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Levatores costarum muscles

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Last Updated: 15 November 2020

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General | Latest Info

Levatores costarum muscles

Details
ActionsAssists in elevation of the thoracic rib cage
InsertionSuperior surfaces of the ribs immediately inferior to the preceding vertebrae
Nervedorsal rami C8-T11 (Intercostal nerves)
OriginTransverse processes of C7 to T11 vertebrae
Identifiers
FMA71312
LatinMusculi levatores costarum
TA22308
TA98A04.4.01.009

Levatores costarum muscles levatores costarum consists of 12 small triangular muscles that connect thoracic vertebrae with adjacent ribs. Locate along either side of the posterior aspect of the thoracic vertebra, they descend adjacent to the spine, spanning the thoracic region from C7 to T12 levels. Together with intercostal muscles, serratus posterior superior and inferior and transversus thoracis, they form intrinsic muscles of chest wall. Intrinsic chest wall muscles are thought to play a role in forced respiration and in preventing the chest from moving inwards during inspiration. Along with being considered chest wall muscle, levatores costarum muscles can also be grouped with the deepest muscles of the back, together with interspinales and intertransversarii muscles. These minor muscles form the fourth layer of deep muscles of back. Levatores costarum functions in elevating ribs, and produces rotation and lateral flexion of thoracic vertebrae. This article will discuss the anatomy and function of levatores costarum muscles.

* Please keep in mind that all text is machine-generated, we do not bear any responsibility, and you should always get advice from professionals before taking any actions.

* Please keep in mind that all text is machine-generated, we do not bear any responsibility, and you should always get advice from professionals before taking any actions

Origin and insertion

There are 12 separate muscle bundles that make up levatores costarum. Each originates from transverse processes of one vertebra and passes obliquely to insert into rib one level below. More specifically, muscle bundles arise from the tip of transverse processes of associated vertebra. It then passes obliquely in inferolateral direction to insert into the external aspect of the superior border of rib, between costal angle and tubercle of rib. Muscles are triangular in shape, with apex pointing toward origin and fanning out to form its base at insertion. Upper eight muscles travel as single muscular bands from origin to insertion. In contrast, lower four muscles split into two fasciculi called longi and breves. A short fascicle passes from muscle origin to attach into the rib located immediately below, while a longer fascicle descends further to attach onto the rib located 2 levels below.

* Please keep in mind that all text is machine-generated, we do not bear any responsibility, and you should always get advice from professionals before taking any actions.

* Please keep in mind that all text is machine-generated, we do not bear any responsibility, and you should always get advice from professionals before taking any actions

Levatores costarum

Levatores costarum are a group of 12 pairs of muscles located in the posterior thorax. They are located on each side of the vertebral column and stretch between transverse processes of vertebrae and ribs find one level below. These muscles lie superficially to external intercostal muscles. Levatores costarum are considered as intrinsic muscles of the chest wall, as well as one of deep muscles of the back. Together with other thoracic muscles, they possibly play a role in forced respiration and preventing the chest from moving inwards during inspiration. Along with interspinales and intertransversarii muscles, they form the fourth layer of deep back muscles, participating in movements of the spine.

* Please keep in mind that all text is machine-generated, we do not bear any responsibility, and you should always get advice from professionals before taking any actions.

* Please keep in mind that all text is machine-generated, we do not bear any responsibility, and you should always get advice from professionals before taking any actions

Introduction

Thoracic wall is made up of five muscles: external intercostal muscles, internal intercostal muscles, innermost intercostal muscles, subcostalis, and transversus thoracis. These muscles are primarily responsible for changing the volume of the thoracic cavity during respiration. Other muscles that do not make up the thoracic wall, but attach to it include pectoralis major and minor, subclavius, and serratus anterior and primary costarum and serratus posterior superior and inferior. Muscles of the anterior thorax provide movements to the arm and shoulder while muscles of the posterior thorax also help change thoracic volume during breathing and reinforce the thoracic wall. The Diaphragm is another muscle in the thorax that serves as the main muscle of inspiration. It also makes up the floor of the thorax, thus separating the contents of the chest from those of the abdomen. Other minor accessory muscles that attach to the thorax include scalene muscles and sternocleidomastoid muscle, both of which may also minimally aid in respiratory efforts.

* Please keep in mind that all text is machine-generated, we do not bear any responsibility, and you should always get advice from professionals before taking any actions.

* Please keep in mind that all text is machine-generated, we do not bear any responsibility, and you should always get advice from professionals before taking any actions

Structure and Function

Muscles that make up the thorax wall include three intercostal muscles, subcostalis, and transversus thoracis. Eleven pairs of intercostal muscles are in each of the intercostal spaces, arranged from superficial to deep. The most superficial layer is external intercostal muscle, which originates from the inferior aspect of rib above and inserts onto the superior aspect of rib below in an inferomedial direction. These muscles extend from rib tubercle posteriorly and attach to costochondral junction anteriorly where they continue as thin connective tissue aponeuroses know as anterior intercostal membrane. During inspiration, external intercostals contract and raise the lateral part of ribs, increasing the transverse diameter of thorax in bucket handle motion. Internal intercostal muscle forms intermediate layer. These muscles originate from the lateral aspect of the costal groove of rib above and are inserted into the superior aspect of rib below in a direction perpendicular to external intercostal muscles. This arrangement allows them to depress ribs and subsequently reduce thoracic volume during forced expiration. Further, these muscles extend from the sternum anteriorly to the rib cage posteriorly where they continue as posterior intercostal membrane. The deepest layer of the thorax wall is made up of the innermost intercostal muscles. They originate from the medial aspect of the costal groove of rib above and are inserted onto the internal aspect of rib below. These muscles are line internally by endothoracic fascia, which appear just superficial to parietal pleura of lungs. They are thought to act on internal intercostal muscle during force expiration. In addition to intercostal muscles, subcostalis and transversus thoracis also make up the thoracic wall. Subcostalis exists on the same layer as innermost intercostal muscle and is present in abundance in lower regions of the posterior thoracic wall. They originate from the internal aspect of one of the lower ribs and are inserted onto the internal aspect of the second or third rib below. Transversus thoracis also appears in the same space at innermost intercostal muscle. They originate from the lower posterior sternum, spread across the inner surface of the thoracic cage, and inserted onto ribs 2 through 6. Both of these muscles aid in depressing ribs during force expiration. Muscles of posterior thorax, such as levatores costarum and serratus posterior superior and inferior, may also aid in respiration. Levatores costarum originates from transverse processes of C7 to T11 and inserts onto the rib below. It minimally aids in inspiration via rib elevation. Serratus posterior superior attaches to ribs 2 through 5 and elevates them during inspiration whereas serratus posterior inferior attaches vertebrae to ribs 8 through 12 and depresses them during force expiration. These muscles, in conjunction with muscles of the thoracic wall, help alter thoracic volume during respiration and altogether reinforce the thoracic wall. The major muscle of inspiration, however, comes from the diaphragm.

* Please keep in mind that all text is machine-generated, we do not bear any responsibility, and you should always get advice from professionals before taking any actions.

* Please keep in mind that all text is machine-generated, we do not bear any responsibility, and you should always get advice from professionals before taking any actions

Blood Supply and Lymphatics

The muscles of the back can be divided into three groups-superficial, intermediate and intrinsic: superficial-associate with movements of the shoulder. Intermediate-associate with movements of the thoracic cage. Deep-associate with movements of vertebral column. Deep muscles develop embryologically in the back, and are thus described as intrinsic muscles. Superficial and intermediate muscles do not develop in the back, and are classified as extrinsic muscles. This article is about the anatomy of deep back muscles-their attachments, innervations and functions. Deep muscles of back are well-develop, and collectively extend from the sacrum to the base of the skull. They are associated with movements of vertebral column, and control of posture. Muscles themselves are covered by deep fascia, which play a key role in their organisation. Anatomically, deep back muscles can be divided into three layers; superficial, intermediate and deep. We shall now look at each layer in more detail.

* Please keep in mind that all text is machine-generated, we do not bear any responsibility, and you should always get advice from professionals before taking any actions.

* Please keep in mind that all text is machine-generated, we do not bear any responsibility, and you should always get advice from professionals before taking any actions

Nerves

Muscles that comprise thoracic wall and posterior thorax are innervate by intercostal nerves, which mainly come from anterior rami of spinal nerves T1 to T11. The anterior ramus of spinal nerve T12 is subcostal nerve. Each intercostal nerve supplies dermatome and myotome. Their afferent fibers provide sensory information to overlying skin while their efferent fibers conduct motor information to muscles of inspiration. Of note, only a portion of the anterior ramus of spinal nerve T1 forms the lower trunk of brachial plexus whereas remaining intercostal nerves do not form plexuses. Innervation to muscles of the anterior thorax arises from different branches of the brachial plexus. Innervation of pectoralis major is by both the lateral pectoral nerve, which innervates the clavicular head, and the medial pectoral nerve, which innervates the sternocostal head. Pectoralis minor receives its innervation by medial pectoral nerve. The Lateral pectoral nerve branches from the lateral cord of the brachial plexus while the medial pectoral nerve comes from the medial cord. Nerve to subclavius innervates subclavius muscle, which arises from the superior trunk of C5 to C6 nerve roots. If present, accessory phrenic nerve, mostly C5 contribution, may also provide motor innervation to subclavius muscle. Last, serratus anterior is innervate by long thoracic nerve, which originate from anterior rami of C5 to C7. Innervation to the diaphragm comes from both right and left phrenic nerves, which originate from anterior rami of C3 to C5. Phrenic nerves provide both motor innervation to allow the diaphragm to contract during inspiration and sensory innervation to parietal pleura and peritoneum covering the central aspect of the diaphragm. The lower six intercostal nerves provide sensory innervation to the periphery of the diaphragm.

* Please keep in mind that all text is machine-generated, we do not bear any responsibility, and you should always get advice from professionals before taking any actions.

* Please keep in mind that all text is machine-generated, we do not bear any responsibility, and you should always get advice from professionals before taking any actions

Physiologic Variants

Rib 07 (R). Image from Human Anatomy Atlas .

LandmarkCharacteristics
Shaft (orange)The longest part of the bone; gives attachment to the intercostals, the external oblique, the iliocostalis lumborum and thoracics, levatores costarum muscles, and the serratus anterior
Tubercle (olive)Eminence that articulates with the transverse process of T07
Neck (dark grey)Attachment site for the anterior costotransverse ligament
Head (pink-orange)Articulates with the bodies of T06 and T07, and acts as the attachment site for the interarticular ligament
Costal cartilage (neon green)Cartilage that allows the ribs to move; attachment site for diaphragm, pectoralis major, rectus abdominis, and transversus thoracis
Costal groove (purple)A groove on the inner part of the bone, through which the intercostal nerves and vessels pass

Multiple studies have reported the existence of anatomical variations of muscles of the thorax either in the case of supernumerary muscles or congenital anomalies. Sternalis muscle is a rare supernumerary muscle variant of anterior thoracic wall found in 8 % of the population that lies vertically between superficial fascia and pectoral fascia, parallel to the right sternal margin. It measures at approximately 7. 0 cm in length and 2. 9 cm in width. Sternalis muscle that may present either unilaterally or bilaterally and is thought to participate in shoulder joint movement or play an accessory role in lower chest wall elevation. There is still much disagreement about its innervation and embryological origin. Some reports have found that muscle receive its innervation either from external or internal thoracic nerves, intercostal nerves, or both. Moreover, some studies have postulated that it is derivative of hypaxial myotomes or dermomyotomes from which ventral and lateral body wall muscles of the thorax and abdomen develop. Meanwhile, other studies endorse that muscle develop either from rectus abdominis sheath or from pectoralis major as a result of defect in muscle patterning. Cases have never reported any clinical symptoms relating to sternalis muscle; however, its existence may present alterations in electrocardiogram or cause misdiagnoses of breast masses on routine mammography due to its parasternal location and relative unfamiliarity among radiologists. It has the potential to interfere with and prolong breast and cardiothoracic surgeries if undetected preoperatively. If it is detected preoperatively, surgeons can use sternalis muscle as muscular flap in reconstructive surgeries of anterior chest wall, head and neck, and breast. Anatomical variations of thorax muscles may also arise as result of varying degrees of congenital anomalies. Poland syndrome is characterized by absence of the sternocostal head of pectoralis major muscle along with variations of hypoplasia or absence of pectoralis minor muscle and even digital anomalies. Other anomalies described in Poland syndrome include absence or hypoplasia of ipsilateral breast, excavatum deformities, and rib aplasia. These defects are most commonly unilateral and typically found on the right side, although some studies have reported rare existence of bilateral manifestations. Many variations of syndrome have been described and range from cases of mild hypoplasia of pectoralis major muscle to cases of severe hypoplasia of the thoracic wall.

* Please keep in mind that all text is machine-generated, we do not bear any responsibility, and you should always get advice from professionals before taking any actions.

* Please keep in mind that all text is machine-generated, we do not bear any responsibility, and you should always get advice from professionals before taking any actions

Sources

* Please keep in mind that all text is machine-generated, we do not bear any responsibility, and you should always get advice from professionals before taking any actions.

* Please keep in mind that all text is machine-generated, we do not bear any responsibility, and you should always get advice from professionals before taking any actions

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