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ALPHABETICAL INDEX
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

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TERMS AND DEFINITIONS
LINKS TO THE VIRTUAL HUMAN BODY
oblique fissure
Fissure dividing the superior and inferior lobes of the left lung, or separating the superior and middle lobes from the inferior lobe of the right lung.

oblique vein of left atrium
Small vein of the posterior part of the left auricle, emptying into the coronary sinus.

obturator artery
Branch of the internal iliac artery, irrigating the hip and pelvic muscles.

obturator nerve
Nerve arising from the lombar plexus, innervating mainly the adductor muscles, as well as the medial region of the thigh.

obturator veins
Veins draining blood from the hip and certain thigh muscles; they join generally the internal iliac vein.

occipital bone
Unpaired bone forming the back and lower part of the skull and protecting the cerebellum and brain stem.

occipital condyle
Protrusion of the occipital bone where the atlas articulates.

occipital lobe
Cerebral lobe at the back of the brain, near the occipital bone, playing a role in vision (decoding visual information).

occipital muscle
Muscle connecting the occipital bone to the epicranial aponeurosis; it allows the scalp to be drawn back.

occipital pole
The most posterior part of each of the hemispheres of the brain.

occipitofrontal muscle
Muscle formed of two heads (occipital muscle and frontal muscle), allowing various movements of the scalp.

oculomotor nerve
Cranial nerve, essentially motor, responsible for the movement of the eye in the orbit, upper eyelid movements and the adjustment of the opening of the pupil to the amount of light.

olecranon
Upper extremity of the ulna, articulating with the humerus and forming the posterior protrusion of the elbow.

olfactory bulb
Nerve structure supported by the ethmoid bone, above the nasal cavity, collecting nerve signals transmitted by the olfactory nerve and relaying them to the olfactory cortex.

olfactory nerve
Sensory cranial nerve carrying olfactory nerve signals from the olfactory epithelium to the olfactory bulb.

olfactory tract
Bundle of nerve fibers arising from the olfactory bulb, constituting the extension of the fibers of the olfactory nerves.

olive
Core of gray matter located behind each pyramid, at the upper part of the medulla oblongata.

ophthalmic nerve
Terminal branch of the trigeminal nerve, whose twigs innervate especially the eyeball and nasal cavity, as well as the skin of the nose and forehead.

opposing muscle of little finger
Muscle connecting the second row of the carpus to the fifth metacarpal; it allows outward rotation of the little finger.

opposing muscle of thumb
Muscle connecting the trapezium bone and retinaculum of the flexor muscles to the first metacarpal; it allows the inner rotation of the thumb.

optic chiasm
Structure formed by the juncture of the optic nerves of the right and left eye, whose fibers partially intersect, above the hypophysis.

optic nerve
Sensory cranial nerve transmitting to the brain nerve signals arising from the photoreceptors of the retina.

optic tract
Bundle of nerve tissues arising from the optic chiasm, comprising the backward extension of the optic nerve fibers.

oral cavity
Anterior cavity of the digestive tract, serving as the entry point for food and ensuring its initial transformation before being directed to the esophagus.

orbicular muscle of eye
Ring-shaped muscle of the face surrounding the orbit and extending into the eyelids; it controls the movements of the eyelids and periphery of the eye.

orbicularis oris muscle
Ring-shaped muscle surrounding the mouth and allowing the lips to close, purse and pucker.

orbital part of orbicular muscle of eye
Part of the orbicular muscle of the eye surrounding the orbit.

orifice of vermiform appendix
Opening through which the vermiform appendix connects to the cecum.

oropharynx
Median part of the pharynx, communicating with the mouth.

ovary
Each of two female genital glands located on either side of the uterus, producing ova and sex hormones (estrogen and progesterone).