Muscles of the neck Flashcards
What are the main muscles of the neck?
Platysma
Sternocleidomastoid
Trapezius
Supra-hyoids
Infra-hyoids
Where does platysma originate?
Inferior border of mandible
subcutanous tissue of lower face
skin of lower face
Where does platysma insert?
Over the clavicle and beginning of the chest wall
What part of the neck does the platysma cover?
Anterior and lateral part on both sides
What innervates the platysma?
Facial nerve - cervical branch
What are the actions of platysma?
Depresses jaw
Depresses corners of mouth
Tenses skin
What is the structure of sternocleidomastoid?
Two heads
- sternal
- clavicular
Where does sternocleidomastoid originate?
Sternal head - manubrium of sternum
Clavicular head - medial clavicle
Where does sternocleidomastoid insert?
Mastoid process
What innervates sternocleidomastoid?
CN11 accessory nerve - spinal part
What are the actions of sternocleidomastoid?
Unilateral contraction - lateral flexion of neck on same side,
rotates head to contralateral side
Bilateral contraction - flexion of neck
How is the sternocleidomastoid examined?
Put hand on one side of patient’s face
offer resistance
ask patient to look over their shoulder on that side
Where does trapezius originate?
External occopitial protruberance
superior nuschal line
nuschal ligament
spinous processes of cervical and thoracic vertebrae
Where does trapezius insert?
Spine of scapula
acromion
lateral third of clavicle
What innervates trapezius?
CN11 accessory nerve - spinal part
What are the actions of trapezius?
Upper fibres - elevate the scapula, rotate the scapula upwards to allow shoulder abduction over 90degrees
Middle fibres - retract scapula
Lower fibres - depress scapula
How is the trapezius examined?
Put hand on patient’s shoulder
offer resistance
ask patient to elevate their shoulder on that side
What are the signs of a damaged accessory nerve to do with the trapezius?
Trapezius is wasted away, scapula is prominent
Shoulder is depressed
What shape are the infra-hyoid muscles?
Strap-like
Where are the infra-hyoid muscles located?
Inferior to the hyoid bone
What is the main infra-hyoid muscle?
Omohyoid
Where does omohyoid originate?
Hyoid bone
Where does omohyoid insert?
Scapula
Where does omohyoid run in the neck?
From hyoid bone, inferiorly down length of neck
posteriorly to sternocleidomastoid muscle
emerges laterally to sternocleidomastoid muscle in posterior triangle
moves towards scapula
What is the structure of omohyoid?
Two bellies
- superior
- inferior
Where is the superior belly of omohyoid located?
Above sternocleidomastoid
Where is the inferior belly of omohyoid located?
Laterally to sternocleidomastoid
What is the action of omohyoid?
Depresses hyoid bone
Where are supra-hyoid muscles located?
Superior to the hyoid bone
What is the main supra-hyoid muscle?
Digastric
What is the structure of digastric?
Two bellies
- anterior belly
- posterior belly
Where does the anterior belly of digastric originate?
Mandible in chin area
Where does the anterior belly of digastric insert?
Hyoid bone
Where does the posterior belly of digastric originate?
Mastoid process
Where does the posterior belly of digastric insert?
Hyoid bone
What are the actions of digastric?
Depresses mandible
Elevates hyoid bone
