Identifying Nerves and Blood Vessels - Anatomy

The sciatic nerve is comprised of the common fibular and tibial portions, which give rise to nerves of the same name. Although not a direct branch of the sciatic nerve, the medial plantar nerve comes from the tibial nerve, which can be traced back to the tibial portion of the sciatic nerve. However, the inferior gluteal nerve does not arise from any part of the sciatic nerve.

The anterior circumflex humeral artery branches from the axillary artery, and primarily supplies blood to the head of the humerus. The posterior circumflex humeral artery also arises from the axillary artery, and supplies blood to the teres minor and deltoid muscles, among others. The thoracoacromial artery branches off the axillary artery as well, supplying the deltoid, subclavius, and other muscles. The profunda brachii does not branch off the axillary artery, but the brachial artery.

The lateral compartment of the leg contains the fibularis longus and fibularis brevis. The muscles of the lateral compartment of the leg are responsible for eversion of the foot and weak plantarflexion of the ankle. The fibularis longus and fibularis brevis are innervated by the superficial fibular nerve (nerve roots L5, S1, S2). The arterial supply consists of perforating branches of the posterior tibial artery and the fibular artery. The great saphenous vein drains, not supplies various compartments of the leg.

The anterior compartment of the thigh is a fascial compartment that contains groups of muscles with their blood supply and nerves. The anterior compartment contains the sartorius muscle and the quadriceps muscles (rectus femoris, vastus lateralis, vastus intermedius, and vastus medialis). The iliopsoas is sometimes considered a component of the anterior compartment of the thigh. The function of the muscles of the anterior compartment is to extend the knee and flex the hip. The anterior compartment is innervated by the femoral nerve (however, the iliopsoas is not innervated by the femoral nerve and is innervated by ventral rami of L1-L3). The blood supply of the anterior compartment is the femoral artery. The femoral artery supplies blood to the anterior compartment and is the largest blood vessel of the lower limb. The gluteal arteries supply the posterior compartment of the lower limb.

The cavernous sinus is unique in which it uses the superior petrosal sinus to drain into the transverse sagittal sinus. Whereas, the straight, superior sagittal sinus, and cerebellar sinus all drain into the confluence of sinuses. Then the confluence of sinuses later drains into the transverse sagittal sinus as well.

The right pulmonary vein supplies blood to the left atrium.

There are 31 pairs of spinal nerves: 8 cervical nerves, 12 thoracic nerves, 5 lumbar nerves, 5 sacral nerves and 1 coccygeal nerve.

Each nerve separates from the spinal cord and exits the spine through the intervertebral foramen found between adjacent vertebrae. The nerves innervate regions of the peripheral nervous system and relay information to and from the central nervous system.

A dermatome is an area of skin innervated by the cutaneous branches of a single spinal nerve. When spinal nerves diverge from the spinal cord, they innervate regions of the periphery and serve to relay information between the periphery and central nervous system. T10 innervates tissue around the level of the umbilicus, or navel. The C4 spinal nerve innervates the top of the shoulder, T4 innervates the level of the chest, T7 innervates slightly lower at the level of the xiphoid process, and L1 innervates the inguinal region around the groin.

When at rest, the neuron initially has a negative membrane potential. At the beginning of an action potential, voltage-gated sodium channels open, allowing sodium ions to enter the cell. This causes the cell to become positively charged compared to the outside of the cell. This process is called depolarization.

After depolarization occurs, the sodium channels close, initiating the absolute refractory period. Voltage-gated potassium channels then open and potassium ions exit the cell. This results in hyperpolarization and the relative refractory period. The potassium channels then close and the sodium-potassium pump returns the cell to its resting potential by removing sodium and collecting potassium.

The aorta has three crucial segments. The aortic arch is the beginning of the aorta, where it exits the left ventricle. Three blood vessels branch from the aortic arch: the brachiocephalic artery, the left subclavian artery, and the left common carotid artery. Around the T4 vertebra the aortic arch transitions into the thoracic aorta. The thoracic aorta has four major branches: the intercostal, bronchial, esophageal, and phrenic arteries. After the thoracic aorta, the vessel transitions into the abdominal aorta.

The vertebral arteries come off of the subclavian arteries, which branch off of the aortic arch (left) and brachiocephalic artery (right).

The arm has a few major veins that drain it. The brachial vein drains the deep portions of the arm, the basilic vein drains the medial superficial portion of the arm, and the cephalic vein drains the lateral superficial portion of the arm. The brachial and basilic veins join in the armpit (axilla) to form the axillary vein.

The vertebral arteries serve to supply blood to the posterior head. They also run into the skull and branch together into the basilar artery. This artery runs along the cerebellum and supplies it and the brain stem with oxygenated blood.

The recurrent branch of the median nerve innervates the lateral two lumbricals and the thenar muscles. Damage along any part of the median nerve will result in the "papal sign" when the patient is asked to make a fist.

The ulnar nerve divides into the deep and superficial branches when it terminates in the hand. The deep branch innervates the third and fourth lumbricals, while the superficial branch innervates the palmaris brevis. The radial nerve innervates several structures, including the biceps brachii and triceps brachii.

The two medial lumbricals are innervated by the deep branch of the ulnar nerve. The lateral two lumbricals are innervated by the digital branches of the median nerve.

The other answer choices show correct muscle-nerve pairings.

The palmar digital branches of the median nerve are responsible for cutaneous innervation of the palmar side of the thumb, index finger, middle finger and half of the ring finger.

The superficial branch of the ulnar nerve innervates the palmaris brevis, while the deep branch of the ulnar nerve innervates the third and fourth lumbricals. The radial nerve innervates several structures including the biceps and triceps brachii.

Compression of the radial nerve in the axilla due to poorly fitted crutches is also known as crutch palsy and causes the pins and needles described in the question.

The median and unlar nerves primarily serve to innervate the hand and wrist, while the musculocutaneous nerve is more involved with forearm movements at the elbow.

The skier likely compressed her superficial peroneal nerve which innervates the dorsum of the foot.

The superficial peroneal nerve wraps around the neck of the fibula and is a common site of compression when people cross their legs or wear high boots.

The plantar surface of the foot is innervated by the tibial nerve, which courses through the posterior leg. The lateral aspect of the foot is innervated by the sural nerve, which arises from the tibial nerve. The first dorsal web space of the foot is innervated by the deep peroneal nerve, which arises from the common peroneal nerve and runs in the anterior leg. The medial aspect of the leg is supplied by the saphenous nerve, which arises from the femoral nerve.

The lateral femoral cutaneous nerve supplies the lateral thigh and is highly visible during the anterior approach to the hip as it lies between the sartorius and the tensor fasciae latae. The lateral femoral cutaneous nerve is part of the lumbar plexus and arises from spinal root L2.

The medial leg is supplied by the saphenous nerve, which arises from the femoral nerve. The groin area is supplied by the ilioinguinal nerve, arising from L1. The anterior leg is innervated by the common peroneal and superficial peroneal nerves, arising from the sciatic nerve. The plantar surface of the foot is innervated by the tibial nerve, which courses through the posterior leg and also arises from the sciatic nerve.

Maxillary is a branch of the trigeminal nerve (V), and not of the facial nerve (VII).

The branches of the facial nerve, from superior to inferior, are: temporal, zygomatic, buccal, mandibular, and cervical.