Ulnar nerve innervates which muscles

Infants can also sustain brachial plexus injuries during childbirth. Some information about each of the roots:. The second level of the brachial plexus consists of three "trunks.

As the three trunks continue toward the shoulder, they each divide into two nerves called an "anterior division" and a "posterior division. The third level of the brachial plexus is called "divisions. The divisions then reorganize to create three new nerves, called "cords. The nerves in the fourth level of the brachial plexus are called "cords" and come from the "divisions" in level three.

The three cords are named lateral, posterior, and medial based on their position in relationship to the brachial artery. Many important nerves come from the cords. Some of these nerves produce motion around the shoulder. Others travel on to become the five main "branches" of the brachial plexus. The fifth and final level of the brachial plexus are the five nerves that feed the shoulder and arm called "branches. Musculocutaneous nerve The musculocutaneous nerve is formed from the C5, C6, and C7 nerve roots of the brachial plexus.

Axillary nerve The axillary nerve is formed from the C5 and C6 nerve roots of the brachial plexus. Brachial plexus The brachial plexus is a group of nerves that control the muscles of the shoulder, arm, forearm, and hand.

Roots The brachial plexus is a group of nerves that control the muscles of the shoulder, arm, forearm and hand. Some information about each of the roots: C5 is the nerve "root" that exits the spinal cord above the fifth vertebra in the neck. It travels into the brachial plexus and eventually becomes the nerves that feed muscles around the shoulder and chest.

It also provides sensation to parts of the upper arm. C6 is the nerve "root" that exits the spinal cord above the sixth vertebra in the neck. It travels into the brachial plexus and eventually becomes the nerves that feed muscles that bend the elbow and straighten the wrist. It also provides sensation to parts of the thumb side of the forearm and hand. C7 is the nerve "root" that exits the spinal cord above the seventh vertebra in the neck.

It travels into the brachial plexus and eventually becomes the nerves that feed muscles that straighten the elbow, bend the wrist, and straighten the fingers. It also provides sensation around the middle finger in the hand. C8 is the nerve "root" that exits the spinal cord below the seventh vertebra in the neck.

It travels into the brachial plexus and eventually becomes the nerves that feed muscles in the hand and muscles that bend the fingers. It also provides sensation on the small finger side of the hand and forearm. T1 is the lowest nerve "root" that becomes part of the brachial plexus. It exits the spinal cord below the first vertebra in the thoracic spine. It eventually becomes the nerves that feed muscles in the hand.

It also provides sensation around the inside of the elbow and upper arm. Metrics details. This study aims to investigate and compare the conduction parameters of nerve bundles in the ulnar nerve that innervates the forearm muscles and hand muscles; routine electromyography study merely evaluates the nerve segment of distal hand muscles. An electrophysiological evaluation, consisting of velocities, amplitudes, and durations of ulnar nerve bundles to 2 forearm muscles and the hypothenar muscles was performed on the same humeral segment.

The velocities and durations of the compound muscle action potential CMAP of the ulnar nerve bundle to the proximal muscles were greater than to distal muscles, but the amplitudes were smaller. Bundles in the ulnar nerve of proximal muscles have larger neuronal bodies and thicker nerve fibers than those in the same nerve in distal muscles, and their conduction velocities are higher.

The CMAPs of proximal muscles also have smaller amplitudes and greater durations. These findings can be attributed to the desynchronization that is caused by a wider range of distribution in nerve fiber diameters. Conduction parameters of nerve fibers with different diameters in the same peripheral nerve can be estimated.

Peer Review reports. Peripheral motor nerve diameter decreases gradually after emerging from the spinal cord toward the target muscles.

In a myelinated nerve fiber, the thickness of the fiber correlates positively with nerve conduction velocity; conduction velocity declines when a fiber's diameter decreases[ 1 ]. Nerve diameter is proportional to the size of the motor nerve body in the anterior horn [ 1 ]. Nerve diameter thickness and conduction velocity correlate with nerve body size. Proximal muscles with bigger masses are innervated by thicker fibers [ 2 — 5 ].

In addition to the sciatic nerve [ 4 , 6 ], the nerve velocities in the ulnar nerve can be recorded and calculated separately between the proximal and distal muscles of the upper extremities. Thus, one can differentiate between the fastest conductive fibers that innervate the proximal and distal muscles electrophysiologically.

In this study, we examined the nerve conduction velocities, compound muscle action potential CMAP amplitudes, and duration of 2 proximally positioned forearm muscles that have greater mass and hypothenar muscles that are distally positioned with smaller mass.

All patients gave informed consent. The patients were included after undergoing a routine electrophysiological protocol to exclude polyneuropathy and any neuropathy. The study was performed in the right upper extremity in all normative subjects 30 subjects: 6 men, 24 women. The subject was lain down. The right arm was positioned degrees to the body, and the forearm lay 90 degrees to the arm; this position was maintained throughout the study.

Ulnar nerve stimuli in the arm segment: A point, 5 cm proximal to the medial epicondyle, was selected as the distal stimulus point. A point, 12 cm proximal to the distal point in the axillary region, was the proximal stimulus point. Ulnar nerve stimuli in the forearm segment: A point, 5 cm distal to the medial epicondyle, was chosen as the proximal stimulus point.

A point, 5 cm proximal to the distal wrist line, served as the distal stimulus point. The supramaximal level of the stimulus intensity was increased slowly until a point was reached at which the CMAP amplitude no longer increased. A-Recording from the flexor carpi ulnaris muscle FCU : The active disc electrode silver, 10 mm in diameter was positioned at a point 2 digits wide from the ulna, where the proximal third and medial third sections of the forearm met.

The reference electrode was positioned on the ulna, transverse to the active electrode [ 7 , 8 ]. The active bar electrode was positioned at the midpoint between the wrist distal line and the metacarpophalangeal joint [ 8 ]. The reference bar electrode was positioned on the metacarpophalangeal joint, a more distal position. After the subject lay down and the right upper extremity was positioned as discussed, the FCU, FDP, and HYT muscles were recorded alternatively by stimulating the arm segment separately for each recording.

Then, a recording of the HYT muscle was made by stimulating the forearm. Thus, nerve conduction velocities and CMAP amplitude and duration were measured in the 3 responses from 3 different muscles in the arm and hand. Amplitude was measured from onset to the negative peak, and duration was measured from the onset of the first negative deflection to the last point at which the potential returned to baseline.

Latency was measured from the stimulus artefact to the onset of negative deflection. Kolmogorov-Smirnov test was performed for the appropriateness of data distribution to the normal distribution. Because all data were distributed normally, we used t-test in paired groups and Bonferroni correction for data comparisons and Pearson's correlation analysis to determine the correlation between the data.

SPSS v. These velocities were also compared with that obtained of the HYP area after stimulation of the forearm segment. The comparison of these velocities are shown in Table 1.

In the CMAP evaluation, comparisons were made by calculating the average CMAP amplitudes, obtained after proximal and distal stimulation of each muscle.

These comparisons are shown in Table 2. We compared the average CMAP duration after proximal and distal stimulation. This comparison is shown in Table 3. The correlation between the 4 groups of velocities, amplitudes, and durations is shown in Table 4. A strong negative correlation from arm to forearm changes was observed between velocity and amplitude and between amplitude and duration. In addition, velocity and duration had a strong positive correlation.

In studies in the hind limb of rats [ 4 ] and lower extremities in humans [ 6 ], n. Cullheim [ 1 ] has shown that motor neuron size in the anterior horn correlates positively with intramedullary axon diameter and axon conduction velocity and that the correlation between the first axon segment and axon conduction velocity is the most powerful one. In their study on the hind limb in mouse, McHanwell and Biscoe [ 3 ] examined motor neuron body areas and showed that body areas of the nerves that travel to proximally positioned femoral muscles are larger than those of distally positioned crucial muscles.

The histograms of body area of proximally positioned muscles are bimodal, and those of the distal foot muscles are unimodal. A man with penile swelling. A man with blood in his urine. PSA Question Bank. Medical Student Finals Question Bank. ABG Quiz. Reading Nerve Supply to the Upper Limb. Share Tweet. Last updated: October 22, Nerve Supply to the Upper Limb. Suggest an improvement. You don't need to tell us which article this feedback relates to, as we automatically capture that information for you.

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This field is for validation purposes and should be left unchanged. Introduction The nerve supply to the upper limb is an important and complex topic which will inevitably appear in anatomy questions, clinical case scenarios and OSCEs.

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Clinical features: Musculocutaneous nerve palsy Clinical features of musculocutaneous nerve palsy include: Sensory loss : numbness over lateral forearm Motor deficit : paralysis of anterior compartment of arm with very weak elbow flexion and weak forearm supination. Absent biceps reflex. Deformity : wasting of the anterior compartment of the arm.

The elbow usually held in extension with forearm pronated. Paralysis of teres minor leading to weak shoulder external rotation. Deformity : wasting of deltoid muscle , making the bones of the shoulder joint very prominent and obvious. The shoulder may appear adducted and internally rotated. In the classical description of a radial nerve injury, the forearm is also pronated, the fingers are flexed, and the thumb adducted.

There may also be wasting of triceps and posterior compartment of forearm. Figure 2. The patient cannot extend their wrist or fingers. Clinical features: Median nerve palsy Clinical features of median nerve palsy include: Sensory loss : numbness of skin over thenar eminence and median distribution of hand.

However, in carpal tunnel syndrome, sensation to the palm is usually preserved due to an intact palmar cutaneous branch. Motor deficit : Paralysis of most of anterior compartment of forearm: weak forearm pronation, wrist flexion and abduction, and weak finger flexion with preservation of DIPJ flexion at ring and little fingers.

Paralysis of thenar eminence: weak pincer grip and overall grip strength, weak thumb opposition. They cannot make a fist with all of their fingers. Wasting of anterior compartment of forearm and thenar eminence Figure 3.

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