3. Neck Flashcards
Sternocleidomastoid
Location
Origin
Insertion
Action
L- two headed muscle located deep to platysma on anterolateral surface of neck; delineate limits of anterior and posterior triangles of the neck
O- manubrium of sternum and medial portion of clavicle. Clavicular head.
I- mastoid process of temporal bone and superior nuchal line of occipital bone
A- flexes and laterally rotates the head; simultaneous contraction of both muscles causes neck flexion; acting alone, each muscle rotated head toward shoulder on opposite side and tilts or laterally flexes head to its own side
Trapezius
Location
Origin
Insertion
Action
L- most superficial muscle of posterior thorax; flat and triangular; upper fibers run inferiorly to scapula; middle fibers run horizontally to scapula; lower fibers run superiorly to scapula
O- occipital bone, ligamentum nuchae, and spines of C and all thoracic vertebrae
I- a continuous insertion along acromion and spine of scapula and lateral third of clavicle
A- stabilizes, elevates, retracts, and rotates scapula; middle fibers retract (adduct) scapula; superior fibers elevate scapula - shrugging shoulders, help extend head when scapula is fixed
Mylohyoid
Location
Action
L- flat, triangular muscle just deep to digastric muscle; this muscle pair forms a sling that forms the floor of the anterior mouth
A- elevates hyoid bone and floor of mouth, enabling tongue to exert backward and upward pressure that forces food bolts into pharynx
Sternohyoid
Location
Action
L- most medial muscle of the neck; superficial except inferiorly, where covered by sternocleidomastoid
A- depression and stabilization of larynx and hyoid bone, aids in swallowing and phonation.
Sternothyroid
Location
Action
L- lateral and deep to sternohyoid
A- depression and stabilization of larynx (thyroid cartilage), phonation and swallowing
Splenius
Location
Action
L- broad bipartite superficial muscle (capitis and cervicis parts) extending from upper thoracic vertebrae to skull
A- extend the head; when splenius muscles on one side are activated, head is rotated and bent laterally toward same side
Stylohyoid
Location
Action
L- slender muscle below angle of jaw; parallels posterior belly of digastric muscle
A- elevates and retracts hyoid; elongates floors of mouth during swallowing
Omohyoid
Location
Action
L- straplike muscle w/two bellies united by an intermediate tendon; lateral to sternohyoid
A-depresses and retracts hyoid bone
Genioglossus
Location
Action
L- extrinsic muscle of tongue; superior mental spine of mandible
A- Protrudes and depresses the tongue
Erector spinae
Location
Action
L- prime mover of back extension. On each side consists of 3 columns - iliocostalis, longissimus, and spinalis muscles- forming the intermediate layer of intrinsic back muscles.
A- provide resistance that helps control action of bending forward at the waist, act as powerful extensors to promote return to erect position.
Digastric - posterior bellies
Location
Action
L- mastoid notch of temporal bone
A- elevates the hyoid bone and depresses the mandible
Digastric - anterior bellies
Location
Action
L- Digastic fossa of mandible
A- Elevates the hyoid bone and depresses the mandible
Geniohyoid
Location
Action
L-narrow muscle in contact w/its partner medially runs; runs from chin to hyoid bone deep to mylohyoid
A- elevates and protracts the hyoid, shortening floor of mouth and widening pharynx for receiving food during swallowing
Thyrohyoid
Location
Action
L- appears as a superior continuation of sternothyroid muscle
A-depresses hyoid bone or elevates larynx if hyoid is fixed
Scalenes
Location
Action
L- located more laterally than anteriorly on neck; deep to platysma and sternocleidomastoid
A-elevate first two ribs (aid in inspiration) flex and rotate neck
