4) Muscles of Respiration

What are the general features of the internal intercostals?

- 11 muscles on each side; 22 total - Located between each rib - Commence at the sternum and cartilages of the ribs; run laterally and dorsally far as the angles of the ribs

What are the general features of the external intercostals?

- 11 muscles on each side; 22 total - These muscles are located between each rib

Lumbar Fascia overview

- A fascial sheath on the lower part of the back into which some of the muscles are attached - Attaches to posterior part of the Illiac crest and spines of the lumbar vertebrae

What is the Brachial plexus?

- A network of nerves arising from the lower 4 cervical and 1st thoracic spinal nerves

The Phrenic Nerve

- Exits the vertebral column at C4-C5 - Spinal cord injury below C5, respiration is possible - Spinal cord injury above C4, usually rapid death - Respiration is possible with artificial respirators, scalenus muscles, or 'froggy breathing'

Abdominal muscles overview

- Muscles of exhalation pull ribs down - Compress the contents of the abdoment; forces diaphragm upwards - Abdominal muscles are innervated by spinal nerves from the lumbar region of the spinal cord

Overview of the Intercostal muscles

- Of all of the thoracic muscles, the intercostals are the most actively involved in speech control - These muscles show active contraction or relaxation in phase with inflections in the voice, speech prosody, etc.

Central Tendon

- The center of the diaphragm is made up of a broad, irregular shaped tendon; aponeurosis - Muscle attaches to the tendon and to other structures of the torso - Above it, the pericardium also attaches

What is the Diaphragm?

- The primary muscle of respiration - Dome shaped muscle that provides a complete seal between the throacic and abdominal cavities; it is a boundary between them - It arches upward into the thoracic cavity like an inverted bowl or dome - Primary inspiratory muscle. This is the only respiratory muscle that is active when a person is unconscious - Innervated in part by the autonomic nervous system

What is the abdominal aponeurosis and what are its landmarks?

- This sheet of fascia overlying ventral abdominal area Landmarks: - Linea alba: the midline thickened portion - Linea semilunaris: Curved lateral line attached to muscles The rectus abdominis muscle is enveloped within the abdominal aponeurosis

What are the three parts of the Scalenus (scaleni)?

1) Anterior 2) Medial 3) Posterior

Diaphragm: Contraction and Relaxation

Contraction: - Pulls central tendon down - Pulls parietal pleura down - Expands the lungs Relaxation: - Lung recoil forces pull the diaphragm up - Exhalation

What is the Origin, Insertion, Innervation, and Action of the Trapezius?

Flat, triangular. Extends over the back of the neck and the upper thorax. Origin: Occipital bone, nuchal ligament, spinous processes of the 7th cervical vertibrae and all 12 thoracic vertibrae. All fibers converge on the upper part of the shoulder Insertion: Lateral 1/3 of clavicle, acromion and crest of spine of the scapula Action: - Fixates and moves the scapula, fixates the shoulder - When the shoulder is fixed, it moves the head backwards and laterally Innervation: Nerves C 3-4

What is the Origin, Insertion, Innervation, and Action of the Rectus Abdominis Muscle?

Origin: Crest of the pubis bone - Contained in an envelope of the abdominal aponeurosis Insertion: Xiphoid process - Long thin muscle adjacent to linea alba - Interrupted by 4 or 5 tendinous inscriptions (insertions) Action: - Flexes vertebral column - Pulls ribs down - Compresses abdominal contents - Exhalation Innervation: Nerves T7-T11

What is the Origin, Insertion, Innervation, and Action of the internal intercostals?

Origin: Ridge on the inside of the rib. Fibers run down and angle laterally in front. Perpendicular to External Intercostals Insertion: Cranial border of rib immediately below Action: To draw the ribs together. These muscles may be either inspiratory or expiratory depending on what the other muscles are doing Innervation: Intercostal nerves of 12 thoracic spinal nerves

What is the Origin, Insertion, Innervation, and action of the Diaphragm?

Origin: Xiphoid process, inner surfaces of lower ribs, lumbar vertebrae Insertion: Central Tendon Innervation: Phrenic Nerve Action: - Contraction pulls the central tendon down, thus enlarging the thoracic cavity and compressing the contents of the contents of the abdominal cavity - These actions are important for inspiration, micturition, defecation, emesis, and parturition

What is the Origin, Insertion, Innervation, and Action of the Serratus Anterior?

Powerful muscles that wrap around sides of the thorax; when flexed they resemble sew teeth on sides, hence their name. Origin: Anterior surfaces of first 8-9 ribs Insertion: Anterior surface and medial border of scapula Action: - Abducts scapula - Lifts ribs when scapula is held stationary; inhalation Innervation: Long thoracic nerve from the brachial plexus

What is the Origin, Insertion, Innervation, and Action of the Internal Abdominal Oblique?

This muscle is beneath the external abdominal oblique Origin: - Pubic crest, inguinal ligament, and the iliac crest - Fibers run diagonally, upwards and medially Insertion: - Abdominal aponeurosis; costal parts of ribs 8-12 Action: - Compresses abdominal contents - Pulls ribs down for expiration Innervation: T 7-11

What is the Origin, Insertion, Innervation, and Action of the Sternocleidomastoid

Anterior and lateral part of the neck. Origin: Upper surface of the sternum and medial end of the clavicle; has 2 heads Insertion: Mastoid process of the skull Action: - Rotate head contralaterally and downward - During heavy breathing: raises sternum and clavicle - Also important for tilting the head Innervation: Spinal part of accessory and C 2-3 Torticolis (spasmodic torticolis) affects this muscle

What is the Origin, Insertion, Innervation, and Action of the Pectoralis Major?

Large broad muscle on the lateral and upper part of the chest. Origin and Insertion: Dependent upon the reference - One end: narrow, attaches to the upper part of the humerous - Other end attaches to entire length of the sternum, ventral surface of sternal half of clavicle and from cartilages of true ribs Action: - With the arm fixed, elevates ribs, pulls them laterally and expands the chest; provides deep inspiration - If the arm moves, different groups of fibers may act differently - Main action is control of arm movement Innervation: C5-C7

What is the Origin, Insertion, Innervation, and Action of the Latissmus Dorsi?

Large, triangular flat muscle. Extends over the lumbar region and lower part of the thorax Origin: - Tendons from spinous processes of lower 6 thoracic vertebrae and from lumbar fascia. Also from crest of the illium and from 3 or 4 lower ribs. - Fibers run laterally, upward, and then converge into thick fasciculus Insertion: Humerous. This forms posterior fold of axilla Action: - Adduct the arm - Helps fixate arm for respiration - Active in coughing and sneezing and in deep inspiration Innervation: Thoracodorsal nerve

What is the Origin, Insertion, Innervation, and Action of the Medial Scalenus?

Largest and Longest of the Scalenus muscles. Origin: Transverse processes of last 6 vervical vertebrae, also atlas Insertion: 1st rib, anterior to tubercle Action: - Raises 1st rib or fixates it - Active during quiet respiration Innervation: Nerves C 3-4

What is the Origin, Insertion, Innervation, and Action of the Anterior Scalenus?

Lies deep in the neck, deep to the sternocleidomastoid. Origin: Transverse process of C 3-6 vertebrae Insertion: 1st rib, anterior to the other scalenus Action: To elevate the first rib or fixate it to allow other ribs to be elevated Innervation: Nerves C 3-4

What is the Origin, Insertion, Innervation, and Action of the External Abdominal Oblique?

Origin: - There are several parts - External surfaces and inferior borders of the lower ribs; like a line running from top to bottom and from front to back Insertion: - The fibers of the last two ribs run almost vertically to insert into the iliac crest (inguinal ligament, pubic symphasis). - the remaining fibers are directed caudally and ventrally to insert on the abdominal aponeurosis Action: - Compresses abdominal contents - Flexes vertebral column - Pulls lower ribs down to assist in expiration Innervation: T 7-11

What is the Origin, Insertion, Innervation, and Action of the external intercostals?

Origin: Caudal border of the upper rib, extending from the rib tubercles on dorsal chest wall around the wall to near the costal cartilages. Fibers are rather short. On the front side, fibers run downward from lateral to medial, while on the back they are medial to lateral. Fibers do not extend to cartilages near midline - variability. Insertion: Cranial border of rib immediately beneath the one of origin. Action: Draw the ribs together; either the lower one goes up or vice versa. Also stiffens chest wall. When the upper 2 ribs are fixed by scalene muscles, their action is expiratory. Innervation: Intercostal nerves from each of the 12 thoracic segments, the spinal nerves. Difficult to investigate this muscle physiologically in normal people.

What is the Origin, Insertion, Innervation, and Action of the Costal Elevators (Levatores Costrum)?

Short muscle in the back, there are 12 of them on each side, 24 in total Origin: Transverse processes of the 7th cervical and upper 11 thoracic vertebrae. Fibers coarse downward and laterally Insertion: Between turbercle and angle of rib below the transverse process. For the lower 4 muscles, the muscles have two slips, one of which goes to the second lower rib. Action: - Elevate the rib, much like the external intercostals - Rotate and laterally flex verterbral column Innervation: Spinal nerves

What is the Origin, Insertion, Innervation, and Action of the Pectoralis Minor?

Small fan shaped muscle lying underneath the Pectoralis Major Origin: Corocoid process of the scapula. Fibers descent ventrally, caudally, and medially Insertion: 3rd, 4th, and 5th ribs near the cartilage articulations Action: - Can pull scapula ventrally and caudally in shoulder movement - Can raise the 3rd, 4th, and 5th ribs in inspiration - forcible Innervation: C7- T1

What is the Origin, Insertion, Innervation, and Action of the Posterior Scalenus?

Smallest and most deeply seated. Origin: Transverse processes of 4, 5, and 6 vertibrae Insertion: 2nd rib Action: - raises 2nd rib or fixates it - bends and rotates neck - All three of the muscles can probably work together for inspiration Innervation: Nerves C 3-4

What is the Origin, Insertion, Innervation, and Action of the Transverse (horizontal) Abdominal Muscle?

The deepest of the abdominal muscles; fibers run transversely, or horizontally Origin: - Inguinal ligament, inner side of iliac crest, lumbar fascia - Inner surfaces of ribs 6-12 Insertion: - Aponeurosis Action: - Compresses the abdominal contents - Flexes vertebral column Innervation: T 7-11

What is the Origin, Insertion, Innervation, and Action of the Transverse Thoracic Muscles?

Thin plate of muscles on inner wall of the chest. Origin: Lower part of the inner surface of the sternum, inner surface of the Xiphoid Process, and sternal ends of ribs 5 thru 7, and ends of costal cartilages of last 3-4 ribs Insertion: Caudal borders and inner surfaces of ribs and costal cartilages of ribs 2-6. Action: - Pulls ventral portion of ribs caudally, which then decreases thoracic volume - Exhalation Innervation: Spinal nerves

Quadratus lumborum

Thin sheet of muscle on the back Origins: Iliac crest and ligament are attached to lumbar vertebrae Insertion: Transverse processes of lumbar vertebrae 1-4, and 12th rib Action: - Pulls lumbar vertebrae laterally, bending to the side - Fixes lower rib and assists in expiration by allowing the intercostals to pull against the lower ribs Innervation: Lumbar spinal nerves