Entrapment of the median nerve between the two heads of the pronator teres muscle. Results in paralysis of wrist flexors, pronators, and thenar muscles, and weak flexion and abduction of the wrist

Deformity with the thumb in the plane of the hand and thenar atrophy due to lesion of the median nerve. Opposition and flexion of the thumb are lost

• Paralysis of most of the wrist flexors
• Weak flexion and abduction at the wrist, with ulnar deviation of the hand
• "Ape hand"
• Inability to oppose or flext the thumb; difficulty in abducting the thumb
• Weakened grip, especially in the thumb, index and middle fingers
• Inability to flex the distal phalanx of the thumb, index, and middle fingers

Inflammation of the synovial sheaths around the flexor tendons in the carpal tunnel causes the median nerve to be compressed agains the unyielding flexor retinaculum, thereby compressing the nerve gradually. This syndrome is characterized by partial paralysis and atrophy of the thenar muscles and burning sensations in the radial half of the palm and palmar aspects of the first 3.5 digits. Decompression of the nerve by section of the flexor retinaculum may be required for relief

Due to lesions to the ulnar nerve. Caused by interosseous atrophy and paralysis of lumbricals 3 and 4. The metacarpophalangeal joints of these fingers remain hyperextended, and the interphalangeal joints are flexed

• Claw hand
• Difficulty in extending the interphalangeal joints of any of the fingers
• Inability to adduct or abduct the fingers
• Inability to adduct the thumb
• Weakened flexion and minimal ulnar deviation at the wrist
• Loss of sensation on the ulnar side of the hand including medial 1/2 of the ring finger and the entire 5th digit

Causes injury to the radial nerve. Results from compression against a chair back or bar

A clinical feature of injury to the radial nerve that is due to paralysis of the extensors and supinator, resulting in pronation of the hand with the wrist and fingers flexed in a characteristic flaccid position with an inability to extend the wrist

Causes difficulty in abduction of the shoulder due to deltoid paralysis and a patch of numbness on the lateral shoulder. Teres minor paralysis causes weakness in lateral rotation of the shoulder

Results from injury to the upper trunk (C5,C6) of the brachial plexus

Clincial manifestations:

Head waiter's tip hand

Weakness of the flexors of the elbow (with decreased supination from the weakened biceps, the forearm and hand will tend to be pronated)

• Biceps through musculocutaneous (C5,6,7)
• Brachialis through musculocutaneous (C5,6,7)
• Brachioradialis through radial (C5,6,7,8,T1)

There is weakness  of the adductors and medial rotators  of the shoulder

• Pectoralis major through lateral pectoral nerve (C5,6,7)
• Latissimus dorsi through thoracodorsal nerve (C6,7,8)

A manifestation fo ERB-Duchenne Paralysis (upper trunk-C5,6 injury) where the hand hangs at the side in medial rotation with the forearm pronated and the fingers and wrist relaxed. This clinical appearance is produced by a paralysis of the shoulder abductors (deltoid & supraspinatus) and lateral rotators (posterior deltoid, teres minor, & infraspinatus), which are innervated by the axillary nerve (deltoid & teres minor) and suprascapular nerve (supraspinatus and infraspinatus)

Results from injury to the lower trunk (C8, T1) of the brachial plexus

There is weakening of the extensors of the elbow, wrist, and fingers due to the C8, T1 contribution to the radial nerve

There is paralysis of the intrinsic muscles of the hand due to loss of deep branch of ulnar nerve (T1). Paralysis of the interosseous muscles and flexors of the fingers results in a "claw hand"

Characterized by pain in the arm, shoulder and neck; associated with atrophy of the small hand muscles and numbness of the hand on the ulnar side

Caused by compression of the subclavian artery and the lower trunk of the brachial plexus by the sclaneus anterior muscle

Inflammatory processes that occur in the anatomical compartments of the deep fascial connections that may affect the functions of structures within the space

A progressive shortening of the medial part of the palmar aponeurosis, producing flexion of the ring and 5th digits

Caused by herniated lumbar intervertebral disk compressing the L5 or S1 nerve roots in the spinal canal that affects muscles of the posterior thigh, leg and foot, and joints of the lower extremity; skin of the foot, leg and posterior thigh

Results from injury to the common fibular nerve or deep fibular nerve (affecting muscles in the anterior compartment of leg), producing weakness of dorsiflexion because the foot passively plantar flexes causing the toes to drag on the floor when walking

Produces sensory deficits (tingling or numbness in dorsum of foot), and motor deficits, such as weakness of foot eversion (lateral compartment muscles), and dorsiflexion (anterior compartment muscles)

1. Medial collateral ligament of knee
2. Medial meniscus
3. Anterior cruciate ligament of knee

These structures are mostly likely to be injured if a torn piece of cartilage is wedged between articular surfaces and the joint becomes locked

Superficial veins that become engorged with blood

Occurs through femoral canal when a loop of intestine or piece of omentum enters the canal and pushes a sac of parietal peritoneum in front of it.  The sac may protrude anteriorly through the saphenous hiatus and expand in the subcutaneous tissue of the groin. The sharp edge of the lacunar ligament may compress the loop of intestine enough to obstruct its blood vessels, causing strangulation of the hernia. Lacunar ligament is divided through surgery to relieve tension on hernial sac. An abberrant obturator artery may cross the lacunar ligament and may be liable to injury if this ligament is severed ("artery of death")

Occur at acromioclavicular joint