What Are the External Intercostal Muscles?

The intercostal external muscles are located outside the intercostal space, a total of 11 pairs. Starting from the lower edge of the upper ribs. The fibers stop from the upper outside to the lower inside, and stop at the upper edge of the lower ribs. During the upper fixation, the ribs are lifted to enlarge the frontal and sagittal diameters of the thorax and inhale.

The intercostal external muscles are located outside the intercostal space, a total of 11 pairs. Starting from the lower edge of the upper ribs. The fibers stop from the upper outside to the lower inside, and stop at the upper edge of the lower ribs. During the upper fixation, the ribs are lifted to enlarge the frontal and sagittal diameters of the thorax and inhale.

Chinese name

Intercostal muscle

Foreign name

intercostales extereni

Behind the range starts at

Intercostal segment

Function

Constitutes the main respiratory muscles

Overview of intercostal external muscles

The intercostal muscle is innervated by the intercostal nerve.

One of the natural thoracic muscles. Located in the intercostal space. This muscle starts from the lower edge of the ribs, the fibers slant forward and downward, and stops at the upper edge of the lower rib. At the costal cartilage, the intercostal external muscles migrate to the intercostal external ligament. This muscle participates in forming the chest wall. Dominated by intercostal nerves (thoracic 1-11).

The intercostales extereni (intercostales extereni) starts from the intercostal segment at the rear and extends to the tendon membrane near the anterior costal cartilage. It is called the intercostal epithelium to the lateral edge of the sternum. It slants forward and down to the lower edge of the lower rib, and muscle fibers slant forward and down to the upper edge of the lower rib.

The intercostal and diaphragmatic muscles form the main respiratory muscles and play an important role in breathing. When inhaling, the intercostal muscles contract, the ribs move upwards and outwards, the volume increases, and the internal pressure decreases to complete the inhalation; when exhaling, the intercostal muscles relax, and the ribs move downwards and inwards, reducing the volume , The internal pressure increases, thereby exhaling.

Intercostal External Muscle Anatomy Features:

1. Upper respiratory tract: Infants and young children have shorter nasal cavity than adults, no nasal hair, narrow nasal tract, soft mucous membranes, rich blood vessels, easy to be infected, and nasal cavity is easily blocked when inflamed, which makes breathing and suckling difficult. The sinus mucosa is continuous with the nasal mucosa and the sinus mouth is relatively large, so acute rhinitis often affects the sinuses. Babies can develop acute sinusitis 6 months after birth. The maxillary sinus and ethmoid sinus are most susceptible to infection. The eustachian tube is wide, straight, and short, and it is horizontal, so it is easy to cause otitis media when nasopharyngitis. The pharynx is also narrower and vertical. Pharyngeal tonsils have developed within 6 months, palatine tonsils gradually increased to the end of the first year of life, peaked at the age of 4 to 10 years, and puberty gradually degraded. Therefore, tonsillitis is common in older children and rare in infants. The larynx is funnel-shaped, the larynx is narrow, the glottis is relatively narrow, the cartilage is soft, the mucous membrane is soft and rich in blood vessels and lymphatic tissue, so slight inflammation can cause hoarseness and difficulty breathing.

2. Lower respiratory tract: Infants and young children have narrow trachea and bronchi, soft cartilage, lack of elastic tissue, weak support, rich mucosal blood vessels, poor cilia movement, weak clearance ability, easy to be congested, edema due to infection, increased secretion, Causes airway obstruction. The left bronchus is slender, with a slanted position, and the right bronchus is thick and short. It is a direct extension of the trachea, and the instructor can easily fall into the right bronchus. Children's lungs have poor development of elastic fibers, rich blood vessels, wider capillaries and lymphoid tissues than adults, strong interstitial development, and fewer alveoli, which cause the lungs to be rich in blood and relatively low in air, making them vulnerable to infection. And easy to cause interstitial inflammation, emphysema or atelectasis.

3. Thoracic: Infants and young children have a short and barrel-shaped thorax; the ribs are horizontal and the diaphragm is high so that the heart is horizontal; the thorax is relatively small and the lungs are relatively large; The lungs cannot expand sufficiently, and ventilation and ventilation are prone to bruising due to hypoxia and carbon dioxide retention. In children, the mediastinum is relatively large, and the body occupying the thorax is relatively large. The tissues surrounding the mediastinum are soft and elastic, so it is easy to cause the mediastinum to shift when the pleural effusion or pneumothorax is large.

Local anatomy of the intercostal muscle :

Inspiratory muscles

Muscles that expand the chest cavity, expand the lungs, and inhale air. The major inspiratory muscles are the diaphragm and intercostal external muscles, and the sternocleidomastoid, oblique, and anterior serratus are considered auxiliary respiratory muscles.

Expiratory muscles: espiratory muscles

Muscles that reduce the volume of the chest cavity and help expel air from the lungs. The main expiratory muscles are the abdominal muscles (rectus abdominis, external obliques, internal obliques) and intercostal muscles