| Meckel's space | The cleft in the meningeal layer of dura of the middle cranial fossa near the tip of the petrous part of the temporal bone; it encloses the roots of the trigeminal nerve and the trigeminal ganglion. Synonym: cavum trigeminale, Meckel's cavity, Meckel's space, trigeminal cavity. (05 Mar 2000) |
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| medial midpalmar space | The more medial of the central palmar spaces, bounded medially by the hypothenar compartment; related distally to the synovial tendon sheaths of digits 3 and 4 and proximally to the common flexor sheath. Synonym: medial midpalmar space, middle palmar space. (05 Mar 2000) |
| mediastinal space | <anatomy> The space in the thoracic cavity behind the sternum and in between the two pleural sacs (containing the lungs). (27 Sep 1997) |
| medullary space | The central cavity and the cellular intervals between the trabeculae of bone, filled with marrow. (05 Mar 2000) |
| respiratory dead space | That portion of the respiratory tract, from the nose and mouth to the terminal bronchioles, in which exchange of oxygen and carbon dioxide does not occur (anatomical dead space), together with the space in alveoli occupied by air that does not participate in oxygen-carbon dioxide exchange (physiologic dead space). It reflects the nonuniformity of ventilation and perfusion in the lung. (12 Dec 1998) |
| retroadductor space | Potential space between the adductor pollicis and first dorsal interosseous muscles. (05 Mar 2000) |
| retroinguinal space | A triangular space between the peritoneum and the transversalis fascia, at the lower angle of which is the inguinal ligament; it contains the lower portion of the external iliac artery. Synonym: Bogros' space, spatium retroinguinale. (05 Mar 2000) |
| retromylohyoid space | The sulcus at the posterior end of the mylohyoid line. (05 Mar 2000) |
| retroperitoneal space | An area occupying the most posterior aspect of the abdominal cavity. It is bounded laterally by the borders of the quadratus lumborum muscles and extends from the diaphragm to the brim of the true pelvis, where it continues as the pelvic extraperitoneal space. (12 Dec 1998) |
| retropharyngeal space | That part of the peripharyngeal spatium located posterior to the pharynx. In the normal adult it measures 4 mm (at C3 level), but is considered abnormal when greater than 7 mm. Can be icreased with a cervical spine fracture, retropharyngeal abscess. Synonym: spatium retropharyngeum, postpharyngeal space. (21 Jun 2000) |
| retropubic space | The area of loose connective tissue between the bladder with its related fascia and the pubis and anterior abdominal wall. Synonym: spatium retropubicum, cavum retzii, Retzius' cavity, Retzius' space. (05 Mar 2000) |
| retrosternal space | On lateral chest radiographs, the region dorsal to the sternum and ventral to the ascending aorta. Synonym: anterior clear space. (05 Mar 2000) |
| Retzius' space | The area of loose connective tissue between the bladder with its related fascia and the pubis and anterior abdominal wall. Synonym: spatium retropubicum, cavum retzii, Retzius' cavity, Retzius' space. (05 Mar 2000) |
| perforated space | See: anterior perforated substance, posterior perforated substance. (05 Mar 2000) |
| Chassaignac's space | Potential space between the pectoralis major and the mammary gland. (05 Mar 2000) |