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