MUSCLESWill Kleinelp

Associate Professor, Biology©2007

MUSCLES OF THE HEAD AND NECK

Digastric

ORIGINAnterior belly: digastric fossa on posterior surface of symphysis menti.

posterior belly: base of medial aspect of mastoid process

INSERTIONFibrous loop to lesser cornu of hyoid bone

ACTIONElevates hyoid bone. Aids swallowing and depresses mandible

Mylohyoid

ORIGINMylohyoid line on internal aspect of mandible

INSERTIONAnterior three quarters : midline raphe. posterior

quarter: superior border of body of hyoid bone

ACTIONElevates hyoid bone, supports and raises floor of

mouth. Aids in mastication and swallowing

Masseter

ORIGINAnterior two thirds of zygomatic arch and zygomatic process of maxilla

INSERTIONLateral surface of angle and lower ramus of mandible

ACTIONElevates mandible (enables forced closure of mouth)

Sternocleidomastoid

ORIGINAnterior and superior manubrium and superior medial

third of clavicle

INSERTIONLateral aspect of mastoid process and anterior half of

superior nuchal line

ACTIONFlexes and laterally rotates cervical spine. Protracts

head when acting together . Extends neck when neck already partially extended

ORIGINTemporal fossa between inferior temporal line

and infratemporal crest

INSERTIONMedial and anterior aspect of coronoid process

of mandible

ACTIONElevates mandible and posterior fibers retract

Temporalis

Occipitalis

Orbicularis oris

ORIGINNear midline on anterior surface of maxilla and

mandible and modiolus at angle of mouth

INSERTIONMucous membrane of margin of lips and raphe

with buccinator at modiolus

ACTIONNarrows orifice of mouth, purses lips and

puckers lip edges

Orbicularis oculi

ORIGINMedial orbital margin and lacrimal sac (orbital,

palpebral and lacrimal parts) INSERTIONLateral palpebral raphe

ACTIONCloses eyelids, aids passage and drainage of

tea

Buccinator

ORIGINExternal 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

INSERTIONDecussates at modiolus of mouth and interdigitates with

opposite side

ACTIONAids mastication, tenses cheeks in blowing and whistling,

aids closure of mouth

Scalenes (anterior)

ORIGINAnterior tubercles of transverse processes

of C3-6 INSERTIONScalene tubercle on superior aspect of 1st

rib

ACTIONAccessory to inspiration. lateral flexion of

neck when 1st rib fixed

Splenius

ORIGINLower ligament nuchae, spinous processes and

supraspinous ligaments T1-3

INSERTIONLateral occiput between superior and inferior nuchal lines

ACTIONExtends and rotates cervical spine

Zygomaticus Major

ORIGINAnterior surface of zygomatic bone

INSERTIONModiolus at angle of mouth

ACTIONElevates and draws angle of mouth

laterally

Zygomaticus Minor

ORIGINLateral infra-orbital margin

INSERTIONSkin and muscle of upper lip

ACTIONElevates and everts upper lip

MUSCLES OF THE CHEST ABDOMEN & SPINE

Pectoralis Major

ORIGINClavicular head-medial half clavicle.

Sternocostal head-lateral manubrium and sternum, six upper costal cartilages and external oblique aponeurosis

INSERTIONLateral lip of bicipital groove of humerus and

anterior lip of deltoid tuberosity

ACTIONClavicular head:flexes and adducts arm.

Sternal head: adducts and medially rotates arm . Accessory for inspiration

Pectoralis Minor

ORIGIN3, 4, 5 ribs

INSERTIONMedial and upper surface of

coracoid process of scapula

ACTIONElevates ribs if scapula fixed,

protracts scapula (assists serratus anterior)

External Oblique

ORIGINAnterior angles of lower eight ribs

INSERTIONOuter anterior half of iliac crest, inguinal lig,

public tubercle and crest, and aponeurosis of anterior rectus sheath

ACTIONSupports abdominal wall, assists forced

expiration, aids raising intraabdominal pressure and, with muscles of opposite side, abducts and rotates trunk

Internal Oblique

ORIGINOrbital surface of maxilla behind

orbital margin

INSERTIONPost/inferior quadrant of sclera

behind equator of eyeball

ACTIONElevates eye in adduction.

Laterally rotates eye in abduction

Transversus abdominis

ORIGINCostal margin, lumbar fascia, anterior two thirds

of iliac crest and lateral half of inguinal ligament

INSERTIONAponeurosis of posterior and anterior rectus

sheath and conjoint tendon to pubic crest and pectineal line

ACTIONSupports abdominal wall, aids forced expiration

and raising intra-abdominal pressure. Conjoint tendon supports posterior wall of inguinal canal

Rectus abdominis

ORIGINPubic crest and pubic symphysis

INSERTION5, 6, 7 costal cartilages, medial

inferiorcostal margin and posterior aspect of xiphoid

ACTIONFlexes trunk, aids forced expiration and

raise intra-abdominal pressure

External Intercostals

ORIGINInferior border of ribs as far back as

posterior angles

INSERTIONSuperior border of ribs below, passing

obliquely downwards and backwards

ACTIONFix intercostal spaces during respiration.

Aids forced inspiration by elevating ribs

Internal Intercostals

ORIGINInferior border of ribs as far back as

posterior angles

INSERTIONSuperior border of ribs below , passing

obliquely downwards and backwards

ACTIONFix intercostal spaces during espiration.

Aids forced inspiration by elevating ribs

Diaphragm

ORIGINVertebral: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

INSERTIONCentral tendon

ACTIONInspiration and assists in raising intra-abdominal

pressure

Erector SpinaeSacrospinalis

ORIGINTransverse processes

INSERTIONTransverse processes several levels above

ACTIONExtends spine

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