ANTERIOR TRIANGLE Flashcards
What are the borders of the anterior triangle
Laterally: Anterior border of the sternocledomastoid
Superiorly: inferior border of the mandible
Midline: midline of the neck
Two categories of muscles in the anterior triangle
Suprahyoid (above hyoid bone)
Infrahyoid (below hyoid bone)
Name the supra hyoid muscles
Stylohyoid, digastric, mylohyoid, geniohyoid
Name the infra hyoid muscles
Omohyoid, sternohyoid, thyrohyoid, sternothyroid
Origin, insertion, innervation, function of stylohyoid
Styloid process, hyoid bone, facial nerve, pulls hyoid upwards in posterosuperior direction
Origin, insertion, innervation, function of digastric anterior belly
Digastric fossa on mandible, hyoid bone, V3, opens mouth by lowering mandible, raises hyoid bone
Origin, insertion, innervation, function of digastric posterior belly
Mastoid process, hyoid bone, facial nerve, pulls hyoid bone upward and back
Origin, insertion, innervation, function of mylohyoid
Mandible, hyoid bone, V3, support and elevation of floor of the mouth
Origin, insertion, innervation, function of geniohyoid
Inner surface of mandible, hyoid, C1, mandible movement and hyoid movement
Origin, insertion, innervation, function of sternohyoid
Sternum, hyoid, C1-C3, depresses hyoid bone after swallowing
Origin, insertion, innervation, function of omohyoid
Superior border of scapular, hyoid, C1-C3, depresses and fixes hyoid bone
Origin, insertion, innervation, function of thyrohyoid
Thyroid cartilage, hyoid bone, C1, depresses hyoid, raises larynx
Origin, insertion, innervation, function of sternothyroid
Sternum, hyoid, C1-C3, draws larynx downward.
What arteries are found in the anterior triangle of the neck
The common carotids and their branches- internal and external carotid
What level do the common carotids branch to internal and external
C3-C4 (level of hyoid bone to upper border of thyroid cartilage)
Describe the branching (from) and location of the common carotids
Left- from the brachiocephalic artery, branches immediately posterior to the left sternoclavicular joint.
Right- from the arch of the aorta travels into the neck posterior to the right sternoclavicular joint.
What is the path of the the common carotids through the neck
After passing though the superior thoracic aperture the common carotids ascend either side of the trachea and oesophagus within the carotid sheath.
Describe the branches of the internal carotid in the neck and where it enters the skull
It has no branches. Goes on to supply the ipsilateral cerebral hemisphere. The lack of branches distinguishes it from the external carotid. It enters the skull at the carotid canal in the petrous part of the temporal bone
Name the branches of the external carotid
Superior thyroid, ascending pharyngeal, lingual artery, facial artery, occipital artery, posterior auricular artery, superficial temporal artery, maxillary artery. *two terminal branches.
Describe the path of the internal carotid
Continues to travel in the carotid sheath medial to the internal jugular vein and anterior to the vagus nerve. Ascends to enter the skull via the carotid canal in the petrous part of the temporal bone
Where are the carotid sinus and carotid bodies found and what do they contain
Carotid sinus- At the bifurcation from the common carotid the internal carotid is dilated forming the carotid sinus which contains baroreceptors.
Carotid bodies. Located behind the bifurcation of the common carotids, contains chemoreceptors
Describe venous drainage of the head
The sigmoid sinus drains into the internal jugular vein which exits the skull via the jugular foramen and descends down the carotid sheath. It joins the subclavian being to form the brachiocephalic vein behind the sternoclavicular joint which then join the superior vena cava.
What does the internal jugular vein receive tributaries from
Inferior petrosal sinus, facial, lingual, pharyngeal, occipital, superior thyroid and middle thyroid veins.
What is JVP and where is it taken
Jugular venous pressure, an important clinical sign that enables us to assess venous pressure and right side heart functioning. With head turned to the left identify IJV- surface between the two heads of SCM, measure the wave height from the top of the sternal angle to meniscus. Usually around 4cm.
Describe the spinal nerves located in the anterior triangle
The cervical plexus from spinal nerves C1-C3 form a loop of nerve fibres called the ansa cervicalis. Branches from C1 form the superior loop and innervate the thyrohyoid muscle. Branches from C2 and C3 form the inferior loop and innervate the sternothyroid, omohyoid, and sternohyoid. Loop runs down internal jugular and internal carotid.
The rest of the cervical plexus is sensory branches in posterior triangle. One enters anterior triangle the transverse cervical which exits herbs point on posterior borders of SCM and travels medially transverse to innervate skin of anterior neck.
Path of glossopharyngeal
Leaves the skull through jugular foramen, lies deep to styloid process and its attachments, runs down and forward between the internal and external carotid arteries. Curves around the lateral border of stylopharyngeus and continues in an anterior direction to reach the base of the tongue.
Path of Vagus nerve
Leaves the skull via jugular foramen, travels down carotid sheath between internal carotid artery and internal jugular vein. At the root of the neck it passes in front of the subclavian artery and behind subclavian vein to enter the mediastinum. Branches of vagus in anterior triangle include a motor branch to pharynx, carotid body, superior laryngeal nerve and possibly a cardiac branch.
Path of accessory nerve
Leaves the skull through the jugular foramen, runs postereolaterally either medial or lateral of internal jugular vein, crosses the transverse process of the atlas and passes medial to the styloid process and posterior belly of digastric to perforate the sternocleidomastoid
Path of hypoglossal nerve
Leaves the skull via the hypoglossal foramen, passes between the internal carotid artery and internal jugular vein crosses the occipital, external carotid and lingual arteries and reaches the tongue. A branch from C1 hitchhiker with it and innervates some of the supra hyoid muscles.
Where is the thyroid gland and describe its basic anatomy
Anterior to the trachea at the root of the neck. Below the thyroid cartilage.
Two lateral lobes connected with the isthmus. The isthmus crosses the second and third tracheal cartilages
Thyroid embryology
Thyroid grows down from the foramen caecum at the base of tongue as the thyroglossal duct. Travels down neck past hyoid bone to reach its final destination. If duct remains patent can cause ectopic thyroid tissue- accessory thyroid, cervical thyroid or pyramidal thyroid.
Blood supply to thyroid
Superior thyroid artery, external carotid
Inferior thyroid, tyhrocervical branch of subclavian
Venous drainage of the thyroid
Superior, middle and inferior thyroid. Superior and middle drain to internal jugular. Inferior brachiocephalic.
What forms the external jugular veins
Retromandibular, posterior auricular, internal jugular
Relations to be aware of for thyroid
The recurrent laryngeal nerve runs posterior to thyroid. Common carotid on either side and internal jugular.
Innervation of the thyroid
Autonomic nervous system- parasympathetic vagus nerve (via recurrent), sympathetic via sympathetic trunk middle ganglia.
Lymphatic drainage of thyroid gland
Drained by paratracheal nodes, deep cervical lymph nodes along internal jugular
