Scalene muscles


364
104 shares, 364 points

The scalene muscles are a group of three pairs of muscles in the lateral neck, namely the anterior scalene, middle scalene, and posterior scalene. They are innervated by the fourth, fifth, and sixth cervical spinal nerves (C4-C6).

The anterior and middle scalene muscles lift the first rib and bend the neck to the same side; the posterior scalene lifts the second rib and tilts the neck to the same side.

The muscles are named from Ancient Greek skalinos (skalenos), meaning ‘uneven’.

The scalene muscles originate from the transverse processes from the cervical vertebrae of C2 to C7 and insert onto the first and second ribs.

The anterior scalene muscle (Latin: scalenus anterior), lies deeply at the side of the neck, behind the sternocleidomastoid muscle. It arises from the anterior tubercles of the transverse processes of the third, fourth, fifth, and sixth cervical vertebrae, and descending, almost vertically, is inserted by a narrow, flat tendon into the scalene tubercle on the inner border of the first rib, and into the ridge on the upper surface of the second rib in front of the subclavian groove. It is supplied by the anterior ramus of cervical nerve 5 and 6.

The middle scalene, (Latin: scalenus medius), is the largest and longest of the three scalene muscles. The middle scalene arises from the posterior tubercles of the transverse processes of the lower six cervical vertebrae. It descends along the side of the vertebral column to insert by a broad attachment into the upper surface of the first rib, posterior to the subclavian groove. The brachial plexus and the subclavian artery pass anterior to it.

The posterior scalene, (Latin: scalenus posterior) is the smallest and most deeply seated of the scalene muscles. It arises, by two or three separate tendons, from the posterior tubercles of the transverse processes of the lower two or three cervical vertebrae, and is inserted by a thin tendon into the outer surface of the second rib, behind the attachment of the anterior scalene. It is supplied by cervical nerves C6, C7 and C8. It is occasionally blended with the middle scalene.

A fourth muscle, the scalenus minimus (Sibson’s muscle), is sometimes present behind the lower portion of the anterior scalene.

The anterior and middle scalene muscles lifts the first rib and bends the neck to the same side as the acting muscle; the posterior scalene lifts the second rib and tilts the neck to the same side.

Because they elevate the upper ribs they also act as accessory muscles of respiration, along with the sternocleidomastoids.

The scalene muscles have an important relationship to other structures in the neck. The brachial plexus and subclavian artery pass between the anterior and middle scalenes. The subclavian vein and phrenic nerve pass anteriorly to the anterior scalene as the muscle crosses over the first rib. The phrenic nerve is oriented vertically as it passes in front of the anterior scalene, while the subclavian vein is oriented horizontally as it passes in front of the anterior scalene muscle.

The passing of the brachial plexus and the subclavian artery through the space of the anterior and middle scalene muscles constitute the scalene hiatus (the term “scalene fissure” is also used). The region in which this lies is referred to as the scaleotracheal fossa. It is bounded by the clavicle inferior anteriorly, the trachea medially, posteriorly by the trapezius, and anteriorly by the platysma muscle.

The anterior and middle scalene muscles can be involved in certain forms of thoracic outlet syndrome as well as myofascial pain syndrome, the symptoms of which may mimic a spinal disc herniation of the cervical vertebrae.

Since the nerves of the brachial plexus pass through the space between the anterior and middle scalene muscles, that area is sometimes targeted with the administration of regional anesthesia by an anesthesia provider. The nerve block, called an interscalene block, may be performed prior to arm or shoulder surgery.

According to the medical codes in the 2016 Procedural Coding Expert, published by the American Academy of Professional Coders, for Current Procedural Terminology (CPT) and other medical codes, the scalenus anticus muscle can be divided by reparative or reconstructive surgery, with (# 21705) or without (# 21700) resection of the cervical rib.

The scalenes used to be known as the lateral vertebral muscles.

The muscles are named from Greek skalinos, or skalenos, meaning uneven as the pairs are all of differing length

Musculi coli base

Scalene muscles. Muscles of the neck. Lateral view.

Scalene muscles. Muscles of the neck. Lateral view.

Section of the neck at about the level of the sixth cervical vertebra. Showing the arrangement of the fascia coli.


Like it? Share with your friends!

364
104 shares, 364 points

What's Your Reaction?

Angry Angry
0
Angry
Confused Confused
0
Confused
Geek Geek
0
Geek
LOL LOL
0
LOL
Love Love
0
Love
Omg Omg
0
Omg
Sad Sad
0
Sad
Scary Scary
0
Scary
Wtf Wtf
0
Wtf
admin

Choose A Format
Personality quiz
Series of questions that intends to reveal something about the personality
Trivia quiz
Series of questions with right and wrong answers that intends to check knowledge
Poll
Voting to make decisions or determine opinions
Story
Formatted Text with Embeds and Visuals
List
The Classic Internet Listicles
Open List
Submit your own item and vote up for the best submission
Ranked List
Upvote or downvote to decide the best list item
Meme
Upload your own images to make custom memes
Video
Youtube, Vimeo or Vine Embeds
Audio
Soundcloud or Mixcloud Embeds
Image
Photo or GIF
Gif
GIF format