Lecture 5: Axilla & Back of Arm Anatomy PDF

Lecture 5 Axilla & back of arm  ILOs Recognize the muscles of back of arm. Mention the boundaries and content of axilla. Recognize intermuscular spaces  Axilla -Axilla is a pyramidal space between the upper part of thoracic wall and upper limb. Boundar...

Lecture 5 Axilla & back of arm  ILOs Recognize the muscles of back of arm. Mention the boundaries and content of axilla. Recognize intermuscular spaces  Axilla -Axilla is a pyramidal space between the upper part of thoracic wall and upper limb. Boundaries: Apex: triangular gap in the upper part of axilla, It is bounded by 3 bones: -Anteriorly: clavicle -Posteriorly: upper border of scapula -Medially: outer border of 1st rib Base: Axillary fascia -A thick layer of deep fascia. -It is attached to areolar tissue around vessels and nerves of axilla resulting in retraction of the base of axilla inwards into a hollow when the arm is abducted. -Anterior wall: 2 layers Superficial layer: by pectoralis major Deep layer: from above downwards as follows Subclavius muscle Clavipectoral fascia Pectoralis minor muscle -Its lower border called ant.axillary fold formed by pectoralis major Posterior wall: longer than anterior wall formed by Subscapularis teres major latissimus dorsi Its lower border called posterior axillary fold formed by teres major & latissimus dorsi Medial wall: Upper 5 ribs with intercostal muscles & Upper part of serratus anterior that arise from the upper 5 ribs Lateral Wall: Upper part of shaft of humerus with coracobrachialis and biceps.  Content of axilla  Axillary artery  Axillary vein  Axillary fat  Axillary lymph nodes  Cords of brachial plexus Muscles of back of arm Triceps  Triceps Origin: by 3 heads: -Long head: from infraglenoid tubercle of scapula -Lateral head: from posterior surface of humerus above spiral groove. -Medial head: lower half of posterior surface of humerus below spiral groove. Insertion: 3 heads unite together and inserted into post. Part of upper surface of olecranon process of ulna. Nerve supply : radial nerve Action: main extensor of elbow joint Long head steadies the lower aspect of capsule of shoulder joint  Intermuscular spaces Quadrangular space Upper triangular space Upper triangular space  Intermucular spaces Quadrangular space Boundaries: Above: teres minor Below: teres major Laterally: surgical neck of humerus Medially: long head of triceps Content: axillary nerve Posterior circumflex humeral vessels  Upper triangular space Boundaries: Above: teres minor Below: teres major Laterally: long head of triceps Content: circumflex scapular vessels  Lower triangular space Boundaries: Above: teres major Medially: long head of triceps Laterally: shaft of humerus Content: Radial nerve Profunda brachii vessels  Summary Boundaries & content of axilla Muscle of back of arm: Triceps Boundaries & contents of intermuscular spaces  Questions *Which of the following has some nerve supply from the radial nerve? a) long head of biceps b) coracobrachialis c) short head of biceps d) brachialis Which of the following muscles shares in anterior wall of axilla? A. Teres major B. Coracobrachialis C. Intercostal muscles D. subclavius Triceps muscle is supplied by ………..…. A. Musculocutaneous nerve B. Radial nerve C. Both above nerves D. Non of the above Mention boundaries and contents of quadrangular intermuscular space.  Refrences Snell, R.S. (2012): Snell Clinical anatomy by region. 9th edition. Chapter 9: Upper limb