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Ant Neck Triangles
Question | Answer |
---|---|
Carotid Sheath | Contains the Common Carotid A, Internal Jugular V, and Phrenic N. **Posterior to Sternocleidomastoid |
Carotid Triangle | Borders: 1.superior belly of omohyoid M. 2.posterior belly of digastric M. 3.anterior border of the Sternocleidomastoid. **Can palpate and ausculate carotid pulse |
Internal Carotid A. | direct continuation of the common carotids, superior to the origin of the external carotid A at the thyroid cartilage. enters cranium through carotid canals of the temporal bone. Becomes the main artery of the brain and orbits |
Superior Thyroid A. | The most inferior of of the 3 anterior branches off ECA, runs inferoanterior, deep to the infrahyoid M and the SCM. Gives rise to the superior laryngeal artery |
Superior Larngeal A. | Arises from the superior thyroid A from the external carotid A. Supplies the Larynx. |
Lingual A. | Arises from anterior aspect of external carotid A. Moves superoanteriorly, passing deep to the hypoglossal N, stylohyoid m, and posterior belly of digastric m. Bifricates into deep and sublingual a. |
6 Branches off External Carotid A before its two terminal branches | 1.Superior Thyroid A* 2.Ascending Pharyngeal A 3.Lingual A* 4.Occipital A 5.Facial A* 6.Posterior Auricular A *arise anteriorly |
Facial A | Arises anteriorly off Ext. Carotid A immediately superior to lingual A. Gives rise to Ascending palatine A and tonsillar branch. Passes superiorly, deep to digastric and stylohyoid m at angle of mandible. Loops anteriorly to supply the submandibular gland |
Internal Jugular V | Originates at the Superior bulb of IJV. Drains most veins in the anterior neck, brain, anterior face, deep muscles of the neck. Largets vein in the neck and moves through the jugular fossa. travels laterally within the carotid sheath. |
Hypoglossal N | CN XII. Motor nerve of the tongue. Enters submandibular triangle triangle deep to posterior belly of digastric. Supplies all intrinsic, and 4/5 extrinsic muscles of tongue. Passes between EJV and Ext carotid A giving off superior root of Ansa Cervicalis |
Vagus N | CN X. Passes through both submandibular and carotid triangles. Gives rise to pharyngeal, laryngeal, and cardiac branches before forming Ant/Post Vagal trunks |
Ansa Cervicalis | Loop consisting of C1-3 spinal nerves. Supplies infra hyoid muscles. Superior root: C1-2 and CN XII. Medial, crosses the lateral cervical region. Inferior root: C2-3. Lateral |
Sternohyoid M (infrahyoid muscle) | Origin: Manubrium/medial clavicle. Insertion: Body of hyoid. Innervation: Ansa Cervicalis. Action: Depresses hyoid after its elevated during swallowing. |
Thyrohyoid M (infrahyoid muscle) | Origin: Thyroid cartilage. Instertion: Inferior body of hyoid bone. Innervation: CN XII. Action: Depresses hyoid, elevates larynx. |
Sternothyroid M (infrahyoid muscle) | Origin: Posterior Manubrium. Insertion: Thyroid cartilage/ hyoid bone. Innervation: Ansa Cervicalis. Action: Depresses Hyoid and larynx. **Deep to sternohyoid and omohyoid (superior belly). |
Omohyoid M (infrahyoid muscle) | Origin: superior border of scapula. Insertion: Inferior Hyoid. Innervation: Ansa Cervicalis. Action: Depresses and retracts the hyoid bone. **Superior and inferior bellies. |
Mylohyoid M (suprahyoid muscle) | Origin: Mylohyoid line on mandible. Insertion: Hyoid Bone. Innervation: N to Mylohyoid Action: Elevates Hyoid, floor of mouth, and tongue during swallowing/speaking. |
Geniohyoid M (suprahyoid muscle) | Origin: Mental spine of mandible. Insertion: Body of hyoid. Innervation: CN XII. Action: widens pharynx. |
Stylohyoid M (suprahyoid muscle) | Origin: Styloid process of temporal bone. Insertion: body of hyoid. Innervation: CN VII. Action: Elongates floor of mouth via elevating and retracting hyoid. |
Digastric M - Anterior Belly (suprahyoid muscle) | Origin: Digastric fossa on mandible. Insertion: Intermediate tendon/hyoid bone Innervation: N to Mylohyoid. Action: Elevates hyoid during swallowing and speaking |
Digastric M - Posterior Belly (suprahyoid muscle) | Origin: Mastoid notch of temporal bone. Insertion: Intermediate tendon/hyoid bone Innervation: Digastric branch of facial N (CN VII). |
Submandibular Gland | located in the submandibular triangle overlying the digastric M |
Thyroid gland | Lies deep to sternothyroid and sternohyoid m. At the level of C5-T1 anterior neck. R and L Lobes are anterolateral to the larynx and trachea. They connected by the isthmus. |
Isthmus of Thyroid Gland | Unites the R and L lobes of the thyroid. |
Superior Thyroid A | Lies between the fibrous capsule and loose fascial sheath. It is the first branch of Ext. Carotid A, supply the anterosuperior aspect. |
Inferior Thyroid A | Largest branches of thyrocervical trunk off the subclavian. runs superomedially posterior to the carotid sheath to reach the posterior aspect of the gland. |
Superior Thyroid V | accompany the superior thyroid A and drain into the superior poles of the thyroid. Drain into IJV. |
Inferior thyroid V | Independent, drains the inferior poles of the thyroid gland. Drains into brachiocephalic V. |
Thyroid cartilage | Largest cartilage, superior border lies opposite of C4 vertebrae. Forms the Laryngeal prominence inferiorly (also known as the adams apple) |
Cricoid cartilage | Shaped like a signet ring. Located just inferior to the cricorthyroid membrane. |
Cricorthyroid membrane | Connects the thyroid cartilage to the cricoid cartilige. **Important when making incision for trach tubes |
Trachea cartilages | Begin just inferior to the Cricoid cartilage. |
Thyrohyoid membrane | connects the superior hyoid bone to the inferior thyroid cartilage. |
Extrinsic laryngeal Muscles | Includes the infrahyoid muscles (depress the hyoid and larynx) and the suprahyoid muscles (elevate the hyoid and larynx) |
Hyoid Bone | U-shaped bone consisting of several parts: body, 2 lesser and 2 greater horns. |
Retromandibular V | Formed just anterior to ear by union of superficial temporal v and maxillary v. It runs posterior and deep to ramus of mandible through the parotid gland. Post div.+ posterior auricular v to form EJV. Drains the parotid gland and masseter muscle. |
Common Facial V | Formed from Ant. div. of retromandibular v, facial v, and lingual v. |
Tracheostomy | Emergency access into the airway through the cricothyroid membrane. **This is a good location because there are no major vessells or nerves in the area. Does however impenge directly on the vocal cords so it isn't good for long term placement. |
Injury to the Phrenic N | Can be seen on a radiograph as one side of the diaphragm elevated like a dome while the function side is depressed during inspiration. |
Injury to Ansa Cervicalis | It is at risk for injury due to its location on the anterior aspect of the carotid sheath. If cut during surgery, will produce an elevated hyoid bone and difficulty swallowing. |