Muscles of Inspiration and Expiration

Diaphragm

-Primary muscle of inspiration which separates the thoracic and abdominal cavities. Dome shaped to accommodate the heart (higher on the right than the left)

Linea alba

Midline for the abdominal aponeurosis.

External oblique abdominis

Most superficial and strongest. Compresses abdominal contents.

Latissimus dorsi

Muscle of the back used for forced expiration. Stabilizes posterior wall of the abdomen.

Internal oblique abdominis

Supports abdominal wall. Assists in forced expiration. Aids in raising the intra-abdominal pressure, and abducts and rotates the trunk with muscles from the other side.

Rectus abdominis

1. "6 pack" 2. Origin: pubic crest and pubic symphysis 3. Insertion: 5, 6, and 7 costal cartilages. 4. Innervation: T7-T12 5. Flexes trunk; aids expiration and raises the intra-abdominal pressure.

External intercostals

1. 11 on either side. 2. located between ribs. 3. courses downwards and inwards 4. Originates: inferior surface of ribs 1-11 5. inserts: superior surface of ribs 2-12 medially 6. Innervation: T1-T11 spinal nerves. *Inspiration

Attachments of the Diaphragm

1. Central tendon 2. Sternal attachment: attaches at the ensiform process. 3. Costal attachment: attaches to the inner surface of the cartilage of ribs 7-12. 4. Vertebral: attaches to upper lumbar vertebrae, the corpus of L1, and the transverse processes of L1-L5.

Transverse abdominis

1. Deepest of the abdominal muscles. 2. Origin: vertebral column 3. Insertion: laterally to inner surfaces of ribs 6-12 and pubis bone. 4. innervation: T7-T12 5. compresses abdomen.

Accessory muscles of inspiration

1. External intercostals 2. Levatus costarum brevis 3. Levatus costarum longis 4. Serratus posterior superior 5. Sternocleidomastoid 6. Scalenes 7. Pectoralis major 8. Pectoralis minor

Innermost intercostals

1. Forced exhalation. 2. Originates on inferior margin of ribs 1-11. 3. Inserts into the rib immediately below, laterally. 4. Depresses the ribs. 5. Deep to the internal intercostals.

Accessory muscles of expiration

1. Internal intercostals 2. innermost intercostals 3. abdominal aponeurosis 4. Rectus abdominis 5. Transverse abdominis 6. Internal oblique abdominis 7. External oblique abdominis 8. Latissimus dorsi

Abdominal aponeurosis

1. Runs from xiphoid process to the pubic symphysis. 2. Linea alba: midline. Thinnest here. 3. courses laterally. 4. Serves as a sheath for the rectus abdominis 5. 3 layers forming a sheath for transverse abdominis, internal, and external obliques. 6. linea semiluminarus

Internal intercostals

1.Used for forced exhalation. 2. Originates on the inferior margin of ribs 1-11. 3. Inserts into ribs immediately below, laterally. 4. Deep to the external intercostals; run at right angles. 5. Depresses the ribs. 6. Innervated by T2-T11.

Pectoralis minor

Accessory muscle of chest. Increases transverse dimension of rib cage. Inspiration.

Pectoralis major

Accessory muscle of chest. Sternal and clavicular head insert into the humerus. Increases transverse dimension of rib cage.

Scalenes (anterior, medius, and posterior)

Accessory muscle of neck. Elevates ribs 1 and 2. Inspiration

Sternocleidomastoid

Accessory muscle of neck. Originates: mastoid process of temporal bone Inserts: sternal head into manubrium Inserts: clavicular head into clavicle. Elevates sternum, and consequently the rib cage. Inspiration.

Levatus costarum longis

Accessory muscle of the back . Longer than LC Brevis. Helps elevate rib cage. Inspiration.

Serratus posterior superior

Accessory muscle of the back. Elevates ribs 2-5. Inspiration.

Levatus costarum brevis

Accessory muscle of the back. Helps elevate rib cage. Inspiration

Innervations of diaphragm

C3, C4, C5. (phrenic nerve)

Contraction of diaphragm

Force directed downwards; results in elongation of cavity formed by ribs so the lungs may expand.