lab practical #2 actions

cwru biol346 (superficial head & neck, brain, cranial nerves, and special senses)

platysma (ACTION)

1.) wrinkles the skin of the neck and upper chest

2.) depresses the corners of the mouth

sternocleidomastoid (ACTION)

1.) bilateral: flexes the neck (anteriorly) AND elevates the sternum during forced inspiration

2.) unilateral: contralateral rotation of the head AND ipsilateral flexion of the neck

digastric (ACTION)

1.) opens mouth by depressing mandible

2.) elevates hyoid bone

mylohyoid (ACTION)

1.) elevates the hyoid bone

2.) raises floor of mouth (for swallowing)

stylohyoid (ACTION)

pulls the hyoid superiorly and posteriorly during swallowing

sternohyoid (ACTION)

depresses the hyoid bone

sternothyroid (ACTION)

depresses thyroid cartilage

thyrohyoid (ACTION)

1.) elevates thyroid cartilage

2.) depresses hyoid bone

omohyoid (ACTION)

depresses hyoid bone

frontalis (ACTION)

1.) elevates the eyebrows

2.) produces horizontal wrinkles in the skin of the forehead

masseter (ACTION)

closes the jaw by elevating the mandible

temporalis (ACTION)

closes the jaw by elevating the mandible

buccinator (ACTION)

compresses the cheek, to hold food between the cheek and the teeth

orbicularis oris (ACTION)

constricts the opening of the mouth (pucker the lips)

orbicularis oculi (ACTION)

1.) tightly closes eyelids

2.) compresses lacrimal (tear) sac

levator palpebrae superioris (ACTION)

retracts and elevates eyelid (opens the eye)

zygomaticus major (ACTION)

draws the angle of the mouth upward and laterally (“sincere smile”)

zygomaticus minor (ACTION)

elevates upper lip

levator labii superioris (ACTION)

elevates the upper lip (“sneer”)

levator labii superioris alaeque nasi (ACTION)

1.) dilates nostril

2.) elevates upper lip and wing of nose (“snarl”)

risorius (ACTION)

draws angle of the mouth laterally

mentalis (ACTION)

1.) elevates and wrinkles the skin of the chin

2.) protrudes the lower lip (pout)

depressor anguli oris (ACTION)

depresses the angle of the mouth (“sad face”)

depressor labii inferioris (ACTION)

depresses lower lip

nasalis (ACTION)

1.) transverse portion: compresses the nostril

2.) alar portion: dilates the nostril

corrugator supercilii (ACTION)

draws eyebrow medially and downward, forming vertical wrinkles in the skin (“frown”)

procerus (ACTION)

depresses the skin between the eyebrows, forming horizontal wrinkles (“frown”)

superior rectus (ACTION)

elevates the eyeball

inferior rectus (ACTION)

depresses the eyeball

lateral rectus (ACTION)

abducts the eyeball

medial rectus (ACTION)

adducts the eyeball

superior oblique (ACTION)

1.) internal rotation of the eye about the optic axis

2.) depresses the eyeball

3.) abducts the eyeball (at extreme contraction)

inferior oblique (ACTION)

1.) external rotation of the eye about the optic

2.) elevates the eyeball

3.) abducts the eyeball (at extreme contraction)