A&P Lab 1 - Muscles

Origin, insertion and action of muscles

Origin: Masseter

Zygomatic arch

Insertion: Masseter

Lateral surface of mandibular ramus and angle

Action: Masseter

closes jaw

Origin: Scalenes

transverse process of cervical vertebrae

Insertion: Scalenes

Ribs 1&2

Action: Scalenes

unilateral contraction → ipsilateral flexion and contralateral rotation: Bilateral contraction → flexes neck; elevates ribs 1&2

Origin: Temporalis

temporal fossa

Insertion: Temporalis

Coronoid process of mandible

Action: Temporalis

elevation, flexion, closes jaw

Origin: Sternocleidomastoid 

manubrium of sternum & medial part of clavicle 

Insertion: Sternocleidomastoid

mastoid process of temporal bone

Action: Sternocleidomastoid

unilateral contraction → ipsilateral flexion and contralateral rotation: Bilateral contraction → flexes neck

Origin: Frontalis

epicranial aponeurosis 

Insertion: Frontalis

skin around eyes

Action: Frontalis

elevation, flexion: raises eyebrows, wrinkles forehead

OriginL Occipitals

Occipital bone

Insertion: occipitalis

epicranial aponeurosis

Action: occipitalis

elevation, flexion: retracts the scalp

Origin: zygomaticus

zygomatic bone

Insertion: zygomaticus

skin and muscle of the corner of the mouth

Action: zygomaticus 

elevation, flextion: smiling

Origin: Trapezius

occipital bone, ligmentum nuchae, and spinal processes of C7-T12

Insertion: trapezius

clavicle, acromion and spine of scapula

Action: trapezius 

stabilizes, retracts, elevates scapula

Origin: rhomboid (major & minor)

Major: spinous process of T2-T5

Minor: spinous processes C7-T1

Insertion: rhomboid (major & minor)

medial border of scapula

Action: rhomboid (major & minor)

retracts scapula, stabilizes

Origin: levator scapulae

transverse processes of C1-C4

Insertion: Levator scapulae

medial border of scapula, superior to scapular spine

Action: levator scapulae

elevates/retracts scapula

Origin: latissimus dorsi

vertebrae T7-L5, lowest 3&4 ribs, and thoracolumbar fascia

Insertion: latissimus dorsi

intertubercular sulcus of humerus

Action: latissimus dorsi

extends and adducts humerus

Origin: Iliocastalis

Iliac crest; ribs 3-6

Insertion: Iliocastalis

ribs 1-12 and transverse processes of C4-C6

Action: Iliocastalis 

extension, lateral flexion, rotation

Origin: Longissimus

transverse processes lumbar to cervical vertebrae

Insertion: Longissimus

transverse processes of thoracic and cervical vertebrae

Action: longissimus 

extension, lateral flexion, rotation, stabilization

Origin: Spinalis

spinous processes of upper lumbar and lower thoracic vertebrae

Insertion: spinalis

spinous processes of cervical and upper thoracic vertebrae

Action: spinalis

extension, lateral flexion, rotation

Origin: pectoralis major

sternal end of clavicle, sternum, costal cartilages of ribs 1-6IN

Insertion: pectoralis major

intertubercular groove and greater tubercle of humerus

Action: pectoralis major

adduction, internal rotation, flexion of humerus 

Origin: pectoralis minor

ribs 3-5

Insertion: pectoralis minor

corocoid process of scapula

Action: pectoralis minor

draws scapula forward and downward

Origin: serratus anterior

ribs 1-8

Insertion: serratus anterior

medial border of scapula

Action: serratus anterior

protracts scapula: pulls inferior angle lateral and upward

Origin: retus abdominus

pubic symphysis and superior margin of pubis

Insertion: rectus abdominus

xiphoid process and costal cartilages of ribs 5-7

Action: rectus abdominus

flexes lumbar region of vertebral column

Origin: transverse abdominus

Iliac crest, inguinal ligament, lumbar fascia, cartilages of lowest 6 ribs

Insertion: transverse abdominus

linea alba; pubic crest

Action: transverse abdominus

stabilization, compression, posture, trunk flexion, pelvic tilt

Origin: external/ internal oblique abdominus

External: lower 8 ribs

Internal: lumbar fascia, iliac crest, inguinal ligament

Insertion: external/ internal oblique abdominus

External: linea alba and pubic crest

Internal: linea alba, pubic crest, lowest 3 ribsA

Action: external/ internal oblique abdominus

bilateral → flex vertebral column and compress abdominal contents: Unilateral → ispilateral flexion and rotation at waist