Upper limb anatomy is a common topic in examinations, and it is important to know certain facts about the nerves and muscles involved. The musculocutaneous nerve is responsible for elbow flexion and supination, and typically only injured as part of a brachial plexus injury. The axillary nerve controls shoulder abduction and can be damaged in cases of humeral neck fracture or dislocation, resulting in a flattened deltoid. The radial nerve is responsible for extension in the forearm, wrist, fingers, and thumb, and can be damaged in cases of humeral midshaft fracture, resulting in wrist drop. The median nerve controls the LOAF muscles and can be damaged in cases of carpal tunnel syndrome or elbow injury. The ulnar nerve controls wrist flexion and can be damaged in cases of medial epicondyle fracture, resulting in a claw hand. The long thoracic nerve controls the serratus anterior and can be damaged during sports or as a complication of mastectomy, resulting in a winged scapula. The brachial plexus can also be damaged, resulting in Erb-Duchenne palsy or Klumpke injury, which can cause the arm to hang by the side and be internally rotated or associated with Horner’s syndrome, respectively.

The knee joint is the largest and most complex synovial joint in the body, consisting of two condylar joints between the femur and tibia and a sellar joint between the patella and femur. The degree of congruence between the tibiofemoral articular surfaces is improved by the presence of the menisci, which compensate for the incongruence of the femoral and tibial condyles. The knee joint is divided into two compartments: the tibiofemoral and patellofemoral compartments. The fibrous capsule of the knee joint is a composite structure with contributions from adjacent tendons, and it contains several bursae and ligaments that provide stability to the joint. The knee joint is supplied by the femoral, tibial, and common peroneal divisions of the sciatic nerve and by a branch from the obturator nerve, while its blood supply comes from the genicular branches of the femoral artery, popliteal, and anterior tibial arteries.

The oblique popliteal ligament separates the origin of the posterior cruciate ligament from the popliteal vessels, while the transverse ligament is situated in front.

The knee joint is the largest and most complex synovial joint in the body, consisting of two condylar joints between the femur and tibia and a sellar joint between the patella and femur. The degree of congruence between the tibiofemoral articular surfaces is improved by the presence of the menisci, which compensate for the incongruence of the femoral and tibial condyles. The knee joint is divided into two compartments: the tibiofemoral and patellofemoral compartments. The fibrous capsule of the knee joint is a composite structure with contributions from adjacent tendons, and it contains several bursae and ligaments that provide stability to the joint. The knee joint is supplied by the femoral, tibial, and common peroneal divisions of the sciatic nerve and by a branch from the obturator nerve, while its blood supply comes from the genicular branches of the femoral artery, popliteal, and anterior tibial arteries.

Guttate psoriasis is frequently seen after a streptococcal infection, with group-A streptococcus being the likely culprit. The condition is characterized by the appearance of small, teardrop shaped red lesions. Scarlet fever, which is also caused by group-A streptococcus, presents with a rough rash, fever, swollen lymph nodes, and a red tongue. Pityriasis rosea, on the other hand, typically follows a viral infection and is identified by a single scaly patch followed by a widespread salmon-pink rash. Acne vulgaris and impetigo are not commonly associated with a streptococcal sore throat.

Guttate psoriasis is a type of psoriasis that is more commonly seen in children and adolescents. It is often triggered by a streptococcal infection that occurred 2-4 weeks prior to the appearance of the lesions. The condition is characterized by the presence of tear drop-shaped papules on the trunk and limbs, along with pink, scaly patches or plaques of psoriasis. The onset of guttate psoriasis tends to be acute, occurring over a few days.

In most cases, guttate psoriasis resolves on its own within 2-3 months. There is no clear evidence to support the use of antibiotics to treat streptococcal infections associated with the condition. Treatment options for guttate psoriasis include topical agents commonly used for psoriasis and UVB phototherapy. In cases where the condition recurs, a tonsillectomy may be necessary.

It is important to differentiate guttate psoriasis from pityriasis rosea, which is another skin condition that can present with similar symptoms. Guttate psoriasis is typically preceded by a streptococcal sore throat, while pityriasis rosea may be associated with recent respiratory tract infections. The appearance of guttate psoriasis is characterized by tear drop-shaped, scaly papules on the trunk and limbs, while pityriasis rosea presents with a herald patch followed by multiple erythematous, slightly raised oval lesions with a fine scale. Pityriasis rosea is self-limiting and resolves after around 6 weeks.

The patient exhibits a positive Trendelenburg sign, indicating weakness in the gluteus medius and minimus muscles responsible for hip abduction and pelvic stabilization. This is likely due to injury to the superior gluteal nerve. In contrast, injuries to the inferior gluteal nerve affect the gluteus maximus muscle and result in difficulty rising from a seated position or climbing stairs. The femoral nerve is responsible for knee extension and does not play a role in hip abduction. The lateral cutaneous nerve of the thigh causes pain in the posterolateral aspect of the thigh but does not cause motor impairment, while the obturator nerve controls thigh adduction and does not cause a positive Trendelenburg sign.

Lower limb anatomy is an important topic that often appears in examinations. One aspect of this topic is the nerves that control motor and sensory functions in the lower limb. The femoral nerve controls knee extension and thigh flexion, and provides sensation to the anterior and medial aspect of the thigh and lower leg. It is commonly injured in cases of hip and pelvic fractures, as well as stab or gunshot wounds. The obturator nerve controls thigh adduction and provides sensation to the medial thigh. It can be injured in cases of anterior hip dislocation. The lateral cutaneous nerve of the thigh provides sensory function to the lateral and posterior surfaces of the thigh, and can be compressed near the ASIS, resulting in a condition called meralgia paraesthetica. The tibial nerve controls foot plantarflexion and inversion, and provides sensation to the sole of the foot. It is not commonly injured as it is deep and well protected, but can be affected by popliteral lacerations or posterior knee dislocation. The common peroneal nerve controls foot dorsiflexion and eversion, and can be injured at the neck of the fibula, resulting in foot drop. The superior gluteal nerve controls hip abduction and can be injured in cases of misplaced intramuscular injection, hip surgery, pelvic fracture, or posterior hip dislocation. Injury to this nerve can result in a positive Trendelenburg sign. The inferior gluteal nerve controls hip extension and lateral rotation, and is generally injured in association with the sciatic nerve. Injury to this nerve can result in difficulty rising from a seated position, as well as difficulty jumping or climbing stairs.

The Sartorius Muscle: Anatomy and Function

The sartorius muscle is the longest strap muscle in the human body and is located in the anterior compartment of the thigh. It is the most superficial muscle in this region and has a unique origin and insertion. The muscle originates from the anterior superior iliac spine and inserts on the medial surface of the body of the tibia, anterior to the gracilis and semitendinosus muscles. The sartorius muscle is innervated by the femoral nerve (L2,3).

The primary action of the sartorius muscle is to flex the hip and knee, while also slightly abducting the thigh and rotating it laterally. It also assists with medial rotation of the tibia on the femur, which is important for movements such as crossing one leg over the other. The middle third of the muscle, along with its strong underlying fascia, forms the roof of the adductor canal. This canal contains important structures such as the femoral vessels, the saphenous nerve, and the nerve to vastus medialis.

In summary, the sartorius muscle is a unique muscle in the anterior compartment of the thigh that plays an important role in hip and knee flexion, thigh abduction, and lateral rotation. Its location and relationship to the adductor canal make it an important landmark for surgical procedures in the thigh region.

Fractures of the clavicle typically occur in the medial third, with the lateral aspect being displaced inferiorly by the weight of the arm and medially by the pull of the pectoralis major muscle. Meanwhile, the medial aspect of the fracture is usually displaced superiorly due to the pull of the sternocleidomastoid muscle.

Anatomy of the Clavicle

The clavicle is a bone that runs from the sternum to the acromion and plays a crucial role in preventing the shoulder from falling forwards and downwards. Its inferior surface is marked by ligaments at each end, including the trapezoid line and conoid tubercle, which provide attachment to the coracoclavicular ligament. The costoclavicular ligament attaches to the irregular surface on the medial part of the inferior surface, while the subclavius muscle attaches to the intermediate portion’s groove.

The superior part of the clavicle medial end has a raised surface that gives attachment to the clavicular head of sternocleidomastoid, while the posterior surface attaches to the sternohyoid. On the lateral end, there is an oval articular facet for the acromion, and a disk lies between the clavicle and acromion. The joint’s capsule attaches to the ridge on the margin of the facet.

In summary, the clavicle is a vital bone that helps stabilize the shoulder joint and provides attachment points for various ligaments and muscles. Its anatomy is marked by distinct features that allow for proper function and movement.

If the superior gluteal nerve is damaged, it will cause a Trendelenburg gait.

The Trendelenburg Test: Assessing Gluteal Nerve Function

The Trendelenburg test is a diagnostic tool used to assess the function of the superior gluteal nerve. This nerve is responsible for the contraction of the gluteus medius muscle, which is essential for maintaining balance and stability while standing on one leg.

When the superior gluteal nerve is injured or damaged, the gluteus medius muscle is weakened, resulting in a compensatory shift of the body towards the unaffected side. This shift is characterized by a gravitational shift, which causes the body to be supported on the unaffected limb.

To perform the Trendelenburg test, the patient is asked to stand on one leg while the physician observes the position of the pelvis. In a healthy individual, the gluteus medius muscle contracts as soon as the contralateral leg leaves the floor, preventing the pelvis from dipping towards the unsupported side. However, in a person with paralysis of the superior gluteal nerve, the pelvis on the unsupported side descends, indicating that the gluteus medius on the affected side is weak or non-functional. This is known as a positive Trendelenburg test.

It is important to note that the Trendelenburg test is also used in vascular investigations to determine the presence of saphenofemoral incompetence. In this case, tourniquets are placed around the upper thigh to assess blood flow. However, in the context of assessing gluteal nerve function, the Trendelenburg test is a valuable tool for diagnosing and treating motor deficits and gait abnormalities.

Methotrexate is a commonly used first-line drug for rheumatoid arthritis. It belongs to the group of disease modifying anti-rheumatic drugs, which also includes sulfasalazine, rituximab, and etanercept.

This medication is taken once a week and works by acting on the immune system. It is effective in treating RA and psoriatic arthritis, as it functions as both an anti-inflammatory and immunosuppressant.

Before starting treatment with methotrexate, blood tests are required to check for FBC, U&Es, LFTs, and protein and blood in the urine.

During treatment, regular monitoring is necessary. FBC should be checked every other week until six weeks after the last dose increase, then monthly for a year, and thereafter as clinically indicated. LFTs should be tested every three months due to the potential impact of methotrexate on the liver, while U&Es should be checked every 6-12 months.

As methotrexate is a folate antagonist, patients may experience side effects such as hair loss and mouth ulcers. To mitigate these effects, patients are often advised to take folate supplements on the days they are not taking methotrexate.

Methotrexate is an antimetabolite that hinders the activity of dihydrofolate reductase, an enzyme that is crucial for the synthesis of purines and pyrimidines. It is a significant drug that can effectively control diseases, but its side-effects can be life-threatening. Therefore, careful prescribing and close monitoring are essential. Methotrexate is commonly used to treat inflammatory arthritis, especially rheumatoid arthritis, psoriasis, and acute lymphoblastic leukaemia. However, it can cause adverse effects such as mucositis, myelosuppression, pneumonitis, pulmonary fibrosis, and liver fibrosis.

Women should avoid pregnancy for at least six months after stopping methotrexate treatment, and men using methotrexate should use effective contraception for at least six months after treatment. Prescribing methotrexate requires familiarity with guidelines relating to its use. It is taken weekly, and FBC, U&E, and LFTs need to be regularly monitored. Folic acid 5 mg once weekly should be co-prescribed, taken more than 24 hours after methotrexate dose. The starting dose of methotrexate is 7.5 mg weekly, and only one strength of methotrexate tablet should be prescribed.

It is important to avoid prescribing trimethoprim or co-trimoxazole concurrently as it increases the risk of marrow aplasia. High-dose aspirin also increases the risk of methotrexate toxicity due to reduced excretion. In case of methotrexate toxicity, the treatment of choice is folinic acid. Overall, methotrexate is a potent drug that requires careful prescribing and monitoring to ensure its effectiveness and safety.

Damage to the axillary nerve results in a loss of sensation in the area of the upper limb known as the regimental badge.

Innervation of Upper Limb Areas:
– Medial aspect of forearm: Innervated by the medial antebrachial cutaneous nerve, which originates from spinal nerves C8 and T1.
– Medial one and a half fingers: Innervated by the ulnar nerve.
– Anterior aspect of lateral three and a half fingers: Innervated by the median nerve.
– Lateral aspect of forearm: Innervated by the lateral antebrachial cutaneous nerve, which originates from spinal nerves C5 and C6.

Upper limb anatomy is a common topic in examinations, and it is important to know certain facts about the nerves and muscles involved. The musculocutaneous nerve is responsible for elbow flexion and supination, and typically only injured as part of a brachial plexus injury. The axillary nerve controls shoulder abduction and can be damaged in cases of humeral neck fracture or dislocation, resulting in a flattened deltoid. The radial nerve is responsible for extension in the forearm, wrist, fingers, and thumb, and can be damaged in cases of humeral midshaft fracture, resulting in wrist drop. The median nerve controls the LOAF muscles and can be damaged in cases of carpal tunnel syndrome or elbow injury. The ulnar nerve controls wrist flexion and can be damaged in cases of medial epicondyle fracture, resulting in a claw hand. The long thoracic nerve controls the serratus anterior and can be damaged during sports or as a complication of mastectomy, resulting in a winged scapula. The brachial plexus can also be damaged, resulting in Erb-Duchenne palsy or Klumpke injury, which can cause the arm to hang by the side and be internally rotated or associated with Horner’s syndrome, respectively.