Part 4 Flashcards
Central tendon
Leafy aponeurosis in the intermediate region of diaphragm. When it is contracted, muscle fibers shorten, allowing lungs to expand when squeezed down.
What are the accessory muscles of the thorax for inspiration?
Diaphragm External intercostal muscles Internal intercostal muscles Levatores costraum Serratus posterior superior
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External intercostal muscles
Significant respiratory muscles for speech, found between the 12 ribs. Diagonal slanting, striated muscle.
Origin- Lower surface of each rib
Insertion- Upper surface of rib immediately below
Action- Elevates rib cage; increases cavity size
Internal intercostal muscles
Chondral; others are expiration.
Origin: Superior surface of ribs 2-12
Insertion: Inferior surface of ribs 1-11
Action: Elevates rib portion near the sternum (parasternal portion)
Levatores costraum
Brevis and longus portions contribute to rib cage elevation. Appear to be muscles of the back, but are actually thoracic muscles.
Brevis portion of levatores costraum
Origin- transverse process extension of vertebrae C7-T11
Insertion- tubercle of rib below
Action- Elevates rib cage
Longus portion of levatores costraum
Origin- transverse process of T7-T11
Insertion- Bypasses the rib below the point of origin and inserts into the next rib
Action- Elevates rib cage, more so than brevis portion
Serratus posterior superior
Origin- Spinous process of C7, T1-T3
Insertion- Ribs 2-5
Action- Elevates ribs 2-5 specifically
What are the muscles of the upper arm and shoulder for inspiration?
Pectoralis major
Pectoralis minor
Serratus anterior
Pectoralis major
Large, fan shaped muscles that originates from 2 different heads
Origin- Sternal head & clavicle head
Insertion- Greater tubercle of humerus
Action- Elevates sternum and increases expansion of rib cage
Pectoralis minor
Under pectoralis major
Origin- ribs 2-5
Insertion- Caracoid process of scapula
Action- With shoulder fixed, elevates ribs 2-5
Serratus anterior
Jagged
Origin- ribs 1-9
Insertion- scapula
Action- with shoulder fixed, elevates ribs 1-9
What are the two muscles of the neck that help with inspiration?
Sternocleidomastoid & Scalenes
Sternocleidomastoid
Provide stability and control for neck flexion and extension in addition to assisting in respiration
Origin- mastoid process of temporal bone
Insertion- sternal head and clavicle
Action- elevates sternum and rib cage
Scalenes
Muscles of neck that provide stability of the head and assist with facilitating rotation. Includes anterior, medial and posterior.
Origin- transverse processes of C2-C7 vertebrae
Insertion- ribs 1-2
Action- elevates ribs 1-2
What are the back muscles of inspiration?
Levator Scapulae
Rhomboideus major
Rhomboideus minor
Trapezius
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Levator scapulae
Provides neck support and helps elevate the scapula
Origin- transverse processes C1-C4
Insertion- medial border of scapula
Action- elevates the scapula
Rhomboideus Major & Minor
Lie deep within the trapezius
Origin- Major spinous process of T2-5; Minor spinous process of C7-T1
Insertion- Scapula
Action- Stabilizes the shoulder girdle
Trapezius
Massive muscle that makes up superficial upper back & neck- upper back triangle
Origin- Spinous processes of C2-T12
Insertion- Scapula and superior surface of clavicle
Action- Elongation of the neck, head control
What are the muscles of expiration of thorax, back & upper limb?
Internal intracostal Transverse thoracis Subcostals Serratus posterior inferior Latissimus dorsi
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Internal intracostal
Interosseous portion
Origin- superior margin of each rib
Insertion- runs up and medially to insert into the inferior surface of the rib above
Action- depresses ribs 1-11
Transverse thoracis
Origin- lower third of sternum
Insertion- inner chondral surface of ribs 2-6
Action- contraction decreases the volume of thoracic cavity
Subcostals
Vary in number, generally course parallel to the internal intercostal muscles.
Origin- inner thorax, inner surface of rib near angle
Insertion- inner surface of 2nd or 3rd rib below
Action- depresses the thorax
Serratus posterior inferior
Origin- spinous processes of T11-T12
Insertion- lower margin of lower 5 ribs
Action- pulls rib cage down