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MAGNETIC RESONANCE IMAGING (MRI):
A radiologic imaging procedure that uses a magnetic field and radiofrequency waves to produce an image.
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MAIN PULMONARY ARTERY:
Artery originating from the conus arteriosus of the right ventricle, and dividing into the right and left pulmonary arteries under the arch of the aorta. Carries deoxygenated blood to the lungs.
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MALLEOLUS:
Rounded bone process located at either side of the ankle joint. The medial malleolus is part of the distal tibia, the lateral malleolus is the distal fibula.
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MALLEUS:
The largest auditory ossicle (small bone), which attaches to the tympanic membrane (ear drum) and connects to the incus.
Through mechanical linkages, the sound vibrations are amplified and transmitted to the oval window of the cochlea.
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MAMMOGRAM:
A radiograph of the breast.
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Breast Cancer
MANDIBLE:
The lower jaw bone.
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MANDIBULAR CONDYLES:
Posterior superior process of the mandibular ramus that articulates with the mandibular fossa of the temporal bone. (You can feel this while chewing, by putting your finger in your external ear canal.
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MANUBRIUM:
The cranial part of the sternum that articulates with the first two pairs of ribs and the clavicles.
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MASSETER MUSCLE:
One of the muscles of mastication (chewing). Muscle raises the mandible and closes the jaw.
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MASTOID AIR CELLS:
The air spaces within the mastoid process of the temporal bone. The communicate with the pharynx via the eustachian tube.
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MASTOID PROCESS:
Process projecting inferoanteriorly from the petrous portion of the temporal bone, anterior to the ear.
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MAXILLA:
The upper jaw bone that contributes to the formation of the orbit, nasal cavity, and the palate.
MAXILLARY ANTRUM:
The large paranasal sinus under the cheekbones, also called the maxillary sinus.
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MAXILLARY ARTERY:
Originates from the external carotid artery and gives these branches: pterygoid rami, deep auricular, anterior tympanic, inferior alveolar, middle meningeal, masseteric, deep temporal, buccal, posterior superior alveolar, infraorbital, descending palatine, sphenopalatine, and artery of the pterygoid canal ("Vidian artery").
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MAXILLARY SINUS:
One of the paransal sinuses, located on either side of the body of the maxillary bone.
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MEDIAL:
Lying or extending toward the median axis of the body.
MEDIAN:
Lying in the midline.
MEDIAL ARTICULAR FACET (TIBIAL PLATEAU):
The articulating surface of the proximal tibia, forming a joint with the medial and lateral condyles of the distal femur.
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MEDIAL MENISCUS:
A semicircular disk of fibrocartilage between the medial condyle and medial tibial plateau, attached to the medial margin of the superior articulating surface of the tibia.
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Torn Meniscus
MEDIAL PTERYGOID PLATE:
On of a pair of projections from the greater wing of the sphenoid bone that help form the lateral wall of the nasal cavity.
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MEDULLA (Oblongata):
The cone of nerve tissue anterior to the cerebellum and connecting the pons with the cervical spinal cord. It contains nerves responsible for respiration, circulation and special senses.
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MEDULLARY CAVITY:
Within a long bone, the portion of the diaphysis containing marrow.
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MEMBRANEOUS URETHRA:
The portion of the urethra located between the pars prostatica ("prostatic urethra") and pars spongiosa ("penile urethra") in the male.
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MENGINGIOMA:
A hard, firm, or rubbery, slowly growing extraaxial neoplasm, hypervascular, and arising from the arachnoid. They are usually attached to the dura. Meningiomas may cause erosion and thinning of the skull, as well as hyperostosis (bone thickening).
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Meningioma
MENISCUS:
Thin cartilaginous discs, found in the knee between the femur and the tibia, in the jaw between the mandibular condyle and fossa, that reduce friction. The menisci can be damaged by trauma or chronic stress.
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Torn Meniscus
METAPHYSIS:
Portion of a long bone, usually funnel-shaped between the shaft (diaphysis) and the epiphyseal (growth) plate. This is a region of growth and remodelling during development.
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METASTATIC LESION:
The transfer of any pathologic process from one body part to another. Metastasis is usually distinguished from "local extension". Metastasis can be carried by blood-flow ("hematogenous metastasis"), by lymphatic fluid, through the CSF dissemination, by the bronchi (lepidic spread), along the urinary tract, etc.
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Metastasis
METATARSALS:
The five long tubular bones of the foot between the tarsus and the phalanges.
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METATARSAL-PHALANGEAL JOINT:
The point of junction between the metatarsals and phalanges of the foot.
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MIDBRAIN:
(Mesencephalon)The portion of the brain developed from the middle of the three primary vesicles in the embryo. In cross-section, the midbrain resembles "Mickey Mouse": the ears are the cerebral peduncles.
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MIDDLE EAR BONE COMPLEX:
The small bones (malleus("hammer"), incus ("anvil") and stapes ("stirrup"))that conduct sound from the tympanic membrane ("ear drum") to the oval window of the inner ear.
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MIDDLE COLIC ARTERY:
Artery which originates from the superior mesenteric artery, and supplies the transverse colon.
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MIDDLE SACRAL ARTERY:
The continuation of the abdominal aorta, that branches into the lowest lumbar artery.
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MRI:
Magnetic Resonance Imaging.
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MUCOSAL FOLD:
A fold of mucous membrane protruding into the lumen (cavity).
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MYELOGRAM:
A roentgenogram of the spinal cord taken after contrast material has been injected (through an LP needle) into the subarachnoid space of the spinal canal.
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MYLOHYOID MUSCLE:
Muscle which originates at the mylohyoid line of the mandible, and inserts into the body of the hyoid bone and median raphe. It elevates the hyoid bone and supports the floor of the mouth.
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Bug Report
Portions © 1997, 2002-2011 J.G. Smirniotopoulos, M.D. and others.