Scalenus medius

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Scalenus medius

The anterior vertebral muscles. (Scalenus medius visible at bottom center-right in red.)

Muscles of the neck. Scalenus medius shown in red.
Latin	Musculus scalenus medius
Gray's	p.396
Origin	Posterior tubercles of the transverse processes of the lower six cervical vertebræ (C2, C3, C4, C5, C6 and C7)
Insertion	Upper surface of the first rib
Artery	Ascending cervical artery (branch of Inferior thyroid artery)
Nerve	Ventral rami of the third to eighth cervical spinal nerves
Actions	Elevate 1st rib, rotate the neck to the opposite side

The Scalenus medius, also known as the middle scalene, is the largest and longest of the three scalene muscles in the human neck.

Anatomy

The middle scalene arises from the posterior tubercles of the transverse processes of the lower six cervical vertebræ. It descendes along the side of the vertebral column to insert by a broad attachment into the upper surface of the first rib, between the tubercle and the subclavian groove. The brachial plexus and the subclavian artery pass anterior to it. Because it elevates the upper ribs, the middle scalene muscle is also one of the accessory muscles of respiration.

Clinical Significance

It is involved in thoracic outlet syndrome, which is compression of the subclavian vessels and nerves of the brachial plexus in the region of the thoracic inlet.

Additional images

Position of scalenus medius (shown in red). Animation.
Scalenus medius (shown in red). Close up.
Scalenus medius (shown in red) without skull.
Still image.
Right first rib.
Horizontal section of the neck at about the level of the sixth cervical vertebra. Showing the arrangement of the fascia coli (scalenus medius visible at center left in green).
Scalenus medius muscle
Scalenus medius
Scalenus medius
Scalenus medius
Brachial plexus.Deep dissection.

References

This article incorporates text from a public domain edition of Gray's Anatomy.

External links

Wikimedia Commons has media related to Scalenus medius muscles.

LUC sm - scalenus medius

List of muscles of head and neck: the neck (TA A04.2, GA 4.387)

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

CN V3 (medial): mylohyoid · anterior belly of digastric

CN VII (lateral): stylohyoid · posterior belly of digastric

C1 (deep): geniohyoid

Infrahyoid/strap

C1: thyrohyoid
C1–C3: sternohyoid · sternothyroid · omohyoid

Fasciae

Deep cervical fascia (Pretracheal fascia, Prevertebral fascia, Investing layer) · Carotid sheath · Alar fascia

pharynx: Buccopharyngeal fascia · Pharyngobasilar fascia

Palatine aponeurosis

Pharyngeal raphe

Pharynx

pharyngeal constrictor (superior, middle, inferior) · longitudinal (stylopharyngeus, salpingopharyngeus)

Larynx

cricothyroid · cricoarytenoid (posterior, lateral) · arytenoid (oblique arytenoid/aryepiglottic, transverse arytenoid) · thyroarytenoid (vocal, thyroepiglottic)

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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