I is for...

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 attatching 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 he 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 possesing 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.