Chapter 10 Notes

axial muscles

Epicranius (Occipitofrontalis)

Bipartite scalp muscle consisting of the frontalis and occipitalis

connected by the galea aponeurotica.

Alternating actions pull the scalp forward and backward

Galea aponeurotica

Cranial aponeurosis that connects the frontalis and occipitalis muscles

aponeurosis: a broad, flat sheet of dense fibrous connective tissue that attaches muscles to bones or other muscles.

What is the Frontalis (Frontal Belly) Origin

Galea aponeurotica

What is the Frontalis (Frontal Belly) Insertion

Skin of eyebrows and root of nose

What is the Frontalis (Frontal Belly) Action

Raises the eyebrows and wrinkles the forehead horizontally

Occipitalis (Occipital Belly) Origin

Occipital and temporal mastoid bones

Occipitalis (Occipital Belly) Insertion

Galea aponeurotica

Occipitalis (Occipital Belly) Action

Fixes the aponeurosis and pulls the scalp posteriorly

Orbicularis Oculi Origin

Frontal and maxillary bones and ligaments around orbit

Orbicularis Oculi Insertion

Tissue of eyelid

Orbicularis Oculi Action

Closes the eye and produces blinking and squinting

Zygomaticus major Origin

Zygomatic bone

Zygomaticus major Insertion

Skin and muscle at corner of mouth

Zygomaticus major Action

Raises lateral corners of mouth upward as in smiling

Risorius Origin

Lateral fascia associated with masseter muscle

Risorius Insertion

Skin at angle of mouth

Risorius Action

Draws corner of lip laterally and tenses lips

Orbicularis Oris Origin

Arises indirectly from maxilla and mandible with fibers blended with other facial muscles

Orbicularis Oris Insertion

Encircles mouth and inserts into muscle and skin at angles of mouth

Orbicularis Oris Action

Closes, purses, and protrudes lips as in kissing and whistling

Mentalis Origin

Mandible below incisors

Mentalis Insertion

Skin of chin

Mentalis Action

Protrudes lower lip and wrinkles chin

Buccinator Origin

Molar region of maxilla and mandible

Buccinator Insertion

Orbicularis oris

Buccinator Action

Compresses cheek and keeps food between grinding surfaces of teeth during chewing

Platysma Origin

Fascia of chest over pectoral muscles and deltoid

Platysma Insertion

Lower margin of mandible and skin and muscle at corner of mouth

Platysma Action

Helps depress mandible, pulls lower lip down, and tenses skin of neck

Masseter Origin

Zygomatic arch and zygomatic bone

Masseter Insertion

Angle and ramus of mandible

Masseter Action

Prime mover of jaw closure and elevates mandible

Temporalis Origin

Temporal fossa

Temporalis Insertion

Coronoid process of mandible through a tendon passing deep to zygomatic arch

Temporalis Action

Closes jaw and elevates and retracts mandible

Suprahyoid Muscles

Muscles superior to the hyoid that…

• form the floor of the oral cavity

• anchor the tongue

• elevate the hyoid

• move the larynx during swallowing

Digastric Origin

Lower margin of mandible at anterior belly and mastoid process of temporal bone at posterior belly

Digastric Insertion

Connective tissue loop to hyoid bone

Digastric Action

Opens mouth and depresses mandible

elevates and steadies hyoid during swallowing and speech

Both the geniohyoid and the digastric muscles depress the jaw

Mylohyoid Origin

Medial surface of mandible

Mylohyoid Insertion

Hyoid bone and median raphe

Mylohyoid Action

Elevates hyoid bone and floor of mouth to force food bolus into pharynx

Geniohyoid Origin

Inner surface of mandibular symphysis

Geniohyoid Insertion

Hyoid bone

Geniohyoid Action

Pulls hyoid bone superiorly and anteriorly and shortens floor of mouth during swallowing

Infrahyoid Muscles

Straplike muscles that depress the hyoid bone and larynx during swallowing and speaking

Sternohyoid Origin

Manubrium and medial end of clavicle

Sternohyoid Insertion

Lower margin of hyoid bone

Sternohyoid Action

Depresses larynx and hyoid bone when mandible is fixed

Sternothyroid Origin

Posterior surface of manubrium of sternum

Sternothyroid Insertion

Thyroid cartilage

Sternothyroid Action

Pulls larynx and hyoid bone inferiorly (depresses)

Omohyoid Origin

Superior surface of scapula

Omohyoid Insertion

Hyoid bone at lower border

Omohyoid Action

Depresses and retracts hyoid bone

Thyrohyoid Origin

Thyroid cartilage

Thyrohyoid Insertion

Hyoid bone

Thyrohyoid Action

Depresses hyoid bone or elevates larynx when hyoid bone is fixed

Thyrohyoid is the only infrahyoid that elevates the larynx

Sternocleidomastoid Origin

Manubrium of sternum and medial portion of clavicle

Sternocleidomastoid Insertion

Mastoid process of temporal bone and superior nuchal line of occipital bone

Sternocleidomastoid Action

Flexes and laterally rotates the head.

Both sides flex neck while one side rotates head toward opposite shoulder and laterally flexes to same side

The muscle that flexes (contracts) is on the side opposite to where your face turns

Scalenes Origin

Transverse processes of cervical vertebrae

Scalenes Insertion

Anterolateral surfaces of first two ribs

Scalenes Action

Elevate first two ribs during inspiration and flex and rotate neck

Splenius Origin

spinous processes of C7 through T6

Splenius Insertion

Mastoid process and occipital bone for capitis and transverse processes of C2 through C4 for cervicis

Splenius Action

Extends or hyperextends head. One side rotates and laterally bends head toward same side

Erector Spinae

Intrinsic back muscle group and prime mover of back extension

consisting of…

1. iliocostalis

2. longissimus

3. spinalis

Lateral to medial order = Iliocostalis, Longissimus, Spinalis (I Like Spaghetti)

Iliocostalis Position

Most lateral muscle group of erector spinae extending from pelvis to neck

Iliocostalis Origin

ribs 3-6 for cervicis

inferior six ribs for thoracis

Iliac crests for lumborum

Iliocostalis Insertion

transverse processes of C6-C4 for cervicis

Angles of ribs for lumborum and thoracis

Iliocostalis Action

Extends and laterally flexes vertebral column and maintains erect posture

Longissimus Position

Intermediate erector spinae muscle group extending from lumbar region to skull

Longissimus Origin

Transverse processes of lumbar through cervical vertebrae

Longissimus Insertion

Transverse processes of thoracic or cervical vertebrae and ribs superior to origin.

Note: Capitis inserts into mastoid process

Longissimus Action

Extends and laterally flexes vertebral column.

Note: Capitis extends head and turns face toward same side

Spinalis Position

Most medial erector spinae muscle group

Spinalis Origin

Inferior spinous processes of upper lumbar and lower thoracic vertebrae

Spinalis Insertion

Spines of upper thoracic and cervical vertebrae

Spinalis Action

Extends vertebral column

Semispinalis Origin

Transverse processes of C7-T12

Semispinalis Insertion

Occipital bone for capitis

superior spinous processes of cervical and upper thoracic vertebrae for cervicis and thoracis

Semispinalis Action

Extends neck and vertebral column and rotates toward opposite side

Multifidus Origin

Sacrum and transverse process of each vertebra

Multifidus Insertion

Spinous process of 3rd of 4th more superior vertebra

Multifidus Action

Extends vertebral column and rotates toward opposite side

Interspinales Origin

Spinous process of each vertebra

Interspinales Insertion

Spinous processes of more superior vertebra

Interspinales Action

Extends vertebral column

Intertransversarii Origin

Transverse processes of each vertebra

Intertransversarii Insertion

Transverse processes of more superior vertebra

Intertransversarii Action

Lateral flexion of vertebral column

Quadratus Lumborum Origin

Iliac crest and lumbar fascia

Quadratus Lumborum Insertion

Transverse processes of upper lumbar vertebrae and lower margin of 12th rib

Quadratus Lumborum Action

Flexes vertebral column laterally, depresses ribs, and fixes floating ribs during forced breathing

External Intercostals Origin

Inferior border of rib above

External Intercostals Insertion

Superior border of rib below

External Intercostals Action

Pull ribs toward one another to elevate rib cage and aid in inspiration

Internal Intercostals Origin

Superior border of rib below

Internal Intercostals Insertion

Inferior border or costal groove of rib above