Regional Muscle Review

1. Regional Muscle Review Will Kleinelp Associate Professor Department of Biology

2. HEAD & NECK MUSCLES

3. Digastric • ORIGIN • Anterior belly: digatric fossa on posterior surface of symphysis menti. posterior belly: base of medial aspect of mastoid process • INSERTION • Fibrous loop to lesser cornu of hyoid bone • ACTION • Elevates hyoid bone. Aids swallowing and depresses mandible

4. Mylohyoid • ORIGIN • Mylohyoid line on internal aspect of mandible • INSERTION • Anterior three quarters : midline raphe. posterior quarter: superior border of body of hyoid bone • ACTION • Elevates hyoid bone, supports and raises floor of mouth. Aids in mastication and swallowing

5. Masseter • ORIGIN • Anterior two thirds of zygomatic arch and zygomatic process of maxilla • INSERTION • Lateral surface of angle and lower ramus of mandible • ACTION • Elevates mandible (enables forced closure of mouth)

6. Sternocleidomastoid • ORIGIN • Anterior and superior manubrium and superior medial third of clavicle • INSERTION • Lateral aspect of mastoid process and anterior half of superior nuchal line • ACTION • Flexes and laterally rotates cervical spine. Protracts head when acting together . Extends neck when neck already partially extended

7. Temporalis • ORIGIN • Temporal fossa between inferior temporal line and infratemporal crest • INSERTION • Medial and anterior aspect of coronoid process of mandible • ACTION • Elevates mandible and posterior fibers retract

8. Occipitalis

9. Orbicularis oris • ORIGIN • Near midline on anterior surface of maxilla and mandible and modiolus at angle of mouth • INSERTION • Mucous membrane of margin of lips and raphe with buccinator at modiolus • ACTION • Narrows orifice of mouth, purses lips and puckers lip edges

10. Orbicularis oculi • ORIGIN • Medial orbital margin and lacrimal sac (orbital, palpebral and lacrimal parts) • INSERTION • Lateral palpebral raphe • ACTION • Closes eyelids, aids passage and drainage of tea

11. Buccinator • ORIGIN • External alveolar margins of maxilla and mandible by molar teeth, to maxillary tubercle and pterygoid hamulus and posterior mylohyoid line respectively, then via pterygomandibular raphe between bones • INSERTION • Decussates at modiolus of mouth and interdigitates with opposite side • ACTION • Aids mastication, tenses cheeks in blowing and whistling, aids closure of mouth

12. Scalenes (ant scalene) • ORIGIN • Anterior tubercles of transverse processes of C3-6 • INSERTION • Scalene tubercle on superior aspect of 1st rib • ACTION • Accessory to inspiration. lateral flexion of neck when 1st rib fixed

13. Splenius • ORIGIN • Lower ligament nuchae, spinous processes and supraspinous ligaments T1-3 • INSERTION • Lateral occiput between superior and inferior nuchal lines • ACTION • Extends and rotates cervical spine

14. Zygomaticus major • ORIGIN • Anterior surface of zygomatic bone • INSERTION • Modiolus at angle of mouth • ACTION • Elevates and draws angle of mouth laterally

15. Zygomaticus minor • ORIGIN • Lateral infra-orbital margin • INSERTION • Skin and muscle of upper lip • ACTION • Elevates and everts upper lip

16. ChestAbdomen & Spine

17. Pectoralis Major • ORIGIN • Clavicular head-medial half clavicle. Sternocostal head-lateral manubrium and sternum, six upper costal cartilages and external oblique aponeurosis • INSERTION • Lateral lip of bicipital groove of humerus and anterior lip of deltoid tuberosity • ACTION • Clavicular head:flexes and adducts arm. Sternal head: adducts and medially rotates arm . Accessory for inspiration

18. Pectoralis minor • ORIGIN • 3, 4, 5 ribs • INSERTION • Medial and upper surface of coracoid process of scapula • ACTION • Elevates ribs if scapula fixed, protracts scapula (assists serratus anterior)

19. External Oblique • ORIGIN • Anterior angles of lower eight ribs • INSERTION • Outer anterior half of iliac crest, inguinal lig, public tubercle and crest, and aponeurosis of anterior rectus sheath • ACTION • Supports abdominal wall, assists forced expiration, aids raising intraabdominal pressure and, with muscles of opposite side, abducts and rotates trunk

20. Internal oblique • ORIGIN • Orbital surface of maxilla behind orbital margin • INSERTION • Post/inferior quadrant of sclera behind equator of eyeball • ACTION • Elevates eye in adduction. Laterally rotates eye in abduction

21. Transversus abdominis • ORIGIN • Costal margin, lumbar fascia, anterior two thirds of iliac crest and lateral half of inguinal ligament • INSERTION • Aponeurosis of posterior and anterior rectus sheath and conjoint tendon to pubic crest and pectineal line • ACTION • Supports abdominal wall, aids forced expiration and raising intra-abdominal pressure. Conjoint tendon supports posterior wall of inguinal canal

22. Rectus abdominis • ORIGIN • Pubic crest and pubic symphysis • INSERTION • 5, 6, 7 costal cartilages, medial inferiorcostal margin and posterior aspect of xiphoid • ACTION • Flexes trunk, aids forced expiration and raise intra-abdominal pressure

23. Diaphragm • ORIGIN • Vertebral:crura from bodies of L1, 2 (left), L1-3 (right). Costal: medial and lateral arcuate ligs, inner aspect of lower six ribs . Sternal: two slips from posterior aspect of xiphoid • INSERTION • Central tendon • ACTION • Inspiration and assists in raising intra-abdominal pressure

24. External Intercostals • ORIGIN • Inferior border of ribs as far back as posterior angles • INSERTION • Superior border of ribs below, passing obliquely downwards and backwards • ACTION • Fix intercostal spaces during respiration. Aids forced inspiration by elevating ribs

25. Internal intercostals • ORIGIN • Inferior border of ribs as far back as posterior angles • INSERTION • Superior border of ribs below , passing obliquely downwards and backwards • ACTION • Fix intercostal spaces during espiration. Aids forced inspiration by elevating ribs

26. Erector Spinae (Sacrospinalis) • ORIGIN • Transverse processes • INSERTION • Transverse processes several levels above • ACTION • Extends spine