Thorax-thoracic muscle wall

what is the thorax

the span of the thoracic vertebrae

name the thoracic body wall muscle, function

rectus sternalis

—flexes sternum

—think a cat’s arched bacl (disappearing in human evolution)

find it, also names the bones in this picture

rectus sternalis (pink) (bottom on anterior portion of sternum)

—vertebrae, clavicle, humerus

what type of thoracic musculature is the rectus sternalis (this is helping us understand the whole picture)

ventral musculature

—the rectus sternalis is anterior)

name, attachment, func

what muscle layer is this

outermost muscle layer

serratus posterior superior muscle

—anchored to spinous process of vertebae

—hinge ribs upwards

serratus posterior inferior muscle

—still anchored to spinous process of vertebrae

—pulls ribs downwards

find it

just the thinnest dark blue line posterior to the vertebrae behind the purple epaxial muscle

name, struc, func

what muscle layer is this

external muscle layer

external intercostal muscles

struc

—inbetween the ribs, oblique angled

—END AT COSTAL CARTILAGES (doesn’t come to the anterior portion of the body)

func

—breathing —→ inhaling —→ expanding lungs (inhalation)

within the external intercostal muscles, in the section between the ribs, what parts are more stable and which parts are more mobile

(top) more stable

(bottom) more mobile

find it

external intercostal muscles (blue) in lateral muscle layers

name, struc, func

what muscle layer is this

internal intercostal muscles

middle muscle layer

struc

—go all the way anterior (to the sternum)

—angled in other direction compared to external intercostal muscles

func

—breathing —→ exhalation

which parts of the internal intercostal muscle are more stable and more mobile

what identifies a portion more stable?

more mobile (top)

more stable (bottom)

more stable=closer to the vertebral column

find it

green in lateral body wall muscles

name, struc, func

what muscle layer of the lateral musculature of the thorax is this

transverse thoracis muscles

internal mucle layer (anterior muscle of the internal layer)

struc

—attaches to sternum and ribs

func

—pulls ribs down (hinge downwards)

—exhalation!

find it

(yellow) on anterior side branching off of thorax-smaller line

name, struc, func

innermost intercostal muscles

-lateral muscle of the internal layer

struc

—muscles segments INTERUPTED BY RIBS

—only on lateral side

—same fiber orientation as internal intercostals

func

—depression of ribs

-exhalation

find it

innermost later muscle wall layer (yellow)

name, struc, func

subcostal muscules

—posterior muscle of the internal layer

struc

—attaches rib to rib

func

—depress the ribs

—exhalation

find it

yellow line adjacent to vertebrae

name, struc, func

diaphram

-specialized floor of thorax from internal layer

struc

—skeletal muscle (voluntary)

func

—inhalation (diaphram contracts) (balloon downwards) (balloon upwards is relaxed)

name, struc, func

what type of musculature is this now

longus colli muscle

-subvertebral musculature (upper quarter of thorax)

struc

—since this is in the subvertebral musculature, the upper thoracic region in the anchor pt, and the cervical region is where the function will take place

—it is pulling on vertebral bodies in the cervical region

func

—cervical flexion, pulls head down

find it

red bumps on posterior portion of body wall, sitting on vertebrae

How was the functional significance of the thoracic muscle wall repurposed?

from lateral angulation/locomotion —→ respiratory movements