CHAPTER 11

Overview of the Muscular System

  • Focus on specific muscles for lab: facial muscles, eye muscles, abdominal muscles.

  • Discuss later on the different shapes of muscles.

Facial Muscles

  • Used primarily for facial expressions.

  • Importance of writing full muscle name or using 'm.'

Frontal Belly of Occipital Frontalis Muscle

  • Function: Wrinkles the forehead.

  • Location: Frontal region, covers the forehead.

Corrugator Supercilii Muscle

  • Common Name: Eyebrow muscle.

  • Function: Wrinkles the eyebrow (e.g., when tweezing).

Temporalis Muscle

  • Superficial Temporalis: On top, helps move the scalp.

  • Deep Temporalis: Attaches to jaw and involved in chewing (mastication).

  • Function: prime mover of the mandible, assists in chewing.

Obicularis Oculi

  • Function: Opens and closes the eyes.

  • Notes: Circular-shaped muscle, classified as sphincter muscle.

Nasalis and Procerus Muscles

  • Function: Move the nose.

  • Location: Nasalis goes across, procerus is between the eyebrows.

Zygomaticus Muscles

  • Zygomaticus Minor: Smaller, assists in smiling.

  • Zygomaticus Major: Larger, aids in laughter.

Risorius Muscle

  • Common Name: Laughter muscle.

  • Function: Pronounced movement in laughter.

Obicularis Oris

  • Common Name: Kissing muscle.

  • Function: Opens and closes the mouth.

  • Also known as: Trumpeter muscle.

Buccinator Muscle

  • Function: Used for sucking cheeks in, playing a trumpet.

  • Location: Deep to the masseter, helps with mastication.

Masseter Muscle

  • Function: Strongest jaw muscle for mastication.

  • Location: Superficial to buccinator.

Mentalis Muscle

  • Function: Moves the lower lip, elevates the chin.

  • Location: Located on the chin area.

Platysma Muscle

  • Function: Tenses during shaving (shaving muscle).

  • Location: Covers neck area.

Sternocleidomastoid Muscle

  • Origin: Sternum and clavicle.

  • Insertion: Mastoid process.

  • Function: Allows head and neck movement.

Depressor Muscles

  • Depressor Anguli Oris: Depresses the corner of the mouth.

  • Depressor Labii Inferioris: Elevates the lower lip.

Levator Muscles

  • Functions of Levators: Elevate upper lip and corners of the mouth.

Eye Muscles

  • Types: Six extrinsic muscles: Four rectus (superior, inferior, medial, lateral) and Two obliques (superior, inferior).

  • Rectus means straight; Oblique means slanting.

Rectus Muscles

  • Superior Rectus: Moves the eye upward.

  • Inferior Rectus: Moves the eye downward.

  • Medial Rectus: Moves the eye medially.

  • Lateral Rectus: Moves the eye laterally.

Oblique Muscles

  • Superior Oblique: Rolls the eye down and out.

  • Inferior Oblique: Rolls the eye up and out; originates at the maxilla.

Functions of Eye Muscles

  • All muscles pull the eyeball to control movement.

  • Medial and lateral rectus contract to move eyes towards the midline or away.

  • Obliques assist with rolling movement.

Anatomical Terminology Reference

  • Use terms related to origin, insertion, and muscle functions for clarity.

  • Important structure: Trochlea is the sling used by the superior oblique muscle.

Lab Preparation

  • Review axial skeleton and bone parts for upcoming quiz.

  • Utilize the Anatomage table for visual learning.