Lecture 18 - Superficial and Deep Neck Structures PDF

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Lecture 18 - Superficial and Deep Neck Structures Friday, 23 March 2018

3:00 PM

The head consists of the cranium and the face. The neck is a tube that connects the head to thorax. The neck is separated into two parts: posterior neck - from the superior nuchal line the occipital bone to the intervertebral disc between C7 and T1. The anterior neck is from t lower border of the mandible down to the clavicles and sternum.

Anterior midline of neck • Hyoid bone - superior to thyroid cartilage • Laryngeal prominence - "adam's apple" • Thyroid gland - inferior to thyroid cartilage

Superficial Structures of the Neck Platysma muscle Thin sheet of muscle that covers the anterolateral aspect of the neck Sternocleidomastoid muscle Important landmark that runs obliquely in the side of the neck Trapezius muscle Covers the posterolateral aspect of the neck

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There are structures superficial to the sternocleidomastoid muscle also. These include the external jugular vein, superficial cervical lymph nodes and cervical nodes. Other superficial structures in the neck include the occipital, submandibular and submental nerves.

Cervical Triangles in the Neck The sternocleidomastoid muscle divides each side of the neck into anterior and posterior cervical triangles. Anterior triangles - there are two of these. Boundaries: anterior border of the sternocleidomastoid muscle, the inferior border of the mandible and the midline of the nec The anterior cervical triangle is divided into smaller triangles: • Submental triangle • Submandibular triangle • Muscular-visceral triangle • Carotid triangle Posterior triangle - one of these. boundaries: posterior border of the sternocleidomastoid muscle, anterior border of the trapezius muscle, middle 1/3rd of the clavicle. The posterior cervical triangle is divided into two smaller triangles: • Occipital triangle • Subclavian triangle

1. Submental Triangle The submental triangle is between the two anterior bellies of the digastric muscles and the hyoid bone. It contains the submental lymph nodes, anterior jugular vein and mylohyoid muscles.

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2. Submandibular Triangle The submandibular triangle boundaries are between the mastoid and mandible above and t anterior and posterior belly of the digastric muscle. The roof structures of the submandibul region are the platysma muscle, facial vein and cervical branch of the facial nerve. It contain • Submandibular salivary gland • Facial artery • Submandibular duct • Lingual nerve • Mylohyoid muscle • Hypoglossal nerve (XII) • Lingual artery submandibular ganglion

3. Muscular Triangle This triangle contains: • Infrahyoid muscles • Thyroid gland, larynx, trachea and oesphagus • Laryngeal nerve, recurrent and external nerves • Inferior laryngeal artery

4. Carotid Triangle This triangle contains: • Carotid sheath ○ Common carotid artery

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Internal jugular vein Vagus nerve

Larynx The larynx is the organ for production of voice and lies at the level C3-C6. It consists of a skeleton made up of cartilages, muscles, ligaments and joints and connects the laryngophar to the trachea. It functions as an air passage, for phonation and prevents entry of food from pharynx into the air passage. Largest cartilage in is the thyroid cartilage - visible as larynge prominence "adam's apple".

Pharynx The pharynx is a muscular tube that serves as a passage to both air and food. It is connected both the oral and nasal cavities and has 3 divisions: nasopharynx, oropharynx, laryngophary

Glands in the Neck Thyroid Gland Located inferior to the thyroid cartilage at the junction between the larynx and trachea. It is largest endocrine gland and produces thyroxine which stimulates metabolic rates. There are lobes - right and lateral lobes connected by an isthmus. The thyroid gland moves up and do during swallowing. In a healthy person the gland is not visible, but can be palpated as a soft

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tissue mass in a clinical examination. Parathyroid Gland The parathryoid glands are 4 small endocrine glands located on the posterior surface of the thyroid gland. They are found in 2 pairs: superior and inferior and produce parathormone w regulates calcium and phosphorous levels.

Deep Structures of the Neck The neck is supported by the spine (cervical vertebral column) and has 4 major compartmen enclosed by a musculofascial layer. Anterior visceral compartment - contains thryoid, parathyroid and thymus glands, and part the respiratory and digestive tracts. Two vascular compartments - contain the major blood vessels and the vagus nerve (X) Posterior vascular compartment - contains the cervical vertebrae, spinal cord and associate postural muscles. All of these compartments are enclosed by a layer of cervical fascia. Fascia are layers of tou fibrous connective tissue that wrap around structures. There are superficial and deep fascia

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Superficial Fascia - deep to the skin This fascia separates the skin from deeper structures (skin moves independently). It does no usually enclose muscles apart from the muscles of facial expression. Superficial fascia in the neck contains a thin sheet of platysma muscle which is innervated by the facial nerve.

Deep Fasciae This fascia covers the deeper structures. There are 4 types of deep fascia in the neck. Investing Fascia This fascia encloses all structures in the neck and wraps around the neck like a collar. It is th most external deep fascia. Pretracheal Fascia (visceral fascia) This fascia is a single midline tube that covers the visceral unit of the neck (trachea, esophag and thryoid gland). The buccopharyngeal fascia is posterior and lateral to the pharynx. Vertebral fascia This fascia is the deepest layer and covers the vertebrae, spinal column and the associated muscles.

Carotid Sheath This is a tube of deep cervical fascia from the base of the skill to the thorax of each side of t neck. It contains the common carotid and internal carotid arteries, internal jugular veins an vagus X cranial nerve.

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Cervical Fascial Spaces These are spaces that exist between the fasciae and underlying organs. These spaces can communicated with spaces in the face and with each other. They connect the spaces of hea and jaws with the spaces of the thorax and can help spread dental infections to vital organs There ae 3 cervical fascial spaces: Previsceral Space • Located between the visceral and investing fascia anterior to the trachea • Contains nodes and cervical vessels • Passes between the neck and the anterior part of the mediastinum • Communicates with the parapharyngeal space Parapharyngeal Space • Located lateral to visceral fascia around the pharynx • Communicates to infratemporal, buccal, masticator, submandibular muscles and retropharyngeal, previsceral spaces • Adjacent to carotid sheath and cranial nerves 9, 11 and 12 Retropharyngeal Space/Retrovisceral Space • Danger space of the neck - infections can travel rapidly along this space • Located posterior to the pharynx, between vertebral and visceral fascia and from the of the skull to the thorax • Communicates with the parapharyngeal space

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