1. MUSCLES
Will Kleinelp
Associate Professor, Biology
©2007

2. MUSCLES OF THE HEAD
AND NECK

3. Digastric
ORIGIN
Anterior belly: digastric 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 (anterior) 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. MUSCLES OF THE CHEST
ABDOMEN & 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. 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

24. 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

25. 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

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

27. Muscles for Next Week OIA
A. Head and Neck
Epicranial Muscles
2.Frontalis
1. Occipitalis
2. Orbicularis oculi
3. Zygomaticus
4. Buccinator (deep)
5. Temporalis
6. Masseter
7. Digastric (both bellies)
8. Mylohyoid
9. Orbicularis oris
10. Platysma
11. Sternocleidomastoid
12. Sternohyoid
15. Omohyoid (2 bellies)
16. Scalanes group
a) Anterior
b) Posterior
c) Middle
17. Splenius (deep)
18. Longissimus thoracis (erector spinae)
B. Chest and Abdomen
1. Pectoralis major
2. Pectoralis minor (deep)
3. Serratus anterior
4. External intercostals (deep)
5. Internal intercostals (deep)
6. Diaphragm (deep)
7. External oblique
8. Internal oblique (deep)
9. Transversus abdominis (deep)
10. Rectus abdominis