Respiratory System: Muscles of Respiration
Levator Costarum Longus and Brevis
12 pairs of these muscles, 1 pair on either side of vertebral column. Brevis inserts into the lower rib and longus will insert 2 subtypes below the origin. Origin: Transverse process of thoracic vertebrae and brevis muscles Insertion: Rib below Function: Elevates rib cage Innervation: SN C8-T11
Muscles of Inspiration
3 primary muscles: diaphragm, external intercostals and internal costals (especially important, interchondral portion). 14 accessory muscles: muscles of the neck, anterior thoracic muscles, posterior thoracic muscles, muscles of the back
Expiration
A *passive* process during quite breathing. However, speech requires active force. Contraction of thoracic, back, upper limb and abdominal wall muscles = forced exhalation.
The Diaphragm
A primary muscle of inspiration that separates the thorax from the abdomen. It forms the floor of the thoracic cavity. Muscle fibers of the diaphragm pull on the central tendon (pulling *downward* during inspiration). Lungs are in the *vertical* dimension, causing *decreased* pressure and leading air to be drawn *inwards*
Left Phrenic Nerve
A spinal nerve providing motor function to this muscle (innervating the muscle)
Diaphragm Insertion
Central tendon (aponeurosis)
Accessory Muscles of Inspiration
Elevates the rib and expands the rib cage.
Muscles of the Ribs
External intercostals elevate the ribs. Internal intercostals (interchondral portion) elevates the ribs. Internal intercostals (interosseous portion) depress the ribs.
Primary Muscles of the Pectoral Girdle
Internal intercostals (interchondral portion, involved in inspiration and interosseous portion, which is involved in expiration).
Anterior Thoracic Muscles of Forced Expiration
Internal intercostals interosseus, Transverse Thoracis Muscle, Subcostal muscles
Diaphragm: Origin
It has three points of origin: Sternum: Xiphoid Process Vertebrae: Lumbar Vertebrae Costal walls: inner aspect of R7-R12.
Pectoralis Major
Origin: Clavicle and sternum Insertion: Humerus Function: Expands the rib cage Innervation: SN C5 and C8
Subcostal muscles
Origin: Lower border of the ribs Insertion: Lower rib Function: Pull down on the ribs Innervation: SN T1 - T11
Internal intercostals Interosseus
Origin: Lower border of the ribs Insertion: Upper surface of the rib below Function: Pull down on the ribs Innervation: T1 - T11 (intercostal nerves)
External Obliques
Origin: Lower ribs (5-12) Insertion: Abdominal Aponeurosis and pelvic girdle Function: Pulls down on the ribs and compresses abdomen Innervation: SN T7-T12
Transverse Abdominis
Origin: Lower ribs and diaphragm Insertion: Abdominal Aponeurosis and Pelvic Girdle Function: Pulls abdominal wall inwards Innervation: SN T7-L1
Lateral Iliocostalis Lumborum
Origin: Lumbodorsal fascia, Lumbar vertebrae,Posterior coxal bone Insertion: R7 - 12 Function: Pulls down on the lower ribs
Internal Obliques
Origin: Pelvic girdle Insertion: Lower ribs (9-12) and linea alba Function: Pulls down on the ribs and compresses the abdomen Innervation: SN T7-L1
Quadratus Lumborum
Origin: Pelvic girdle Insertion: Transverse process of the lumbar vertebrae and Rib 12 Function: Pulls down on Rib 12 Innervation: SN T12 - L3
Scalene Posterior
Origin: Posterior Tubercles of Cervical Vertebrae Insertion: Rib 2 Function: Lift the ribs on contraction Innervation: Spinal nerves C2-C8
Subclavius
Origin: Rib 1 and cartilage Insertion: clavicle Function: Elevates 1st rib Innervation: SN C5 and C6
Serratus Posterior Superior
Origin: Spinous process of cervical and thoracic vertebrae Insertion: True ribs Function: Elevates true ribs Innervation: SN T2 and T3
Serratus Posterior Inferior
Origin: Spinous process of thoracic and lumbar vertebrae Insertion: False and Floating Ribs Function: Pulls down on the lower ribs Innervation: SN T9 - T12
Transverse Thoracis
Origin: Sternum and middle ribs Insertion: True Ribs Function: Pull down on the ribs Innervation: SN T2 - T6
Latissimus Dorsi
Origin: Thoracic and Lumbar vertebrae, Sacrum, and Lower Ribs Insertion: Humerus Function: Elevate the lower 3 ribs Innervation: SN C6 - C8
Scalene Anterior
Origin: Transverse Process of cervical vertebrae Insertion: Rib 1 Function: Lift the ribs on contraction Innervation: Spinal nerves C2-C8
Scalene Medius
Origin: Transverse Process of cervical vertebrae Insertion: Rib 1 Function: Lift the ribs on contraction Innervation: Spinal nerves C2-C8
Serratus Anterior
Origin: True ribs and first two false ribs Insertion: Ribs and scapula Function: Elevates ribs Innervation: SN C5 and C7, T2 and T3.
Pectoralis Minor
Origin: Upper ribs (deep to the pectoralis major) Insertion: Scapula Function: Elevates the ribs Innervation: SN C5 and C8
Intercostals
Origin: lower border of the ribs Insertion: Upper surface of the rib below Function: Elevate and expand the rib cage. Innervation: T1-T11 intercostal nerves
Sternocleidomastoid
Origin: sternum (anterior manubrium) and clavicle (proximal-sternal end) Insertion: mastoid process Function: elevates the sternum and clavicle Innervation: CN XI, spinal nerves C1-C5
Lateral Iliocostalis Cervicis
Originates on upper ribs and inserts onto the certical vertebrae, elevating the upper ribs
Diaphragm Innervation
Phrenic Nerve, referred to as C3, C4 and C5.
Foramen Vena Cava
Provides path through which inferior vena cava vein transfers oxygen and blood towards the heart.
Posterior Thoracic Muscles of Forced Expiration
Quadratus Lumborum, Serratus Posterior Inferior, Lateral Iliocostalis Lumborum
Inspiration
This is an *active* process. Creates greater volume in our lungs, drawing negative pressure into our lungs. It requires muscular effort to move the rib cage and uses many muscles: primary vs. accessory.
Rectus Abdominis
This is what we know as the 6-pack Origin: Pelvic girdle Insertion: Middle Ribs and Xiphoid process Function: Pulls down on the lower ribs and compresses the abdominal wall Innervation: SN T7-T12
Anterior Abdominal Muscles of Forced Expiration
Transverse Abdominus, Internal Obliques, External Obliques and Rectus Abdominus
Abdominal Aorta
Behind hiatus that is the major blood vessel transporting oxygenated blood to abdomen and lower half of the body.
Accessory Posterior Thoracic Muscles
Lateral Iliocostalis Cervicis, Lateral Iliocostalis Thoracis, Serratus Posterior Superior, Latissimus Dorsi,
Right Phrenic Nerve
Nerve that emerges from C3, C4 and C5 on right side
Lateral Iliocostalis Thoracis
Origin lower ribs, insertion: upper ribs, function: stabilizes the posterior rib cage wall.
Accessory Muscles of the Pectoral Girdle
Sternocleidomastoid (sternal and clavicular heads) - accessory muscle of the neck that assists in inspiration
Accessory Muscles of the Thorax
Sternocleidomastoid, clavicular head and sternal head, Pectoralis major, Pectoralis minor and Subclavius muscle, Serratus anterior, Levator costarum and Serratus posterior superior
Forced Expiration
The abdominal muscles are considered the primary muscles of forced expiration with thoracic ones are secondary. During inspiration we're trying to expand volume of lungs in ribcage. In expiration, we're collapsing our lungs to send pressure out
Accessory Muscles of the Neck
The anterior, middle and posterior Scalenes, which helps lift the ribs on contraction.
Origin
The end of a muscle that attaches to the less mobile structure
Insertion
The end of the muscle that attaches to the more mobile structure, and moves toward the origin on contraction
Internal Intercostals
The interchondral portion that are deep. There are 11.
Right and left crus of vertebral attachment
The legs that attaches the diaphragm at the level of the lumbar spine
External Intercostals
They are lateral and superficial and there are 11.
Esophageal Hiatus
Where the esophagus passes through the diaphragm. When someone has a hernia, we often see it will happen in the place of the stomach so the esophagus bulges. As I breathe, diaphragm is moving around this pathway. Now that there's an outpouching (hernia), it causes pain when breathing
