Skeletal and Muscular Systems Lecture Notes

Comprehensive vocabulary based on skeletal anatomy, joint classification, and muscular physiology from chapters 7, 8, and 9.

Acetabul-

Vinegar cup: acetabulum-depression of the hip bone that articulates with the head of the femur.

Ax-

Axis: axial skeleton-bones of the skull, vertebral column, ribs, and sternum.

Osteoblast

A cell that will form bone tissue; a bone-forming cell.

Osteoclast

A cell that breaks down or resorbs bone tissue.

Hematopoiesis

The process of blood cell formation.

Long bones

Bones with long longitudinal axes and expanded ends, such as the femur and humerus.

Epiphysis

The expanded portion at each end of a long bone that forms a joint with another bone.

Diaphysis

The shaft of a long bone located between the epiphyses.

Periosteum

A tough, vascular covering of dense connective tissue that encloses a bone, except for the articular cartilage on its ends.

Compact bone

Also called cortical bone; tightly packed tissue that forms the wall of the diaphysis with a continuous extracellular matrix and no gaps.

Spongy bone

Also called cancellous bone; bone tissue consisting of many branching bony plates called trabeculae.

Osteon

A cylinder-shaped unit formed by osteocytes and layers of extracellular matrix (lamellae) concentrically clustered around a central canal in compact bone.

Perforating canals

Also known as Volkmann's canals; transverse canals that connect central canals and contain larger blood vessels and nerves.

Epiphyseal plate

A band of hyaline cartilage that remains between the primary and secondary ossification centers, serving as the growth area for a long bone.

Vitamin D

A nutrient necessary for proper absorption of dietary calcium in the small intestine; deficiency causes rickets in children and osteomalacia in adults.

Axial skeleton

The division of the skeleton consisting of the bony and cartilaginous parts that support and protect the organs of the head, neck, and trunk.

Appendicular skeleton

The division of the skeleton consisting of the bones of the upper and lower limbs and the bones that anchor the limbs to the axial skeleton.

Sutures

Immovable joints where the flat bones of the skull are tightly joined along irregular lines.

Fontanels

Fibrous membranes or "soft spots" in an infantile skull that permit molding during childbirth.

Atlas

The first cervical vertebra (C1) which supports the head and articulates with the occipital condyles.

Axis

The second cervical vertebra (C2) which bears a toothlike dens (odontoid process) that allows the head to turn side to side.

Fibrous joints

Joints where dense connective tissue holding bones together includes many collagen fibers; examples include syndesmosis, sutures, and gomphosis.

Synovial joints

Freely movable joints (diarthrotic) that consist of articular cartilage, a joint capsule, and a synovial membrane that secretes synovial fluid.

Menisci

Articular discs of fibrocartilage that partially or completely divide some synovial joints into two compartments.

Bursae

Fluid-filled sacs lined with synovial membrane that cushion and aid the movement of tendons over bony prominences.

Flexion

Bending parts at a joint so that the angle between them decreases and the parts come closer together.

Abduction

Moving a part away from the midline or away from the axial line of the limb.

Proprioception

The underlying basis for movement and force facilitated by how nerves stimulate muscles.

Fascia

A layer of fibrous connective tissue that surrounds an entire muscle and is continuous with the epimysium.

Sarcomere

The functional unit of muscle contraction, extending from one Z line to the next along a myofibril.

Myosin

The protein that composes thick filaments in muscle fibers, featuring heads that can form cross-bridges with actin.

Actin

The primary protein that composes thin filaments, featuring binding sites for myosin heads.

Acetylcholine (ACh)

The neurotransmitter used by motor neurons to control skeletal muscle contraction.

Creatine phosphate

The initial source of energy available to regenerate ATP from ADP and phosphate in muscle cells.

Myoglobin

A pigment synthesized in muscle cells that can loosely bind oxygen, increasing its availability for aerobic respiration.

Oxygen debt

The amount of oxygen required by liver cells to convert accumulated lactic acid to glucose and by muscle cells to resynthesize ATP and creatine phosphate.

Twitch

The contractile response of a single muscle fiber to a single impulse.

Motor unit

A motor neuron and all of the muscle fibers it controls.

Isotonic contraction

A contraction that involves a change in muscle length while the force remains constant; includes concentric (shortening) and eccentric (lengthening) types.

Isometric contraction

A contraction where tension increases but the muscle does not change length, such as pushing against a wall.

Peristalsis

Wavelike motion of certain tubular organs produced by alternate contractions and relaxations of visceral smooth muscle.

Intercalated discs

Complex intercellular junctions that connect the ends of cardiac muscle cells, allowing impulses to travel rapidly from cell to cell.

Agonist

A muscle that causes a specific action; also known as a prime mover if it provides most of the force.

Antagonist

A muscle that works against or opposes a specific action.

Synergist

A muscle that contributes to an action by helping the agonist.