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Myology

Muscles of

the Head

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NAMING OF MUSCLES

1. Direction of muscle fibers:a. Rectus: fibers run parallel to the midline (rectus

abdominis) b. Transverse: fibers run perpendicular to the midline (transverse abdominis)

c. Oblique: fibers run diagonally to the midline (external oblique)

2. Location: a. named for a nearby bone: (frontalis) frontal bone b. position relative to a bone: (tibialis anterior) tibia c. section of a muscle having more than one part (anterior deltoid)

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NAMING OF MUSCLES (cont)

3. Size:a. large muscle (gluteus maximus)b. small muscle (gluteus minimus)c. long muscle (extensor digitorum longus)d. short muscle (peroneus brevis)

4. Number of origins:a. two origins: biceps femorisb. three origins: triceps brachiic. four origins: pronator quadratus

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NAMING OF MUSCLES (cont)

5. Shape:a. triangular: deltoidb. trapezoid: trapezius

c. saw-toothed: serratus d. rhomboid or diamond shaped: rhomboids

6. Origin and Insertion:a. sternum, clavicle, and mastoid process: SCM

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NAMING OF MUSCLES (cont)

7. Action: a. decreases an angle of a joint: flexor digitorum b. increases an angle of a joint: extensor carpi ulnaris c. moves bone away from midline: abductor pollicis brevis d. moves bone closer to midline: adductor longus e. upward movement: levator scapulae

f. downward movement: depressor labiig. turns palm up or anteriorly: supinatorh. turns palm down or posteriorly: pronatori. decreases size of an opening: external anal sphincter

j. makes a body part more rigid: tensor fascia latae k. moves a bone around its longitudinal axis: rotator

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Muscles of Head Overview

Divided into 3 groups

Muscles of the Scalp

Muscles of the Face (Eyes, Nose, and Mouth)

Muscles of Mastication

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Muscles of the Head Overview

• Muscle of head are located superficially in the fascia and therefore move the fascia of the scalp and/or face.

– Muscles of scalp move scalp, ears, eyebrows

– Muscles of facial expression subdivided into muscles that move:

• Skin around eyes

• Skin around nose

• Skin around mouth

– Muscles of mastication attach to mandible which is necessary for chewing i.e. mastication.

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Muscles of Head Overview

• Innervation:– Muscles of scalp innervated by facial nerve

(CNVII).– Muscles of facial expression innervated by facial

nerve (CN VII)– Muscles of mastication innervated by trigeminal

nerve (CN V).

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Muscles of the Scalp• Occipitofrontalis:

– Can be considered 2 separate muscles the occipitalis and frontalis– Both attach into the galea aponeurotica

• Galea aponeurotica is broad flat tendon also known as the epicranial aponeurosis

• Temporoparietalis:– Also attaches into galea aponeurotica.– Degree of development varies; some people it is thin other it is non- existent.–Occipitofrontalis and temporoparietalis are known as the epicranius

• Auriculares:–One, two, or all three are nonfunctional in many people–Smallest is anterior auricularis, largest is posterior auricularis

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O: Occipital & temporal bones

I: Galea aponeurotica

A: draws scalp posteriorly

I: CN VII (Facial nerve)

Occipitalis

Palpation: page 15

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O: Galea aponeurotica

I: Fascia and skin superior to the eye and nose

A: draws scalp anteriorly and elevates the eyebrows

I: CN VII (Facial nerve)

Frontalis

Palpation: page 15

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Temporoparietalis

O: Fascia superior to ear

I: Lateral border of galea aponeurotica

A: Elevates ear and Tightens the scalp

N: CN VII (Facial nerve)

Palpation: page 18

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AuricularisO: Anterior: anterior fascia of the ear Superior: lateral margin of the galea aponeurotica Posterior: temporal bone

I: Anterior: Spine of helix Superior: Superior aspect of cranial surface of the ear Posterior: Posterior ear

A: Anterior: draws ear anteriorly Superior: elevates ear Posterior: draws ear posteriorly

N: CN VII (Facial nerve)

Palpation: page 20