Masseter

*Jaw, bigger, cheek to neck; Powerful, covers lateral aspect of mandib. ramus

O-zygomatic arch & zygomatic bone
I-angle & ramus of mandible

A-Prime mover of jaw closure; elevates mandible

Genioglossus

*Jaw, Forms bulk of inf. part of tongue, its attachment to madible prevents tongue from falling backward & obsructing breathing

O-Internal surface of mandible near symphysis
I-inf. aspect of the tongue & body of hyoid bone

A-Protracts tongue, depress/retract tongue

Hyoglossus

*Jaw. Flat quadrilateral muscle

O-body & greater horn of hyoid bone
I-inferolateral tongue

A-Depresses tongue & draws its sides inferiorly

Buccinator

*Jaw; thin horizontal cheek muscle; principle muscle of cheek; deep to masseter

O-molar region of maxilla & mandible
I-orbicularis oris

A-Compress cheek (whistle/suck); holds food betw teeth during chewing w/trampoline like action; draws corner of mouth laterally. NURSING INFANTS

Orbicularis oris

*Around mouth; complicated, multilayered muscle of the lips w/mafibers that run in many directins (most circularly)

O-arises indirectly from maxilla & mandible; fibers blend w/fibers of other facial muscles assoc'd w/lips
I-encircles mouth; inserts into muscles & skin at angles of mouth

A-purses & protrudes lips; kissing/whisteling

SUPRAHYOID muscles

Muscles that help form floor of oral cavity, anchor tongue, elevate hyoid & move larynx superiorly during swallowing; lie superior to hyoid bone

Digastric
Stylohyoid
Mylohyoid
Geniohyoid

Digastric

*Suprahyoid muscle under jaw; consists of 2 bellies united by an intermed. tendon, ofrming v-shape under chin

O-lower margin of mandible (ant. belly) & mastoid process of temporal bone (post. belly)
I-by a connective tissue loop to hyoid bone

A-open mouth & depress mandible; acts in concert to elevate hyoid bone & steady it during swallowing/speech

Stylohyoid

*Suprahyoid muscle; slender muscle below angle of jaw; parallels posterior belly of digastric muscle

O-styloid process of temporal bone
I-hyoid bone

A-Elevates & retracts hyoid, elongating floor of mouth during swallowing

Mylohyoid

*Suprahoid muscle; flat/trangular muscle just deep to digastric muscle; this muscle pair make a sling that forms floor of the ant. mouth

O-medial surface of mandible
I-hyoid bone & median raphe

A-elevates hyoid bone & floor of mouth, enabling tongue to exert backward & upward pressure that forces food into pharynx

Geniohyoid

*Suprahyoid muscle; narrow muscle in contact w/its partner medially; runs from chin to hyoid bone deep to mylohyoid

O-inner surface of mandib. symphysis
I-hyoid bone

A-pulls hyoid bone superiorly & anteriorly

INFRAHYOID MUSCLES

Straplike muscles that depress the hyoid bone & larynx during swallowing/speaking

Sternohyoid
Sternothyroid
Omohyoid
Thyrohyoid

Sternohyoid

*Infrahyoid muscle; most medial muscle of neck; thin; superficial except inferiorly, where covered by sternocleidomastoid

O-manubrium & medial end of clavicle
I-lower margin of hyoid bone

A-Dpresses larynx & hyoild bone if mandible is fixe; may also flex skull

Sternothyroid

*Infrahyoid muscle; lateral & deep to sternohyoid

O-posterior surface of manubrium of sternum
I-thyroid cartilage

A-pulls larynx & hyoid bone inferiorly

Omohyoid

*Infrahyoid muscle; straplike muscle w/2 bellies united by an intermed. tendon; lateral to sternohyoid

O-superior surf. of scapula
I-hyoid bone, lower border

A-Depresses & retracts hyoid bone

Thyrohyoid

*Infrayoid muscle; appears as superior continuation of sternothyroid muscle

O-thyroid cart.
I-hyoid bone

A-Depresses hyoid bone or elevates larynx if hyoid is fixed

Sternocleidomastoid

*Clavicle to skull; 2-headed muscle located deep to platysma on anterolateral surf. of neck; fleshy parts on either side of neck delineate limits of ant. & post. triangles; KEY muscular landmark in neck

O-manubrium of sternum & medial portion of clav.
I-mastoid process of temporal bone & superior nuchal line of occipital bone

A-Flexes & laterally rotates head

Scalenes

*rib/clav. to jaw; located more laterally than anteriorly on neck; deep to platysma & sternocleidomastoid

O-transverse processes of cervical vert.
I-anterolaterally on 1st 2 ribs

A-Elevate 1st 2 ribs; flex/rotate neck

Splenius

*posterior neck; is a broad bipartite suprficial muscle extending from upper thoracic vert. to skull; capitis/cervicis parts "capitis aka bandage musckle)

O-ligamentum nuchae, spinous processes of vert C7-T6
I-mastoid processes of C2-C4 vert

A-extend or hyperextend head

Trapezius

*Posterior back/triangle hypotenus on vertebrae, to skull to deltoid; is most superficial muscle of posterior thorax

O-occiptial bone ligamentum nuchae & spinous processes of C7, & all thoracic vert.
I-continuous insertion along acromion & spine of scapula & lateral 1/3 of clav.

A-Stabilizeds, raises, retracts & rotates scapula. Shrug shoulders

Levator scapulae

*back & side of neck, deep to trapezius; thick straplike muscle

O-transverse processes of C1-C4
I-medial border of scapula, superior to spine

A-elevates/adducts scapula; tilts glenoid cavity downward when scap. is fixed

Rhomboid major & minor

*back attached to scapula; 2 roughly diamond shaped muscles lying deep to trapezius & inferior to levator scapule; rhomboid minor is superior

O-spinous process of C7 & T1 (minor); spinous processes of T2-T5 (major)
I-medial border of scapula just under levator scapulae

A-stabilize scapula, acts together to retract scapula, squaring shoulders (lowering arm against resistance like paddling canoe)

Latissimus dorsi

*posterior back, under scapula; broad, flat triangular muscle of lower back (lumbar); extensive superfical origins; covered by trapezius superiorly, contributes to posterior wall of axilla

O-indirect attachment via lumbodorsal fascia into spines of lower 6 T vert., lumbar vert., lower 3-4 ribs & iliac crest; also from scapulas' inferior angle
I-spirals around teres major to insert in floor of intertubercular sulcus of humerus

A-prime mover of arm extension; powerful arm adductor; medially rotates arm at shoulder (lowers arm in power stroke like using hamer, swilling, rowing)

Teres major

*posterior back, just above latissimus dorsi; thick rounded muscle, inferior to teres minor, helps form posterior wall of axilla

O-posterior surface of scapula at inferior angle
I-crest of lesser tubercle on ant. humerus; insertion tendon fused w/that of latissimus dorsi

A-extends, medially rotates & adducts humers, synergist of latissiums dorsi

Deltoid

*Mostly front over shoulder; thick, multipennate muscle forming rounded shoulder muscle mass; common site for intramuscular injection

O-embraces insertion of trapezius; lateral 3rd of clavicle; acromion & spine of scapula
I-deltoid tuberosity of humerous

A-prime mover of arm abduction when all its fibers contract simultaneously; antag. of pectoralis major & latissimus dorsi which adduct arm,

Pectoralis major

*front titty muscle; large fan-shaped muscle covering superior portion of chest, forms anterior axillary fold, ivided in to clavicular & sternal parts

O-sternal end of clav., sternum, cartilage of ribs 1-6 (or 7), & aponeurosis of external oblique muscle
I-fibers converge to insert by a short tendon into intertubercular sulcus & greater tubercle of humerus

A-prime mover of arm flexion,; rotates arm medially; adducts arm against resistancde, helps climbing, throwing, pushing, forced inspiration

Pectoralis minor

*flat thin muscle directly beneath & obscured by pectoralis major

O-ant. surfaces of ribs 3-5 or 2-4
I-coracoid process of scapula

A-w/ribs fixed, draws scapula forward & downward

Diaphragm

*borad, pierced by aorta, inferior vena cava, & esophagus, forms floor of thoracic cavity; dome shaped in relaxed state; fibers converge from margins of thoracic capge toward a boomerang shaped central tendon

O-inferior , internal surf. of rip cage & sternum, costal cartlages of last 6 ribs & lumbar vert.
I-central tendon

A-prime mover of inspiration; flattens on contraction, when strongly contracted, dramatically increases intra-abdominal pressure

External intercostals

*betw. ribs; 11 pairs lie betw ribs, fibers run obliquiely (down & forward) from each rib to rib below; in lower intercostal spaces, fibers are continuous w/externaloblique muscle forming part of abdom. wall

O-inf. border of rib above
I-superior border of rib below

A-w/1st ribs fixed by scalene muscles, pull ribs toward 1 another to elevate rib cage, aid inspiration, synergist of diaphragm

Internal intercostals

*11 pairs lie betw ribs; fibers run deept to and at right angles to those of external intercostals; lower internal intercostal muscles are continuous w/fibers of internal oblique muscle of abdom wall

O-inf., internal surf. of rib cage & sternum, cotstal cartilages of last 6 ribs & lumbar vert.
I-central tendon

A-prime mover of inspiration; flattens on contraction