Muscles of the posterior cervical triangle; origin, insertion, innervation, action

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Splenius capitis - insertion

-Mastoid process and inferior to the superior nuchal line

SCALENES SUMMARY:

-Middle + anterior insert onto rib 1, therefore elevate rib 1 -Posterior inserts onto rib 2, therefore elevates rib 2 -Anterior innervation: ant rami c4-c7 -Middle innervation: ant rami c3-c7 -Posterior innervation: ant rami c5-c7

Muscles in the posterior cervical triangle innervated by CN XI:

-SCM -Trapezius (motor)

SCM - action

-Unilateral contraction (tilt head towards shoulder on the same side, and turning head to opposite side) [ex: tilt head to right, turn head to left only right SCM contracts] -Bilateral contraction (extending neck at 1st and 2nd cervical vertebrae, raises head when laying down, if laying down and then raise thorax while head is fixed) (for bilateral probably good enough toknow that it contracts on both sides to draw the head forward)

Omohyoid - action

-Depresses hyoid after swallowing -Fixes hyoid

Trapezius - action

-Helps rotate scapula when abducting humerus -Bunch of other upper limb movements

Trapezius - insertion

-Lateral 1/3 of clavicle -Acromion of scapula -Spine of scapula

Splenius capitis - origin

-Lower half of ligamentum nuchae -Spinous processes of vertebrae C4 to C7

Middle scalene - origin

Transverse processes of C2-C7

Levator scapulae - origin

Transverse processes of vertebrae C1 to C4

Omohyoid - innervation

Anterior rami of C1-C3 through ansa cervicalis

SCM - innervation

Anterior rami of C2 - C3 through CN XI

Anterior scalene - innervation

Anterior rami of C4-C7

Posterior scalene - innervation

Anterior rami of C5-C7

SCM (sternal head) - origin

Anterior surface of manubrium

Anterior scalene - action

Elevates rib 1

Middle scalene - action

Elevates rib 1

Posterior scalene - action

Elevates rib 2

SCM (sternal head) - insertion

lateral part of superior nuchal line, mastoid

Splenius capitis - innervation

posterior rami of middle cervical nerves

Anterior scalene - insertion

rib 1

Middle scalene - insertion

rib 1

Posterior scalene - insertion

rib 2

Omohyoid - origin

superior border of scapula

Levator scapulae - insertion

upper medial border of scapula

Trapezius - origin

-Superior nuchal line -External occipital protuberance (aka inion) -Spinous processes of C7 -Ligamentum nuchae

Splenius capitis - action

-Unilateral contractions: draws and rotates head to same side -Bilateral contractions: draws head backwards (compare with SCM)

List all muscles that are part of the posterior cervical triangle

1. Omohyoid (also part of anterior cervical triangle) 2. Sternocleidomastoid (SCM) - sternal head and clavicular head 3. Trapezius 4. Splenius capitis 5. Levator scapulae 6. Anterior, middle, posterior scalenes

SCM - parts

1. Sternal head 2. Clavicular head

Levator scapulae - innervation

C3 - C4 and dorsal scapular nerve (C4, C5)

Trapezius - innervation

Motor: CN XI Sensory (proprioception): C3 and C4

Anterior scalene - origin

Transverse processes of vertebrae C3 to C6 (anterior tubercles)

Posterior scalene - origin

Transverse processes of vertebrae C4 to C6

Middle scalene - innervation

anterior rami of C3-C7

Levator scapulae - action

elevates scapula

Omohyoid - insertion

hyoid bone


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