Anatomía - Músculos Masticadores (Origen e Inserción, Relaciones, Acción)

Masticatory Muscles Overview

In this section, the instructor introduces the topic of masticatory muscles, discussing their origin, insertion, relationships, innervation, and action within the stomatognathic system.

Masticatory Muscles Composition

• The masticatory muscles belong to the stomatognathic system composed of soft tissues, bones, and nervous elements responsible for vital functions like speech, swallowing, and chewing.

Classification of Masticatory Muscles

• There are four main masticatory muscles derived from the first pharyngeal arch along with the trigeminal nerve and internal maxillary artery.

• These muscles share common innervation through the mandibular division of the trigeminal nerve and are predominantly supplied by the internal maxillary artery.

• The four muscles include temporalis muscle, masseter muscle (medial and lateral parts), and medial pterygoid muscle.

• While some sources include the gastric muscle in this group, it is often studied separately due to its region-specific functions.

Temporalis Muscle Anatomy

• The temporalis muscle is a broad triangular muscle located in the temporal fossa. It originates from various points including the inferior temporal line and extends downwards passing through the middle third of the internal face of zygomatic arch.

• Its insertion occurs at structures such as coronoid process via a strong shiny tendon.

Relationships of Temporalis Muscle

• The temporalis muscle has two faces and three edges; while edges are less significant, faces play crucial roles.

• The deep face rests on the temporal fossa while interacting with deep temporal arteries and nerves.

• Arteries like anterior deep temporal artery originate from internal maxillary artery whereas nerves like anterior deep temporal nerve stem from mandibular nerve.

Vascular Supply & Innervation

This section delves into vascular supply and innervation details concerning the temporalis muscle.

Vascular Supply Details

• The arterial supply to the temporalis muscle includes branches from both superficial (temporal) and deep (anterior/posterior) temporal arteries originating from external carotid artery branches.

• Additionally, blood supply comes through superficial temporal artery branches ensuring adequate perfusion.

Innervation Insights

• Nerve supply involves anterior/posterior deep temporal nerves stemming from mandibular nerve that elevate mandible effectively.

• These nerves work alongside other structures like facial arteries to ensure proper functioning during jaw movements.

New Section

This section discusses the muscles involved in jaw movement and their origins.

Temporal Muscle

• The temporal muscle causes retraction of the jaw, positioning the lower dental arch behind the upper arch.

Masseter Muscle

• The masseter muscle is powerful and crucial for chewing, originating from the zygomatic arch.

• It has superficial and deep fascicles originating from different parts of the zygomatic arch.

Muscular Relations

• The masseter muscle extends to the outer face of the mandible's ramus.

• It interacts with other muscles like the buccinator and structures like Bichat's fat pad.

Muscle Anatomy

• Describes the deep and superficial faces of the masseter muscle.

• Covers relationships with adjacent structures like facial vessels and nerves.

Vascular Supply

• Receives blood supply from various arteries including facial arteries.

New Section

This part focuses on vascular supply, innervation, and actions of the masseter muscle.

Blood Supply

• The masseter receives rich blood supply due to its high metabolic activity.

Innervation

• Innervated by branches of facial nerves related to chewing functions.

Muscle Action

New Section

In this section, the speaker discusses the muscles and their relationships in the oral cavity.

Muscles and Their Relationships

• The quadrilateral muscle, also known as the masseter muscle or internal pterygoid muscle, is related to the lateral walls of the pharynx and the pharyngeal fascia.

• The tensor veli palatini muscle is externally related to the external pterygoid muscle.

• The medial pterygoid muscle receives dual blood supply: one from the facial artery in its neck course and another branch from the internal maxillary artery.

• The medial pterygoid muscle is innervated by a branch of the mandibular nerve directly from its trunk.

• The lateral pterygoid muscle has two fascicles (superior and inferior) that insert into different areas around the temporomandibular joint.

New Section

This section delves into further details about muscles' origins, insertions, and relationships within the oral cavity.

Muscle Origins, Insertions, and Relationships

• The lateral pterygoid muscle's insertion includes areas such as infra temporal crest, trigon process, tuberosity of maxilla, and external wing of sphenoid bone.

Deep Temporal Arteries and Nerve Connections

In this segment, the speaker discusses the deep temporal arteries and their association with nerve connections.

Deep Temporal Arteries and Nerve Innervation

• The deep temporal arteries are innervated by the lateral pterygoid nerve, which arises directly from the mandibular nerve.