Anatomy - Neck Viscera

Deep Superficial Cervical Fascia

Begins from the vertebral spinous processes and splits to enclose the trapezius. Splits again to invest the sternocleidomastoid (SCM) and strap muscle

Deep Middle Cervical Fascia

Encloses the thyroid gland, trachea, pharyngeal constrictor muscle, and esophagus. Extends from the hyoid bone down to the sternal attachments and is continuous with the fibrous pericardium

Danger Space

Potential space created between the alar fascia and the prevertebral fascias. Considered as “danger” because it communicates directly with the mediastinum

Retropharyngeal Space

Lines the entire length of the neck. Between the visceral fascia and alar fascia. From the skull base and extends all the way down to T1

Carotid Space

Sheath formed by the 3 layers of the deep fascia. Contains the carotid artery, the internal jugular vein, and the vagus nerve

Common Carotid Artery

The most important artery of the neck

Origin: Right side: Rises from the brachiocephalic artery; Left side, Rises rom the aortic arch

Cross by: Omohyoid muscle, Superior thyroid vein, Middle thyroid vein

Divides into: Internal carotid artery, External carotid artery

Internal Carotid Artery

Crosses by: Hypoglossal nerve, Occipital artery, Posterior belly of the digastric muscle

Near the skull base, it crosses by: Glossopharyngeal nerve, Stylohyoid, Stylopharyngeus, Styloglossus muscle, Styloid process.

Does not give off any branches in the neck, Goes straight to the cerebral circulation

External Carotid Artery

Crosses superficially to: Styloglossus, Stylopharyngeus muscle

Terminal branches passing behind the condylar process

Main blood supply of the head and neck

Superior Thyroid Artery

First branch of the external carotid artery. At the level of the greater horn of the hyoid bone. Supplies the following: Superior part of the thyroid gland, Larynx, Sternocleidomastoid muscle (SCM)

Ascending Pharyngeal Artery

At the level of the superior thyroid artery posteriorly. Supplies the following: Pharynx, Palate, Tonsil, Middle ear, Meninges

Lingual Artery

Above the superior thyroid artery. Runs anterior and superior. Passes beneath the hyoglossus muscle to enter the tongue

Facial Artery

On the anterior surface of the carotid, deep to the digastric muscle. Passes through the submandibular gland, Crosses the inferior border of the mandible. Branches in the neck: Ascending palatine artery, Tonsilar artery, Branches of the submandibular gland, Submental artery

Occipital Artery

Originates from the posterior surface of the external carotid artery. The hypoglossal nerve hooks around it. Supplies the following: Suboccipital region of the scalp, Sternocleidomastoid muscle, Digastric muscle, Stylohyoid muscle

Posterior Auricular Artery

Located posteriorly at the level of the upper border of the digastric muscle. Passes between: Mastoid, Ear. Its branches supply the following: Parotid gland, Auricle, Scalp

Superficial temporal artery, Maxillary artery

What are the terminal branches of the external carotid artery?

Maxillary artery

A terminal branch of the external carotid artery that passes through the infratemporal fossa then through the pterygopalatine fissure and into the pterygopalatine fossa

Thyrocervical Trunk

Arises from the first part of the subclavian artery just anterior to the scalenus anterior muscle. The transverse cervical branch supplies the sternocleidomastoid muscle (SCM) and trapezius. Where the inferior thyroid artery arises and is deep to the carotid sheath. Supplies the following: Inferior portion of the thyroid, Superior and inferior parathyroid gland, Portion of the larynx and trachea. Enter the thyroid at the level of the cricoid cartilage

Internal Jugular Vein

Most important vein of the neck. Sigmoid sinus drains into the internal jugular vein, which drains towards the subclavian vein. Major tributaries: Inferior petrosal sinus, Common facial vein, Lingual vein, Superior thyroid vein, Middle thyroid vein

External Jugular Vein

Deep to the platysma but superficial to the sternocleidomastoid. Terminates in the subclavian vein. At its midportion, it is joined by the posterior external jugular vein

External Jugular Vein

The posterior auricular vein and the posterior branch of the retromandibular vein combine to form the?

Glossopharyngeal Nerve

Has sensory, motor, and parasympathetic components. Has a superior and inferior ganglion. Relationships: Anterior to the internal carotid artery. Deep to the external carotid artery. Passes between the superior and middle constrictor muscle. Innervates the tonsil, pharynx, and tongue

Vagus nerve

Has superior and inferior ganglion at the jugular foramen. Has sensory, motor, and parasympathetic fibers. As it courses through the neck, the nerve separates into the superior and inferior branches

Recurrent laryngeal nerve

A branch of the vagus nerve, controls the intrinsic muscles of the larynx except the cricothyroid

Superficial Laryngeal Nerve

Divides into the external and internal branches. Internal branch - pierces the thyrohyoid membrane to enter the larynx and gives sensation to it. External branch - passes inferiorly with the superior thyroid vessels to the inferior pharyngeal constrictor muscle and supplies the cricothyroid muscle

Right inferior branch

Loops around the right subclavian artery. Goes back to the larynx as the right recurrent laryngeal nerve

Left inferior branch

Loops around the arch of the aorta. Returns back to the larynx as the left recurrent laryngeal nerve

Spinal Accessory Nerve

Spinal components: consist of motor (C2–C4). Lateral to the internal jugular vein (IJV). Emerges 1 cm above the Erb’s point. Supplies the sternocleidomastoid muscle and the trapezius

Phrenic Nerve

Passes downward and inward over the anterior surface of the scalenus anterior muscle. Beneath the following: Oohyoid muscle, Transversalis colli and suprascapular arteries, The left side of the thoracic duct. Innervates the diaphragm

Brachial Plexus

Formed by intercommunications among the ventral rami (root) of the lower 4 cervical nerves (C5–C8) and the first thoracic nerve (T1). Innervates all muscles of the upper extremity except the trapezius and levator scapulae

Level I

Coincides with the posterior belly of the digastric muscle, mandible, and hyoid. Level IA - Submental group. Level IB - Submandibular group. Drains: Upper and lower lip, cheek skin, nasal skin and mucosa, medial canthus, anterior alveolus, anterior tonsillar pillar, soft palate, ⅔ anterior of the tongue, submandibular salivary gland

Level II

Nodes located in the upper ⅓ of the jugular chain. Level IIA - medial to CN XI. Level IIB - lateral to CN XI. Harbors metastasis from the naso-, oro-, hypopharynx, oral cavity, nasal cavity, thyroid, larynx, and parotid

Level III

Nodes in the middle third of the jugular nodal chain. Harbors metastasis from the oro- and hypopharynx, oral cavity, larynx, and thyroid

Level IV

Nodes in the lower ⅓ of the jugular nodal chain. Harbors metastasis from the hypopharynx, oral cavity, larynx, and thyroid

Level V

Located in the lower half; posterior to CN XI. Level VA and VB are separated by a horizontal plane marking the inferior border of the arch of the cricoid cartilage. Harbors metastasis from the naso-, oro-, hypopharynx and the thyroid

Level VI

Includes the pre- and paratracheal nodes, precricoid, and the perithyroidal nodes. Harbors metastasis from the thyroid, larynx, and cervical oesophagus

Thoracic Duct

Empties through multiple branches into the lowest portion of the IJV, the subclavian vein or both. Main duct may extend as high as 5 cm above the clavicle. Drains chyle

Chyle

Milky bodily fluid consisting of lymph and emulsified fats, or free fatty acids (FFAs)

Thoracic Duct

Passes up through mediastinum → left root of the neck → posterior to the carotid sheath & medial to the anterior scalene muscle.

Thyroid

Brownish-red, highly vascular gland. Located at anterior neck at C5–T1. Overlays the 2nd–4th tracheal rings. Average width: 12–15 mm (each lobe). Average height: 50–60 mm long. Average weight: 25–30 g in adults (slightly more in women). Enlarges during menstruation and pregnancy

Thyroid Pyramidal Lobe

Often ascends from the isthmus or the adjacent part of either lobe (usually the left) up to the hyoid bone. May be attached by a fibrous/fibromuscular band or “levator” of the thyroid gland

Inner true capsule

Under the middle layer of deep cervical fascia (pretracheal), the thyroid has this structure. Thin and closely adherent to the gland. Extends within the gland to form septae, dividing it into lobes and lobules

Principal Cells

Follicular cells, Responsible for the formation of colloid (iodothyroglobulin)

Parafollicular Cells

C cells (clear, light). Lie adjacent to follicles within the basal lamina. Produce calcitonin, which increases calcium absorption

Thyroid Hormone

Regulates the basal metabolic rate. Increases oxygen consumption in most target tissues. Its permissive actions increase the sensitivity of target tissues to catecholamines. Elevates lipolysis, glycogenolysis, and gluconeogenesis.

Thyroid Hormone

Critical for the normal development of the skeletal system and musculature. Essential for normal brain development and regulates synaptogenesis, neuronal integration, myelination, and cell migration

Cretinism

Constellation of defects resulting from untreated neonatal hypothyroidism

Superior Thyroid Artery

First anterior branch of the external carotid artery (ECA). Descends laterally to the larynx under the omohyoid and sternohyoid muscles. Runs superficially on the anterior border of the lateral lobe, sending a branch deep into the gland before curving toward the isthmus where it anastomoses with the contralateral artery

Inferior Thyroid Artery

Originates from the thyrocervical trunk. Ascends vertically and then curves medially to enter the tracheoesophageal groove (posterior to carotid sheath). Branches penetrate the posterior aspect of the lateral lobe

Recurrent laryngeal nerve

It is very important during thyroidectomy (surgical procedure to remove the thyroid) that this nerve is identified before ligating the inferior thyroid artery

Superior thyroid vein (STV)

Ascends along superior thyroid artery. Becomes a tributary of the internal jugular vein

Middle thyroid vein (MTV)

Directly lateral to the internal jugular vein

Right inferior thyroid vein

Passes anterior to innominate artery R BCV or anterior trachea L BCV

Left inferior thyroid vein

Drains into left brachiocephalic vein. **occ - both inferior veins form a common trunk, the thyroid ima vein, which empties into left brachiocephalic vein

Recurrent Laryngeal Nerve

Lies just inferior to the thyroid gland. Innervates all larynx muscles except cricothyroid. Closely associated with the inferior thyroid artery

Right vagal branch

Loops around the right subclavian artery. Inserts itself into the inferior constrictor muscles

Left vagal branch

Loops around the arch of the aorta. Passes through the tracheoesophageal groove. Inserts into the inferior constrictor muscles

Superior laryngeal nerve

Pierces through the thyrohyoid membrane. Supplies sensation to the vocal cords

Non-recurrent laryngeal nerve

In approximately 5 out of 1000 patients which is usually on the right side. Directly enters the larynx without looping around the subclavian artery

Parathyroids

Controls the amount of calcium in the body. Appearance: About the size of a grain of rice, Yellow-mustard in colour

Parathyroids

Produces PTH, which stimulates osteoclasts to resorb bone and release calcium into the blood. Increased activity (hyperparathyroidism) causes: Osteoporosis, Osteopenia, Kidney stones, Arrhythmia, Atrial fibrillation

Primary Hyperparathyroidism

Condition characterized by an inappropriate excess of PTH secretion. Results in hypercalcemia and hypophosphatemia. Usually caused by parathyroid adenomas

Secondary Hyperparathyroidism

Usually caused by chronic kidney disease. Overproduction of parathyroid hormone occurs in response to hyperphosphatemia, hypocalcemia and impaired 1,25-dihydroxyvitamin D production

Tertiary Hyperparathyroidism

State of excessive secretion of parathyroid hormone after long-standing secondary hyperparathyroidism and resulting in hypercalcemia. Autonomous hypersecretion of parathyroid hormone causing hypercalcemia. May be due to monoclonal expansion of parathyroid cells (nodule formation within hyperplastic glands)

Trachea

Extends from the larynx to the superior border of T5. Divides into right and left primary bronchi. 16–20 C-shaped rings of hyaline cartilage. A mobile cartilaginous and membranous tube. Begins in the neck as a continuation of the larynx at the lower border of the cricoid cartilage at the level of the sixth cervical vertebra

Tracheostomy

An alternate route for breathing for patients with upper airway obstruction

Esophagus

Connects the pharynx to the stomach. Muscular tube; 22-2-5 cm in length in adults. Collapsed at rest. Flat in upper ⅔ & rounded in lower ⅓ . Commences at the lower border of the cricoid cartilage (C6)

Thoracic Inlet

Most common site of esophageal impaction. Defined as the area between the clavicles on chest radiograph. Site of anatomical change from skeletal muscle to smooth muscle of the esophagus. About 70% of blunt foreign bodies that lodge in the esophagus do so at this location

Lamier’s dehiscence

A triangular area in the wall of the pharynx found in between the oblique fibers of the inferior constrictor muscle, and the transverse fibers of the cricopharyngeus muscle through which the Zenker’s diverticulum occurs.

Upper oesophageal sphincter (UES)

A 2–3 mm zone of elevated pressure between pharynx & oesophagus. Relates to cricopharyngeal muscle

Lower oesophageal sphincter (LES)

Located at the junction between the esophagus and stomach. Usually localized at or just below the diaphragmatic hiatus. Despite its distinct physiological function, it is not easily distinguished anatomically

Cervical Esophagus

What region of the esophagus is supplied by the Right and left superior and inferior thyroid arteries?

Thoracic Esophagus

What region of the esophagus is supplied by the Aorta (tracheo-bronchial tree)?

Abdominal Esophagus

What region of the esophagus is supplied by the Branches of the left gastric artery, Branches of splenic artery posteriorly?

Deep cervical lymph nodes

What is the lymphatic drainage of the proximal third of esophagus?

Superior and posterior mediastinal nodes

What is the lymphatic drainage of the middle third of esophagus?

Gastric and celiac lymph nodes

What is the lymphatic drainage of the distal third of esophagus?

Parasympathetic

What region of the esophagus does this innervation supply: Vagus - Motor to muscular coats, Secretomotor to glands?

Sympathetic

What region of the esophagus does this innervation supply: From cervical and thoracic sympathetic chain, Contraction of sphincters, Wall relaxation, Peristalsis?

Intramural

What region of the esophagus does this innervation supply: Combination of all innervation form plexuses and ganglia, In muscular layers - myenteric or Aurbach’s plexus, In submucosa - Meissner plexus?

SLN

Cephalad to the superior pole, the external branch of ___ runs with STA before turning medially to supply cricothyroid muscle