A&P 1 - Axial Muscles

origin

the attachment of the muscle’s tendon to the stationary bone

usually proximal

insertion

the attachment of the muscle’s other tendon to the movable bone

usually distal

agonist/prime mover

contracts to cause an action

antagonist

stretches and yields to the effects of the agonist

agonist/prime mover

antagonist

in flexing the elbow, the biceps is the ______ and triceps is the ______

orbicularis oculi

muscle closes the eye

orbicularis oris

closes the mouth and protrudes the lips

buccinator

muscle pulls the cheeks into the teeth

assists sucking motion

platysma

muscle pulls the corners of the mouth down and tenses the skin of the neck

muscles of mastication

move the mandible to assist with chewing, eating and talking

4 muscles: 

temporalis 

masseter

medial and lateral pterygoid

temporalis

muscle elevates (closes) and retracts mandible

masseter

strongest muscles

action: elevates and protracts the mandible; closes the mouth

origin: zygomatic arch (of temporal bone)

insertion: ramus (of mandible)

medial and lateral pterygoids

elevate and protract mandible; move mandible side to side

allow grinding motion

muscles that move head and neck

sternocleidomastoid

scalenes

longissimus capitis

sternocleidomastoid

origin: manubrium and sternal end of clavicle

insertion: mastoid process (temporal bone)

action:

• bilateral contraction

• unilateral contraction

bilateral contraction

in sternocleidomastoid

flexes the neck

unilateral contraction

in sternocleidomastoid

lateral flexion to its own side and rotation of the opposite side

scalenes

muscles flex (bend) the neck and laterally flex (side bend) the neck

anterior, middle and posterior

muscles of respiration/breathing

diaphragm

internal intercostals

external intercostals

diaphragm

muscle that separates the thoracic and abdominal cavities

action:L contracts during inspiration and relaxes during expiration

internal intercostals

depress the ribs during forced expiration

external intercostals

elevate the ribs during inspiration

abdominal muscles

rectus abdominis

transverse abdominis

external obliques

internal obliques

rectus abdominis

action: trunk flexion and compression of abdomen

transverse abdominis

action: compression of abdomen

internal and external obliques

action:

bilateral: trunk flexion

muscles of vertebral column

erector spinae group:

iliocostalis

longissimus

spinalis