5: Musculo-neuro-vascular systems of pectoral and dorsal regions Flashcards
What is muscle
Contractile tissue made of myocytes
Muscle origin
Proximal attachment (usually remains fixed)
Muscle insertion
Distal attachment (usually moves)
Skeletal muscle consists of :
myocytes bundled into fascicles, bundled into muscle
Brachial
Relating to, or situated in the arm
Plexus
A network of anastomosing or interlacing blood vessels or nerves
Brachial plexus
The system of nerves that emerge lateral to the spinal cord and
Allow motor nerves to send their signals from brain to upper limb muscles
Allow sensory nerves to send their signals back to the brain
Movements of the scapula
Elevation + depression
Protraction + retraction
Upward + downward rotation
Scapular movers/ stabilizers (6)
Trapezius
Levator scapulae
Rhomboid minor
Rhomboid major
Pectoralis minor
Serratus anterior
Origin of trapezius
External occipital protuberance
Nuchal ligament
Spinous process of C7-T12 vertebrae
Insertion of trapezius
Spine of scapula
Acromion of scapula
Lateral 1/3 of clavicle
Innervation of trapezius
Spinal accessory nerve (cranial nerve 11)
Actions of trapezius (4)
Powerful retractor of scapula
Elevates scapula
Depresses scapula
Upward rotation of scapula
Origin of levator scapula
Transverse processes of C1-4 vertebrae
Insertion of levator scapula
Superior part of medial border of scapula
Innervation of levator scapula
Dorsal scapular nerve (C4 - 5)
Actions of levator scapula
Elevates medial border of scapula
Downward rotation of scapula
Origin of rhomboid minor
Spinous process of C7-T1 vertebrae
Insertion of rhomboid minor
Medial border of scapula root of the spine
Innervation of rhomboid minor
Dorsal scapular nerve (C4 - 5)
Actions of rhomboid minor
Retracts scapula
Downward rotation of scapula
Roots of dorsal scapular nerve
Spinal nerve roots C4 -5
Course of dorsal scapular nerve
Passes inferiorly, medial to medial border of scapula
Origin of pectoralis minor
Anterior surface of ribs 3-5
Insertion of pectoralis minor
coracoid process of the scapula
What does the dorsal scapular nerve innervate
Levator scapula
Rhomboid minor
Rhomboid Major
Actions of pectoralis minor
Protracts and stabilizes scapula by pulling it antero-inferiorly onto posterior thoracic wall
Origin of serratus anterior
Medial border of scapula, anterior surface
Insertion of serratus anterior
Individual muscle slips that insert into anterolateral surface of ribs 1-8
Actions of serratus anterior
Protracts and stabilizes scapula by pulling it anteriorly against thoracic wall
Assists with upward rotation of scapula by pulling inferior angle laterally
Innervation of pectoralis minor
Medial pectoral nerve (C8-T1)
Course of medial pectoral nerve
Arises from medial cord of brachial plexus
Formed by contributions from spinal nerve roots C8 - T1
Innervation of serratus anterior
Long thoracic nerve (C5-7)
Course of long thoracic nerve
Formed from spinal nerve roots C5 -7
Passes inferiorly over the lateral surface of serratus anterior
Innervates serratus anterior
Is the long thoracic nerve protected?
Protected when limbs at side, but is vulnerable when limbs elevated
Cause of long thoracic nerve palsy
Injuries to the long thoracic nerve, due to trauma, heavy weightlifting, repeated throwing
Consequences of long thoracic nerve palsy
Scapula can not be held firmly against posterior aspect of thoracic cage due to paralysis of serratus anterior
Origin of pectoralis major
Clavicular head: medial 1/2 clavicle
Steroncostal head: sternum, upper 6 costal cartilages
Insertion of pectoralis major
Lateral lip of bicipital groove
Innervation of pectoralis major
Medial pectoral nerve (C8 -T1)
Lateral pectoral nerve (C5-7)
Actions of pectoralis major
Flexes shoulder from the extended position
Adducts + internally rotates humerus
Course of medial pectoral nerve
Arises from medial cord of brachial plexus
Formed by contributions from spinal nerve roots C8-T1
Passes inferiorly deep to pectoralis minor providing innervation
Course of lateral pectoral nerve
Arises from lateral cord of brachial plexus
Formed by contributions from spinal nerve roots C5-7
Descends deep to pectoral muscles and innervates them from posterior
Insertion of latissimus dorsi
Floor of bicipital groove
Origin of latissimus dorsi (5)
Thoracolumbar fascia
Inferior ribs
Posterior iliac crest of pelvis
Inf 6 thoracic vertebrae
Actions of latissimus dorsi
Extends, adducts, medially rotates humerus
Downward rotation of scapula
Innervation of latissimus dorsi
Thoracodorsal nerve C6 - 8
Course of thoraco-dorsal nerve
Arises from the posterior cord of the brachial plexus
Formed by contributions from C6-8 spinal nerves
Passes inferiorly between scapula and thorax to reach and innervate latissimus dorsi
Upon reaching L. Dorsi - runs obliquely along L. Dorsi , innervating the whole muscle
What does the dorsal scapular nerve innervate?
Levator scapula
Rhomboid minor
Rhomboid major
Origin of rhomboid major
Spinous process of T2- T5 vertebrae
Insertion of rhomboid major
Medial border of scapula (inferior 2/3)
Innervation of rhomboid major
Dorsal scapular nerve (C4 -5)
Actions of rhomboid major
Retracts scapula
Downward rotation of scapula
As the subclavian artery crosses the lateral border of the 1st rib it becomes known as…
The axillary artery
3 parts of axillary artery
Proximal to pectoralis minor (1 branch )
Deep to pectoralis minor (2 branches)
Distal to pectoralis minor (3 branches)
Once the axillary artery passes the inferior border of the teres major muscle, it becomes known as…
The brachial artery
Part 1: superior thoracic artery course
Passes anteriorly and inferiorly between pectoralis major and minor
Supplies P. Major and P.Minor
Part 2: thoracoacromial artery course
Runs over pectoralis minor and divides into four branches supplying
Clavicle
Deltoid
Acromion
Pectoral muscles
Part 2: lateral thoracic artery course
Descends along lower border of pectoralis minor to supply
Serratus anterior
Pectoral muscles
(Breast)
Part 3: anterior circumflex humeral artery
Passes anteriorly around surgical neck
of humerus anastomosing with posterior circumflex humeral artery
Part 3: posterior circumflex humeral artery
Passes posteriorly around surgical neck of humerus anastomosing with anterior circumflex humeral artery
Part 3: subscapular artery
Largest branch of axillary artery
Divides into circumflex scapular artery and thoracodorsal artery
What supplies medial and superior scapula
Terminal branches from subclavian artery
What supplies inferior and lateral scapula
Terminal branches from axillary artery