Muscle Practical 1 Anatomy Lab 430 GMU

Buccinator

Origin: Alveolar processes of maxilla and mandible

Insertion: Fibers of orbicularis oris

Action: Compresses cheek

Orbicularis Oris

Origin: Maxilla and mandible; muscles around the mouth

Insertion: Encircles mouth; inserts into corners of mouth

Action: Compress & purse lips

Orbicularis oculi

Origin: Frontal and maxilla bones

Insertion: Encircles orbit;

inserts into tissue of eyelid

Action: Closes eye

Occipitofrontalis (frontal belly)

Origin: Epicranial aponeurosis

Insertion: Skin of eyebrow and bridge of nose

Action: Raises eyebrows, wrinkles forehead

Occipitofrontalis (occipital belly)

Origin: occipital bone and mastoid process

Insertion: epicranial aponeurosis

Action: draw scalp posteriorly

Platysma

Origin: Fascia of pectoralis major and deltoid (in between cartilage of 2nd rib and acromion)

Insertion: Mandible, skin and muscle at corner of mouth

Action: Tense skin of neck; depress mandible; pulls lower lip back and down

Masseter

Origin: Zygomatic arch

Insertion: Ramus and angle of mandible

Action: Elevates and protracts mandible

Temporalis

Origin: Temporal bone (fossa)

Insertion: Coronoid process of mandible

Action: Elevates and retracts mandible

Sternocleidomastoid

Origin: Sternal end of clavicle and manubrium

Insertion: Mastoid process of temporal bone

Action: Single - Lateral flexion; rotation to opposite side

Dual - Neck flexion

Scalenes

(anterior, middle, posterior)

Origin: Transverse processes of cervical vertebrae

Insertion: Superior surface of 1st 2 ribs

Action: Single - Lateral flexion, rotation to opposite side;

Dual - Elevate ribs; neck flexion

External intercostals

Origin: Inferior border of rib above

Insertion: Superior border of rib below

Action: Elevates ribs (during inspiration)

Internal intercostals

Origin: Superior border of rib below

Insertion: Inferior border of rib above

Action: Depresses ribs

(during forced expiration)

Diaphragm

Origin: Inferior border of rib cage and sternum, cartilage of last 6 ribs and lumbar vertebrae

Insertion: Central tendon

Action: Flattens to increase thoracic volume for inspiration

Rectus Abdominis

Origin: Pubic crest and symphysis

Insertion: Xiphoid process and costal cartilage of ribs 5-7

Action: Pull ribs downward,

flex vertebral column,

compress abdomen

External oblique

Origin: Outer surface of last 8 ribs

Insertion: Linea alba, pubic crest and tubercle, and iliac crest

Action: Pull ribs downward,

flex and rotate vertebral column, compress abdomen

Internal oblique

Origin: Lumbar fascia, iliac crest and inguinal ligament

Insertion: Linea alba, pubic crest and last 3 ribs

Action: Pull rib downward,

flex and rotate vertebral column, compress abdomen

Transversus abdominis

Origin: Inguinal ligament, lumbar fascia, cartilage of last 6 ribs and iliac crest

Insertion: Linea alba and pubic crest

Action: Compresses Abdomen

Levator scapulae

Origin: Transverse processes of C1-C4

Insertion: Superior medial border of scapula

Action: Elevate and adduct scapula

Pectoralis minor

Origin: Anterior surface of ribs 3-5

Insertion: Coracoid process of scapula

Action: Depress and protract scapula

Rhomboid minor

Origin: Spinous processes of C7-T1

Insertion: Medial border of scapula near spine

Action: Retract (adduct) and stabilize scapula

Rhomboid major

Origin: Spinous processes of T2-T5

Insertion: Medial border of scapula from spine to inferior angle

Action: Retract (adduct) and stabilize scapula

Serratus anterior

Origin: Lateral aspect of ribs 1-8

Insertion: Anterior surface of medial border of scapula

Action: Protract and rotate scapula upward

Trapezius

Origin: Occipital bone, ligamentum nuchea, spinous processes of C7 and all thoracic vertebrae

Insertion: Lateral clavicle & acromion and spine of scapula

Action: Superior fibers - elevate scapula, neck extension

Middle fibers - retract (adduct) scapula

Inferior fibers - depress scapula

Pectoralis major

Origin: cartilage of ribs 1-6, sternum, and sternal end of clavicle

Insertion: Greater tubercle and intertubercular sulcus of humerus

Action: Flexion (clavicular portion)

Extension: (sternal portion)

Adduction, medial rotation at shoulder

Deltoid

Origin: Lateral clavicle, acromion and spine of scapula

Insertion: deltoid tuberosity of humerus

Action: arm abduction

Anterior fibers - flexion and medial rotation

Posterior fibers - extension and lateral rotation

Subscapularis

Origin: Subscapular fossa of scapula

Insertion: Lesser tubercle of humerus

Action: Medial rotation at shoulder

Supraspinatus

Origin: Supraspinous fossa of scapula

Insertion: Greater tubercle of humerus

Action: Abduction at the shoulder

Infraspinatus

Origin: Infraspinous fossa of scapula

Insertion: Greater tubercle of humerus

Action: Lateral rotation at shoulder

Teres minor

Origin: Lateral border of scapula

Insertion: Greater tubercle of humerus

Action: Lateral rotation at shoulder

Teres major

Origin: Posterior inferior angle of scapula

Insertion: intertubercular sulcus of humerus

Action: arm extension, adduction, and medial rotation

Latissimus dorsi

Origin: spinous processes of T7-L5 vertebrae, last 4 ribs and iliac crest

Insertion: Intertubercular sulcus of humerus

Action: arm extension, adduction, and medial rotation