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Anatomy of the left arm (from glenohumeral joint to the metacarpals and phalanges) Essay Example

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1ANATOMY OF THE LEFT ARM

Anatomy of the Left Arm

Anatomy of the Left Arm

The muscular anatomy of the forearm, and thus the left arm, are grouped into two categories. The two categories include extensor and flexor muscles and these are separated by the interosseous membrane. The flexor category of muscles is divided into three groups while the posterior group is divided into two groups. All the muscles in the flexor category, besides the one found on the thumb, start off from the medial epicondyle. The epicondyle is the common flexor region. The other group, the superficial group, only flexes the wrist and they consist of the flexor carpi radialis, Palmaris longus, and the flexor carpi ulnaris. The flexor carpi radialis is supplied by the median nerve and it acts on flexing the wrist as well as to radial deviate the hand. The Palmaris longus is controlled by the median nerve and acts to flex the wrist. On the other hand, the flexor carpi ulnaris is served by the ulnar nerve and acts to flexes the wrist and ulnar deviate the hand (Hattersley, 2014).

It is important to note that all the muscles, apart from the muscle that links to the thumb, start off from the medial epicondyle which is the common flexor origin. The intermediate group serves to flex the proximal interphalangeal joint. The flexor digitorum superficialis muscles, belonging to the intermediate group, are served by the median nerve and act to flex the fingers at the proximal interphalangeal joint. The other group of muscles is the deep group, which serve to flex the distal interphalangeal joint. They consist of the flexor digitorum profundus that are served by the median nerve and act to flex the fingers at the distal interphalangeal joint, as well as the flexor pollicis longus that are served by the median nerve and act to flex the thumb at the interphalangeal joint (Hattersley, 2014).

Anatomy of the left arm (from glenohumeral joint to the metacarpals and phalanges)

Source: Hattersley (2014)

The other major group of muscles in the forearm is the extensor group. Similar to the flexor group of muscles, the flexor muscles mainly start off from an epycondyle. However, they originate from the lateral epicondyle, which is the general extensor origin, but unlike the flexor muscles group, the extensor muscles only consist of two layers (Hattersley, 2014).

Anatomy of the left arm (from glenohumeral joint to the metacarpals and phalanges) 1

Source: Hattersley (2014)

A number of distinctions can be made between the superficial group and the deep group of muscles. First, the anconeneus muscles, which belong to the superficial group, serve to extend the elbow while the supinator muscles, belonging to the deep group of muscles, serve to supinate the forearm. The extensor carpi radialis longus, belonging to the superficial group, serve to extend and radially deviates the hand, while the abductor pollicis longus, which fall under the deep group, serve to abduct the thumb. Thirdly, the extensor carpi ulnaris, which fall under the superficial group of muscles, serve to extend as well as ulnar deviate the hand. On the other hand, the extensor pollicis longus, belonging to the deep group of muscles, serve to extend the thumb. The extensor digiti minimi, which falls under the superficial group, serve to extend the little finger, while the extensor pollicis brevis of the deep group serve to extend the thumb. Lastly, the nextensor digitorum of the superficial group extends all the fingers, while the extensor indicis of the deep group serve to extend the index finger. It is worthwhile to note that all these muscles are served by the radial nerve, apart from those with ‘ulnaris’ (Gest & Schlesinger, 1995).

There are four main nerves that supply the arm, regardless of whether it is the left arm or the right arm. These include the musculocutaneous, median, radial, and ulnar nerves. The musculocutaneous nerve is responsible for supplying all the anterior sections of the arm and the sensory innervations to the lateral forearm. The median nerve passes through the anterior section of the arm ans lies anterior to the elbow next to the branchial artery. The ilnar nerve passes through the posterior section of the am and lies behind the medial epicondyle at the elbow. The radial nerve is responsible for supplying all posterior or anterior sections of the forearm and arm (Na, 2007). The figure below provides a clear picture of how these nerves supply the arm.
Anatomy of the left arm (from glenohumeral joint to the metacarpals and phalanges) 2

Source: Hattersley (2014)

It is important to understand the anatomical knowledge of the arm in the medical field for several reasons. To begin with, understanding the anatomy of the arm is important in the medical field because it helps to learn about how the body works and enhances proficiency in the medical practice. This is important especially when it comes to providing quality patient care and staying current with medical research and career advancement. Secondly, an understanding of the anatomy of the arm is vital especially for doctors and surgeons who work in medical specialties like paramedics, radiology, orthopedics, and histopathology. In a general sense, an understanding of the anatomy of the arm is essential for any medical practitioner.

One of the injuries to the arm that can be visible to a paramedic is a dislocation of the elbow. A dislocation of the elbow often occurs when an individual falls on an outstretched arm. When the arm hits a hard surface during a fall, the force is relayed to the elbow. Normally, there is a twisting motion in the force and it can rotate or drive the elbow to come out of its socket. A dislocation of the elbow can also occur in car accidents when a passenger reaches forward to try to cushion the impact of the car crash (Hattersley, 2014).

There are two types of dislocations. These include simple dislocations and complex dislocations. Simple dislocations do not cause major bone injuries. On the other hand, complex dislocations can cause severe injuries to the bones and ligaments. Furthermore, severe dislocations result in injury to the nerves and blood vessels that run through the elbow. This poses a great risk of losing an arm. However, it is important to note that some individuals are born with more looseness or laxity in the ligaments. Such individuals stand a greater risk of elbow dislocations. Similarly, some individuals are born with an ulna that has a shallow groove at the elbow hinge section. These individuals stand a slightly greater risk of dislocation. Fortunately, these defects can be rectified with surgery (Hattersley, 2014).
Anatomy of the left arm (from glenohumeral joint to the metacarpals and phalanges) 3

Source: Hattersley (2014)

References

Gest, T. R. & Schlesinger, J. (1995) MedCharts Anatomy. New York: ILOC.

Hattersley, L. (2014) Elbow Wrist and Hand. Anatomy, Movements, Dysfunctions, Manipulations.Availableat:http://www.anatomy4beginners.com/resources/Elbow%2C%20wrist%20and%20hand.pdf

Na. (2007) Functional Anatomy of the Upper Extremity Chapter 5. Available at: http://downloads.lww.com/wolterskluwer_vitalstream_com/sample-content/9780781791281_Hamill/samples/Hamill_ch05_137-186.pdf