Week 2 Anatomy

 Bony features of the clavicle

 

Boundaries  and contents of the axilla.

Borders

• Apex – posterior border clavicle, lateral border of first rib and superior border of scapula
• Medial – serratus anterior, chest wall
• Lateral – intertubecular grove of humerus,
• Anteriorly – pec major and minor
• Posterioirly – subscapularis, teres major and lat dorsi, scapula

 Smallest space when arm is fully abducted

Outlets

• mostly through inferiorly into arm.
• Quadangular space  posteriorly – axillary nerve exits and post circumflex artery of humerus(subscapularis/teres minor above, teres major below, long head of triceps medially and humerus laterally)
• Clavipectoral traingle – pass cephalic vein and medial and lateral pectoral nerves (clavicle, pec major and deltoid)
• Triangular Interval – Contain radial nerve and profunda brachii artery, Borders Teras major superiorly, Long head of triceps medially, and humerus laterally.

 

Contents

• Axillary artery, vein, brachial plexus, tendons of biceps and corochobrachialis, Lymph nodes

 

 

Brachial plexus.

Musculocutaneous Nerve

• Roots: C5, C6, C7.
• Motor Functions: Innervates the brachialis, biceps brachii and corocobrachialis muscles.
• Sensory Functions: Gives off the lateral cutaneous branch of the forearm, which innervates the lateral half of the anterior forearm, and a small lateral portion of the posterior forearm.

Axillary Nerve

• Roots: C5 and C6.
• Motor Functions: Innervates the deltoid, teres minor and the long head of the triceps brachii.
• Sensory Functions: Gives off the superior lateral cutaneous nerve of arm, which innervates the inferior region of the deltoid (“regimental badge area”).

Median Nerve

• Roots: C6 – C8 and T1.
• Motor Functions:  Innervates most of the flexor muscles in the forearm, the thenar muscles, and the two lateral lumbrical muscles that move the index and middle fingers.
• Sensory Functions: Gives off the palmar cutaneous branch, which innervates the lateral part of the palm, and the digital cutaneous branch, which innervates the lateral three and a half fingers on the anterior (palmar) surface of the hand.

Radial Nerve

• Roots: C5-C8 and T1.
• Motor Functions: innervates the triceps brachii, and the extensor muscles in the posterior compartment of the forearm.
• Sensory Functions: Innervates the posterior aspect of the arm and forearm, and the posterior, lateral aspect of the hand.

 

Ulnar Nerve

• Roots: C8 and T1.
• Motor Functions: Innervates the muscles of the hand (apart from the thenar muscles and two lateral lumbricals), flexor carpi ulnaris and medial half of flexor digitorum profundus.
• Sensory Functions: Innervates the anterior and posterior surfaces of the medial one and half fingers, and associated palm area.

 

Sterno-clavicular joint.

• saddle type of synovial joint but functions as a ball-and-socket joint.
• The SC joint is divided into two compartments by an articular disc attaching to ant and post sternoclavicular ligaments.
• These ligaments as well as costoclavicular and interclavicular ligament give the joint stability +++ so rare to displace and also shock absorbs.
• Articular surface covered in fibrocartilage- articulates with manubrium and 1st costal cartilage.
• Movements – elevation 60o, rotation along longitudinal axis, AP of 25-30o, circumduction.
• Fractures most commonly post fall onto shoulder or outstretched hand – medial2/3 -lateral 1/3 junction.
• Fracture leads to lateral end being pulled medially and inferiorly and medial end pulled superiorly
• The superior displacement can damage suprascapular nerves and result in unopposed medial rotation of arm

 

Acromio clavicular joint

• Atypical plane synovial joint
• Articular surface covered in fibrocartilage and has an incomplete wedge articular disc.
• Acromioclavicular ligament
• Main stabiliser is external ligamnt – coracoclavicular ligaments – conoid and trapezoid ligaments which asre often seprated by a bursa.
• Only passive movement occurs at this joint.
• Lateral pec and axillary nerve, lateral supraclavicular nerve.

 

Branches of the axillary artery ?

• 3 parts – first medial to pec minor, 2nd posterior to pec minor and 3rd lateral to pec minor.

Send The Lord to Say A Prayer

1 – Superior Thoracic

2 – Thoraco acromial

3 – Lateral thoracic

4 – Subscapluar

5 – Anterior circumflex of humerus

6 – Posterior Circumflex of humerus

 

Subclavian artery – related to anterior scalene

• Starts from arch of aorta(at level of T4) or brachiocephalic trunk(behind Right SC joint). Travels between anterior and middle scalene muscles. Finishes at lateral border of first rib.
• In relation to scalene anterior:
  • Medial – vertebral,  internal thoracic, thyrocervical trunk(very short and divides in thyroid artery, transverse cervical and suprascapular artery)
  • Posterior – costocervical trunk, sometimes dorsal scapular.
  • Lateral – sometimes dorsal scapular.

 

Lymph nodes of the axilla.

• Superficial lymph follows superficial veins and deep follow deep.
• Efferent vessels from cubital lymph nodes ascend in the arm and terminate in the humeral (lateral) axillary lymph nodes.
• Most superficial lymphatic vessels accompanying the cephalic vein cross the proximal part of the arm and the anterior aspect of the shoulder to enter the apical axillary lymph nodes; however, some vessels previously enter the more superficial deltopectoral lymph nodes.
• Deep lymphatic vessels, less numerous than superficial vessels, accompany the major deep veins in the upper limb and terminate in the humeral axillary lymph nodes.
• Axillary LN clearance can endanger long thoracic nerve and result in winged scapula

 

Lymph drainage of the breast.

• 75% of Lymph drain to axillary LN (pectoral) and apical LNs
• Rest drain to internal thoracic LNs and contralateral breast and contralateral Axillar lymph nodes.