The ramus of the mandible, also known as the mandibular ramus, is a long, vertical bone that extends from the mandible’s body and forms the posterior part of the mandibular angle. The mandible is the lower jawbone and is a vital structure in the human body that plays a key role in the chewing process, as well as in speech and facial expression.
Structure
The ramus of the mandible is a flat, triangular bone that is located on the posterior aspect of the mandible. It is composed of two surfaces, two borders, and two extremities.
The superior surface of the ramus is convex and is covered by a thin layer of muscle called the masseter muscle. The inferior surface is concave and is in contact with the pterygoid muscles.
The anterior border of the ramus is sharp and forms the mandibular angle, while the posterior border is rounded and serves as the attachment site for the temporalis muscle.
The inferior extremity of the ramus is called the condyle, which is a rounded protuberance that articulates with the temporal bone of the skull at the temporomandibular joint (TMJ). The superior extremity of the ramus is called the coronoid process, which is a sharp projection that serves as the attachment site for the temporalis muscle.
Location
The ramus of the mandible is located on the posterior aspect of the mandible, just below the ears. It extends from the body of the mandible to the mandibular angle, where it meets the mandibular body at the mandibular foramen.
The mandibular foramen is a small opening located on the inner surface of the mandible and serves as the passage for the inferior alveolar nerve and vessels. These nerves and vessels supply the lower teeth with blood and sensation.
Function
The main function of the ramus of the mandible is to provide attachment for the muscles of the jaw and neck, including the masseter, temporalis, and pterygoid muscles.
The masseter muscle is a powerful muscle that is responsible for closing the jaw and is attached to the superior surface of the ramus. The temporalis muscle is a large muscle located on the side of the head and is responsible for moving the mandible laterally and protruding the jaw. It is attached to the coronoid process and the posterior border of the ramus.
The pterygoid muscles are located in the floor of the mouth and are responsible for moving the mandible forward and backward. They are attached to the inferior surface of the ramus.
In addition to providing attachment for the muscles of the jaw and neck, the ramus of the mandible also plays a vital role in the chewing process. The condyle at the inferior extremity of the ramus articulates with the temporal bone of the skull at the temporomandibular joint (TMJ), allowing for the mandible to move up and down and side to side during chewing.
