Muscular Triangle: Thyroid Gland Flashcards
Site
- Dark red endocrine gland lying in lower part of neck front
Content
Consists of 2 pyramidal shaped lobes connected by an intermediate band (isthmus) which lies over 2nd, 3rd, and 4th tracheal rings
Extent
Each lobe extends from thyroid cartilage oblique line (lobe apex) till 5th or 6th tracheal rings (lobe base)
Relations Isthmus
- Skin
- Deeply
- At upper border
- At lower border
Relations Isthmus: superficial
- Skin
- Fascia
- Anterior jugular veins
- Sternohyoid
Relations Isthmus: deep
2nd, 3rd, 4th rings
Relations Isthmus: at upper border
Anastomosis between 2 superior thyroid arteries
Relations Isthmus: at lower border
Beginning of inferior thyroid veins and termination of thyroidea ima artery
Relations thyroid lobe (3 surface)
- Anterolateral surface
- Posterior surface
- Medial surface
Anterolateral surface
- Skin
- Superficial fascia (contains Platysma
- Deep investing fascia
- Sternomastoid
- Sternohyoid
- Sternothyroid
- Pretracheal fascia
Posterior surface
- Parathyroid glands (superior and inferior)
- Medial part carotid sheath
- Inferior thyroid artery
- Prevertebral muscles and fascia
Medial surface
Above:
1. Larynx
2. Pharynx
3. External laryngeal nerve
Below:
1. Trachea
2. Esophagus
With recurrent laryngeal nerve in between
Arterial blood supply
- Superior thyroid artery
- Inferior thyroid artery
- Thyroidea ima artery:
- may be absent
- from aortic arch to isthmus
Superior thyroid artery site and course
- From ECA anterior aspect below to of hyoid greater horn
- Descends downwards and forwards (closely related to external laryngeal nerve which supplies circothyroid) deep to infrahyoid muscles towards gland apex
Superior thyroid artery end
Divides into terminal anterior and posterior branches