Anterior Triangle Flashcards
Anterior boundary of Ant. Triangle
Median line of neck
Posterior boundary of ant. Triangle
Ant border of SCM
Superior boundary of ant triangle
Inferior border of mandible
Apex of the ant triangle
Jugular notch in the manubrium of the sternum
Roof of the ant triangle
Formed by subcutaneous tissue constraining the platysma
Floor of ant triangle
Formed y pharynx, larynx, and thyroid gland
Ant triangle is divided into 4 smaller triangles :
Submental, submandibular, carotid, and muscular
What are the two muscles that divides the ant triangle into smaller triangles
Digastric and omohyoid muscles
Contents of the submental triangle
Several small submental lymph nodes
Small veins that unite to form the ant. Jugular vein
Boundaries of the submental triangle
apex: at the mandibular symphysis.
Base: hyoid bone.
Laterally: right and left anterior bellies of the digastric muscles.
Floor: two mylohyoid muscles, which meet in a median fibrous raphe.
Boundaries of the submandibular triangle
Superior: inferior border of the mandible.
On each side: anterior and posterior bellies of the digastric muscle.
Floor: mylohyoid and hyoglossus muscles.
Contents of the submandibular triangle
Submandibular gland Submandibular lymph nodes Hypoglossal nerve (CNXII) Nerve to mylohyoid muscle Parts of facial artery and vein Submental artery
Boundaries of the carotid triangle
Superiomedial: posterior belly of the digastric.
Inferiormedial: superior belly of the omohyoid.
Laterally: anterior border of the SCM.
Contents of the carotid triangle
Common carotid artery
Carotid sinus
Carotid body
at the level of the superior border of the thyroid cartilage (C4 vertebral level), divides into the internal and external arteries.
Common carotid artery
at the bifurcation, slight dilation of the proximal part of the internal carotid artery.
Innervated principally by the glossopharyngeal nerve (CN IX) through the carotid sinus nerve.
It is a baroreceptor that reacts to changes in arterial blood pressure.
Carotid sinus
an ovoid mass of tissue, lies on the bifurcation of CCA close to carotid sinus.
Supplied mainly by the carotid sinus nerve (CN IX).
It is a chemoreceptor that monitors the level of oxygen in the blood.
Carotid body
Boundaries of the muscular triangle
Superiolaterally, superior belly of the omohyoid muscle.
Inferiolaterally, the anterior border of SCM.
Medially, median plane of the neck.
Contents of the muscular triangle
The infrahyoid muscles and viscera, such as the thyroid and parathyroid glands
What are the four suprahyoid muscles
Mylohyoid
Geniohyoid
Stylohyoid
Digastric
These muscles are superior to the hyoid bone and connect it to the cranium.
These muscles also help in elevating the hyoid and larynx during swallowing and speaking
Suprahyoid muscles
Mylohyoid muscle O: I: N: A:
Origin: Mylohyoid line of mandible
Insertion: Mylohyoid raphe and body of hyoid bone.
Innervation: Nerve to mylohyoid, a branch of inferior alveolar nerve (from ma mandibular nerve, V3).
Action: elevates hyoid, floor of mouth, and tongue during swallowing and speaking.
Geniohyoid muscle
O, I, N, A
Origin: Inferior mental spine of mandible.
Insertion: Body of hyoid bone.
Innervation: C1 via hypoglossal nerve (XII).
Action: Pulls hyoid anterosuperiorly; shorten floor of mouth; widens pharynx.
Stylohyoid muscle
O,I, N, A
Origin: Styloid process of temporal bone.
Insertion: Body of hyoid bone.
Innervation: Stylohyoid branch of facial nerve (VII).
Action: Elevates and retracts hyoid, thus elongating floor of mouth.
Digastric muscle
O,I,N, A
Origin:
Anterior belly: Digastric fossa of mandible.
Posterior belly: mastoid notch of temporal bone.
Insertion: Intermediate tendon to body and greater horn of hyoid. (Intermediate tendon, joins the two bellies of digastric muscle and pass through a fibrous sling which connects this tendon to the body and greater horn of hyoid bone)
Innervation:
Anterior belly: nerve to mylohyoid (branch of inferior alveolar nerve).
Posterior belly: digastric branch of facial nerve (VII).
Action: depresses mandible against resistance; elevates and steadies hyoid during swallowing and speaking.
These muscles connect the hyoid to the sternum, clavicle, and scapula, so depress the hyoid ad larynx during swallowing and speaking
Infrahyoid muscles
The two planes the infrahyoid muscles are split into:
Superficial plane: sternohyoid and omohyoid
Deep plane: sternothyroid and thyrohyoid
Sternohyoid muscle
O,I,N, A
Origin: Manubrium of sternum and medial end of clavicle.
Insertion: Body of hyoid bone.
Innervation: C1-C3 by a branch of ansa cervicals
Action: Depresses hyoid after elevation during swallowing.
Omohyoid muscles
O,I,N,A
Origin: Superior border of scapula near suprascapular notch.
Insertion: Inferior border of hyoid.
Innervation: C1-C3 by a branch of ansa cervicalis.
Action: Depresses, retracts, and steadies hyoid bone.
Two bellies united. By an intermediate tendon which is connected to the clavicle by a fascial sling
Omohyoid
Sternothyoid muscle
O,I,N,A
Origin: Posterior surface of manubrium of sternum.
Insertion: Oblique line of thyroid cartilage immediately superior to the thyroid gland, so it covers the lateral lobe.
Innervation: C2 and C3 by a branch of ansa cervicalis.
Action: Depresses hyoid bone and larynx.
Lies under the sternohyoid, but is wider
Sternothyroid
Appears to be a continuation of the sternothyroid muscle
Thyrohyoid muscle
Thyrohyoid muscle
O,I,N,A
Origin: Oblique line of thyroid cartilage.
Insertion: Inferior border of body and greater horn of hyoid bone.
Innervation: C1 via hypoglossal nerve.
Action: It depresses hyoid and elevates larynx.
Arteries in the Ant. Triangle region
Common carotid artery (arteries) Internal carotid arteries External carotid arteries Maxillary artery Superficial temporal artery Ascending pharyngeal artery Occipital artery Posterior auriclar artery Superior thyroid artery Lingual artery Fascial artery
ascend within the carotid sheath with the IJV and vagus nerve to the level of the superior border of thyroid cartilage: where it divides into: internal and external carotid arteries.
Right and left common carotid artery
begins at the bifurcation of the brachiocephalic trunk behind the right sternoclavicular joint.
Right common carotid artery
arises from the arch of the aorta and ascends in the neck.
Left common carotid artery
The direct continuation of the common carotid arteries, have no branches in the neck.
They enter the cranium through the carotid canals and become the main arteries of the brain and structures in the orbits.
Internal carotid arteries
Supply most structures external to the cranium except part of the forehead and scalp which are supplied by supraorbital artery.
External carotid arteries
It begins from at the superior border of thyroid cartilage and passes poster-superiorly to the region between the neck of the mandible and lobule of the auricle within the parotid gland.
External carotid arteries
Gives rise to 6 branches before it divides into two terminal branches: maxillary artery and superficial temporal artery
External carotid arteries
The 6 branches the external carotid artery gives rise to
Ascending pharyngeal artery Occipital artery Post. Auriclar artery Superior thyroid artery Lingual artery Facial artery
Veins in the ant. Triangle region
Internal jugular vein with tributaries: Inferior petrosal sinus Fascial vain Lingual vein Pharyngeal vein Superior and middle thyroid veins
The IJV drains blood from the
Brain, ant face, cervical viscera, and deep muscles of the neck
begins as the direct continuation of the sigmoid sinus at the jugular foramen from the superior bulb (dilation).
IJV
Posterior to the sternal end of the clavicle, the _______ unites with the subclavian vein to form the brachiocephalic vein.
IJV
The inferior end of the IJV dilates to form the _____________. It’s guarded by valve that permits the blood to go inferiorly.
inferior bulb of the IJV
Nerves in the ant triangle region
Transverse cervical nerve (C2 and C3)
Hypoglossal nerve (CN XII)
Glossphargyneal
Vagus
Supplies the skin covering the ant triangle region
Transverse cervical nerve
Entrees the submandibular triangle deep to the posterior belly of the digastric muscle to supply the muscles of the tongue
Hypoglossal (CN XII)
It’s branches are located in the submandibular and carotid triangles
Glossopharyngeal
It’s branches are located int eh submandibular and carotid triangles as well
Vagus nerve
Posterior to the sternal end of the clavicle, the IJV unties with the ____ to form the _____.
Subclavian vein, brachiocephalic vein
What does the inferior end of the internal jugular vein dilate to form? What is it guarded by?
The inferior bulb of the IJV. It’s guarded by valve that permits the blood to go inferiorly
What are tributaries to the internal jugular vein?
Inf petrosal sinus
Facial vein
Lingual vein
Pharyngeal vein
Superior and middle thyroid veins
What nerves make up the transverse cervical nerve?
C2 and C3
What does the transverse cervical nerve supply?
The skin covering the anterior triangle region
The hypoglossal nerve (CN___) enters the _____ ___ Deep to the:
XII
Submandibular triangle
Posterior belly of the digastric muscle to supply the muscles of the tongue
Where are the glossopharyngeal branches located?
In the submandibular and carotid triangles
Where are the vagus nerves branches located?
In the submandibular and carotid triangles
