Muscles of Thoracic Cage Flashcards
Describe function of muscles of pharynx and larynx
Pathways for air AND for food will converge in pharynx
During swallowing pharynx can only manage flow of food, as a result will close of the airway
Epiglottis (leaf-like lid) shuts over the larynx during swallowing to prevent any form of aspiration - so patient does not inhale food or foreign bodies into lungs
Phalangeal muscles prevent collapse of upper airways by creating some -ve pressure during inspiration
muscular impairment from neurological disorder, i.e. CVA, where swallow is affected this can have knock on effect to respiratory status
State muscles of respiration
Muscles of the pharynx and larynx
Muscles of the ribcage, thoracic spine and neck
Muscles of the abdominal wall, and lumbar spine
Give muscles of ribcage
4 muscles
diaphragm
external intercostals
internal intercostals
innermost intercostals
Give main functions of muscles of ribcage
Increase thoracic dimensions during inspiration - pump, bucket handles
Support the thoracic cage - keep in good position
Intercostal muscles prevent any recession or bulging of the intercostal spaces
Inhibit the lungs natural tendency to collapse - help to splint airways open
Give position of diaphragm
Unpaired, domed (parachute) shape skeletal muscle situated in the trunk.
Separates abdominal and thoracic cavities by filling the inferior thoracic aperture
Short anterior fibres and longer posterior fibres give the appearance of an inverted letter J when viewed from the side. When viewed from the front, two small domes (cupolae) on either side of the central tendon can be seen, that on the right being at a slightly higher level than the left: the central part lies opposite the xiphisternal joint
Give attachments of diaphragm
Origin -
Lumbar part: upper three lumbar vertebrae as right crus and upper two lumbar vertebrae as left crus and adjacent IV discs; Medial arcuate lig (spans between vertebral body L2 and TP L1 ) and Lateral arcuate lig (spans TP L1 to tip of Rib 12)
Costal part - inner surface of lower 6 ribs and CCs
Sternal part - post surface Xiphoid process
Insertion: Fibres converge and arch superomedially to insert into central tendon situated towards the front of the muscle; fibrous pericardium enclosing the heart is firmly attached to the middle central tendon
Give action of diaphragm
Major muscle of inspiration
Core stability
Active contraction in labour (parturition), miticurtation, vomiting
Give innervation of diaphragm
Left and right phrenic nerves C3,4,5
Describe zone of apposition (ZoA)
Refers to a vertical area of the diaphragm that begins at their insertion point on the inside of the lower ribs and extends to the top of the diaphragms.
Important for proper diaphragmatic function - will affect diaphragmatic tension
Abdominal surgery or distended abdomen - will have an impact on diaphragmatic function
Controlled by abdominal muscles
What are the structures passing between thorax and ribcage via diaphragm
major tubular structures = inferior vena cava, oesophagus and aorta
these structures do so by named openings; they may be accompanied by nerves and/or other vessels.
Describe the structures passing through caval opening
Caval opening is in the central tendon to the right of the midline and transmits the inferior vena cava and right phrenic nerve
It is level with the lower border of T8.
Consequently, the inferior vena cava is constantly held open.
Describe structures of oesophageal opening
At the level of T10, is to the left of the midline surrounded by fibres of the right and left crura
The oesophagus, the trunks of the vagus nerves (now known as the gastric nerves) and the oesophageal branches of the left gastric vessels pass through the opening.
The left phrenic nerve pierces the muscular part of the diaphragm near the oesophageal opening in front of the left part of the central tendon.
Describe structures passing through aortic opening
Lies behind the diaphragm, in front of T12, as the two crura cross each other.
The aorta and thoracic duct pass into and out of the abdomen, respectively.
The azygos vein is partly covered by the right crus, whereas the greater and lesser splanchnic nerves pierce the crura to enter the abdomen passing towards the coeliac ganglion.
Describe structures passing behind medial and lateral arcuate ligaments
Sympathetic trunk passes behind medial arcuate lig
Subcostal nerve passes behind lateral arcuate lig.
Describe structures passing between sternal and costal attachments of the diaphragm
Anteriorly between the sternal and costal attachments of the diaphragm, the superior epigastric artery enters the rectus sheath to supply the upper part of rectus abdominis
Describe other important features of the diaphragm
Surface area = 900cm2
Muscle fibres can reduce in length by up to 40%
Lots of functional reserve
Damage to C3,4,5 = issues with breathing
Describe position of external intercostals
Outer layer of muscles within intercostal spaces
Give attachments of external intercostals
Origin: Inferior border of the rib above
Insertion: Fibres pass obliquely inferomedially to superior border of the rib below
Give action of external intercostals
Most active during inspiration - causing elevation of the rib below towards the rib above
Stabilise chest wall - so diaphramatic change can cause drop in intrathoracic pressure
Give position of internal intercostals
Middle layer of muscles within intercostal spaces
Give attachments of internal intercostals
Origin: Inferior border of the costal cartilage and costal groove of the rib above
Insertion:
Fibres pass obliquely inferolaterally (90o to external intercostal) to superior border of the rib below; deep to corresponding external intercostal
Give action of internal intercostals
Most active during expiration - causing depression of rib above to rib below
Support intercostal space
Give position of innermost intercostals
Inner layer of muscles within intercostal space
Give attachments of innermost intercostals
Origin: Inferior borders and internal surfaces CC of ribs 2-6
Insertion:
Fibres pass obliquely inferolaterally (similar to internal intercostals) to inferior and deep surface of body of sternum, Xiphoid process and CC of ribs 4-7
Give action of innermost intercostals
Act within internal intercostals
Give innervation of intercostals
anterior primary rami of adjacent intercostal (thoracic) nerves
Give main muscles of inspiration
2 muscles:
Diaphragm
External intercostals
(Serratus posterior superior)
Give position of Serratus posterior superior
Thin flat muscle lying anterior to the rhomboids
Give attachments of Serratus posterior superior
Origin:
Inferior part of the ligamentum nuchae and spinous processes of C7- T3 and adjacent supraspinous ligaments
Insertion:
Fibres pass inferolaterally to attach superior borders of ribs 2-5, lateral to angles
Give action of Serratus posterior superior
Attachment to the ribs 2-5 causes them to be elevated, thus assisting inspiration
Give accessory muscles of inspiration
Sternocleidomastoid Scaleni Serratus Anterior (Serratus Posterior Superior) Pectoralis Major Pectoralis minor Latissimus Dorsi
Give position of sternocleidomastoid
Long straplike muscle arising from two heads running obliquely around the side of the neck close to the midline anteriorly
Give attachments of sternocleidomastoid
Origin:
Sternal head: superior part of anterior surface of manubrium sterni
Clavicular head: superior surface of medial third of the clavicle
Insertion:
Sternal head: Lateral half of superior nuchal line of the occipital bone
Clavicular head: Lateral surface of mastoid process of the temporal bone
Give action of sternocleidomastoid
Unilateral contraction: cervical spine: neck ipsilateral flexion, neck contralateral rotation
Bilateral contraction:
Inferior cervical vertebrae: neck flexion
Reversed origin: elevation of clavicle and manubrium of sternum in forced inspiration
How to palpate sternocleidomastoid
laterally flex the neck to the same side and then rotate the head to the opposite side against resistance.
Both sternal and clavicular heads can be gripped between the fingers, with the gap between them easily identifiable.
The round muscle belly is palpable throughout its length, as is the flat tendon attaching to the mastoid process.
Give position of scaleni muscles
Anterior: deep to sternomastoid in front of scalenus medius
Medius: middle and largest of the scalene muscles
Posterior: smallest and most posterior scalene muscle
Give attachments of scaleni muscles
Anterior: anterior tubercles of TP C3-6 to scalene tubercle inner border of rib 1
Medius: TP C1-2 and posterior tubercles of TP C3-7 to impression on superior surface rib 1, posterior to subclavian groove
Posterior: posterior tubercles of TP C4-6 to outer surface rib 2, posterior to serratus anterior attachment
Give actions of Scaleni muscles
Reversed origin:
Elevate ribs 1-2 in forced inspiration
All 3 unilateral= ipsilateral side flexion
Two anterior bilateral = neck flexion
Give position of Serratus anterior
Large, flat, muscular sheet covering the side of the thorax lying between the ribs and scapula
Sandwiched between pectoralis major, anteriorly, and latissimus dorsi posteriorly
Give attachments of serratus anterior
Origin:
fleshy digitations just anterior to the midaxillary line to the outer surfaces of the upper eight or nine ribs and intervening intercostal fascia
Insertion:
Costal surface of entire medial border of scapula
Give actions of serratus anterior
Protraction, retraction of scapula
Respiratory distress: elevate upper 8-9 ribs to increase AP diameter of thorax
How to palpate serratus anterior
muscular subject, the digitations of serratus anterior can be felt and often seen running forwards in the region of the midaxillary line, especially when performing ‘press-ups’.
Give position of pectoralis major
Thick, triangular muscle located on the upper half of the anterior surface of the thoracic wall; forms anterior fold of axilla
Give attachments of pectoralis major
Clavicular fibres: anterior surface of medial 1/2 clavicle
Sternocostal fibres: anterior surfaces of manubrium, body of sternum, upper 6 CCs, rib 6 and aponeurosis of EO
Insertion:
Lateral lip of intertubercular sulcus of humerus
Give action of pectoralis major
Shoulder ADD, MR (against resistance)
Clavicular fibres: shoulder flexion (to 90o flexion)
Sternocostal fibres: extension (back to neutral against resistance)
Respiratory distress: elevate upper 7 ribs to increase AP diameter of thorax
How to palpate pectoralis major
Clavicular part can be readily palpated if the arm is flexed to 60° and held against downward pressure, and the sternocostal part is best palpated if this same position is maintained against upward pressure
Give position of pectoralis minor
thin, flat, triangular muscle situated on the anterior chest wall deep to pectoralis major
Give attachments of pectoralis minor
Origin:
Anterior surfaces of ribs 3-5, close to CCs and intervening intercostal fascia
Insertion:
Fibres converge to a short, flat tendon as they pass superolaterally to attach to the upper surface and medial border of the coracoid process of the scapula
Give actions of pectoralis minor
Assists depression and protraction of scapula (working with serratus anterior)
Assists MR of scapula (against resistance)
Scapula and upper limb fixed: Elevate ribs 3-5 during forced inspiration
Give position of latissimus dorsi
Large, flat, triangular sheet of muscle running between the trunk and humerus
“wing” muscle
Give attachments of lattissimus dorsi
Origin:
TLF into SP of T7-12, all lumbar and sacral vertebrae and adjacent supraspinous and interspinous ligaments; adjacent iliac crest, lower 3-4 ribs and inferior angle of scapula
Insertion:
Fibres converge, passing superolaterally and rotating to floor of intertubercular sulcus of the humerus
Give actions of latissimus dorsi
Shoulder extension, ADD, MR (against resistance)
Respiratory distress: assist forced expiration in coughing by attachment to lower 3-4 ribs
Assists in singing
How to palpate latissimus dorsi
asking the subject to raise the arm to 90° flexion and to hold it steady against an upwardly directed pressure.
The muscle can be felt contracting if the posterior axillary fold is held between finger and thumb while the subject coughs.
Adduction of the abducted arm against resistance also enables latissimus dorsi to be seen and felt
What are the muscles of forced expiration
Intercostals - internal and innermost
Transversus thoracis
Subcostals
Rectus abdominis
External oblique
Internal oblique
Transversus abdominis
Quadratus lumborum (QL)
Latissimus dorsi
Give position of transversus thoracis
Inner aspect of the anterior thoracic wall
Give attachments of transversus thoracis
Origin:
Posterior surface of the xiphoid process , lower 1/2 body of the sternum and 4-7 costal cartilages.
Insertion:
inner surface of the 2-6 costal cartilages
Give action of transversus thoracis
Depress costal cartilages articulating with the sternum downwards and so contributes to expiration
Give position of subcostals
Irregular slips of muscle extending across one or two intercostal spaces
Give attachments of subcostals
Origin:
Internal aspect of lower ribs
Insertion:
Fibres pass inferiorly to inner surface of the rib 1 or 2 levels below near the angle
Give action of subcostals
depress the ribs and so aid expiration
Give position f serratus posterior inferior
Lying deep to latissimus dorsi
Give attachments of serratus posterior inferior
Origin:
SP T11- L2, adjacent supraspinous ligts via TLF
Insertion:
fibres run horizontally to attach to the lower four ribs at their angles
Give action of serratus posterior inferior
pull the lower four ribs inferoposteriorly and so may assist expiration
