Platysma, sternocleidomastoid and cervical fascia

Question 1

Platysma

Answer 1

• Thin, flat and wide skin muscle
• Origin: at the level of the 2nd rib from the fascia m. pectoralis majoris and fascia deltoidea
• Runs craniomedially to the inferior margin of corporis mandibulae
• Insertion: skin over basis mandibulae
• Dorsal muscle fibres insert themselves to fascia parotidomaseterica
• Medial fibres don’t connect together
• Lies below the skin superficially to the superficial cervical fascia
• Innervation: cervical branch of the facial nerve
• Function: stretches cervical skin

Question 2

Sternocleidomastoid muscle

Answer 2

• Strong long muscle
• Origin: two parts

1. Medial (pars sternalis) from manubrium sterni
2. Lateral (pars clavicularis) from medial end of clavicle

• Both parts ascend cranially and laterally
• Insertion: processus mastoideus and to the lateral part of the superior nuchal line
• Innervation: Accessory nerve from the cervical plexus
• Function: UC - lateroflexion of head to HLS, BC - dorsiflexion of the cervical column, and at fixed head and cervical backbone it lifts sternum and clavicula and helps inspiration (auxillary inspiratory muscle)

Question 3

Cervical fascia

Answer 3

• Divided into three laminae:

1. Superficial lamina
2. Praetracheal lamina
3. Praevertebral lamina

Question 4

Superficial lamina

Answer 4

• Under skin and platysma
• Cranially attached to mandible
• Caudally to manubrium and clavicle
• Dorsally it encircles the sternocleidomastoid muscle (around it the lamina divides into the superficial and profound layers)
• Posteriorly it passes into the nuchal fascia

Question 5

Praetracheal lamina

Answer 5

• Cranially attached to hyoid bone
• Caudally attached to clavicle and manubrium
• Covers the anterior surface of infrahyoid muscles and thyroid gland
• Part of it participates on the fascial cover of the neurovascular bundle - vagina carotica
• Laterally, at the dorsal margin of the sternocleidomastoid m. the lamina is connected witht he superficial lamina of the cervical fascia
• Above the manubrium, between the superficial and praetracheal lamina there is an area - spatium suprasternale, where arcus venosus juguli is located

Question 6

Praevertebral lamina

Answer 6

• Covers praevertebral muscles
• Attaches to the transverse process of cervical vertebrae
• Passes ventrally on mm. scaleni, dorsally on m. levator scapulae and further laterally it passes into the superficial lamina