Lecture 3: Anterior Trianglers Of The Neck I: Musculature And Thyroid/parathyroid Glands Flashcards
What are the roof and floor of the anterior triangle?
Roof: deep investing fascia around muscles
Floor: Pretracheal fascia and carotid sheath
What are the broad functions of suprahyoid muscles?
Elevate the hyoid (e.g. during swallowing)
Elevate the larynx (tone production)
What are the origin, insertion and action of mylohyoid?
Origin: mylohyoid line of mandible
Insertion: body of hyoid and fibres of opposite mylohyoid
Action: Elevates hyoid and floor of mouth. Reinforces floor of oral cavity
What are the origin, insertion and action of digastric muscles?
Origin: anterior belly is digastric fossa on medial aspect of mandible/Posterior belly is mastoid notch on medial aspect of mastoid process.
Insertion: intermediate tendon at hyoid
Actions: anterior belly is elevation of hyoid and opening of mandible/posterior belly elevates and retracts hyoid bone
What is the nerve innervation of the digastric muscles?
Anterior belly = nerve to mylohyoid (branch of CNV3)
Posterior belly = Digastric branch of facial nerve (CNVII)
What is the origin, insertion and action of stylohyoid? What nerve innervates it?
Origin: styloid process
Insertion: body of hyoid
Action: pulls hyoid upward
Innervation: Facial nerve (CNVII)
What is the origin, insertion and action of geniohyoid? What nerve innervates it?
Origin: mental spine of mandible
Insertion: body of hyoid
Action: fixed mandible - elevates and pulls hyoid forward. Fixed hyoid - pulls mandible down and inward.
Nerve supply: Anterior ramus of C1
What is the origin, insertion and action of sternohyoid? What nerve innervates it?
Origin: posterior surface of sternoclavicular joint & manubrium
Insertion: body of hyoid (medially)
Action: depresses hyoid after elevation during swallowing
Nerve supply: Anterior rami of C1-C3
What is the origin, insertion and action of omohyoid? What nerve innervates it?
Origin: superior belly - its intermediate tendon. Inferior belly - superior body of scapula.
Insertion: superior belly - body of hyoid laterally. Inferior belly - intermediate tendon in posterior triangle.
Action: depress and fix the hyoid
Nerve supply: C1-3
What is the origin, insertion and action of thyrohyoid? What nerve innervates it?
Origin: oblique line on thyroid cartilage
Insertion: greater horn and adjacent body of hyoid
Action: depresses hyoid; can raise larynx when hyoid is fixed
Nerve supply: C1. Fibres also run with HYPOGLOSSAL nerve.
What is the origin, insertion and action of sternothyroid? What nerve innervates it?
Origin: posterior surface of manubrium
Insertion: Oblique line on thyroid cartilage
Action: draws larynx downward
Nerve supply: C1-3
What is the arterial supply to the thyroid gland?
Superior thyroid artery (first branch ECA)
Inferior thyroid artery
What is the venous drainage to the thyroid gland
Superior thyroid vein (into IJV)
Middle thyroid vein (into IJV)
Inferior thyroid vein (into brachiocephalic)
What is the nerve supply to the thyroid and parathyroid glands?
Thyroid branches of the cervical ganglia
Which nerve is at risk of damage during neck surgery?
Recurrent laryngeal nerve (especially right). Symptoms include hoarseness or aphonia.
