Infrahyoid muscles

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Infrahyoid muscles
Muscles of the neck seen from the front. The infrahyoid muscles are coloured in violet.
Latin Musculi infrahyoidei
Gray's p.393
Origin
Insertion   
Artery
Nerve Ansa cervicalis
Actions Depress the hyoid bone

The infrahyoid muscles (strap muscles) are a group of four pairs of muscles in the anterior (frontal) part of the neck. The four infrahyoid muscles are; the sternohyoid, sternothyroid, thyrohyoid and omohyoid muscles.

The infrahyoid muscles either originates from or insert on to the hyoid bone.

The term infrahyoid refers to the region below the hyoid bone, while the term strap muscles refers to the long and flat muscle shapes which resembles a strap. The stylopharyngeus muscle is considered by many to be one of the strap muscles, but is not an infrahyoid muscle.

Individual muscles

The origin, insertion and innervation of the individual muscles:[1]

Muscle Origin Insertion Innervation
sternohyoid posterior surface of manubrium sterni, adjoining parts of clavicle and the posterior sternoclavicular ligament medial part of lower border of hyoid bone ansa cervicalis
sternothyroid posterior surface of manubrium sterni and adjoining part of first costal cartilage oblique line of thyroid cartilage ansa cervicalis
thyrohyoid oblique line of thyroid cartilage lower border of the body and the greater cornu of the hyoid bone cervical spinal nerve 1 via the hypoglossal nerve
omohyoid (superior belly) intermediate tendon hyoid bone C1; superior root of ansa cervicalis
omohyoid (inferior belly) superior border of scapula intermediate tendon C1-C3; ansa cervicalis

Innervation

All of the infrahyoid muscles are innervated by the ansa cervicalis from the cervical plexus (C1-C3) except the thyrohyoid muscle, which is innervated by fibres only from the first cervical spinal nerve travelling with the hypoglossal nerve.

Action

The infrahyoid muscles function to depress the hyoid bone and larynx during swallowing and speech.

See also

References

  1. ↑ Ellis, Harold; Susan Standring; Gray, Henry David (2005). Gray's anatomy: the anatomical basis of clinical practice. St. Louis, Mo: Elsevier Churchill Livingstone. pp. 538–539. ISBN 0-443-07168-3. 
Cervical

CN VII (superficial, PC): platysma
CN XI (deep): sternocleidomastoid

C1–C6 (anterior): Prevertebral muscles: longus (capitis, colli)

C3–C8 (lateral): scalene (anterior, medius, posterior)
Suboccipital

C1: rectus capitis posterior (major, minor) · obliquus capitis (inferior, superior)

C1–C6 (anterior): Prevertebral muscles: rectus capitis (anterior, lateralis)
Suprahyoid
Infrahyoid/strap
Fasciae
Pharynx
Larynx

M: MUS, DF+DRCT

anat (h/n, u, t/d, a/p, l)/phys/devp/hist

noco (m, s, c)/cong (d)/tumr, sysi/epon, injr

proc, drug (M1A/3)

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