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MS Anatomy:

Posterior cruciate ligament prevents anterior displacement of the femur relative to the tibia when the kneeis flexed. It attaches to the posterior part of the intercondylar area of the tibia and the anterior lateral surfaceof the medial epicondyle of the femur

Common peroneal nerve injury as it traces the lateral aspect of the femoral neck is common. Bony facture

and compression are the most common causes. Clinically this manifests as foot drop. The radial nerve is responsible for extension of the hand. Damage to the radial nerve results in wrist drop. The psoas muscle originates from the anterior surface of the transverse processes and lateral surface of the

corresponding vertebral bodiesT12 L5 The psoas muscle acts primarily to flex the thigh at the hip Itcontributes somewhat to lateral rotation and abduction of the thigh as well

The deep brachial artery and radial nerve course along the posterior aspect of the humerus. Fractures of thehumerus midshaft risk injury to these structures. Supracondylar fractures are associated with injury to the

brachial artery. The sternocleidomastoid muscle originates on the medial clavicle and manubrium and inserts on the

mastoid process of the skull. Itis innervated by CN Xl and functions to turn the head in the oppositedirection.

The Valsalva maneuver increases vagal tone and can be used to abolish paroxysmal supraventriculartachycardia. The rectus abdominis is the most important muscle in achieving the increased intraabdominal

and intrathoracic pressure of the Valsalva maneuver. The common peroneal nerve is vulnerable to injury where it courses around the neck of the fibula. Fibularneck fractures can lesion this nerve, causing weakness of dorsiflexion (deep peroneal nerve) and eversion(superficial peroneal nerve) of the foot as well as loss of sensation over the dorsum of the foot. Inversionand plantarflexion would remain intact due to the action of the tibial nerve.

Ulnar nerve injury classically causes a claw hand deformity. The ulnar nerve can b e injured either nearthe medial epicondyle of the humerus or in Guyons canal near the hook of the hamate and pisiform bone inthe wrist.

The most commonly injured structure in rotator cuff syndrome is the tendon of the supraspinatus muscle.Because the supraspinatus is an abductor of the humerus injury to its tendon causes pain on abduction ofthe arm.

Flattening of the deltoid muscle after a shoulder injury suggests anterior shoulder dislocation This injurymost commonly results from forceful external rotation and abduction at the shoulder joint. Axillary nerve

injury resulting in deltoid paralysis and loss of sensation over the lateral arm is often associated The most commonly injured structure in rotator cuff syndrome is the tendon of the supraspinatus muscle.Because the supraspinatus is an abductor of the humerus injury to its tendon causes pain on abduction ofthe arm. This tendon is vulnerable to injury due to impingement between the acromion and the head of thehumerus.

The musculocutaneous nerve innervates the flexor muscles of the upper arm and provides sensoryinnervation to the lateral forearm. The musculocutaneous nerve is derived from the upper trunk of the

brachial plexus and can be injured by forceful injuries that cause separation of the neck and shoulder. Sudden upward stretching on the arm at the shoulder can damage the lower trunk of the brachial plexus.

This trunk carries nerves from the CS and Ti spinal levels that ultimately form the median and ulnar nerves.These nerves innervate all of the intrinsic muscles of the hand.

Repeated and prolonged kneeling can cause prepatellar bursit is. Dubbed housemaids knee, today it ismost commonly seen in roofers, carpenters and plumbers. Signs and symptoms of prepatellar bursitis

include knee pain, erythema, swelling and inability to knee on the affected side. 1) Injury to the superior gluteal nerve causes weakness of the gluteus medius and gluteus minimus muscles, producing a positive Trendelenburg test.2) The inferior gluteal nerve innervates the gluteus maximus muscle. Injury of the inferior gluteal nervecauses difficulty rising from the seated position and climbing stairs.

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The serratus anterior muscle serves to fix the scapula against the posterior chest wall and rotate the scapulato allow abduction of the arm over the head. Paralysis of this muscle occurs with injury to the long thoracicnerve and results in winging of the scapula.

Trauma or sustained pressure to the neck of the fibula can cause injury to the common peroneal nerve as itcourses superficially and laterally to this structure.

The median nerve courses between the humeral and ulnar heads of the pronator teres muscle and then runs between the flexor digitorum superficialis and the flexor digitorum profundus muscles before entering thewrist and hand within the carpal tunnel.

The tibial nerve innervates the flexors of the lower leg, the extrinsic digital flexors of the toes, and the skinof the sole of the foot.

Improperly fitted crutches can cause radial nerve injury resulting in weakness of all forearm, wrist andfinger flexors (Wristdrop).

Mastectomy is a commonly tested cause of long thoracic nerve injury, but any trauma or surgery in theaxillary region is at risk of damaging this nerve. Injury to this nerve causes winging of the scapula andinability to abduct the shoulder past 90 degrees.

The anterior cruciate ligament (ACL) can be damaged by forceful anterior motion of the tibia with respectto the femur. ACL injury can occur as part of the unhappy triad, which also includes injury to the medial

meniscus and medial collateral ligament. Injections given in the superomedial part of the buttock risk injury to the gluteal nerves. Injections given in

the inferomedial part of the buttock risk injury to the sciatic nerve. The superolateral quadrant of the buttock is a safe site for intramuscular injections

The obturator nerve is the only major nerve that exits the pelvis through the obturator foramen. This nervesupplies the muscles of the medial (adductor) compartment of the thigh and can be damaged during pelvicsurgery, especially in procedures such as lymph node dissection.

The lunate bone can be identified on a hand X-ray as the more medial of the two carpal bones thatarticulate with the radius. It lies immediately medial to the scaphoid bone.

A femoral neck fracture can damage the blood supply to the femoral head and neck This is most commonwith displaced fractures The medial femoral circumflex artery provides the majority of the blood supply tothe femoral head and neck injury to this vessel can cause avascular necrosis of the femoral head