Superficial Muscles & Muscle Triangles of the Neck

Uncategorized Muscles

Platysma
O: Superficial fascia of chest
I: Base of mandible
A: Draws lower lip & angle of mouth downward & laterally
N: VII

Sternocleidomastoid
O: Jugular notch of sternum
I: Mastoid process of mandible
A: Flexes & laterally rotates cervical spine. Rotates & bends head laterally in conjunction with other        muscles. Extends head forward when already partially extended.
A: XI & branches C2-3

Suprahyoid Muscles
Mnemonic: Diana Styles Mylo's Hair (In)Geniously. The "Hair" is to remind you that all of the muscles except digastric attach to the hyoid bone. 

Digastric Muscle - Ant Belly
O: Digastric fossa of mandible
I: Body of hyoid bone
A: Opens mouth by lowering mandible and raising hyoid bone
N: Mylohyoid n from Inf. alveolar n (V3)

Digastric Muscle - Post Belly
O: Mastoid notch of mastoid process of temporal bone
I: Body of hyoid bone
A: Opens mouth by lowering mandible & rasing hyoid bone
N: Mylohyoid n from Inf. alveolar n (V3)

Stylohyoid
O: Styloid process of temporal bone
I: Lateral area of body of hyoid bone
A: Raises hyoid in posterosuperior direction
N: VII

Mylohyoid
O: Mylohyoid line of mandible
I: Body of hyoid bone
A: Raises roof of mouth, elevates hyoid bone (aids in mastication, swallowing)
N: Mylohyoid n from Inf. alveolar n (V3)

Geniohyoid (N.B. The origin of genio is "chin" or "beard")
O: Mental spine of mandible
I: Body of Hyoid bone
A: Elevates hyoid bone
N: C1 fibres carried by XII

Infrahyoid Muscles
Mnemonic: SHunning STella THroughout OmaHa

Sternohyoid
O: Manubrium of sternum
I: Body of hyoid bone
A: Depresses hyoid & larynx
N: Ansa cervicalis (C1-3)

Sternothyroid
O: Medial posterior aspect of manubrium of sternum
I: Oblique line of thyroid cartilage
A: Depresses larynx
N: Ansa cervicalis (C1-3)

Thyrohyoid
O: Oblique line of thyroid cartilage
I: Inf. border of body of hyoid bone
A: Elevates larynx, depresses hyoid
N: C1 fibres carried by XII

Omohyoid (N.B. Origin of "omo-" means shoulder/scapula)
O: Upper scapula
I: Inf. border of body of hyoid bone
A: Depresses hyoid & larynx
N: Ansa cervicalis (C1-3)

Muscle Triangles of the Neck

Submandibular Triangle
Borders: Inferior border of mandible
               Ant. belly digastric m
               Post. belly digastric m

Contents:
1. Submandibular gland
2. CN VII
3. Facial a
4. CN XII

Submental Triangle
Borders: Inferior border of mandible
              Right and Left ant. belly of digastric mm

Contents:
1. Lymph nodes

Carotid Triangle
Borders: Post. belly digastric m
              Sup. belly omohyoid m
              Sternocleidomastoid m

Contents:
1. ICA
2. Common carotid a
3. IJV
4. EJV
5. CN X
6. CN XII
7. Sup. laryngeal n
8. Cervical portion of sympathetic trunk

Supraclavicular Triangle
Borders: Clavicle
              Sternocleidomastoid m
              Trapezius m

Divided into: Omoclavicular triangle (inferior) & Omotrapezoid by inf. belly of omohyoid m

Contents:
1. EJV
2. Subclavian a & its branches
3. CN XI
4. Phrenic n
5. Cervical plexus
6. Trunks of brachial plexus