| placenta, accessory | An extra placenta separate from the main placenta. Also called a succenturiate or supernumerary placenta. Placenta accreta: the abnormal adherence of the chorionic villi to the myometrium. The vascular processes of the chorion (a foetal membrane that enters into the formation of the placenta) grow directly in the myometrium (the muscular portion of the uterus). Normally there is tissue intervening between the chorionic villi and the myometrium. Here there is not. The word accreta comes from the latin accretio from ad meaning to or toward + crescere meaning to grow. Placenta accreta can progress to placenta percreta. (12 Dec 1998) |
|---|---|
| companion lymph nodes of accessory nerve | The nodes of the lateral deep cervical group that are located along the accessory nerve; their efferent vessels pass to the supraclavicular lymph nodes. Synonym: companion lymph nodes of accessory nerve, nodi lymphatici comitantes nervi accessorii. (05 Mar 2000) |
| cranial root of accessory nerve | <anatomy, nerve> The roots of the accessory nerve which arise from the medulla; the nerve fibres of the cranial root join the intracranial portion of the vagus nerve and are distributed to the pharyngeal plexus, providing the motor innervation of the soft palate (except the tensor veli palati) and the pharynx. Synonym: pars vagalis nervi accessorii, radices craniales, accessory portion of spinal accessory nerve, cranial roots, vagal part of accessory nerve, vagal part. (05 Mar 2000) |
| spinal accessory nerve | <anatomy, nerve> The eleventh cranial nerve enervates the sternocleidomastoid muscles and the trapezius muscles. Lesions of the eleventh result in drooping of the shoulder and inability to rotate the head away from the affected side. (27 Sep 1997) |
| spinal part of accessory nerve | <anatomy, nerve> Originates from the upper five or six cervical spinal segments, emerges from the lateral surface of the spinal cord and ascends through the foramen magnum to join the cranial root. Synonym: radices spinales nervi accessorii, ramus externus nervi accessorii, pars spinalis nervi accessorii, spinal part of accessory nerve. (05 Mar 2000) |
| spinal root of accessory nerve | <anatomy, nerve> Originates from the upper five or six cervical spinal segments, emerges from the lateral surface of the spinal cord and ascends through the foramen magnum to join the cranial root. Synonym: radices spinales nervi accessorii, ramus externus nervi accessorii, pars spinalis nervi accessorii, spinal part of accessory nerve. (05 Mar 2000) |
| dorsal accessory olivary nucleus | A detached part of the olivary nucleus dorsal to the latter's main body. Synonym: nucleus olivaris accessorius dorsalis. (05 Mar 2000) |
| inferior accessory fissure | The fissure that commonly separates the medial basal segment of the right lower lobe of the lung from the other basal segments, seen as an oblique line near the right heart border on chest radiographs. (05 Mar 2000) |
| internal branch of accessory nerve | <anatomy, nerve> Branch of the accessory nerve trunk which carries fibres from the cranial root and which unites with the vagus nerve in the jugular foramen. See: accessory nerve. Synonym: ramus internus nervi accessorii, internal ramus of accessory nerve. (05 Mar 2000) |
| internal ramus of accessory nerve | <anatomy, nerve> Branch of the accessory nerve trunk which carries fibres from the cranial root and which unites with the vagus nerve in the jugular foramen. See: accessory nerve. Synonym: ramus internus nervi accessorii, internal ramus of accessory nerve. (05 Mar 2000) |
| external branch of accessory nerve | <anatomy, nerve> Portion of the accessory nerve trunk which exits independently from the jugular foramen, carrying fibres from the spinal root of the accessory nerve to the sternocleidomastoid and trapezius muscle. (05 Mar 2000) |
| anastomotic veins | See: inferior anastomotic vein, superior anastomotic vein. (05 Mar 2000) |
| anonymous veins | An obsolete term for brachiocephalic veins. (05 Mar 2000) |
| anterior cardiac veins | Two or three small veins in the anterior wall of the right ventricle opening directly into the right atrium independently of the coronary sinus. Synonym: venae cordis anteriores. (05 Mar 2000) |
| anterior cardinal veins | See: cardinal veins. (05 Mar 2000) |