Abduction — Movement of an extremity away from the body.

Abscess — A pus-filled area that affects skin or organs.

Acromegaly — Overgrowth of the bones of the hands, feet, and face.

Acromion process — A lateral condensation of bone that is the attachment site for the lateral and posterior two thirds of the deltoid muscle.

Acupuncture — The insertion of needles into precisely defined points on the body; thought to realign imbalances of yin-yang and qi and thereby bring harmony to the “climate” of an individual

Adduction — Movement of an extremity toward the body.

Adenopathy — Enlargement of the glands.

Adhesive capsulitis — Self-limiting condition resulting from any inflammatory process about the shoulder in which capsular scar tissue is produced, resulting in pain and limited range of motion; also called frozen shoulder

Allergen — A substance that produces an allergic reaction. Allograft Biologic tissue from a cadaver that is used to surgically replace damaged tissue

Ambulatory condition — Assessment of the injured athlete where the athlete is seen by the athletic trainer at some point following the injury.

Amenorrhea — Loss of the menstrual cycle. Considered part of the female athlete triad.

Anabolic steroids — Synthetic derivatives of testosterone originally developed to treat hypogonadism in men, lost muscle mass in patients debilitated by illness, and severe anemia. Sometimes used to enhance muscle-building effects in athletes.

Anaerobic exercise — Exercise of short duration, not requiring the body’s utilization of oxygen to make fuel available

Anaerobic metabolism — Oxygen debt; when the cardiovascular system is unable to meet the needs of the working muscles, the anaerobic metabolism is activated Analgesia The relief of pain

Analgesic — A pain-relieving effect with no loss of consciousness. Anaphylaxis A violent hypersensitivity reaction, resulting in shock.

Angina — Chest pain.

Ankylosing spondylitis — An inflammatory disorder that affects the low back and pelvis and produces stiffness and pain

Ankylosis — Marked stiffness of a joint typically observed with end-stage arthritis, following a complex intra-articular fracture, delayed treatment of septic arthritis, or severe rheumatoid arthritis

Annulus fibrosus — A region of the intervertebral disk that provides support for the nucleus.

Antagonists — Muscles that produce body movement in opposing directions.

Anterior compartment syndrome — Increased soft-tissue pressure in the anterior compartment of the lower leg, resulting in pain, decreased sensation, and muscle paralysis

Anterior cruciate ligament tears — An acute knee injury that occurs when the foot is planted, the knee is flexed, and a valgus force is applied to the knee with the lower leg in external rotation; commonly occurs in sports that require twisting, jumping, and pivoting.

Anterior superior iliac spine — Blunt bony projection on the anterior border of the ilium, forming the anterior end of the iliac crest. Serves as the origin of the sartorius muscle.

Anterior surface — Surface at the front of the body, facing the examiner

Anteromedial rotatory instability — When the medial plateau of the tibia rotates anteriorly and medial joint opening occurs, indicating disruption of the superficial tibia collateral ligament, medial and posteromedial capsular structures, and anterior cruciate ligament

Anteroposterior (AP) view — Anterior-posterior view in which the x-ray tube is in front and the film cassette is in back. The x-ray beam passes from front to back. Antidote A substance that can counteract a poison.

Antigens — Foreign substances that can infiltrate the body, including bacteria, fungi, parasites, toxic chemicals, and abnormal body cells, prompting the production of antibodies that attempt to destroy the substances.

Anulus fibrosus — The outer ring of fibrous material surrounding the nucleus of the intervertebral disks

Aponeurosis — A broad, fibrous sheet that attaches one muscle to another.

Apophysis — A cartilaginous structure at the insertion of major muscle groups into bone that may be susceptible to overuse syndromes and acute fractures in pediatric athletes.

Appendicitis — Inflammation of the appendix, the small intestinal pouch that extends from the cecum.

Arrythmia — Irregular heartbeat.

Arterioles — Small tubular branches of the arteries.

Arthrocentesis — Aspiration of a joint

Arthrodesis — The surgical fusion of a joint. The procedure removes any remaining articular cartilage and positions the adjacent bones to promote bone growth across a joint. A successful fusion eliminates the joint and stops motion. The usual purpose is pain relief or stabilization of an undependable joint

Arthrography — A procedure in which a contrast medium is injected into a joint to outline soft tissues such as the meniscus in the knee or a torn structure such as the rotator cuff in the shoulder. MR arthrography is a technique in which a diluted contrast medium such as gadolinium is injected into a joint to improve the delineation of soft tissues. Standard MRI is obtained following the injection.

Arthrokinematic motion — Vertebral motion that occurs within the joint capsule at the articulations.

Arthroplasty — Procedure to replace or mobilize a joint, typically performed by removing the arthritic surfaces and replacing them with an implant. Total joint arthroplasty is replacement of both sides of the joint. Hemiarthroplasty replaces only one side of a joint

Arthroscopy — A form of minimally invasive surgery in which a fiberoptic camera, the arthroscope, is introduced into an area of the body through a small incision

Articular cartilage — A smooth, glistening surface that covers the ends of bones that articulate with each other to form a joint.

Aspiration — Removal of fluids from a body cavity; often done to obtain specimens for analysis

Atlantoaxial subluxation (AAS) — An orthopaedic problem seen frequently in athletes with Down syndrome that poses a significant risk to athletes participating in sports that involve bodily contact. Joint looseness, ligamentous laxity, or malformation of the vertebrae or surrounding structures causes the C1 vertebra to slip forward and compress the spinal cord, particularly when the neck is in flexion or extension.

Atlanto-occipital fusion — A rare condition consisting of congenital fusion of the ring of the atlas to the occiput; considered an absolute contraindication for contact sports.

Atlas — The first cervical vertebra (C1).

Atrium — The upper chambers of the heart, composed of the left and right atria.

Autograft — Biologic tissue from the patient’s own body that is used to surgically replace damaged tissue

Autonomic dysreflexia — A health concern for athletes with a spinal cord injury above level T8 in which the athlete experiences dizziness, sweating, headaches, and potentially severe hypertension. A plugged urethral catheter