Exam 7 Anatomy cohort UE Axilla Brachial Plexus

Axilla

 Gateway to the upper limb

 Formed by the  clavicle, scapula, and upper thoracic wall, humerus, and related muscles

 Pyramidal shape

 Has an inlet and a base/floor

 

Axillary Inlet

 Formed by lateral border of Rib 1, posterior surface of the clavicle, and the superior border of the scapula up to the coracoid process

 Axillary artery, vein and brachial plexus; ­Artery and vein are separated by the anterior scalene muscle

Loocated at the axilla and differentiate at the inlet

Anterior axillary wall muscles

­Pectoralis major and minor muscles

­Subclavius muscles

­Clavipectoral fascia

Pectoralis major

 Largest and most superficial muscle of the anterior wall

 Its inferior margin underlies the anterior axillary fold

What are the head of pectoralis major?

clavicular: Originate at the median half of the clavicle

Sternocostal head : ­Origin-medial part of the anterior thoracic wall

­Can join the abdominal muscles.

Pectoralis Major

 Inserts into the lateral lip of the intertubercular sulcus of the humerus

 Innervated by the lateral (travels between Pec minor and subclavius) and medial pectoral nerves (pierces through the Pec minor)

Pectolaris major insert

  into the lateral lip of the intertubercular sulcus of the humerus

What innervate the pectoralis major?

 by the lateral (travels between Pec minor and subclavius) and medial pectoral nerves (pierces through the Pec minor)

Pectoralis Minor

 Small triangular muscle deep to the pectoralis major

 Originates at rib 3, 4, 5 and inserts at the coracoid process of the scapula

 Protracts the scapula anteriorly

 Innervated by the medial pectoral nerve

Subclavius

 Small muscle deep to the pectoralis major

 Passes between the clavicle and rib 1

 Originates as a tendon from rib 1

Subclavius

inserts as a muscular attachment on the inferior surface of the middle third of the clavicle

Depresses the clavicle and pulls the clavicle medially to stabilize the sternoclavicular joint.

 Thick sheet of connective tissue connecting the clavicle to the floor of the axilla

 Encloses the subclavius and pectoralis minor muscles

Clavipectoral fascia

Clavipectoral fascia

 Cephalic vein, thoraco-acromial artery and the lateral pectoral nerve passes between these muscles.

Medial axillary wall

­Serratus Anterior muscle

­Upper thoracic wall

­Ribs and intercostal tissues

 Originates as multiple slips from ribs 1-9

 Inserts primarily on the costal surface of the medial border of the scapula

 Pulls the scapula forward over the thoracic wall and contributes to scapular rotation

Serratus anterior

Serratus anterior

 Innervated by the long thoracic nerve which travels along the surface of the serratus anterior

 Passes directly through the medial axillary wall

 Supplies the skin on the upper posteromedial side of the arm (part of the T2 dermatome)

Intercostobrachial nerve

 Narrow and formed entirely by the intertubercular sulcus of the humerus

Lateral Axillary wall

posterior axillary wall

 Bone framework is formed by the costal surface of the scapula.

Muscles of the posterior wall

­Subscapularis

­Distal part Latissimus dorsi

­Distal part Teres major

­Proximal part of the long head of the triceps brachii

­Formed spaces occur in the posterior wall.

 Largest component of the posterior wall

 Originates from the subscapular fossa

 Inserts on the lesser tubercle of the humerus

Part of the rotator cuff

Subscapularis

Subscapularis

 Innervated by the superior and inferior subscapular nerves

 Forms inferolateral aspect of the posterior wall

 Along with the l. dorsi, mark the posteroinferior border of the axilla

 T. major marks the beginning of the brachial artery at its inferior border

Teres major and latissimus dorsi

Teres major and latissimus dorsi

 Tendon of the latissimus dorsi also forms inferolateral aspect

 Flat tendon curves around the inferior margin of the teres major and inserts on the floor of the intertubercular sulcus of the humerus.

Gateways in the posterior wall

 Quadrangular space

 Triangular space

 Triangular interval

Quadrangular space

 Axillary nerve, and the posterior circumflex humeral artery and vein pass between axilla and the scapular and deltoid regions

Quadrangular space boundaries

­Inferior margin of the teres minor muscle

­Surgical neck of the humerus

­Superior margin of the teres major

­Lateral margin of the long head of the triceps brachii.

 The circumflex scapular artery and vein pass through from axilla to the scapular region

Triangular space

­Medial margin of the long head of the triceps brachii muscle

­Superior margin of the teres major muscle

­Inferior margin of the teres minor muscle

Triangular space boundaries

 Radial nerve passes from the axilla to the posterior compartment of the arm

Triangular interval

Triangular interval Boundaries

­Lateral margin of the long head of the triceps brachii muscle

­Shaft of the humerus

­Inferior margin of the teres major muscle

Floor of the axilla

 Formed by fascia and a dome of skin

 Anterior fold is more superior than posterior fold

Contents of the axilla

 Muscles

 Major vessels

 Nerves

 Lymphatics

Brachial Plexus

 Somatic plexus formed by the anterior rami of C5-C8 and most of the anterior rami of T1

 Originates in the neck and passes laterally and inferiorly over rib 1 where it enters the axilla

 Innervates the upper limbs

Draw the plexus brachial

Compositions of plexus brachial

­Roots:5

­Trunks:3

­Divisions3&3:

­Cords: 3

Roots of the brachial plexus

 Roots are the anterior rami of C5-C8 and T1

 Roots enter the posterior triangle of the neck passing between the anterior and middle scalene muscles

 Lie superior and posterior to the subclavian artery

 Superior trunk

­Made from union of C5 and C6 roots

 Middle trunk

­C7 root

 Inferior trunk

­C8 and T1 roots

Trunks of the brachial plexus

 Each of the three trunks divide to an anterior and posterior division.

 Anterior- ultimately give rise to nerves associated with the anterior compartments

 Posterior-ultimately give rise to the nerves associated with the posterior compartment

 *no  peripheral nerves originate directly from the divisions of the brachial plexus

Divisions of the brachial plexus

Cords of the brachial plexus

 Three Cords and are related to the second part of the axillary artery and most peripheral nerves of the upper extremity originate from the cords.

 Lateral-union of the anterior divisions of the upper/superior and middle trunks and is positioned lateral to the second part of the axillary artery

­C5-C7 origin

 Medial-medial to the second part of the axillary artery and is a continuation of the anterior division of the inferior trunk

­C8-T1

 Posterior-posterior to the second part of the axillary artery and is a union of all three posterior divisions

­Contains all roots of the brachial plexus

Cords of the brachial plexus

Branches of the roots

 C5 contribution to the phrenic nerve

 C5-Dorsal scapular nerve

­Passes posteriorly usually piercing the middle scalene muscle

­Travels along the medial border of the scapula

­Innervates the rhomboid major and minor muscles

 C5-C6-Nerve to the subclavius muscle

­From the superior trunk

­Passes anteroinferiorly over the subclavian artery and vein

­Innervates the the subclavius muscle

Branches of the roots

 C5-C7- long thoracic nerve

­Passes vertically down the neck through the axillary inlet and down the medial wall of the axilla

­Supplies the serratus anterior muscle

 C5-C8 Small segmental branches to the muscles of the neck

 Suprascapular nerve

­Originates from the superior trunk

­Passes laterally through posterior triangle on the neck and the suprascapular foramen to enter the posterior scapular region

­Innervates supraspinatus and infraspinatus muscles

 Musculocutaneous nerve-anterior compartment of the arm

 Lateral cutaneous nerve of the forearm-sensory to the lateral skin of the arm

 Lateral root of the median nerve-anterior forearm and some intrinsic hand muscles

 Lateral pectoral nerve-pectoralis major

Branches of the medial cord

 Medial pectoral nerve- pectoralis minor

 Medial cutaneous nerve of the arm-skin over distal third of the arm

 Intercostobrachial nerve-upper part of the medial surface of the arm and the axilla floor

 Medial cutaneous  nerve of the forearm-skin over the anterior and medial skin of the forearm

 Medial root of the median nerve-anterior forearm and some intrinsic hand muscles

 Ulnar nerve-all intrinsic muscles of the hand (minus the three thenar muscles and the two lumbrical muscles) also innervates the skin over the little finger and the medial half of the ring finger

 All lymphatics of the upper limb drain to the axilla

 20-30 axillary nodes divide into groups

­Humeral (lateral ) nodes

­Pectoral (anterior) nodes

­Subscapular (posterior) nodes

­Central nodes-receive from the three above

­Apical nodes- include cephalic vein area

Axillary lymphatics

 Ulnar

 Median

 Radial

Injury to Brachial Plexus