Anatomy and Physiology: Skeletal, Muscular, and Nervous Systems

Perichondrium

A sheath of connective tissue that covers cartilage.

Tendons

Tough, rope-like bands of connective tissue made of collagen fibers that connect skeletal muscles to bones.

Ligaments

Connective tissue bands that connect bone to bone.

Hyaline Cartilage

Smooth type of cartilage located at joints.

Fibrocartilage

Collagen-rich, weight-bearing cartilage found in the vertebral column that is immovable and least flexible.

Elastic Cartilage

Flexible cartilage found in the ears, epiglottis, larynx, and auditory (eustachian) tube.

Hematopoiesis

The process of blood cell production occurring in red bone marrow.

Yellow Marrow

Bone marrow that stores adipose tissue and triglycerides for energy.

Red Marrow

Bone marrow responsible for blood cell production (hematopoiesis).

Hydroxyapatite

Inorganic calcium phosphate compound that constitutes 65\text{/%} of the bone matrix.

Osteogenic Cells

Unspecialized stem cells capable of replication that differentiate into osteoblasts.

Osteoblasts

Bone-building cells located at the periosteum that form the bone matrix and drive ossification.

Osteocytes

Mature bone cells located in lacunae that receive nutrients through cellular extensions called canaliculi.

Osteoclasts

Large, multinucleated cells derived from monocytes/macrophages that resorb bone by releasing acids and lysosomal enzymes.

Compact Bone

Dense, strong outer layer of bone beneath the periosteum composed of structural units called osteons (Haversian systems).

Spongy Bone

Porous bone tissue containing trabeculae, lacunae, and osteocytes, typically filled with marrow and found in short, flat, and irregular bones.

Diaphysis

The central shaft of a long bone, containing compact bone and a medullary cavity.

Epiphysis

The expanded end of a long bone, composed mostly of spongy bone with a thin outer layer of compact bone.

Articular Cartilage

A specialized layer of hyaline cartilage covering the ends of long bones within a joint.

Epiphyseal Plate

The cartilage growth plate situated between the epiphysis and diaphysis that converts to the epiphyseal line in adults.

Periosteum

A membrane of connective tissue that covers the outer surface of bones.

Medullary Cavity

The central cavity inside the diaphysis of a long bone that contains bone marrow.

Ossification

The process of bone formation, beginning around the 6th to 7th week of embryonic life.

Intramembranous Ossification

Bone development process occurring from fetal life to adolescence where bone forms directly within dense irregular connective tissue.

Endochondral Ossification

Bone formation process that uses a hyaline cartilage model as a template to construct new bone.

Calcitonin

A hormone secreted by parafollicular cells (C cells) when blood calcium levels are high to inhibit osteoclasts.

Glabella

A smooth region of the frontal bone located between the two orbits.

Foramen Magnum

A large opening at the base of the occipital bone through which the spinal cord connects with the brainstem.

Sella Turcica

A saddle-shaped depression in the sphenoid bone that houses and protects the pituitary gland.

Crista Galli

A crest on the ethmoid bone that serves as an attachment site for meningeal membranes.

Perichondrium

A sheath of connective tissue that covers cartilage.

Tendons

Tough, rope-like bands of connective tissue made of collagen fibers that connect skeletal muscles to bones.

Ligaments

Connective tissue bands that connect bone to bone.

Hyaline Cartilage

Smooth type of cartilage located at joints.

Fibrocartilage

Collagen-rich, weight-bearing cartilage found in the vertebral column that is immovable and least flexible.

Elastic Cartilage

Flexible cartilage found in the ears, epiglottis, larynx, and auditory (eustachian) tube.

Hematopoiesis

The process of blood cell production occurring in red bone marrow.

Yellow Marrow

Bone marrow that stores adipose tissue and triglycerides for energy.

Red Marrow

Bone marrow responsible for blood cell production (hematopoiesis).

Hydroxyapatite

Inorganic calcium phosphate compound that constitutes 65\text{%} of the bone matrix.

Osteogenic Cells

Unspecialized stem cells capable of replication that differentiate into osteoblasts.

Osteoblasts

Bone-building cells located at the periosteum that form the bone matrix and drive ossification.

Osteocytes

Mature bone cells located in lacunae that receive nutrients through cellular extensions called canaliculi.

Osteoclasts

Large, multinucleated cells derived from monocytes/macrophages that resorb bone by releasing acids and lysosomal enzymes.

Compact Bone

Dense, strong outer layer of bone beneath the periosteum composed of structural units called osteons (Haversian systems).

Spongy Bone

Porous bone tissue containing trabeculae, lacunae, and osteocytes, typically filled with marrow and found in short, flat, and irregular bones.

Diaphysis

The central shaft of a long bone, containing compact bone and a medullary cavity.

Epiphysis

The expanded end of a long bone, composed mostly of spongy bone with a thin outer layer of compact bone.

Articular Cartilage

A specialized layer of hyaline cartilage covering the ends of long bones within a joint.

Epiphyseal Plate

The cartilage growth plate situated between the epiphysis and diaphysis that converts to the epiphyseal line in adults.

Periosteum

A membrane of connective tissue that covers the outer surface of bones.

Medullary Cavity

The central cavity inside the diaphysis of a long bone that contains bone marrow.

Ossification

The process of bone formation, beginning around the $6\text{th}$ to $7\text{th}$ week of embryonic life.

Intramembranous Ossification

Bone development process occurring from fetal life to adolescence where bone forms directly within dense irregular connective tissue.

Endochondral Ossification

Bone formation process that uses a hyaline cartilage model as a template to construct new bone.

Calcitonin

A hormone secreted by parafollicular cells (C cells) when blood calcium levels are high to inhibit osteoclasts.

Glabella

A smooth region of the frontal bone located between the two orbits.

Foramen Magnum

A large opening at the base of the occipital bone through which the spinal cord connects with the brainstem.

Sella Turcica

A saddle-shaped depression in the sphenoid bone that houses and protects the pituitary gland.

Crista Galli

A crest on the ethmoid bone that serves as an attachment site for meningeal membranes.

Epimysium

Connective tissue sheath that surrounds an entire skeletal muscle organ.

Perimysium

Layer of connective tissue that surrounds individual bundles of muscle fibers known as fascicles.

Endomysium

Delicate connective tissue layer that surrounds individual muscle fibers within a fascicle.

Sarcolemma

The plasma membrane of a muscle fiber cell.

Transverse Tubules (T-tubules)

Invaginations of the sarcolemma that propagate action potentials deep into the center of a muscle fiber.

Sarcoplasmic Reticulum

Specialized smooth endoplasmic reticulum in skeletal muscle fibers that stores high concentrations of calcium ions.

Sarcomere

The basic structural and functional unit of muscle contraction, bounded by two Z-disks.

Isometric Contraction

Muscle contraction where tension increases while muscle length remains unchanged.

Isotonic Contraction

Muscle contraction where muscle length changes while tension remains constant.

Rigor Mortis

The rigid stiffening of muscles several hours after death caused by an absence of ATP required to release myosin heads from actin.

Central Nervous System

Nervous system division consisting of the brain and spinal cord.

Peripheral Nervous System

Nervous system division consisting of all nerves and ganglia located outside the brain and spinal cord.

Dendrites

Short neuronal processes that receive incoming electrical signals and transmit them toward the cell body.

Axon

Long neuronal process that transmits action potentials away from the cell body toward synaptic terminals.

Astrocytes

Star-shaped neuroglial cells in the central nervous system that provide structural support and form the blood-brain barrier.

Oligodendrocytes

Neuroglial cells responsible for forming myelin sheaths around axons in the central nervous system.

Schwann Cells

Neuroglial cells responsible for forming myelin sheaths around axons in the peripheral nervous system.

Depolarization

Phase of an action potential in which voltage-gated $Na^+$ channels open, allowing $Na^+$ to rush into the cell and reverse the membrane potential.

Repolarization

Phase of an action potential where $Na^+$ channels close and voltage-gated $K^+$ channels open, allowing $K^+$ to exit and restore the negative membrane potential.

Wernicke's Area

Cortical area located in the left hemisphere responsible for the comprehension and understanding of written and spoken language.

Broca's Area

Cortical area located in the frontal lobe of the left hemisphere responsible for speech production and motor planning of speech.