Surface anatomy head and neck

 Head and Neck

Thyroid gland

First draw the Isthmus. Then the lobes are to be drawn from it.

a) Isthmus

1^st point:  1.25 cm below the cricoid cartilage

2^nd point: 1.25cm below the 1^st point

Draw two 1.25 cm long horizontal lines along the 1^st and 2^nd point.

b) Lobes (Right & Left)

Upper pole is conical:

1^st point: lateral end of upper border of isthmus (upper border of isthmus situated - 1.25cm below the cricoid cartilage)

2^nd point: at the anterior margin of the Sterno- cleidomastoid at the level of the laryngeal prominence.

Joined these point by a line

Lower pole is blunt end

1^st point: lateral end of lower border of isthmus

2^nd point:  just 1.25 cm below from the 1^st point

3^rd point: 2.5 cm lateral from the previous point  

Joined these point by a curve line

For each lobe of thyroid glands: Joined the 2^nd point of upper pole and 3^rd point of lower pole by a curve line directed outward

Related questions

What type of gland it is?

ans: endocrine because it has no duct. Its secretion passes through capillaries

Parts of this gland:

 Parenchyma (glandular portion) and stroma (connective tissue)

Histology:

Thyroid follicles are present. (Each follicle is lined by simple cuboidal epithelium, two types of cells present in each follicle, follicular cells and parafollicular cells)

Each follicle is filled by colloid which contain secretion of thyroid gland

Secretion of thyroid gland: 1. Follicular cells secrete: T3, T4 2.Para-follicular cells secrete:  calcitonin 

Development of glands:

Parenchyma: endodermal in origin (thyroglossal duct which arises from foramen ceacum of tongue) 

Stroma: mesodermal in origin

Follicular cells: endodermal in origin and parafollicular cells: neural crest (from ultimobrochial body)

Facial artery (In the neck)

1) 1^st   point- Just above the greater cornu of the hyoid bone.

2) 2^nd point- On the body of the mandible at the antero-inferior angle of the Masseter.

    Joint the points by a line which runs at first upwards & forwards under cover of the ramus of the mandible terminating above to the 2^nd point.

Facial artery (In the face)

1^st point- On the body of the mandible at the antero-inferior angle of the Masseter.

(This pint is to be taken by clenching the teeth when the Messeter becomes hardened).

2^nd point-1.25 cm  lateral to the angle of the mouth.

3^rd point- at the medial angle of eye

 Joint the 1^st with the 2^nd point by a tortuous line and the  with the 3^rd point by a slight convex line almost nearing the ala of the nose.

Parotid gland 

1^st point- At the upper border of the condyle of the mandible.

 2^nd point- A little above the centre of the Masseter.

  3^rd point: - Just below & behind the angle of the mandible.

4^th point: tip of mastoid process

Joined 1st, 2^nd & 3^rd points.

Joined 1^st and 4^th point by a  curve line  passing just below the external auditory meatus 

Parotid duct:

1^st point: just in front and below the tragus

2^nd point : between the ala of nose and the sharp margin of the upper lip

Join the 1^st and 2^nd point. The middle third of this line is parotid duct

Related questions:What type of gland it is? Ans: exocrine gland (because it has a duct)

According to the nature of secretion: it is pure serous in nature

Parts of this gland: Parenchyma (glandular portion )and stroma (connective tissue)

Histology: Serous acini are present. (Serous acini are darkly stain and cells of acini contain round nuclei)

Duct is present

Development of glands: Parenchyma: endodermal in origin. Stroma: mesodermal in origin

Opening of parotid duct: at the vestibule of mouth opposite the crown of 2^nd molar teeth

Frontal air sinus

1^st point- On the nasion

2^nd point- 2.5 cm above the 1^st point.

3^rd point- At the junction of the medial 1/3 and the lateral 2/3 of the supra- orbital margin.

Join the points.

Related information:

Drainage areas: middle meatus of nasal cavity

Lining epithelium: pseodustratified ciliated columnar epithelium 

Functions of sinus: resonance of voice, lightening the wt of bone 

What is the name of sinus containing bones: pneumatic bone

Maxillary air sinus

1^st point- On the lacrimal tubercle.

2^nd point- On the Zygomatic bone at the junction of the inferior with the lateral margin of the orbit.

3^rd point- On the alveolar process just above the 3^rd moral tooth.

4^th point- On the alveolar process just above the 2^nd premoral tooth.

Join the points.

Related information:

Drainage areas: middle meatus of nasal cavity

Lining epithelium: pseostratified ciliated columnar epithelium 

Functions of sinus: resonance of voice, lightening the wt of bone 

What is the name of sinus containing bones: pneumatic bone

 How hiatus of maxilla is reduce?