muscle pt 4

two phases of breathing

• inspiration(inhaling)

• expiration(exhaling)

inspiratory muscles include

diaphram and external intercostals, contraction causes rib cage to enlarge.

expiration(exhaling)

brought on by relaxation of inspiratory muscles, as well as contraction of internal intercostals. relaxation decreases size of rib cage

external intercostals description

fibers run down and forward from each other to rib below. fibers are continuous with external oblique muscle, forming part of abdominal wall

external intercostals action

elevate ribs to aid in inspiration

internal intercostals description

fibers run deep to and at right angles to those of external intercostals

internal intercostals action

Pull ribs together and depress rib cage for expiration

diaphram description

forms floor of thoracic cavity

diaphram action

flattens during inspiration to increase verticle dimension of thorax

muscles of the abdominal wall: 4 paired muscles

• rectus abdominis

• external obliques

• internal obliques

• transversus abdominis

action of the abdominal wall muscles

• Flexion, lateral flextion and rotation of trunk

• helps promote urination, defecation, childbirth, coughing, etc

Rectus abdominis description

extend from pubis to rib cage

Rectus abdominis action

flex and rotates vertebral column

external oblique description

largest and most superficial of the three lateral muscles

external oblique action

flex vertebral column and compress abdominal wall

internal oblique description

muscle fans so it's inferior fibers run downward and medially

internal oblique action

flex vertebral column and compress abdominal wall

transversus abdominis Description

deepest muscle of abdominal wall, fibers run horizontally

transversus abdominis action

compresses abdominal contents, creates “deep” corset around the internal organs, and compressing them, and supporting them.

actions of superficial muscles if the anterior and posterior thorax

elevation, depression, rotation, protraction, retraction

superficial muscles if the anterior and posterior thorax: 2 groups

• muscles of anterior thorax

• muscles of posterior thorax

pectoralis minor Description

flat, thin muscle beneath and obscured by pectoralis major

pectoralis minor action

pulls scapula forward and downward

serratus anterior description

fan shaped muscles; deep into scapula and pectoral muscles

serratus anterior action

rotates scapula, protracts

subclavius description

small cylindrical muscle, extending from rib 1 to clavicle

subclavius action

stabilizes and depresses pectoral girdle

muscles of posterior thorax

• trapezius

• levator scapulae

• rhomboids

trapezius description

flat and triangular. most superficial muscle of posterior thorax

trapezius action

stabilizes, elevates, retracts, and rotates scapula

levator scapulae description

located at back and side of neck, deep to trapezius

levator scapulae action

elevates and adducts scapula

rhomboids description

lies deep to trapezius and inferior to levator scapulae

rhomboids action

stabilizes scapula