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107 • Where are sesamoid bones found? • What does the formation of bone depend on? • What are the bones of the fetus composed of? • What bones are soft body parts covered by? • What do haversian canals contain? • Where can we fin red bone marrow/yellow bone marrow? • What’s the difference between red bone marrow and yellow bone marrow? • What is osseous tissue? • What types of bones are there? • What’s the difference between cartilage and osseous tissue? • What is the diaphysis?/epiphysis? • What is the function of articular cartilage? • What is compact bone? UNIT 4 1. Translate the text. Parts of a Tooth All teeth no matter what type consist of the same three parts: a root em‑ bedded in a socket in the alveolar process of a jaw bone, a crown projecting upward from the gum and a narrowed neck between the root and the crown, which is surrounded by the gum. The incisors, canines and premolars have a double root. The lower molars have two flattened roots, and the upper mo‑ lars have three conical roots. At the apex of each root is the apical foramen, which leads successively into the root canal and root cavity. Each tooth is composed of dentine, enamel, cement and pulp. The den‑ tine is the extremely sensitive yellowish portion surrounding the pulp cavity. It forms the bulk of the tooth. The enamel is the insensitive white covering of the crown. It is the hardest substance in the body. In order to cut through enamel, a dentist’s drill spins at about half a million revolutions per minute. The cement is the bonelike covering of the neck and root. The pulp is the soft core of the connective tissue that contains the nerves and blood vessels of the tooth. Teeth are derived from the same tissue as the skin. The enamel is formed from the embryonic epidermis, and the dentine, pulp, and cement are formed from the embryonic dermis.