PULMONARY, _pulmonic_ (L. _pulmo_, the lungs). Relating or belonging to the lungs. PULSE (L. _pulsus_, a stroke). A beating or striking; and hence, the stroke or beat of an artery. PUNCTA LACHRYMALIA. The external commencements of the lacrymal ducts. PUPILA (L. dim. of _pupa_, a puppet). The pupil, or the round aperture in the center of the iris of the eye. PYLORUS (Gr. _púle_, a gate, _ora_, care). Literally a _gate-keeper_. The lower and contracted orifice of the stomach, guarding the entrance into the bowels. Q QUARTZ. A species of silicious minerals. R RAMIFICATION (L. _ramus_, a branch, _fio_, to become). The issuing of a small branch from a large one, as of the minute branches from the larger arteries. RAMUS. A branch of a tree; the designation of portions of several bones. RECTUM (L. _rectus_, straight). The last portion of the intestines. REFRACTION (L. _refractus_, broken back). The property of light, by which a ray becomes bent, or _refracted_, when passing from a rarer into a denser medium, and _vice versá_. RESPIRATION. The function of breathing. RETINA (L. _rete_, a net). The _net_ like expansion of the optic nerve on the inner surface of the eye. S SAC (L. _saccus_, a bag). A term applied to a small cavity, as the lacrymal sac. SACRUM (L. _sacred_). The bone which forms the basis of the vertebral column; so called from its having been offered in sacrifice, and hence considered _sacred_. SACRO. A term applied to parts connected with the sacrum. Hence we have _sacro_-iliac symphysis, _sacro_-spinal ligament, _sacro_-vertebral angle, &c. SALIVA. The insipid, transparent, viscous liquid secreted by the salivary glands, principally the parotid. SANGUIS. Blood; the fluid which circulates in the heart, arteries and veins. SARTORIUS (L. _sartor_, a tailor). The muscle by means of which the tailor crosses his legs. SCAPULA. The shoulder-blade. SCHNEIDERIAN MEMBRANE. The _pituitary membrane_, which secretes the mucous of the nose; so named from Schneider, who first described it. SCLEROTICA (Gr. _sklēròs_, hard). The dense fibrous membrane which, with the _cornea_, forms the external tunic of the eye ball. SEBACEOUS (L. _sebum_, suet). Suety; a term applied to _follicles_, which secrete a peculiar oily matter, and are abundant in some parts of the skin, as in the nose, &c. SECRETION (L. _secerno_, to separate). A substance _secreted_ or separated from the blood by the action of a secreting organ. SERUM. The thin yellowish fluid constituent of the blood. SINCIPUT. The fore part of the head. The back part is called _occiput_. SINEW. The ligament which joins two bones. SINUS. A gulf. Hence it denotes a cavity or cell within the substance of a bone, as of the forehead; also a large venous canal, as those of the dura mater.