what muscles form the boundary of the posterior cervical triangle
trapezius
sternocleidomastoid
platysma
sternocleidomastoid
-origin
sternal head
-anterior surface of manubrium
clavicular head
-superior surface of middle 1/3 of clavicle
sternocleidomastoid
-insertion
lateral surface of mastoid process
lateral 1/2 of superior nuchal line
sternocleidomastoid
-actions
alone -laterally flexes neck -rotates head superiorly and to contralateral side bilaterally -neck flexion
sternocleidomastoid
-innervation
spinal accessory nerve (CN XI)
cervical nerves C2, C3 (may be primarily sensory for proprioceptive information and are from ventral rami)
platysma
-origin
fascia and skin over pec major and deltoid
platysma
-insertion
inferior border of mandible
skin of lower face
platysma
-actions
tenses skin of neck
draws corner of mouth inferiorly
assists in depressing mandible
platysma
-innervation
cervical branch of facial nerve (CN VII)
what muscles form the floor of the posterior cervical triangle
splenius capatis levator scapulae posterior scalene middle scalene anterior scalene
posterior scalene
-origin
posterior tubercles of transverse processes C4-C6
posterior scalene
-insertion
external border of second rib
posterior scalene
-actions
flexes neck laterally
elevates 2nd rib during forced inspiration
posterior scalene
-innervation
ventral rami of C7, C8
middle scalene
-origin
posterior tubercles of transverse process C2-C7
middle scalene
-insertion
superior surface of first rib, posterior to groove of subclavian artery
middle scalene
-actions
flexes neck laterally
elevates 1st rib during forced inspiration
middle scalene
-innervation
ventral rami of C3-C8
anterior scalene (hidden behind SCM) -origin
anterior tubercles of transverse processes C3-C6
anterior scalene
-insertion
scalene tubercle of inner border of 1st rib and near groove of subclavian artery
anterior scalene
-actions
flexes neck forward and laterally
laterally rotates neck to contralateral side
elevates 1st rib during forced inspiration
anterior scalene
-innervation
ventral rami of C4-C6
what are the suprahyoid muscles
mylohyoid
geniogyoid
stylohyoid
digastric
mylohyoid
-origin
mylohyoid line of mandible
mylohyoid
-insertion
midline raphe and body of hyoid bone
mylohyoid
-actions
elevates hyoid bone, floor of mouth and tongue during swallowing and speaking
mylohyoid
-innervation
nerve to mylohyoid
-branch of inferior alveolar nerve (CN V3)
geniohyoid
-origin
inferior mental spine of mandible
geniohyoid
-insertion
body of hyoid
geniohyoid
-actions
pulls hyoid bone anterosuperiorly, shortening floor of mouth and widening pharynx
geniohyoid
-innervation
C1 via hypoglossal nerve (CN XII)
stylohyoid
-origin
styloid process of temporal bone
stylohyoid
-insertion
body of hyoid
stylohyoid
-action
elevates and retracts hyoid bone, elongating floor of mouth
stylohyoid
-innervation
cervical branch of facial nerve (CN VII)
digastric
-origin
anterior belly
-digastric fossa of mandible
posterior belly
-mastoid notch of temporal bone
digastric
-insertion
intermediate tendon to body and greater horn of hyoid bone
digastric
-action
depresses mandible
raises hyoid bone and steadies it during swallowing and speaking
digastric
-innervation
anterior belly
-nerve to mylohyoid (branch of inferior alveloar nerve (CN V3))
posterior belly
-cervical branch of facial nerve (CN VII)
muscles of the prevertebral region
longus colli (longus cervicis)
longus capitis
rectus capitis anterior
rectus capitis lateralis
longus colli (longus cervicis) -origin
bodies of T1-T3
transverse process of C3-C6
longus colli (longus cervicis) -insertion
anterior tubercle of C1
bodies of C2,C3
longus colli (longus cervicis) -action
flexes neck forward
upper fibers laterally flex the neck
lower fibers rotate neck to opposite side
longus colli (longus cervicis) -innervation
ventral rami of C2-C6
longus capitis
-origin
anterior tubercles of transverse process of vertebrae C3-C6
longus capitis
-insertion
anterior and inferior surface of occipital bone
longus capitis
-action
flexes neck and head
longus capitis
-innervation
ventral rami of C1-C2
rectus capitis anterior
-origin
anterior surface of lateral mass of atlas and transverse process
rectus capitis anterior
-insertion
inferior surface of occipital bone, anterior to occipital condyle
rectus capitis anterior
-action
flexes head at AO joint?
these small muscles in addition to suboccipital muscles probably act at AA and AO as stabilizers rather than prime movers
rectus capitis anterior
-innervation
ventral rami of C1-C2
rectus capitis lateralis
-origin
upper surface of the transverse process of atlas
rectus capitis lateralis
-insertion
inferior surface of jugular process of occipital bone
rectus capitis lateralis
-action
flexes head laterally?
these small muscles in addition to suboccipital muscles probably act at AA and AO as stabilizers rather than prime movers
rectus capitis lateralis
-innervation
ventral rami of C1-C2
infrahyoid muscles (strap muscles)
sternohyoid
sternothyroid
thyrohyoid
omohyoid
sternohyoid
-origin
manubrium of sternum and medial end of clavicle
sternohyoid
-insertion
body of hyoid bone
sternohyoid
-action
depresses hyoid bone after it has been elevated for swallowing
sternohyoid
-innervation
C1-C3 from ansa cervicalis
sternothyroid
-origin
posterior surface of manubrium of sternum
sternothyroid
-insertion
oblique line of thyroid cartilage
sternothyroid
-action
depresses hyoid bone and larynx
sternothyroid
-innervation
C2, C3 from ansa cervicalis
thyrohyoid
-origin
oblique line of thyroid cartilage
thyrohyoid
-insertion
inferior border of body and greater horn of hyoid bone
thyrohyoid
-action
depresses hyoid bone
elevates larynx
thyrohyoid
-innervation
C1 vya hypoglossal nerve (CN XII)
omohyoid
-origin
superior border of scapula near suprascapular notch
omohyoid
-insertion
inferior border of hyoid bone
omohyoid
-action
depresses, retracts, and steadies hyoid bone
omohyoid
-innervation
C1-C3 from ansa cervicalis
