Musculoskeletal anatomy – part 3

The anterior border is convex forward on the lateral end. Palpate your own clavicle to confirm that.

Supraspinatus initiates arm abduction. It is responsible for the first 15 degree of arm abduction before the deltoid takes over the movement.

The only odd one out is the pectoralis major that attaches to the humerus, clavicle and sternum. The pectoralis minor attaches to the coracoid process of the scapula.

Biceps brachii crosses the shoulder joint and elbow joint

The rest are covered by hyaline cartilage

The axillary nerve runs at close proximity to the surgical neck of the humerus and passes through the quadrangular space.

The axillary nerve gives rise to the upper lateral cutaneous nerve of arm that supplies the skin over the area of the deltoid muscle

PCHA is a branch of the axillary artery that runs alongside the axillary nerve posterior to the surgical neck of the humerus. They both pass through the quadrangular space.

The common flexor tendon attaches to the medial epicondyle of the humerus and gives attachment to the superficial layer forearm muscles. The flexor digitorum profundus originates from the proximal ventral ulnar.

The lateral cord gives off three branches (C5, 6, 7): 1. Lateral pectoral nerve (C5, 6, 7). 2. Lateral root of the median nerve (C5, 6, 7). 3. Musculocutaneous nerve (C5, 6, 7). The medial cord gives off five branches (C8, T1). 1. Medial pectoral nerve (C8, T1). 2. Medial root of the median nerve (C8, T1). 3. Ulnar nerve (C8, T1). 4. Medial cutaneous nerve of the arm (C8, T1). 5. Medial cutaneous nerve of the forearm (C8, T1). The posterior cord gives off five branches (C5, 6, 7, 8, T1): 1. Upper subscapular nerve (C5, 6). 2. Lower subscapular nerve (C5, 6). 3. Thoracodorsal nerve (nerve to latissimus dorsi) (C6, 7, 8). 4. Axillary nerve (C5, 6). 5. Radial nerve (C5, 6, 7, 8, T1).