Muscular System (Part 1) - Introduction and Muscles of the head

Summary

This module introduces the muscular system in dogs, focusing on skeletal muscles. It covers the head, trunk, thoracic limb, and pelvic limb muscles, detailing their actions and clinical importance. Key terms like tendons, aponeurosis, origin, insertion, belly, intrinsic, and extrinsic muscles are explained. The lecture discusses masticatory and facial expression muscles, noting the digastricus as the jaw opener and the temporalis as the strongest jaw closer. It also touches on muscles of the tongue and extraocular muscles, emphasizing their roles in facial expression and eye movement.

Takeaways

• 💪 Module 4 focuses on the muscular system, particularly the skeletal muscles of dogs.
• 📚 The module provides an overview of common muscles observed during dissection and their physiological and clinical importance.
• 📖 Topics are organized by body region to simulate the experience of actual muscle dissection.
• 🦴 Skeletal muscles are the bulk of muscles in the body and are categorized by their region: head, trunk, thoracic limb, and pelvic limb.
• 🔍 Important muscle terms include tendons, aponeurosis, origin, insertion, belly, intrinsic, and extrinsic muscles.
• 🦷 Masticatory muscles are powerful and associated with chewing, having attachments to the mandible.
• 😸 Mimetic muscles, also known as muscles of facial expression, move the skin and appendages of the face and ears.
• 👅 The tongue muscles and extraocular muscles are also part of the head muscles discussed.
• 🔑 The digastricus is the only muscle that opens the jaw, while others like the masseter and temporalis are involved in closing the jaw.
• 😏 Muscles of facial expression include the platysma, which draws the angle of the mouth caudally, and the boxinator, which draws the cheek inward.
• 👁️ Extraocular muscles enable eye movement and are divided into rectus, oblique, and retractor muscles.

Q & A

What is the primary function of the muscular system?

The primary function of the muscular system is to contract to produce movement.

What type of muscle is mainly focused on in this module?

This module mainly focuses on the skeletal muscle of the dog.

How is the muscular system organized in this module?

The muscular system is organized per region of the body: head, trunk, and limb regions.

What is the difference between tendons and aponeurosis?

Tendons are fibrous bands of collagen connecting muscles to bone, while aponeurosis are tendons associated with flat muscles.

What is the origin and insertion in the context of muscles?

The origin is the less movable attachment of a muscle, and the insertion is the more movable attachment.

What is the term for the thick fleshy central part of a muscle?

The thick fleshy central part of a muscle is called the belly.

How are intrinsic muscles different from extrinsic muscles?

Intrinsic muscles lie completely within one region of the body, having their origin and insertion within that region, whereas extrinsic muscles run from one region of the body to another.

What are the main groups of muscles in the head?

The main groups of muscles in the head are the masticatory muscles, facial expression muscles (mimetic muscles), tongue muscles, and extraocular muscles.

Which muscle is responsible for opening the jaw?

The digastricus, also known as the biventor, is the only muscle that opens the jaw.

What is the role of the masseter muscle?

The masseter muscle closes the jaw and lies lateral to the mandible.

What are the functions of the temporalis muscle?

The temporalis muscle closes the jaw and is the strongest muscle of the head in carnivores.

What are the main actions of the muscles of facial expression?

The muscles of facial expression move the skin and appendages of the face and head, such as the ears, to show reactions like aggression.