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The musculoskeletal system of the human being

One of the acute effects in muscle during resistance training is the depletion of metabolic substrates, such as creatine phosphate and glycogen. The depletion of those two fuel sources during resistance training causes muscle power production to decrease. Another significant the musculoskeletal system of the human being muscle adaptation during… The muscle groups and their actions The following sections provide a basic framework for the understanding of gross human muscular anatomy, with descriptions of the large muscle groups and their actions.

The various muscle groups work in a coordinated fashion to control the movements of the human body. The neck The motion of the neck is described in terms of rotation, flexion, extension, and side bending i. The direction of the action can be ipsilateral, which refers to movement in the direction of the contracting muscle, or contralateral, which refers to movement away from the side of the contracting muscle.

Muscles of the neck. Rotation is one of the most-important actions of the cervical neck spine. Rotation is accomplished primarily by the sternocleidomastoid muscle, which bends the neck to the ipsilateral side and rotates the neck contralaterally. Together, the sternocleidomastoid muscles on both sides of the neck act to flex the neck and raise the sternum to assist in forced inhalation. The anterior and middle scalene muscles, which also are located at the sides of the neck, act ipsilaterally to rotate the neck, as well as to elevate the first rib.

The splenius capitis and splenius cervicis, which are located in the back of the neck, work to rotate the head.

Side bending also is an important action of the cervical spine. The sternocleidomastoid muscles are involved in cervical side bending. The posterior scalene muscles, located on the lower sides of the neck, ipsilaterally bend the neck to the side and elevate the second rib.

Human muscle system

The splenius capitis and splenius cervicis also assist in neck side bending. The erector spinae muscles iliocostalis, longissimus, and spinalis are large, deep muscles that extend the length of the back.

All three act to ipsilaterally side bend the neck. Neck flexion refers to the motion used to touch the chin to the chest. It is accomplished primarily by the sternocleidomastoid muscles, with assistance from the longus colli and the longus capitis, which are found in the front of the neck. Neck extension is the opposite of flexion and is accomplished by many of the same muscles that are used for other neck movements, including the splenius cervicis, splenius capitis, iliocostalis, longissimus, and spinalis muscles.

The back The back contains the origins of many of the muscles that are involved in the movement of the neck and shoulders. In addition, the axial skeleton that runs vertically through the back protects the spinal cordwhich innervates almost all the muscles in the body. Muscles of the back. The erector spinae muscles, for example, extend the back bend it backward and side bend the back. The semispinalis dorsi and semispinalis capitis muscles also extend the back.

  • They are usually found in regions near the agonist and often connect to the same bones;
  • The oxygen from myoglobin allows muscles to continue aerobic respiration in the absence of oxygen;
  • Muscles of the forearm posterior view.

The small muscles of the vertebrae the multifidi and rotators help rotate, extend, and side bend the back. The quadratus lumborum muscle in the lower back side bends the lumbar spine and aids in the inspiration of air through its stabilizing affects at its insertion at the 12th rib the last of the floating ribs. The scapula shoulder blade is elevated by the trapezius musclewhich runs from the back of the neck to the middle of the back, the musculoskeletal system of the human being the rhomboid major and rhomboid minor muscles in the upper back, and by the levator scapulae muscle, which runs along the side and back of the neck.

The shoulder The shoulder is a complex ball-and-socket joint comprising the head of the humerusthe clavicle collarboneand the scapula. Muscles of the shoulder. Shoulder flexion is movement of the shoulder in a forward motion. An example of shoulder flexion can be seen when reaching forward to grasp an object. That action is accomplished primarily by the combined actions of the deltoid muscle in the uppermost extent of the arm, the pectoralis major muscle in the chest, the coracobrachialis muscle on the inside of the upper arm, and the biceps brachii muscles on the front of the upper arm.

Extension of the shoulder is opposite to flexion. Pure shoulder extension is the movement of the arm directly behind the body, as in receiving a baton in a relay race. That movement is accomplished by the actions of the deltoid muscle, the latissimus dorsi muscle in the back, the teres major muscle in the armpit area, the musculoskeletal system of the human being the triceps muscle in the back of the upper arm.

The triceps, as the name suggests, consists of three heads that originate from different surfaces but share the same insertion at the olecranon process of the ulna a bone in the forearm ; the three heads together act to extend the elbow. Shoulder adduction and abduction serve to lower the arm toward and lift the arm away from the body, respectively. They can be visualized by picturing someone doing jumping jacks. Adduction is accomplished primarily by the pectoralis major, latissimus dorsi, teres major, triceps, and coracobrachialis.

The deltoid and the supraspinatus, a muscle that runs along the scapula in the back, are the two main abductors of the shoulder. An example of external rotation of the shoulder is seen in a tennis backhand stroke.

External rotation is attributed primarily to the deltoid, the teres minor in the armpit area, and the infraspinatus muscle, which covers the scapula. Internal rotation of the shoulder is the opposite of external rotation.

An example is the shoulder movement that occurs when reaching into a back pocket.

What are the main functions of the muscular system?

That movement is achieved through the coordinated action of the pectoralis major, latissimus dorsi, deltoid, teres major, and subscapularis muscles. The subscapularis is a deep muscle situated on the anterior, or front-facing, surface of the scapula.

The teres minor, subscapularis, supraspinatus, and infraspinatus muscles together form the rotator cuff, which stabilizes the humeral head the ball portion of the ball-and-socket shoulder joint.

The muscles of the rotator cuff are common sites of injury in adults, particularly among people who perform overhead motions repeatedly e. Several of the rotator cuff muscles have tendons that run under the acromion, a bony prominence at the distal end of the scapula. The term distal describes a relative position away from the centre of the body; it often is contrasted with the term proximal, which describes a relative position near to the centre of the body.

Muscular System

The position of the tendons and of the subacromial bursae fluid-filled sacs located beneath the acromion leaves them vulnerable to compression and pinching, which can result in an injury known as shoulder impingement syndrome.

The arm In addition to aiding the movement of the shoulder, the muscles of the upper arm produce various movements of the forearm. For example, the primary muscles involved in forearm flexion, in which the angle formed at the elbow becomes smaller i.

  • When a motor neuron receives a signal from the brain, it stimulates all of the muscles cells in its motor unit at the same time;
  • Muscles continue contraction as long as they are stimulated by a neurotransmitter;
  • Intrinsic muscles of the foot arise in the foot and do not cross the ankle joint;
  • The diaphragm causes our lungs to expand and contract when we breathe;
  • The skull The skull consists of many different bones.

Minor contributions to forearm flexion are provided by the coracobrachialis and by flexor muscles situated in the anterior compartment of the forearm the palm side of the forearm; also known as the flexor compartmentincluding the pronator teres, the flexor carpi radialis, the flexor digitorum superficialis, the palmaris longus, and the flexor carpi ulnaris.

Muscles of the upper arm. Muscles of the human forearm anterior view, superficial layer. Extension of the forearm increases the angle at the elbow, moving the hand away from the shoulder.

That action is accomplished primarily by the triceps brachii. Other muscles that make minor contributions to forearm extension include the extensor muscles of the posterior compartment of the forearm the side of the forearm that is contiguous with the back of the hand; also known as the extensor compartmentincluding the extensor carpi radialis longus, the extensor carpi radialis brevis, the extensor digitorum, the extensor carpi ulnaris, and the anconeus.

The wrist Wrist flexion refers to movement of the wrist that draws the palm of the hand downward. That action is carried out by the flexor carpi radialis, the flexor carpi ulnaris, the flexor digitorum superficialis, the flexor digitorum profundus, and the flexor pollicis longus. Muscles of the forearm posterior view.

Wrist extension, by contrast, shortens the angle at the back of the wrist. The muscles responsible for that action are the extensor carpi radialis longus and the extensor carpi radialis brevis, which also abduct the hand at the wrist move the hand in the direction of the thumb, or first digit ; the extensor digitorum, which also extends the index to little finger the second to fifth digits ; the extensor digiti minimi, which also extends the little finger and adducts the hand moves the hand in the direction of the little finger ; and the extensor carpi ulnaris, which also adducts the hand.

Other small muscles that cross the wrist joint may add to wrist extension, but they do so to only a small degree. Wrist supination is the rotation of the wrist that brings the palm facing up. The supinator muscle in the posterior compartment acts to supinate the forearm. The biceps brachii also adds to supination. Pronation is the musculoskeletal system of the human being opposing action, in which the wrist is rotated so that the palm is facing down.

The pronator quadratus, a deep muscle in the anterior compartment, along with the pronator teres, pronates the forearm. The hand The hand is a complex structure that is involved in fine motor coordination and complex task performance. Its muscles generally are small and extensively innervated. Even simple actions, such as typing on a keyboard, require a multitude of precise movements to be carried out by the hand muscles. Because of that complexity, the following paragraphs cover only the primary action of each hand muscle.

Several muscles that originate at the posterior surface of the ulna or the radius the other bone in the forearm have their actions in the hand. Those include the abductor pollicis longus, which abducts and extends the thumb; the extensor pollicis brevis, which extends the metacarpophalangeal MCP joint of the thumb; the extensor pollicis, which extends the distal phalanx finger bone of the thumb; and the extensor indicis, which extends the index finger at the MCP joint.

MCP joints are located between the metacarpal bones, which are situated in the hand, and the phalanges, which are the small bones of the fingers. Although several of the muscles that move the hand have their origins in the forearm, there are the musculoskeletal system of the human being small muscles of the hand that have both their origin and their insertion within the hand.

Those are referred to as the intrinsic muscles of the hand. They include the palmaris brevis, which assists with grip; the umbricals, which flex the MCP joints and extend the interphalangeal joints IPs; the joints between the phalanges of the fingers; the palmar interossei, which adduct the fingers toward the middle finger the third digit ; and the dorsal interossei, which abduct the fingers away from the middle finger.

About the Muscular and Skeletal Systems

The thenar eminence is located on the palm side of the base of the thumb and is composed of three muscles, the abductor pollicis brevis, the flexor pollicis brevis, and the opponens pollicis, all of which are innervated by the median nerve.

The abductor pollicis brevis abducts the thumb; the flexor pollicis brevis flexes the MCP joint of the thumb; and the opponens pollicis acts to oppose the thumb to the other fingers. The adductor pollicis, which is not part of the thenar eminence, acts to adduct the thumb. The hypothenar enimence is located on the palm side of the hand below the little finger.

It contains three muscles that are innervated by the deep branch of the ulnar nerve. The abductor digiti minimi abducts the little finger. The flexor digiti minimi flexes the little finger. The opponens digiti minimi opposes the little finger with the thumb. The abdomen There are three muscular layers of the abdominal wall, with a fourth layer in the middle anterior region.

The fourth layer in the midregion is the rectus abdominis, which has vertically running muscle fibres that flex the trunk and stabilize the pelvis. To either side of the rectus abdominis are the other three layers of abdominal muscles. The deepest of those layers is the transversus abdominis, which has fibres that run perpendicular to the rectus abdominus; the transversus abdominis acts to compress and support the abdomen and provides static core stabilization.

The internal oblique layers run upward and forward from the sides of the abdomen, and the external oblique layers, which form the outermost muscle layers of the abdomen, run downward and forward.

The musculoskeletal system

Muscles of the abdominal wall. The hip The hip joint is a complex weight-bearing ball-and-socket joint that can sustain considerable load. The socket of the joint is relatively deep, allowing for stability but sacrificing some degree in range of motion. The movements described in this section include flexion, extension, abduction, and adduction.