2. Posterior and anterior triangles of the neck, thyroid, parathyroid Flashcards
Boundaries of the anterior triangle of the neck?
Bounded by inferior border of mandible, anterior border of SCM & midline of neck
What fascia forms the roof and floor of the anterior triangle?
Roof= Deep investing fascia around muscles Floor= Pretracheal fascia and carotid sheath
What are the 4 subdivisions of the anterior triangle?
Submandibular, submental, carotid & muscular triangles
What are the contents of the submandibular subdivision of the anterior triangle?
Contains submandibular gland, lymph nodes, (parts of) CN XII, mylohyoid nerve & parts of the facial artery & vein
What are the contents of the submental subdivision of the anterior triangle?
Submental lymph nodes
Small veins
What are the contents of the carotid subdivision of the anterior triangle?
Contains thyroid gland, larynx, pharynx, carotid sheath (& its contents), branches of cervical plexus, superior root of the ansa cervicalis, deep cervical lymph nodes & (parts of) CN XI & XII
What are the contents of the muscular subdivision of the anterior triangle?
Muscles: Sternothyroid and Sternohyoid
Glands: Thyroid and parathyroid
Which bone divides the muscles of the anterior compartment?
The hyoid bone, all are either:
- above and connect to skull or mandible
- Below and connect to inferior structure (e.g. sternum, scapula, thyroid, cartilage)
Except: Sternothyroid
Name the 8 muscles above and below the hyoid bone in the anterior compartment of the neck?
Suprahyoid muscles
- Mylohyoid
- Digastric
- Stylohyoid
- Geniohyoid
Infrahyoid muscles
- Sternohyoid
- Omohyoid
- Thyrohyoid
- Sternothyroid*
*Sternohyoid doesn’t attach to the hyoid bone. Attaches from sternal notch to the thyroid cartilage
Action of suprahyoid muscles
Raise the hyoid bone as required during swallowing
Attachment and action of the mylohyoid bone?
Mylohyoid originates at mylohyoid line on mandible; inserts into body of hyoid & fibres of opposite mylohyoid
Actions:
Elevates the hyoid & the floor of the mouth
Supports floor of mouth
Digastric:
Bellies?
Attachments?
Actions?
Bellies: Anterior and posterior
ANTERIOR BELLY
Attachment: From digastric fossa on lower meal aspect of mandible to intermediate tendon at hyoid
Action: Raises hyoid and opens mouth by lowering mandible
POSTIOR BELLY
Attachment: Mastoid notch on medial side of mastoid process to the intermediate tendon at the hyoid bone
Action: Elevates and retracts hyoid bone
Innervation of mylohyoid?
Nerve to mylohyoid i.e. inferior alveolar branch of CN V3
Innervation of anterior belly of digastric?
Nerve to mylohyoid i.e. inferior alveolar branch of CN V3
innervation of posterior belly of digastric?
Digastric branch of CN VII
Stylohyoid:
Attachment?
Action?
Innervation?
Stylohyoid originates at the styloid process & inserts into body of hyoid (laterally)
Action: Pulls hyoid bone upward (posterosuperior direction)
Innervation via CN VII