (collapse).

Vital Capacity (VC)

The maximum volume of air capable of being moved through the lungs, calculated in the text as the sum of: $\text{TV} + \text{IRV} + \text{RV}$.

Total Lung Capacity (TLC)

The total volume of air the lungs can hold, defined as: $\text{TLC} = \text{TV} + \text{IRV} + \text{ERV} + \text{RV}$ or $\text{TLC} = \text{VC} + \text{RV}$.

Isovolumetric Ventricular Contraction

Cardiac cycle phase occurring at the onset of ventricular systole where internal pressure rises rapidly while both AV valves and semilunar valves remain closed, resulting in zero net volume change.

Isovolumetric Relaxation

Cardiac cycle phase occurring at early ventricular diastole where ventricular pressure plummets while both AV and semilunar valves are closed, preceding ventricular filling.