Lab Activity 11: Group I Muscles Martini Chapter 11 Portland Community College BI 231
Origin and Insertion Origin: The place where the fixed end attaches to a bone, cartilage, or connective tissue. Insertion: The site where the movable end attaches to another structure. 2
Frontalis Epicranial Aponeurosis Origin: Epicranial aponeurosis Insertion: Skin over forehead Action: Elevates eyebrows and wrinkles skin of forehead 3
Occipitalis Origin: Occipital and temporal bones Insertion: Epicranial aponeurosis Action: Fixes epicranial aponeurosis and pulls scalp posteriorly 4
Orbicularis Oculi Origin: Medial orbital margin and zygomatic bone Insertion: Skin surrounding eye Action: Closes eyelids and depresses skin of forehead 5
Temporalis Origin: Temporal fossa Insertion: Coronoid process of mandible Action: Elevates and retracts mandible 6
Masseter Origin: Zygomatic process and arch Insertion: Angle and ramus of mandible Action: Elevates mandible 7
Orbicularis Oris Origin: By muscular skips to surround muscles Insertion: Muscles interlace to surround mouth Action: Closes and purses lips 8
Zygomaticus Major Origin: Zygomatic arch Insertion: Corner of mouth Action: Elevates corner of mouth 9
Risorius Origin: Fascia of masseter Insertion: Corner of mouth Action: Draws corner of mouth laterally 10
Omohyoid Origin: Medial tip of suprascapular notch Insertion: Body of hyoid bone Action: Depresses hyoid bone 11
Sternohyoid Origin: Posterior surface of manubrium, and medial clavicle Insertion: Hyoid bone Action: Depresses hyoid bone 12
Mylohyoid Origin: Mylohyoid line of mandible Insertion: Hyoid bone Action: Elevates hyoid bone and floor of mouth, depresses mandible 13
Digastric Anterior Belly Origin: Lower border of mandible near midline Insertion: Intermediate tendon Action: Elevates hyoid bone and base of tongue, depresses mandible 14
Digastric Posterior Belly Origin: Mastoid notch of temporal bone Insertion: Intermediate tendon Action: Moves hyoid bone back 15
Sternocleidomastoid Origin: Manubrium and medial third of clavicle Insertion: Mastoid process Action: Rotates head to opposite side, extends head, and flexes vertebral column 16
Trapezius Origin: External occipital protuberance, superior nuchal line and spinous process of C 7 -T 12 Insertion: Anterior border of scapular spine, acromion process, lateral third of clavicle Action: Elevates, adducts, and depresses scapula 17
Latissimus Dorsi Origin: Spinous processes of lower 6 thoracic vertebrae, thoracolumbar fascia, crest of ilium Insertion: Intertubercular groove of humerus Action: Extends, rotates humerus medially, draws shoulder down and backward 18
Levator Scapula Origin: Transverse processes of C 1-4 Insertion: Superior angle spine of scapula Action: Elevates scapula 19
Rhomboid Major Origin: Spinous process of T 1-5 and supraspinous ligament Insertion: Medial border below spine of scapula Action: Adducts scapula and performs downward rotation 20
Rhomboid Minor Origin: Spinous process of C 7 -T 1 Insertion: Medial border of scapula at base of spine Action: Adducts scapula and performs downward rotation 21
Serratus Anterior Origin: Lateral surface of upper 8 ribs Insertion: Anterior lip of medial border of scapula Action: Holds scapula to chest wall, medially rotates scapula in abducting or extending humerus 22
Erector Spinae Origin: Sacrum, iliac crest, spinous processes of lumbar vertebrae and T11,12 Insertion: Angles of the ribs. Spinous & Transverse processes of vertebrae Action: Extension of vertebral column 23
Quadratus Lumborum Origin: Iliolumbar ligament and crest of ilium Insertion: Lower border of 12th rib, transverse process of upper lumbar vertebrae Action: Depresses rib cage inferiorly and laterally flexes trunk 24
Scalenes Anterior Origin: Transverse processes of C 3 -C 6 Insertion: 1 st rib Action: Elevates 1st rib, flexes neck forward and laterally, rotates neck 25
Scalenes Middle Origin: Transverse processes of C 2 -C 7 Insertion: 1 st rib Action: Elevates 1st rib, flexes neck forward and laterally, rotates neck 26
Scalenes Posterior Origin: Transverse processes of C 4 -C 6 Insertion: 2 nd rib Action: Elevates 2nd rib, flexes neck laterally, slightly rotates neck 27
External Intercostal Origin: Inferior border of rib above Insertion: Superior border of rib below Action: Elevates rib cage during inspiration 28
Internal Intercostal Origin: Superior border of rib below Insertion: Inferior border of rib above Action: Depresses rib cage during expiration 29
Pectoralis Major Origin: Medial half of clavicle, sternum, costal cartilages, aponeurosis of external abdominal oblique Insertion: Intertubular groove of humerus Action: Flexes, adducts, and medially rotates humerus, draws body upward in climbing 30
Pectoralis Minor Origin: Anterior surface of ribs 3 to 5 Insertion: Coracoid process of scapula Action: Draws scapula down and forward and elevates ribs 31
Rectus Abdominus Origin: Pubis symphysis and crest of pubis Insertion: Xiphoid process and cartilages of ribs 5 to 7 Action: Tenses abdominal wall and flexes vertebral column 32
External Abdominal Oblique Origin: External surface of lower 8 ribs Insertion: Anterior half of iliac crest and linea alba Action: Compresses abdomen, contralaterally rotates and flexes vertebral column 33
Internal Abdominal Oblique Origin: Lateral half of inguinal ligament, anterior iliac crest and thoracolumbar fascia Insertion: Lower four ribs, linea alba and by conjoined tendon to pubis Action: Compresses abdomen, ipsilaterally rotates and flexes vertebral column 34
Transverse Abdominis Origin: Lateral third of inguinal ligament, anterior iliac crest, and thoracolumbar fascia Insertion: Linea alba, and by conjoined tendon to pubis Action: Compresses abdomen 35
The End 36