Músculos de la masticación

Introduction to Temporomandibular Joint

In this section, the speaker introduces the topic of the muscles of mastication and provides an overview of the temporomandibular joint (TMJ).

Temporomandibular Joint (TMJ)

• The TMJ is a synovial joint that connects the mandible to the temporal bone.

• It consists of two compartments: one between the disc and the mandibular fossa, and another between the disc and the condyle of the mandible.

• The upper compartment allows sliding movement of the disc on the fossa during jaw opening, while the lower compartment enables natural movements of opening and closing.

Types of TMJ Movements

This section discusses different types of movements facilitated by the TMJ.

Types of Movements

• The TMJ allows various movements such as opening, closing, protrusion, retraction, and lateral movements.

• These movements are essential for processes like chewing and speech production.

Ligaments and Stabilization of TMJ

Here, we learn about ligaments that stabilize the TMJ.

Ligaments

• The TMJ is stabilized by ligaments, including:

• Lateral ligament: Divided into transverse and oblique portions. The transverse portion limits backward movement of the condyle, while the oblique portion prevents excessive downward displacement.

• Sphenomandibular ligament: Extends from spine-like process in sphenoid bone to near angle of mandible.

• Stylomandibular ligament: Runs from styloid process to angle of mandible.

Maximum Opening of the Jaw

This section discusses the maximum opening capacity of the jaw and potential risks.

Maximum Opening

• The maximum opening of the jaw is typically around 25 millimeters, equivalent to three fingers.

• Opening beyond this range may risk condyle displacement and subluxation, leading to potential injuries.

TMJ in Different Positions

Here, we explore how the TMJ appears in different positions.

TMJ Positioning

• In a closed mouth position, the condyle is properly aligned with the disc and fossa.

• During jaw opening, the condyle moves forward while maintaining contact with the disc.

• Excessive opening can cause anterior displacement of the condyle, requiring reduction to restore proper alignment.

Visualization of TMJ on Imaging

This section focuses on visualizing the TMJ using imaging techniques.

Imaging of TMJ

• Imaging techniques like MRI can provide detailed visualization of various components of the TMJ.

• These images help identify any abnormalities or displacements that may require further evaluation or treatment.

The transcript provided does not cover all aspects discussed in the video.

New Section

This section discusses the different movements of the mandible and their association with various processes.

Movements of the Mandible

• The mandible allows for different movements, including mandibular depression (opening the mouth), mandibular elevation (closing the mouth), protraction (bringing the jaw forward), and retraction (moving the jaw backward).

• These movements are a fusion of different actions and are referred to as arcs of mobility. They are essential for vital functions such as eating and speaking.

New Section

This section explores specific muscles involved in mandibular movements.

Muscles Involved in Mandibular Movements

• The temporal muscle, located in the temporal fossa, is responsible for jaw elevation. It originates from the coronoid process and inserts into the anterior part of the mandibular ramus.

• The masseter muscle originates from the lower border of the zygomatic arch and inserts into the angle of the mandible. It aids in jaw elevation and is one of the strongest muscles involved in chewing.

• The medial pterygoid muscle has its origin at both the tuberosity of maxilla and deep portion at pterygoid process. It inserts on inner side at angle of mandible known as mylohyoid line.

• The lateral pterygoid muscle has two portions: superior and inferior. Its origin is at greater wing of sphenoid bone, while it inserts superficially into articular disc and joint capsule, and inferiorly at neck region of condyle process.

New Section

This section discusses the coordination of muscles during different mandibular movements.

Coordination of Muscles in Mandibular Movements

• Different muscles work together to perform various actions. For example, jaw elevation is assisted by the temporal muscle, masseter muscle, and medial pterygoid muscle.

• The specific combination of muscles involved depends on the desired movement, such as opening, closing, ascending, descending, or retracting the jaw.

New Section

This section explores the blood supply and innervation of the mandible and associated muscles.

Blood Supply and Innervation

• The muscles involved in mandibular movements are generally supplied by the maxillary artery. Specific branches include the anterior tympanic artery, inferior alveolar artery (which enters the mandibular canal), mental artery (supplying lower teeth), and middle meningeal arteries (supplying temporal region).

• Venous drainage occurs through a plexus called the maxillary venous plexus. Blood is collected from both superficial and deep areas and drains into the retromandibular vein.

New Section

This section provides information about drainage pathways for blood from the mandible.

Drainage Pathways

• Venous blood from the mandible is drained through a network called the maxillary venous plexus. It then flows into the retromandibular vein via a branch known as Vena Emissaria de Santorini.

Trigeminal Nerve Branches

This section discusses the three branches of the trigeminal nerve and their respective functions.

Trigeminal Nerve Branches

• The first branch is called the ophthalmic branch, which provides sensory innervation to the eye area.

• The maxillary branch supplies sensory innervation to the middle third of the face, including the mucosa, sinuses, and teeth.

• The mandibular branch is the only mixed branch among the three. It provides sensory innervation to the lower third of the face and motor innervation to the muscles of mastication.

Sensory Innervation of Teeth

This section focuses on the sensory innervation of teeth by discussing the superior alveolar nerves.

Sensory Innervation of Teeth

• The superior alveolar nerves are responsible for providing sensation to each individual tooth.

Mandibular Branch Function

This section explains in detail about the mandibular branch of the trigeminal nerve and its functions.

Mandibular Branch Function

• The mandibular branch is responsible for providing sensory innervation to the lower third of the face through a terminal nerve called nervus antonius.

• It also supplies motor innervation to all muscles involved in mastication.

• Additionally, it provides vascular supply to all lower teeth.

Timestamps are provided in seconds (s).