The Respiratory System in the Head and Neck

The Nose :

The nose consists of the external nose and the nasal cavity, both of which are divided by a septum into right and left halves.

External Nose :

The external nose has two elliptical orifices called the nostrils, which are separated from each other by the nasal septum .

Nasal Cavity : The nasal cavity extends from the nostrils in

front to the posterior nasal apertures or choanae behind, where the nose opens into the nasopharynx.

The nasal vestibule is the area of the nasal cavity lying just inside the nostril . The nasal cavity is divided into right and left halves by the nasal septum .

The septum is made up of the septal cartilage, the vertical plate of the ethmoid , and the vomer.

Blood Supply of the External Nose:

The skin of the external nose is supplied by branches of the ophthalmic and the maxillary arteries . The skin of the ala and the lower part of the septum are supplied by branches from the facial artery.

Nerve Supply of the External Nose:

The infratrochlear and external nasal branches of the ophthalmic nerve (V 1) and the infraorbital branch of the maxillary nerve (V2).

Larynx

• Def. : it’s the organ of voice & acts also as an air passage

• Site : in the median regoin of neck extending from root of tongue to trachea(C4 – C6 cervical vertebra)

• Relation : • ant. :infrahyoid strap muscle• On each side : thyroid gland• post. : pharynx

• Structure of larynx : is formed of cartilages that are held together by ligaments and

membranes, moved by muscles, and lined by mucous membrane

Cartilage of larynx:• Single

1) Epiglottis

2) thyroid cartilage

3) cricoid cartilage

• Paried

1) arytenoid cartilage

2) Corniculate

3) cuniform cartilage

1) Epiglottis : It’s leaf-like shaped of elastic cartilage located behind

tongue& the hyoid bone infront 2) thyroid cartilage: It is formed of 2 laminae of hyaline cartilage meeting in

the midline in the prominent V angle (the so-called Adam's apple).

3) the cricoid cartilage : it’s shaped like a signet ring of hyaline cartilage lies below thyroid cartilage

4) Arytenoid cartilage : It’s pyramidal in shape that articulate with upper border

of cricoid cartilage lies at the back of larynx.

5) Corniculate cartilage :

It’s articulate with apex of arytenoid catilage

6) Cuniform cartilage :

It’s articulate in front of corniculate cartilage.

Membranes of larynx 1 ) thyrohyoid membrane: It connects upper margin of the catilage below to hyoid bone a bove.

2) Quadrangular membrane: This extends between the epiglottis and the arytenoid cartilages . 3) cricothyroid membane & ligament: It connects the thyroid cartilag & cricoid cartilage

• It’s the lower part of the fibroelastic membrane linning the larynx.• The ant. Median part of this membrane is called median

cricothyroid lig.• The lateral part of the cricothyroid membrane is called cricovocal

membrane.

Muscles of the larynx

It’s divided into 2 groups :

1) Intrinsic muscles (cicothyroid muscle)

2) Extrinsic muscles .

Intrinsic muscles

cicothyroid muscle:

1. Origin : side of cricoid cartilage

2. Insertion : lower border of thyroid cartilage

3. N. Supply : External laryngeal nerve

4. Action: movement of vocal cords

Extrinsic muscles It’s divided into :2 groups

• Elevator of larynx:

Which include:

• Digasteric • Stylohyoid • Mylohyoid • Geniohyoid• Stylopharyngeus• Salpingopharyngeus• palatopharyngeus

• Depressors of larynx:

Which include:

• Sternothyroid • Sternohyoid • Omohyoid

Nerve supply of larynx

1) motor : * All intrinsic Ms. Of the larynx are supplied by

recurrent laryngeal nerve EXCEPT cricothyroid Ms. Which is supplied by by external laryngeal nerve.

2) sensory : Mucous membrane of larynx which: * A bove the vocal folds is supplied by internal

laryngeal nerve. *Below the vocal folds is supplied by recurrent

laryngeal nerve .

Trachea

• Cartilaginous and membranous tube

• Starts from the lower border of the cricoid cartilage

• Ends by dividing into two main bronchi (Carina point) at the level of the 4th and 5th thoracic vertebrae

Trachea in the neck

• Blood supply: inferior thyroid arteries

• Nerve supply: vagus, recurrent laryngeal, sympethatic trunk

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