The primary structures of the head are comprised of several key elements, namely the lacrimal glands, eyelids, teeth and palate. The lacrimal glands are exocrine glands located in the superolateral aspect of the orbit of each eye responsible for the production and distribution of tears to lubricate the eyes. This serous secretion is passed over the conjunctiva and cornea, and drained from the eye through the lacrimal apparatus into the nasal cavity. The eyelids, which are small folds of skin, not only protect the eyes from excessive light and trauma but also aid in the distribution of tears.
The teeth, organised into the upper and lower arches, are situated within the oral cavity. There are 20 primary teeth that typically appear in the 6-month-old infant, and these are later replaced by the permanent, adult dentition, comprised of 32 teeth. The four main types of teeth are incisors, canines, premolars and molars, each of which has two structural elements: a crown and a root.
The palate, or roof of the mouth, separates the nasal and oral cavities into two distinct parts: the hard palate in the anterior section and the soft palate in the posterior section.
Incisors, which are located in the front of the mouth, are the smallest teeth and are used primarily for cutting and biting. Canines are the pointy teeth used for tearing foods, and premolars and molars also support the cutting, grinding and crushing of food.
The lacrimal glands, which are exocrine glands, are located in the superolateral aspect of the orbit of each eye and are primarily responsible for producing and secreting tears to lubricate the eyes. The tears are formed by the serous secretion of the lacrimal glands, which pass over the conjunctiva and cornea, and are then drained through the lacrimal apparatus into the nasal cavity. The lacrimal glands are important for the protection of the eyes as they provide tears that not only help to flush out foreign particles or irritants from the surface of the eyes, but also contain proteins, electrolytes, and other elements that protect the eyes from infection.
The eyelids play an important role in the protection of the eyes. The eyelids, which are small folds of skin, serve to protect the eyes from excessive light and trauma, while also aiding the lacrimal glands in the distribution of tears through the eyes. In addition to this protective role, the eyelids also serve to lubricate and moisturize the eyes by collecting tears and redistributing them across the surface of the eye.
The palate, also known as the roof of the mouth, is the boundary between the nasal and oral cavities and is divided into two distinct parts – the hard palate, which is located in the anterior section, and the soft palate, which is located in the posterior section. The hard palate serves as a supportive structure for the mouth and as a base for the internal nasal cavities, while the soft palate serves as a supportive structure for speech and swallowing. In addition, the soft palate also helps to prevent food from entering the nasal cavities during swallowing.
