HSB – Neck SUPRAHYOID MUSCLES

Melanie Grace Cruz, MD 1. Digastric – Ant. Belly

RCCO 2021 • N – nerve to mylohyoid
• A – depress mandible or elevates hyoid
NECK 2. Digastric – Post. Belly
• N – Facial n.
• Boundaries:
o SUPERIORLY: Lower border of mandible • A – depress mandible or elevates hyoid
o INFERIORLY: Clavicle 3. Stylohyoid
o POSTERIORLY: Trapezius • N – Facial n.
o ANTERIORLY: Anterior midline of neck • A – Elevates hyoid bone
4. Mylohyoid
• N – nerve to mylohyoid
• A – depress mandible or elevates hyoid/ floor of
mouth
5. Geniohyoid
• N – first cervical
• A – depress mandible or elevates hyoid

SCHEMATIC REPRESENTATION

Anterior triangle INFRAHYOID MUSCLES

• Digastric • Deep group
• Carotid o Thyrohyoid
• Muscular o Sternohyoid
• Superficial group
Posterior triangle o Omohyoid
• Supraclavicular o Sternohyoid
• Occipital
INFRAHYOID MUSCLES
1. Omohyoid – Superior/Inferior
• N – Ansa cervicalis C1, C2, C3
• A – depresses hyoid
HYOID MUSCLES 2. Sternohyoid
SUPRAHYOID MUSCLES • N – ansa cervicalis
• Digastric (Anterior/Posterior belly) • A – depresses hyoid
• Mylohyoid 3. Sternothyroid
• Stylohyoid • N – ansa cervicalis
• Geniohyoid • A – depresses larynx

Source: PPT from HSB department 1 of 8

 4. Thyrohyoid SUBMENTAL TRIANGLE
• N – first cervical Boundaries:
• A – depresses hyoid, elevates larynx • Anterior belly of digastric muscle
• Hyoid bone
o Floor – myohyoid

Contents:
• Submental lymph nodes
• Veins that unite w/ anterior jugular vein

SUBMANDIBULAR TRIANGLE
Boundaries:
• Digastric m. (anterior & posterior belly)
• Inferior border of mandible
ANTERIOR TRIANGLE
Boundaries:
• ANTERIORLY: Anterior midline
• SUPERIORLY: Mandible
• POSTERIORLY: Sternocleidomastoid

Contents:
• Submandibular gland
• Submandibular duct
• CN XII, nerve to mylohyoid
• Submental artery
• Submental lymph nodes
• Suprahyoid muscles
COMPONENTS:
• Submental triangle
• Submandibular or Digastric
triangle
• Muscular
• Carotid

Source: PPT from HSB department 2 of 8

 CAROTID TRIANGLE NERVES: ANTERIOR TRIANGLE
Boundaries: • Hypoglossal
• Superior belly of omohyoid • Vagus
• Posterior belly of digastric • Glossopharyngeal
• Anterior border of sternocleidomastoid • Transverse cervical
o Supplying the skin over the anterior triangle

Contents: POSTERIOR TRIANGLE

• Carotid body – baroreceptor
• Carotid sinus – chemoreceptor
• Carotid sheath – common carotid artery, vagus nerve,
internal jugular vein
• Ansa cervicalis

MUSCULAR TRIANGLE OCCIPITAL TRIANGLE

Boundaries: • Apex contains portion of occipital bone
• Superior belly of omohyoid • Occipital artery is found in the superior part
• Posterior belly of digastric • Accessory nerve crosses the triangle
• Anterior border of sternocleidomastoid
SUPRACLAVICULAR TRIANGLE
• a.k.a SUBCLAVIAN TRIANGLE
• Superficial landmark is supraclavicular fossa
• Crossed by external jugular vein and subclavian artery

POSTERIOR TRIANGLE COMPONENTS:

Contents:
• Sternohyoid
• Sternothyroid
• Thyrohyoid
• Visceral organs – thyroid, parathyroids, larynx

1. Splenius capitis
• O – ligamentum nuchae, spines of C7-T3
• I – lateral superior nuchal line and mastoid
• N – lower cervical nerves
• A – draws head back and lateral; rotate head to
same side together; extends head and neck

Source: PPT from HSB department 3 of 8

 2. Levator scapula CERVICAL VEINS OF CLINICAL IMPORTANCE
• O – transverse process of C1-C4 • Neck veins used for TPN and CVP monitoring
• I – medial border of scapula above spine 1. Subclavian vein
• N – dorsal scapular nerve
• A – elevates scapula
3. Scalene posterior
• O – transverse process of C4-C6
• I – 2nd rib
• N – C6-C8
• A – elevates 2nd rib; flexes cervical vertebra
4. Scalene medius
• O – transverse process of C1-C7
• I – 1st rib
• N – lower cervical nerves
• A – elevates 1st rib; flexes and rotates cervical 2. Internal jugular vein
column to opposite side
5. Scalene anterior
• O – transverse process of C3-C6
• I – scalene tubercle of 1st rib
• N – lower cervical nerves
• A – raise 1st rib; slight rotation of neck

CLINICAL CORRELATION
INFECTION OF THE NECK
• Infection of skin, URTI, etc.
• Infection that occurs between the investing and
pretracheal layers of fascia, it can spread into the
thoracic cavity anterior to the pericardium
CLINICAL CORRELATION OF CAROTID ARTERY
CAROTID OCCLUSION AND ENDARTERECTOMY
• RETROPHARYNGEAL ABSCESS
• Due to artherosclerosis
• Partial occlusion leads to transient ischemic attack
(TIA), a sudden loss of neurological function that
disappears within 24 hours
• Minor stroke – loss of neurological function (weakness
or sensory loss) on one side of the body that exceeds
24 hours but disappears within 3 weeks
• Detected with the use of doppler color study
• Carotid endarterectomy – stripping off the
atherosclerotic plaque with the intima
CONGENITAL TORTICOLLIS o Possible nerves injured with above procedure
• Torticollis is a flexion deformity of the neck ▪ CN IX
• The most common cause of torticollis (wry neck) results ▪ CN X
from a fibrous tissue tumor (fibromatois colli) that ▪ CN XI
develops in the sternocleidomastoid before birth. ▪ CN XII
• Sternocleidomastoid maight be injured when an infant’s
head is pulled too much during a difficult birth, tearing
its fibers (muscular torticollis).

LESION OF THE CERVICAL SYMPATHETIC TRUNK

Results to HORNER SYNDROME:
• Contraction of the pupil (miosis), due to paralysis of the
dilator pupillae

Source: PPT from HSB department 4 of 8

 • Drooling of the superior eyelid (ptosis), resulting from INJURY TO THE SUPRASCAPULAR NERVE:
paralysis of the smooth (tarsal) musle intermingled with • Happen in fracture of
the striated muscle of the levator palpebrae superioris middle 1/3 of the
• Sinking in the eye (enophthalmos), possibly cause by clavicle
paralysis of the smooth (orbitalis) muscle in the floor of • Paralysis of the SITS
the orbit muscle (supraspinatus,
• Vasodilation and absence of sweating on the face and infraspinatus, teres
neck (anhydrosis), caused by lack of sympathetic minor, subscapularis)
(vasoconstrictive) nerve supply to the blood vessels and • Loss of lateral rotation
sweat glands and initial abduction of
the upper limb
• Waiter’s tip position – relaxed limb rotates medially

INJURY TO LARYNGEAL NERVES:

1. Inferior laryngeal nerves
• Due to thyroidectomy
• Paralysis of vocal fold,
leading to hoarseness
of voice
• Bilateral paralysis
LESIONS OF CERVICAL NERVES resulting to stridor
LESIONS OF SPINAL ACCESSORY: (high pitch, noisy respiration)
• Not common; but it is the most common iatrogenic 2. Superior laryngeal nerves
nerve injury in the neck • Paralysis of the cricothyroid muscle
• Causes:
o Penetrating trauma (bullet or knife)
o Surgical procedure (iatrogenic)
o Tumors at the cranial base or cancerous
cervical LN
o Fracture of the jugular foramen where CN XI
leaves the cranium
• Manifestation:
o Weakness and atrophy of sternocleidomastoid
and trapezius, impairing neck movement
o Difficulty in elevating the upper limb LESIONS OF THYROID GLAND
o Drooping of the shoulder THYROGLOSSAL DUCT CYST:
• Thyroid gland begins in the floor of the tongue
(foramen cecum), then descends passing anterior
to the hyoid and thyroid cartilage to reach its final
position
• During this descent, the thyroid gland is attached
to the foramen cecum by the thyroglossal duct that
normally disappears. Remnant of its epithelium
forms thyroglossal duct cyst forming a soft mass at
the anterior part of the neck.

INJURY OF PHRENIC NERVE

• Results to paralysis of the corresponding half of the
diaphragm
• Temporary paralysis – anesthetic injection (lung
surgery)
• Prolonged paralysis – iatrogenic injury dyring neck
dissection
• Paralysis of diaphragm detected a paradoxical
movement seen in x-ray THYROID ENLARGEMENT:
GRAVE’S DISEASE
1. Diffuse thyroid
enlargement
2. Hyperthyroidism
3. Exophthalmos

Source: PPT from HSB department 5 of 8

NEOPLASM: ASPIRATION OF FOREIGN BODIES
Benign: • Obstruct vestibule of larynx
1. Papillary adenoma o Death within 5-10 minutes
2. Follicular adenoma o Heimlich maneuver
3. Hurtle cell adenoma o Insertion of large bore needle to cricothyroid
Malignant: membranes or cricothyrotomy
1. Papillary carcinoma
2. Follicular carcinoma
3. Hurtle cell carcinoma
4. Medullary carcinoma
5. Anaplastic carcinoma

Thyroidectomy:
• Indications:
o Thyroid carcinoma
o Grave’s disease
o Goiter with pressure symptoms and for
cosmetic reasons TRACHEA
• Types: TRACHEOSTOMY
o Total or near total thyroidectomy • To establish an airway
o Subtotal thyroidectomy • Use of tracheostomy tube
o Lobectomy with or without isthmectomy
• Complication
o Injury of recurrent laryngeal nerve
o Hypoparathyroidism
o Bleeding

LESIONS OF PARATHYROID GLAND

HYPERPARATHYROIDISM
• Due to parathyroid adenoma
HYPOPARATHYROIDISM ESOPHAGUS
• Due to iatrogenic removal of the gland during INJURIES
thyroidectomy
• Results to tetany → Death TRACHEOESOPHAGEAL FISTULA:
• Most common congenital anomaly
of the esophagus

LARYNX
FRACTURE OF THE LARYNX
ESOPHAGEAL CARCINOMA:
• Due to accidents (automobile)
• Subcutaneous edema
• Respiratory obstruction, hoarseness of voice

Source: PPT from HSB department 6 of 8

 ZONES OF THE NECK QUESTIONS:
1. In thyroidectomy, the nerve that maybe injured during
ligation of superior thyroid artery”
a. Internal laryngeal
b. Superior laryngeal
c. External laryngeal
d. Inferior laryngeal

ZONE I
• Extends from the clavicle and manubrium to the level of
the interior border of cricoid cartilage:
o Cervical pleura
o Apices of lungs
o Thyroid and parathyroid glands
o Trachea
o Esophagus
o Common carotid arteries
o Jugular veins
o Cervical region of the vertebral column
ZONE II
• Extends from the cricoid cartilage to the level of the
2. Forms the laryngeal prominence in the neck:
angles of the mandible:
a. Cricoid cartilage
o Superior pole of the thyroid gland
b. Thyroid cartilage
o Larynx
c. Epiglottis
o Laryngopharynx
d. Arytenoid cartilage
o Caroid arteries
o Jugular veins
o Esophagus
o Cervical region of the vertebral column
ZONE III
• Angle of the mandible up to the base of the skull
o Salivary glands
o Oropharynx
o
o Nasopharynx 3. Vertebral prominence is the other name of
o Oral and nasal cavities a. Cervical 1
b. Cervical 2
c. Cervical 5
d. Cervical 7

FRACTURE OF THE CERVICAL VERTEBRAL COLUMN

Source: PPT from HSB department 7 of 8

4. The right common carotid artery originates from the: 5. All of the following are suprahyoid muscles, except:
a. Brachiocephalic trunk a. Digastric
b. Right subclavian b. Geniohyoid
c. Arch of aorta c. Omohyoid
d. Ascending aorta d. Mylohyoid

6. The muscle that divides the posterior triangle of the

neck into occipital and supraclavicular triangles?
a. Superior belly of omohyoid
b. Inferior belly of omohyoid
c. Anterior belly of digastric
d. Posterior belly of digastric

7. Sustained tension of the vocal chords is best achieved

thru the action of what intrinsic muscle of the the larynx?
a. Posterior cricoarytenoid
b. Lateral cricoarytenoid
c. Cricothyroid
d. Thyroarytenoid

Source: PPT from HSB department 8 of 8