Subscapular is muscle forms the posterior wall of axilla.
Subscapular artery descends down on the posterior wall of axilla.
Winging of scapula is due to the paralysis of serratus anterior muscle. It could also result from the paralysis of trapezius muscle.
Ape hand deformity is due to Median nerve injury
Palmaris longus passes superficial to the flexor retinaculum.
Serratus anterior is a protractor of scapula. It also cause lateral rotation of scapula along with trapezius and both muscles are involved in overhead abduction.
Musculocutaneous nerve supplies three muscles in the arm: biceps brachii, brachialis and coracobrachialis.
Scapular anastomosis involves:
a. Suprascapular artery
b. Dorsal scapular artery / Deep branch of transverse cervical artery
d. Circumflex artery
Levator scapulae muscle is mainly an elevator of scapula.
Inferior angle lies opposite the seventh thoracic spine when the arm is by the side.
Rotator cuff is contributed by supraspinatus, infraspinatus, teres minor and subscapularis (SIT/S).
Extensor pollicis longus & Extensor pollicis brevis form the boundaries of the anatomical snuff box. Scaphoid bone lies at the floor of this box and its fracture leads to tenderness in the box.
Axillary nerve injury often results from shoulder joint dislocation or fractures at the surgical neck of the humerus. The injury causes deltoid muscle paralysis and skin anesthesia over the lateral deltoid region. Shoulder contour may be lost with time as the deltoid atrophies. Arm abduction is lost when the arm is abducted beyond the first 15 degrees.
Midhumeral fracture may involve the deep brachial artery and the radial nerve as they wind about the posterior aspect of the humerus. Arterial injury produces ischemic contracture; nerve injury paralyzes the wrist extensors and extrinsic extensors of the hand ("wrist-drop").
Except on the ulnar side (flexor carpi ulnaris and 4-5 flexor digitorum profundus), the forearm flexor compartment is innervated by the median nerve.
Scaphoid fracture is the most common hand bone break because it transmits forces from the abducted hand directly to the radius. Because the blood supply enters distally, the proximal portion of the scaphoid is especially prone to avascular necrosis.
Lunate dislocation is most common in falls on the out-stretched hand, compressing the median nerve within the carpal tunnel and producing carpal tunnel syndrome.
Extension of the medial four digits at the metacarpophalangeal joints and interphalangeal joints is accomplished by the extensor digitorum in the forearm, innervated by the radial nerve. In addition, extension of the interphalangeal joints of the medial four digits is carried out by the lumbricals, which are innervated by both the median nerve (lumbricals 1-2 on the lateral side) and ulnar nerve (lumbricals 3-4 on the medial side). lumbricals also flex the metacarpophalangeal joints of the medial four digits.
Proximal phalangeal flexion at the metacarpophalangeal joint is by:
a. The interossei (ulnar nerve) and lumbricals muscles;
b. The flexor digitorum superficialis (median nerve) muscle;
c. The flexor digitorum profundus (medial and ulnar nerves) muscles. Middle phalangeal flexion at the proximal interphalangeal joint is by (b) and (c). Distal phalangeal flexion at the distal interphalangeal joint is by (c)
Digital abduction is a function of the dorsal interossei ("DAB"-dorsal abduction); digital adduction is a function of palmar interossei ("PADâ palmar adduct).The ulnar artery is the principal supply to the superficial palmar arch in the hand.
Lymphatic drainage from the palmar hand and digits is toward the dorsal subcutaneous space of the hand, explaining the extreme swelling of this region that accompanies infections of the digits or volar surface.
Radial sensory function is tested in the web space of the thumb; ulnar sensory function is tested along the fifth digit. The digital branches of the median and ulnar nerves lie along the sides of the fingers where they may be anesthetized
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