Anterior Triangles of the Neck

Question 1

Important Landmarks of the neck

Answer 1

1) Laryngeal Prominence 2) Thyroid notch 3) suprasternal (jugular) notch 4) supraclavicular fossa

Question 2

Hyoid Bone

Answer 2

It is an unpaired bone which lies superior to the laryngeal prominence. It consists of a body and greater and lesser horns. It is the only “boney” structure in the anterior triangles of the neck.

It is sort of just sitting there with tendons and such holding it

Question 3

Thyroid Cartilage

Answer 3

Consists of 2 fused lamina, each with superior and inferior horn. It is a V-shape, it is open in the back

Question 4

Cricoid Cartilage

Answer 4

Consisting of lamina (oval “signet” which faces posteriorly) and an anterior arch which lies b/t thyroid cartilage and first tracheal “ring”. It is the only true ring!

Question 5

Mastoid Process

Answer 5

of temporal bone

Question 6

Transverses Process of Cervical Vertebrae

Answer 6

Designated by the “O’s”

Question 7

Know the layers of fascia in the neck

Answer 7

1. Superficial Fascia
2. Investing layer
3. Infrahyoid fascia
4. Pretracheal Fascia
5. Carotid Fascia
6. Prevertebral (deep cervical) fascia

Question 8

Superficial Muscles

Answer 8

1. Platysma
2. Sternocleidomastoid muscle
3. Trapezius muscle

Question 9

Veins of the neck

Answer 9

1) Internal Jugular Vein: Behind the sternocleidomastoid
2) External Jugular Vein: In front of the sternocleidomastoid

Question 10

Borders of the Anterior Triangle of the Neck

Answer 10

BORDERS:

1. Anterior: anterior median line
2. Posterior: Sternocleidomastoid muscle
3. Superior: inferior border of the mandible
4. Apex: jugular notch
5. Roof: subcutaneous fascia & platysma m.
6. Floor: pharynx, larynx and thyroid gland covered by pretracheal fascia.

Question 11

Suprahyoid Muscles

Answer 11

They are the muscles ABOVE the hyoid bone.

1. Mylohyoid: Innervated by the nerve to mylohyoid
2. Digastric: Innervated by two nerves. Posterior belly by facial nerve or CN VII. Anterior belly by V3.
3. Geniohyoid: Hypoglossal nerve or C1
4. Stylohyoid: fascial nerve or CN VII

Question 12

Infrahyoid muscles

Answer 12

BELOW the hyoid bone. They are apart of the muscular triangle.

1. Sternohyoid Muscle: Ansa Cervicalis (C1-C3)
2. Sternothyroid Muscle: Ansa Cervicalis (C1-C3)
3. Thyrohyoid Muscle: Nerve to thyrohyoid (C1 traveling with hypoglossal nerve CN XII)
4. Omohyoid Muscle: Ansa Cervicalis (C1-C3)

Question 13

Nerves in the Anterior Triangles of the Neck

Answer 13

Question 14

Function of Hyoid Bone

Answer 14

Unlike other bones, the hyoid is only distantly articulated to other bones by muscles or ligaments. The hyoid is anchored by muscles from the anterior, posterior and inferior directions, and aids in tongue movement, vocalization and swallowing. The hyoid bone provides attachment to the muscles of the floor of the mouth and the tongue above, the larynx below, and the epiglottis and pharynx behind.

Question 15

Submandibular Triangle Contents

Answer 15

1. Submandibular Gland
2. Submandibular Lymph nodes
3. Mylohyoid nerve (V3)
4. Facial Artery (and vein)
5. Submandibular duct
6. Lingual nerve (V3) and submandibular ganglion
7. Hypoglossal nerve (XII)

Question 16

Submental Triangle Contents

Answer 16

Mylohyoid muscle is what is important here. It is the floor of this triangle. Contains lymph nodes and small veins that unite to form anterior jugular vein

Mylohyoid muscle functions to lift your tongue

Question 17

Contents of the Carotid Triangle

Answer 17

The aortic arch has three large branches:

1. Brachiocephalic trunk (innominate artery); The brachiocephalic trunk divides into the right common carotid a. and the right subclavian a.
2. Left Common Carotid artery.
3. Left Subclavian artery.

The common carotid a. divides into the internal and external carotid aa. Each internal carotid a. ascends the neck (with no major branches) to enter the cranial cavity via the carotid foramen (canal). The internal carotid a. supplies the orbit, pituitary gland, and a large part of each cerebral hemisphere.

The external carotid a. is responsible for supplying the neck and face (superficial and deep). The carotid triangle contains the superior portion of the common carotid a., a large part of the internal carotid a., and the external carotid a. and many of its branches.

Question 18

Branches of the External Carotid Artery: “SALFOP SuperT Max” or SALFORMS

Answer 18

Branches of the External Carotid Artery: “SALFOP SuperT Max” or SALFORMS

1. Superior Thyroid a. – to thyroid gland, infrahyoid region & larynx. The superior laryngeal artery branches from the superior thyroid artery. This artery pierces the thyrohyoid membrane with the internal laryngeal nerve.
2. Ascending Pharyngeal a. – to pharynx, prevertebral muscles, meninges (via jugular & hypoglossal canals), tympanic membrane, soft palate.
3. Lingual a. – to tongue & oral mucosa, suprahyoid region, sublingual gland, tonsils; runs deep to hyoglossus m.
4. Facial a. – to submandibular gland, lips, nose, facial muscles, and angle of the eye; runs deep to submandibular gland.
5. Occipital a. – to sternocleidomastoid m., meninges and posterior scalp. This artery is “held” against the external carotid artery by the hypoglossal nerve (CN XII) .
6. Posterior Auricular a. – to tympanic membrane, ear, posterior scalp.
7. Superficial Temporal a. – to parotid gland, ear, face, zygomatic & temporal regions of the face.

nGives off the transverse facial a. before ascending.

8.Maxillary a. – infratemporal fossa, nasal cavity and superior pharynx.

Question 19

Nerves of the Carotid Triangle

Answer 19

Vagus N (CN X):

§Runs between the internal carotid and the internal jugular vein within the carotid sheath.

Spinal accessory N. (CN XI):

§Enters the carotid triangle from behind the posterior belly of digastric and runs to the posterior aspect of the SCM.

§Innervates SCM & trapezius.

Hypoglossal (CN XII):

§Enters the carotid triangle from behind the posterior belly of digastric.

§Then runs anterior, slightly inferior, exits triangle and “loops” into the floor of the mouth.

Cervical Sympathetic trunk (chain):

§This is located behind the posterior wall of the carotid sheath. Primary structures visible here include the superior, middle and inferior cervical ganglia, and the external carotid artery plexus.

Question 20

Branches of the Vagus Nerve

Answer 20

The vagus nerve gives off several branches in the neck:

1. Pharyngeal branch - participates in the pharyngeal plexus which supplies motor innervation to the pharynx and palate.
2. Superior Laryngeal n. - This nerve divides to form two branches:

A. Internal laryngeal n. -pierces thyrohyoid membrane to provide sensory innervation to laryngeal structures above the true vocal folds. This nerve pierces the thyrohyoid membrane along with the superior laryngeal branch of the superior thyroid artery.

B. External laryngeal n. - second branch of the superior laryngeal n. which courses inferiorly to supply the cricothyroid m. of the larynx.

3. N. to the Carotid Body - sensory innervation to this chemoreceptor.
4. Cardiac nerves - One or two nerves which enter the thorax and participate in the cardiac plexus of nerves to the heart (provides parasympathetic innervation).
5. Recurrent laryngeal n. –

A.On the right, this nerve loops around the subclavian a. (from anterior to posterior), runs in the groove between the trachea and the esophagus (tracheoesophageal groove), and provides motor innervation to all of the muscles of vocalization with the exception of the cricothyroid m.

B.The left recurrent laryngeal n. wraps around the arch of the aorta (from anterior to posterior), just lateral to the ligamentum arteriosum. Its full course will be seen in more detail during dissection of the thorax.