Suprahyoid and infrahyoid muscles

Question 1

Suprahyoid

Answer 1

1. Mylohyoid m.
2. Digastric m.
3. Stylogyoid m.
4. Geniohyoid m.

Question 2

Mylohyoid m.

Answer 2

• Flat muscle
• Origin: mylohyoid line of the mandible
• Runs dorsomedially and caudally
• Insertion: body of the hyoid bone and to the mylohyoid raphe in the midline (tendinous strip where the two mylohyoid muscles meet)
• Mylohyoid raphe runs in the midsagittal plane from the hyoid bone to the spina mentalis of the mandible
• Innervation: mylohyoid nerve (branch of the mandibular nerve)
• Function: mandibular depression and during swallowing elevates the hyoid bone

Question 3

Digastric muscle

Answer 3

• Has two bellies
• Posterior belly which originates from the incisura mastoidea ossis temporalis and passes together with the stylohyoid muscle along the medial side of the sternocleidomastoid m. and into the inserting tendon
• The inserting tendon passes through the bufurcated tendon of the stylohyoid m.
• And is attached to the hyoid bone with a fibrous band to the lesser horn of the hyoid bone
• This tendon then turns anteriorly and cranially and passes into the anterior belly
• The anterior belly attaches to the digastric fossa of the mandible
• Innervation: AB - mylohyoid n. (from the mandibular nerve), PB - digastric branch of the facial nerve
• Function: at fixed hyoid the AB causes mandibular depression, and at fixed mandibula both bellies cause elevation of the hyoid bone

Question 4

Stylohyoid muscle

Answer 4

• Long thin muscle
• Origin: styloid process of the temporal bone
• Runs anteriorly and mediocaudally
• Insertion: lesser horn of the hyoid bone
• Tendon bifurcates before attachment, inserting tendon of digastric muscle passes through it
• Innervation: facial nerve
• Function: during swallowing it elevates the hyoid bone and pulls it dorsally

Question 5

Geniohyoid muscle

Answer 5

• Lies over the mylohyoid muscle
• Origin: spina mandibulae
• Insertion: body of the hyoid bone
• Innervation: branch from C1-C2 (their axons run in the common neural bundle of the hypoglossal nerve
• Function: mandibular depressin, and during swallowing elevates the hyoid bone

Question 6

Infrahyoid muscles

Answer 6

• Sternohyoid
• Sternothyroid
• Thyrohyoid
• Omohyoid

Question 7

Sternohyoid muscle

Answer 7

• Thin, band-shaped muscle
• Origin: dorsal side of the manubrium and the sternoclavicular articulation
• Run cranially
• Insertion: inferior margin of hyoid bone

Question 8

Sternothyroid muscle

Answer 8

• Thin muscle and is shorter than the previous muscle
• Behind the sternhyoid m.
• Origin: dorsal side of manubrium and the 1st rib gristle
• Ascends cranially
• Insertion: linea obliqua of thyroid cartilage
• Partially overlaps the thyroid gland

Question 9

Thyrohyoid muscle

Answer 9

• Cranial enlargement of the sternothyroid muscle
• Origin: linea obliqua of thyroid cartilage
• Ascends cranially
• Insertion: lateral part of the body of the hyoid bone and its greater horn

Question 10

Omohyoid muscle

Answer 10

• Long, slim, digastric muscle
• Inferior belly - starts from the superior margin of the scapula, in the area of the superior transverse ligament of the scapula and runs mediocranially behind the clavicle, where it passes into the inserting tendon
• Superior belly - proceeds ventrally and cranially and inserts itself to the lateral part of the greater horn of the hyoid bone laterally from the sternohyoid muscle

Question 11

Innervation and function of the infrahyoid muscle

Answer 11

• Innervation: cervicle plexus (mostly from ansa cervicalis profunda)
• Function: fixate the hyoid bone or pull the hyoid bone towards the sternum