Anterior and Posterior Thorax Muscle Flashcards
Muscles can be named after these three things
Action, Shape, Location (origin and insertion)
These muscles attach the upper limb to the axial skeleton via the pectoral girdle
Muscles of the anterior and posterior thorax
These muscle stabilize the shoulder and move the scapula
Muscles of the anterior and posterior thorax
Name the 6 muscles of the anterior thorax
- Pectoralis Minor
- Serratus Anterior
- Subclavius
- Sternocleidomastoid
- Anterior Scalene
- Pectoralis Major
A triangular shaped muscle with the apex attached to the coracoid process, distally attached to ribs 3-5
Pectoralis Minor
Located on the anterior wall of thorax and is covered by pectoralis major muscle
Pectoralis Minor
Innervation of the pectoralis minor
medial pectoral nerve
Stabilizes the scapula through the coracoid process, and can sometimes lift the ribs up
Pectoralis Minor
Muscle with scalloped origin, serratis saw, sometimes called the boxers muscle
Serratus Anterior
Holds the scapula against the chest wall and is important to protract the scapula
Serratus Anterior
Needed to elevate the arm above 90 degrees by rotating laterally, paralysis would inhibit raising arm above 90 degrees
Serratus Anterior
Origin and insertion of serratus anterior
Origin: Lateral aspects of ribs 1-8
Insertion: Posteriorly to vertebral border of scapula
Innervatation of the serratus anterior
the long thoracic nerve
Small muscle lying below the clavicle and holds the clavicle in the sternoclavicular joint
Subclavius
Protects the underlying subclavian vessels if there is a fracture of the clavicle, which could pierce the subclavian artery which supplies the upper extremity
Subclavius
Origin and insertion of the subclavius
Origin: Costal cartilage of rib one
Insertion: Inferior surface of the lateral third of the clavicle
Innervation of the clavicle is the nerve to the ___ which is a branch of the brachioplexus
Subclavius
Action is to stabilize the pectoral girdle and help to depress the shoulder
Subclavius
The anterior neck muscle with two heads, one clavicular and the other sternal
Sternocleidomastoid
Attaches pectoral girdle to the axial skeleton and bilaterally flexes head foward
Sternocleidomastoid
Unilaterally flexes head to the same side
Sternocleidomastoid
The sternocleidomastoid is innervated by
the spinal accessory nerve (cranial nerve 11)
Bilaterally contracted causes head to move forward
Sternocleidomastoid
Group of three muscles located beneath the sternocleidomastoid
Scalene (Anterior, Middle, and Posterior)
Lies directly deep to sternocleidomastoid muscle
Anterior Scalene
Origin and insertion of anterior scalene
Origin: Cervical Transverse Processes 3/4-6
Insertion: Rib one
Innervation of the anterior scalene
Branches of cervical spinal nerves
If contracted, it depends on which part is fixed
Neck is fixed -> ribs will elevate as in deep inspiration
If rib is fixed -> neck flexes forward, especially when contracting bilaterally
One side is contracted -> lateral flexion to same side
Anterior Scalene
A very large artery runs posterior to the anterior scalene
Subclavian Artery
Covers the sternocleidomastoid and is considered a muscle of facial expression
Platysma
The five muscles on the posterior thorax
Trapezius Levator Scapulae Rhomboid Major Rhomboid Minor Latissimus Dorsi
Muscle on posterior thorax that attaches the pectoral girdle to the trunk, has a trapezoid shape, and its fibers divide into three actions
Trapezius
Three actions of the trapezius
Elevates Scapula
Retracts Scapula
Depresses Scapula
This muscle also braces the shoulders by pulling the scapulae posteriorly and superiorly, fixing them in position on the thoracic wall with tonic contraction
Therefore, weakness of the muscle causes droopy shoulders
Trapezius
Originates from the occipital bone from the ligamentum nucae
Trapezius
A very thick ligament attached to the spinous processes of the upper cervical vertabrae
ligamentum nucae
Attaches to spinous cervical 7-12 thoracic vertebrae
Trapezius
Laterally attaches to clavicle, acromion process of scapula , and spine of scapula
Trapezius
Innervated of the trapezius
Spinal Accessory Nerve (cranial nerve 11)
Upper fibers of trapezius do this to the scapula
Middle fibers do this
The lower fibers do this
Elevate the scapula
Retract the scapula
Depress the scapula
If trapezius is reflected, muscle which elevates the scapula is shown
Levator scapulae
This muscle fixes the scapula and extends the neck
Located superior to the rhomboids at the superior angle of the scapula
Levator Scapulae
Innervation of the levator scapulae
Dorsoscapular Nerve
If the scapulae does not move when levator scapular is contracted, what happens to the neck
If one scapulae stays fixed for unilateral contraction does what
Pulls the neck posteriorly
Extends the neck
Flexes the neck laterally to the same side, or ipsilateral side
Muscles shaped like a parallelogram or rhombus, lie deep to the trapezius and form broad parallel bands
Rhomboid Major and Minor
Form large parallel bands from vertabra to medial border of the scapulae
Rhomboids
Minor is located superior to major, 3-4 times less wide than major
Rhomboid minor
Retract the scapula, can be tested by putting hands on hips and pushes with elbows posteriorly against resistance, they can be felt along medial border of the scapula
Rhomboids
Origin and insertion of rhomboid major and minor:
Spinous processes of vertebrae
Minor: C7-T1
Major: T2-T5
Inserts at medial border of scapula
Innervation of the rhomboids
Dorsoscapular Nerve
An action that brings the pectoral girdle anteriorly and laterally is called
Protraction
An action that brings the pectoral girdle posterior and medially is called
Retraction