The pterygomandibular space is a potential anatomical area located in the head, near the back of the lower jaw. It is a fascial-lined cleft filled with loose connective tissue. This paired space is important for understanding dental procedures and related health concerns.
Anatomy of the Pterygomandibular Space
This space is situated between the inner surface of the jawbone and a major chewing muscle. Specifically, the lateral boundary is formed by the medial surface of the mandibular ramus, which is the inner part of the ascending jawbone. The medial boundary is defined by the medial pterygoid muscle, a muscle involved in closing the jaw and moving it side to side. An aponeurosis, or fibrous sheet, known as the interpterygoid fascia also contributes to its boundaries, extending between the medial and lateral pterygoid muscles.
Several important structures pass through this confined area. The inferior alveolar nerve, a branch of the trigeminal nerve, travels through the space before entering the mandibular foramen, an opening on the inner surface of the jawbone. This nerve is responsible for providing sensation to all the lower teeth, the gum tissue on the cheek side of the lower teeth, and the skin of the chin and lower lip on its side.
Another significant structure within the space is the lingual nerve, which provides general sensation and taste perception to the front two-thirds of the tongue. Alongside these nerves are the inferior alveolar artery and vein, which supply blood to and drain blood from the lower jaw and teeth. The nerve to mylohyoid and the sphenomandibular ligament are also present in this anatomical region.
The Target for Dental Anesthesia
Dentists frequently target the pterygomandibular space to achieve numbness in the lower jaw, a procedure known as an Inferior Alveolar Nerve Block (IANB). This common injection aims to deposit local anesthetic solution precisely next to the inferior alveolar nerve before it enters the bone of the mandible. The goal is to temporarily block nerve impulses, thereby eliminating pain sensation in the areas supplied by this nerve.
As a result, the teeth in the lower jaw on that side, along with the surrounding gum tissue, become numb. This provides comprehensive anesthesia for various dental treatments.
Performing an IANB requires a thorough understanding of the specific anatomical landmarks within the pterygomandibular space. The dentist must accurately identify the injection site, typically near the mandibular foramen, to ensure the anesthetic is delivered effectively to the nerve. The procedure is considered technique-sensitive due to the varying positions of the nerve and surrounding structures, making accurate needle placement a skill developed through experience. This technique is routinely employed for procedures such as tooth extractions, fillings, root canals, and other treatments involving the lower teeth and jawbone.
Infections and Complications
The pterygomandibular space can become involved in infections, often originating from dental issues. An infected lower molar tooth, for instance, can allow bacteria to spread into this fascial space, leading to an abscess. Such infections often manifest with pain in the jaw area, facial swelling, and difficulty in opening the mouth, a condition known as trismus.
These infections require prompt medical or dental intervention. Treatment usually involves antibiotics, often combined with surgical drainage of the abscess. Without timely treatment, these infections can spread to other fascial spaces in the head and neck, leading to widespread complications.
Injections into the pterygomandibular space, while generally safe, can occasionally lead to complications. One common issue is a hematoma, a deep bruise resulting from the needle inadvertently piercing a blood vessel, typically the inferior alveolar artery or vein. This can cause swelling and discoloration, usually resolving on its own over several days.
Another potential complication is post-injection trismus, where the muscles of mastication, particularly the medial pterygoid, experience soreness or spasm after the injection. This can make it temporarily difficult to open the mouth wide. Although rare, direct trauma to the inferior alveolar or lingual nerve by the needle can occur, leading to temporary or, in very infrequent cases, permanent numbness or altered sensation in the affected areas.