IDIOPATHIC SCOLIOSIS – Structural lateral curvature of an unknown cause.
ILIAC BONE – A part of the pelvic bone that is above the hip joint and from which autogenous bone grafts are frequently obtained.
ILIAC CREST – The large, prominent portion of the pelvic bone at the belt line of the body.
ILIOPSOAS MUSCLE – Large muscles starting at L-1 and becoming wider as it picks up segments from the lower lumbar spine; combines with the iliacus muscle before attaching to the lesser trochanter of the hip.
IMMOBILIZATION – Limitation of motion or fixation of a body part usually to promote healing.
INFANTILE SCOLIOSIS – Lateral curvature of the spine that begins before age 3.
INFRATENTORIAL – Beneath the tentorium.
INFUNDIBULUM – A stalk extending from the base of the brain to the pituitary gland.
INSTRUMENTATION – the use of instruments such as metal screws or braces during a surgical procedure to support bone as it heals.
INTERBODY – between the bodies of two adjacent vertebrae
INTERCOSTALS – The muscles between the ribs.
INTERNAL FIXATION – The immobilization of bone fragments or joints with implants in order to promote healing or fusion.
INTERSPINOUS LIGAMENT – Ligament between each of the spinous processes.
INTERSPINOUS PSEUDARTHROSIS – Formation of a false joint between two spinous processes.
INTERVERTEBRAL DISC – See Disc (Intervertebral).
INTERVERTEBRAL DISC NARROWING – Narrowing of the space between any two vertebral bodies.
INTRA-AORTIC BALLOON COUNTER PULSATION DEVICE – A pump which is inserted into the main vessel of the body, the aorta, to help the heart deliver blood to critical organs such as the brain or kidneys.
INTRACEREBELLAR – Within the cerebellum.
INTRA-ARTERIAL CATHETERIZATION ANGIOGRAPHY – An invasive study in which a catheter (a small tube) is placed in the artery and contrast material is injected to which makes the blood vessels visible on an X-Ray image. The catheter is inserted in the groin into the femoral artery (the artery to the leg) through a needle, and is guided into the arteries in the neck and head. This study is associated with a very small (less than 0.05 % chance of serious complications) and requires the patient to lie in bed for approximately six hours to allow the leg vessel to heal.
INTRACEREBRAL – Within the cerebrum.
INTRACEREBRAL HEMATOMA – A blood clot within the brain.
INTRACRANIAL – Within the cranium of the skull.
INTRACRANIAL PRESSURE (ICP) – The overall pressure inside the skull.
INTRAOPERATIVE CISTERNOGRAPHY – Administration of a contrast dye into the ventricles which are chambers in the brain that contain brain fluid.
INTRAMEDULLARY – Refers to medullaris, marrow; (1) withing the medulla oblongata of the brain, (2) within the spinal cord, and (3) within the marrow cavity of bone.
INTRINSIC – Situated entirely within or pertaining exclusively to a part.
IN VITRO – Describing biological phenomena that are made to occur outside the living body traditionally in a test tube. In vitro is Latin for in glass.
IN VIVO – Within a living body. In vivo is Latin for in life.
INFERIOR – Situated below or directed downward.
INFORMED CONSENT – Consent of the patient who has received sufficient information to have surgery, receive medication, or participate in a clinical study.
INSTITUTIONAL REVIEW BOARD (IRB) – A committee designated by an institution, such as a hospital, to review and approve research projects; e.g., clinical studies in that institution.
INVESTIGATIONAL DEVICE EXEMPTION (IDE) – A FDA regulatory status which permits the human use of an unapproved medical device for the purposes of collecting clinical data under strictly controlled conditions.
ISCHEMIA – Inadequate circulation of blood generally due to a blockage of an artery.
ISOLA – A posterior fixation device.
ISOMETRIC – Of equal dimensions. In physiology, denoting the condition when the ends of a contracting muscle are held fixed so that contraction produces increased tension at a constant overall length.
ISOTONIC – Relating to isotonicity or isotonia. Having equal tension; denoting solutions possessing the same osmotic pressure; more specifically, limited to situations in which cells can neither swell nor shrink.
ISTHMIC – The lesion is in the pars interarticularis. Three types occur: lytic, fatigue fracture of the pars interarticularis; elongated but intact pars interarticularis; and acute fracture of the pars interarticularis.