Anatomy and Physiology: Axial Skeleton, Appendicular Skeleton, Joints, and Muscle Tissue

Comprehensive vocabulary flashcards covering the axial skeleton, appendicular skeleton, joints and their movements, and skeletal, cardiac, and smooth muscle tissues.

Axial skeleton

Forms the longitudinal axis of the body and includes 80 bones of the skull, vertebral column, and thoracic cage.

Calvaria (skullcap)

The upper portion of the cranium formed by the occipital, right and left parietal, and the frontal bones.

Lambdoid suture

An immovable joint connecting the occipital bone to the two parietal bones.

Coronal suture

An immovable joint that connects the frontal bone to the parietal bones.

Sagittal suture

The joint connecting the two parietal bones along the midline of the skull.

Squamous sutures

The joints that attach the temporal bones to the parietal bones.

Maxillary sinuses

The largest sinuses; air-filled pockets contained in the maxillae.

Vomer

Bone forming the inferior portion of the bony nasal septum that divides the nasal cavity into left and right.

Inferior nasal conchae

Two bones that slow inhaled air, create turbulence in the nasal cavity, and increase epithelial surface area to warm and humidify inhaled air.

Orbital complex

The structure composed of seven bones that make up the orbit: frontal, sphenoid, ethmoid, lacrimal, palatine, zygomatic, and maxilla.

Primary curves

The thoracic and sacral spinal curves present during fetal development that accommodate internal organs.

Secondary curves

The cervical and lumbar spinal curves that appear after birth and shift body weight to permit an upright position.

Kyphosis

An excessive posterior curvature of the thoracic vertebral column.

Lordosis

"Sway back" caused by an anterior exaggeration of the lumbar curvature.

Scoliosis

An excessive lateral curvature of the spine occurring in one or more of the movable vertebrae.

Intervertebral foramina

Gaps that form between the pedicles of adjacent vertebrae that permit the passage of nerves to and from the spinal cord.

True ribs

Ribs 1 to 7 that connect directly to the sternum via separate costal cartilages.

False ribs

Ribs 8 to 12 that do not attach directly to the sternum.

Floating ribs

Ribs 11 and 12; false ribs that do not connect to the sternum at all.

Appendicular skeleton

Forms the 126 bones of the limbs and the supporting bone girdles that connect the limbs to the trunk.

Pectoral (shoulder) girdle

Bony structure connecting each arm to the trunk, consisting of one clavicle and one scapula.

Olecranon

The proximal end of the ulna that forms the point of the elbow.

Coronoid process

Process forming the inferior lip of the trochlear notch that fits into the coronoid fossa of the humerus when the elbow bends.

Carpal tunnel syndrome

Condition where inflammation of connective tissues between the ligament and carpal bones compresses the median nerve, causing pain.

Pollex

The thumb; contains two phalanges (proximal and distal).

Pelvic girdle

Girdle consisting of two hip bones (coxal bones) that articulates with the axial skeleton at the sacrum.

Acetabulum

Depression on the hip bone that articulates with the head of the femur to connect the pelvis to the lower limbs.

Pelvic brim

A bony ridge that separates the false pelvis from the true pelvis.

Patella

The kneecap; a sesamoid bone that connects the quadriceps muscles to the tibia.

Hallux

The big toe; contains two phalanges (proximal and distal).

Synarthrosis

An immovable joint that can be classified as fibrous, cartilaginous, or bony.

Amphiarthrosis

A slightly movable joint that can be classified as fibrous or cartilaginous.

Diarthrosis

A freely movable joint; includes all synovial joints.

Synchondrosis

A rigid, immovable hyaline cartilage connection between two bones.

Symphysis

A joint where articulating bones are connected by a pad of fibrocartilage.

Synostosis

A rigid, immovable ossified joint where two bones fuse and the boundary between them disappears.

Synovial fluid

A clear, viscous solution providing lubrication between articulating surfaces, distributing nutrients, and cushioning joints subject to compression.

Meniscus

A fibrocartilage pad located between opposing bones in a synovial joint.

Bursae

Small pockets filled with synovial fluid that reduce friction and act as shock absorbers where tendons or ligaments rub.

Pronation

A movement that rotates the forearm so that the radius rolls across the ulna and the palm faces posteriorly.

Supination

A movement that rotates the forearm so that the palm turns anteriorly.

Inversion

A special movement that twists the sole of the foot medially.

Eversion

A special movement that twists the sole of the foot laterally.

Dorsiflexion

Flexion at the ankle that elevates the sole and lifts the toes.

Plantar flexion

Extension at the ankle that elevates the heel and points the toes downward.

Annulus fibrosus

Tough outer fibrocartilage layer of an intervertebral disc that attaches the disc to the vertebrae.

Nucleus pulposus

Soft, gelatinous core of an intervertebral disc that works as a shock absorber.

Glenoid labrum

A rim of fibrocartilage that increases the depth of the glenoid cavity and deepens its socket.

Epimysium

A layer of collagen fibers that surrounds the entire skeletal muscle and separates it from surrounding tissues.

Perimysium

Connective tissue sheath that divides skeletal muscle into a series of compartments, each containing a muscle fiber bundle called a fascicle.

Endomysium

Delicate connective tissue that surrounds individual muscle fibers and interconnects them.

Myosatellite cells

Stem cells located in the endomysium that function to repair damaged muscle tissue.

Sarcolemma

The plasma membrane of a muscle fiber that surrounds the sarcoplasm and maintains a resting membrane potential.

Transverse tubules (T tubules)

Narrow tubes continuous with the sarcolemma that transmit electrical impulses from the cell surface into the cell interior.

Sarcoplasmic reticulum (SR)

A tubular network similar to the smooth ER surrounding each myofibril that stores and releases calcium ions.

Triad

A combination of a pair of terminal cisternae and an intervening transverse tubule ($2$ terminal cisternae + $1$ T tubule).

Sarcomere

The repeating structural and functional unit of a myofibril bounded by Z lines.

Tropomyosin

Protein strand covering the active sites on G-actin in resting muscle, preventing actin-myosin interaction.

Troponin

A globular protein that holds tropomyosin in place and binds to calcium ions to expose active sites on thin filaments.

Resting membrane potential of skeletal muscle cells

The electric potential across the sarcolemma of an unstimulated skeletal muscle cell, equal to $-85\,\text{mV}$.

Neuromuscular junction (NMJ)

The specialized synapse between a motor neuron and an individual skeletal muscle fiber.

Motor end plate

The region of the skeletal muscle fiber sarcolemma containing junctional folds, acetylcholine receptors, and AChE.

Acetylcholinesterase (AChE)

An enzyme located in the synaptic cleft and motor end plate that breaks down acetylcholine, ending action potential generation.

Myoglobin

A red pigment found in slow fibers that reversibly binds oxygen molecules.

Intercalated discs

Specialized cell junctions connecting the sarcolemmas of adjacent cardiac muscle cells via gap junctions and desmosomes.

Pacemaker cells

Specialized cells in cardiac muscle tissue that spontaneously generate electrical signals to initiate contraction without neural input.

Dense bodies

Structures distributed throughout the cytoplasm of smooth muscle cells to which thin filaments attach.