Lab 5 Questions

What is the function of the platysma muscle?

The platysma muscle, though largely located in the neck, is considered a facial muscle. By inserting on the corners of the mouth and lower lip, it is able to lower these structures during many different facial expressions.

Of the three nerves listed, which two supply cutaneous innervation and which supplies motor innervation?
-lesser occipital nerve
-CN XI
-great auricular nerve

The lesser occipital and great auricular nerves supply the skin inferior and posterior to the ear. The spinal accessory nerve innervates the sternocleidomastoid and trapezius mm.

What is the innervation of the digastric muscle bellies?

a. Anterior Belly of Digastric Muscle: Nerve to mylohyoid, a branch of inferior alveolar nerve.
b. Posterior Belly of Digastric Muscle: Digastric branch of facial nerve (CN VII).

What muscles are innervated by the Hypoglossal nerve?

The hypoglossal nerve supplies all the extrinsic and intrinsic muscles of the tongue, except palatoglossus (innervated by CN X).

What is torticollis and with structure(s) is/are affected?

Torticollis can be either congenital or acquired. Trauma to the sternocleidomastoid muscle or prolonged postural problems can cause shortening of one sternocleidomastoid muscle, resulting in the head being abnormally side-bent to the affected side and rot

Since the ansa cervicalis is located on the anterior aspect of the carotid sheath, injuries or surgical procedures in the area can put it at risk. What symptoms are associated with injury to the ansa cervicalis?

Because the ansa cervicalis innervates the infrahyoid strap muscles, damage results in a permanently elevated hyoid bone (the suprahyoid mm are unopposed) and, therefore, difficulty swallowing.

What is the function of the stylohyoid muscle?

Along with the other suprahyoid muscles, the stylohyoid muscle elevates the hyoid during swallowing. [Remember that it originates on the styloid process of the cranium, hence the name].

The hyoid is unique among bones for its isolation from the remainder of the skeleton. It is suspended from the styloid processes of the temporal bones by the stylohyoid ligament and is firmly bound to the thyroid cartilage. What is the function of the hyo

The hyoid bone serves as an attachment for anterior neck muscles and a prop to keep the airway open

The infrahyoid muscles are named using their origin and insertions. Based upon these attachments, what do you think is the most likely action of each muscle?

a. Sternohyoid muscle: Depresses hyoid after elevation during swallowing
b. Sternothyroid muscle: Depresses hyoid and larynx
c. Thyrohyoid muscle: Depresses hyoid and elevates larynx

Note how the following arteries are connected:
Subclavian artery
Vertebral artery
Internal thoracic artery
Thyrocervical trunk
Suprascapular artery

What is the isthmus of the thyroid gland?

A relatively thin structure that unites the right and left lobes of the thyroid gland over the trachea, usually anterior to the second and third tracheal rings.

What artery does the superior thyroid artery arise from?

External carotid artery

What artery does the inferior thyroid artery arise from?

Thyrocervical trunk via the subclavian artery

How do you think a blockage of the external carotid artery could affect the supply of the thyroid gland?

The right and left superior and inferior thyroid arteries anastomose extensively within the gland, ensuring its supply and providing collateral circulation between the subclavian and external carotid arteries.