Muscular Triangle: Infrahyoid Muscles

Question 1

Infrahyoid muscles

Answer 1

1. 4 strap muscles on each side of neck midline below hyoid
2. Lie deep to skin, superficial fascia (containing Platysma), and deep fascia
3. They cover larynx (thyroid and circoid cartilages), trachea, and thyroid gland

Question 2

Arranged as

Answer 2

2 superficial:
1. Medial:
Sternohyoid
2. Lateral:
Superior belly omohyoid
2 deep:
1. Below oblique line: Sternothyroid
2. Above oblique line:
Thyrohyoid

Question 3

Sternohyoid

Answer 3

May be absent or double

Question 4

Nerve supply all muscles

Answer 4

Ansa cervicalis except thyrohyoid (C1, via hypoglossal nerve)

Question 5

Action all muscles

Answer 5

Depression hyoid and thyroid cartilage during swallowing

Question 6

Origin

Answer 6

Posterior surface of manubrium and medial end clavicle

Question 7

Sternohyoid insertion

Answer 7

Lower border hyoid body

Question 8

Omohyoid origin

Answer 8

1. Inferior belly: Suprascapular notch and ligament
2. Superior belly: intermediate tendon omohyoid

Question 9

Omohyoid insertion

Answer 9

1. Inferior belly: intermediate tendon omohyoid
2. Superior belly: hyoid body lateral to Sternohyoid
   Intermediate tendons is attached to to clavicle medial end by fibrous sling

Question 10

Sternothyroid

Answer 10

1. Deep
2. Partly medial to Sternohyoid

Question 11

Sternothyroid origin

Answer 11

Posterior aspect manubrium and 1 costal cartilage

Question 12

Sternothyroid insertion

Answer 12

Oblique line thyroid cartilage

Question 13

Thyrohyoid

Answer 13

Oblique line thyroid cartilage

Question 14

Thyrohyoid insertion

Answer 14

Body and greater horn hyoid