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The scalene muscles are a group of three muscles on each side of the neck, namely the anterior, middle, and posterior scalene. They are involved in flexion, lateral flexion, and rotation of the neck, and also act as accessory muscles of respiration. The scalene muscles receive innervation from the anterior rami of cervical spinal nerves C3 to C8, with contributions from both the cervical and brachial plexuses. The innervation to the scalenus medius (middle scalene) is provided by the anterior rami of cervical spinal nerves C3-C8, while the scalenus posterior (posterior scalene) is innervated by the anterior rami of spinal nerves C6-C8. The scalene muscles have important anatomical relationships with surrounding structures, such as the brachial plexus and subclavian artery, which pass between the anterior and middle scalenes.
| Characteristics | Values |
|---|---|
| Innervation | Anterior rami of cervical spinal nerves C3-C8, including the brachial plexus and the cervical plexus |
| Function | Flexion, lateral flexion, and rotation of the neck; accessory muscles of respiration, elevating the ribs during forced inspiration |
| Attachments | Originate from the transverse processes of cervical vertebrae C2-C7 and attach to the first and second ribs |
| Blood supply | Ascending cervical branch of the inferior thyroid artery |
| Location | Deep and positioned laterally in the neck |
| Clinical significance | Relevant in central venous catheterization via the subclavian approach; their proximity to major vessels increases the risk of vascular or nerve injury |
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What You'll Learn
- The scalenus anterior is innervated by the anterior rami of C5-C6
- The scalenus medius is innervated by the anterior rami of C3-C8
- The scalenus posterior is innervated by the anterior rami of C6-C8
- The scalene muscles are innervated by the cervical plexus
- The scalene muscles are innervated by the brachial plexus
The scalenus anterior is innervated by the anterior rami of C5-C6
The scalene muscles are a group of three muscles on each side of the neck, identified as the scalenus anterior (anterior scalene), scalenus medius (middle scalene), and scalenus posterior (posterior scalene). They are involved in flexion, lateral flexion, and rotation of the neck, and they also act as accessory muscles of respiration, elevating the ribs during forced inspiration.
The scalenus anterior is the anteriormost of the three scalene muscles. It originates from the anterior tubercles of the transverse processes of the C3-C6 vertebrae and inserts into the scalene tubercle on the inner border of the first rib. The muscle helps elevate the first rib and contributes to lateral flexion of the neck.
The innervation of the scalenus anterior muscle is provided by the anterior rami of the cervical spinal nerves C5-C6. These nerves emerge on the lateral surface of the muscle and continue towards the rhomboids and serratus anterior muscles, supplying them respectively. The subclavian vein and phrenic nerve pass anteriorly to the scalenus anterior, with the phrenic nerve running vertically down the muscle and the subclavian vein oriented horizontally.
The scalenus anterior serves as an important landmark for identifying nearby anatomical structures such as the subclavian artery, the brachial plexus, and the phrenic nerve. It also plays a role in conditions such as thoracic outlet syndrome (TOS) and reduced ventilatory capacity, where medical interventions aim to decrease excessive muscle tone or restore physiological length.
Understanding the anatomy and function of the scalenus anterior muscle is crucial for clinicians when managing various conditions in the cervicothoracic area. Its proximity to major vessels, such as the subclavian vein and artery, highlights the importance of comprehending its innervation and structure to prevent vascular or nerve injuries during medical procedures.
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The scalenus medius is innervated by the anterior rami of C3-C8
The scalene muscles are a group of three muscles on each side of the neck: the anterior, middle, and posterior. They are named from the Ancient Greek σκαληνός (skalēnós), meaning 'uneven'. The scalenus medius, or middle scalene, is the largest and longest of the three scalene muscles. It arises from the posterior tubercles of the transverse processes of the lower six cervical vertebrae. It then 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 middle scalene is innervated by the anterior rami of cervical spinal nerves C3-C8. The scalene muscles as a whole receive innervation from the anterior branches of the cervical spinal nerves spanning C3 to C8. The brachial plexus and subclavian artery pass between the anterior and middle scalene muscles, providing an important anatomical landmark in anaesthetics for performing an interscalene block.
The scalene muscles have several important functions. They facilitate accessory breathing and contribute to neck and head movement, as well as postural stability between the neck and head. They elevate the first and second ribs during forced inspiration, functioning as secondary respiratory muscles. They also enable flexion, lateral flexion, and rotation of the neck.
The scalenus medius receives its blood supply from the ascending cervical branch of the inferior thyroid artery. The contraction of this muscle produces strong ipsilateral flexion of the neck and helps to stabilize or raise the first rib during respiration.
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The scalenus posterior is innervated by the anterior rami of C6-C8
The scalene muscles are a group of three muscles on each side of the neck: the anterior, middle, and posterior. They are named from the Ancient Greek "σκαληνός" (skalēnós), meaning 'uneven'. The scalenus posterior is the smallest and most deeply seated of the three scalene muscles. It arises from the posterior tubercles of the transverse processes of the fourth, fifth, and sixth cervical vertebrae (C4-C6).
The scalene muscles are innervated by the third to the eighth cervical spinal nerves (C3-C8). The scalenus posterior muscle, in particular, is innervated by the anterior rami of spinal nerves C6-C8. It receives its vascular supply from the ascending cervical branch of the inferior thyroid artery, as well as some blood from the superficial branch of the transverse cervical artery, a branch of the thyrocervical trunk.
The scalene muscles have an important relationship with other structures in the neck. They receive innervation from both the cervical plexus and the brachial plexus, which contributes to their complex functional role. The brachial plexus and subclavian artery pass between the anterior and middle scalene muscles, constituting the scalene hiatus or scalene fissure.
The scalenus posterior is involved in elevating the second rib and tilting the neck to the same side. When the vertebral attachment is fixed, unilateral contraction of the scalenus posterior helps stabilize or elevate the second rib during respiration. This muscle also contributes to neck movements and postural stability between the neck and head. Dysfunction of the scalene muscles can lead to pathological conditions such as thoracic outlet syndrome (TOS), reduced ventilatory capacity, and cervical pain.
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The scalene muscles are innervated by the cervical plexus
The scalene muscles are a group of three muscles on each side of the neck: the anterior, middle, and posterior. They are involved in neck flexion, lateral flexion, and rotation, as well as accessory breathing. Dysfunction of these muscles can lead to pathological conditions such as thoracic outlet syndrome, reduced ventilatory capacity, and cervical pain.
The anterior scalene muscle, also known as scalenus anterior, is located deep to the sternocleidomastoid on the lateral aspect of the neck. It originates from the anterior tubercles of the transverse processes of C3-C6 and attaches to the scalene tubercle on the inner border of the first rib. Its functions include elevating the first rib and contributing to neck flexion and rotation.
The middle scalene muscle, or scalenus medius, is the largest and longest of the three scalene muscles. It arises from the posterior tubercles of the transverse processes of the lower six cervical vertebrae and inserts into the upper surface of the first rib. The middle scalene muscle produces strong ipsilateral flexion of the neck and helps stabilize or raise the first rib during respiration.
The posterior scalene muscle, or scalenus posterior, is the smallest and deepest of the scalene muscles. It originates from the posterior tubercles of the transverse processes of C5-C7 and attaches to the second rib. This muscle is responsible for elevating the second rib and contributing to lateral flexion of the neck.
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The scalene muscles are innervated by the brachial plexus
The scalene muscles are a group of three muscles on each side of the neck: the anterior, middle, and posterior. They are involved in flexion, lateral flexion, and rotation of the neck, and they also act as accessory muscles of respiration, elevating the ribs during forced inspiration. The scalene muscles are innervated by the brachial plexus, which is a network of nerves that originate from the spinal cord in the neck and supply the arm and hand. The trunks of the brachial plexus can be seen emerging between the anterior and middle scalene muscles.
The brachial plexus plays a crucial role in the functioning of the scalene muscles. It provides innervation to these muscles, enabling them to perform their respective functions in neck movement and respiration. The scalene muscles are also innervated by the cervical plexus, contributing to their complex functional role. Dysfunction of the scalene muscles can lead to pathological conditions such as thoracic outlet syndrome (TOS), reduced ventilatory capacity, and cervical pain.
The anterior scalene muscle is located deep within the lateral aspect of the neck. It originates from the anterior tubercles of the transverse processes of the cervical vertebrae C3-C6 and attaches to the scalene tubercle on the inner border of the first rib. The middle scalene muscle is the largest and longest of the three scalene muscles. It arises from the posterior tubercles of the transverse processes of the cervical vertebrae C2-C7 and attaches to the upper surface of the first rib.
The posterior scalene muscle is the smallest and deepest of the scalene muscles. It originates from the posterior tubercles of the transverse processes of the cervical vertebrae C5-C7 and attaches to the second rib. Unlike the other two scalene muscles, it inserts into the second rib. The scalene muscles receive their blood supply from the ascending cervical branch of the inferior thyroid artery.
The scalene muscles are relevant in central venous catheterization via the subclavian approach due to their proximity to major vessels, which can increase the risk of vascular or nerve injury. Understanding the anatomy and function of these muscles is important for clinicians when managing various conditions in the cervicothoracic area.
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Frequently asked questions
The scalene muscles are a group of three muscles on each side of the neck, identified as the anterior, middle, and posterior.
The scalene muscles are innervated by the third to the eighth cervical spinal nerves (C3-C8). The innervation to the scalenus medius (middle scalene) is delivered by the anterior rami of cervical spinal nerves C3-C8. The scalenus posterior (posterior scalene) is innervated by the anterior rami of spinal nerves C6-C8.
The scalene muscles have several functions, including flexion, lateral flexion, and rotation of the neck. They also act as accessory muscles of respiration, elevating the ribs during forced inspiration.
