Posterior Triangle

Question 1

Splenius capitus

Answer 1

Origin: Lower Ligamentum nuchae & spines of upper thoracic vertebrae
Insertion: Back of mastoid process & Superior nuchal line
Action: Extends, rotates, flexes head and neck
Innervation: Dorsal rami of cervical Nn.

Question 2

Levator scapulae

Answer 2

Origin: Transverse processes of cervicals 1-4
Insertion: Upper border of the scapula
Action: Elevates scapula
Innervation: Ventral rami of C3-5

Question 3

Scalenus anterior

Answer 3

Origin: Transverse processes of cervical vertebrae
Insertion: Scalene tubercle of 1st rib
Action: Elevate ribs, and laterally flex neck
Innervation: Ventral rami of cervical Nn.

Question 4

Scalenus medius

Answer 4

Origin: Transverse processes of all cervical vertebraes
Insertion: 1st rib behind groove for subclavius
Action: Elevate ribs and laterally flex neck
Innervation: Ventral rami of cervical Nn.

Question 5

Scalenus posterior

Answer 5

Origin: Transverse processes of cervical vertebrae 4-6
Insertion: Outer side of 2nd rib
Action: Elevate ribs and laterally flex neck
Innervation: Ventral rami of cervical Nn.

Question 6

Sternocleidomastoid

Answer 6

Origin: By two heads from anterior surface of manubrium and upper surface of clavicle
Insertion: Short tendon to outer surface of mastoid process and lateral 1/3 of superior nuchal line
Action: Flexes, rotates, and laterally flexes head and neck; elevates sternum and ribs
Innervation: Spinal Accessory N.

Question 7

Platysma

Answer 7

Origin: Skin and fascia of pectoral and anterior deltoid regions
Insertion: Lower border of mandible
Action: Tenses skin of neck
Innervation: Facial N.