Muscular system - voluntary and face Flashcards
What are the four main functions of the muscles?
Produce movement of the body or within the body
Maintain posture or facial contours
Cause heat production to maintain body temperature
Assist with venous return
What is the origin of the muscle?
The part where the muscle originates (where it is attached to the bone).
What is the insertion?
Where the muscle is attached to a moveable part , tissue or fascia. During contraction this part of the muscle moves, acting as a lever to bring about an action.
How does a voluntary muscle contract?
Receives stimulus from the motor nerve attached the the muscle fibre and have sufficient energy supply. This results in actin filaments sliding further between the myosin filament shortening the muscle fibres.
What causes the striated appearance?
The protein filaments actin and myosin. Actin are thinner, myosin are thicker they are arranged in alternating bands.
Location and function of frontalis
Forehead, lifts the eyebrows which causes horizontal crease to appear.
Location and function of corrugator
In between eyebrows draws eyebrows together as in frowning.
Location and function of orbicular oculi
Surrounds the eye. Closes the eye and causes wrinkles a the corners.
Location and function of Masseter
Extends downwards from the zygomatic bone to the jaw in the lower cheek area. Lifts the jaw and exerts pressure on the teeth.
Location and function of the zygomaticus - major and minor
Extends upwards, diagonally from the corners of the mouth. Pulls the corners of the mouth upwards and out as in smiling.
Location and function of risorius
Runs horizontally in the cheeks from the corner of the mouth.
Location and function of orbicularis oris
Round the mouth, forms the lips, purses the mouth closes the mouth
Location and function of Buccinator
Deep muscle in between mandible and maxilla for blowing maintains tension in the cheeks
Location and function of Digastric
Under the chin. Lowers the mandible and elevates the hyoid bone used when speaking and swallowing.
Location and function of platysma
Starts at the chest and covers the front of the neck up to the mandible. Pulls the jaw and lower lip down causes the neck to wrinkle.
