A & P Chapter 11

Pectoralis major

Origin: Clavicular head, sternum and cartilage of ribs 2-6. Insertion: Humerus (greater tubercle) Action: Adducts and medially rotates arm. Clavicular head flexes arm, sternocostal head extends flexed arm to side of trunk.

Brachialis

Origin: Humerus Insertion: Ulna Action: flexes elbow

External oblique

Origin: Inferior 8 ribs Insertion: Iliac crest and linea alba Action: compress abdomen and flex and rotate

Latissimus dorsi

Origin: Inferior thoracic vertebrae, lumbar vertebrae, sacrum, ilium, inferior 4 ribs. Insertion: Intertubercular sulcus of humerus Action: Extends, adducts, medially rotates the arm.

Infraspinatus

Origin: Infraspinous fossa of scapula Insertion: greater tubercle of humerus Action: Laterally rotates and adducts arm at shoulder joint.

Extensor carp ulnaris

Origin: Lateral epicondyle of humerus and posterior border of ulna Insertion: Fifth metacarpal. Action: Extends and adducts hand at wrist joint.

Extensor digitorum

Origin: Lateral epicondyle of humerus. Insertion: Distal and middle phalanges of each finger. Action: Extends phalanges and hand.

Extensor carpi radialis longus

Origin: Lateral supracondylar ridge of humerus Insertion: Second metacarpal. Action: Extends and abducts hand at wrist joint.

Masseter

Origin: Maxilla and zygomatic arch. Insertion: Angle and ramus of mandible. Action: Elevates mandible to close mouth

Pronator teres

Origin: Medial epicondyle Insertion: Radius. Action: turns palm of hand down towards floor.

Flexor digitorum superficialis

Origin: Medial epicondyle of humerus and ulna and radius Insertion: Middle phalanx of each finger. Action: Flexes proximal and middle phalanx of each finger.

Flexor carpi radialis

Origin: Medial epicondyle of humerus. Insertion: Second and third metacarpals. ACtion: Flexes and abducts the hand.

Palmaris longus

Origin: Medial epicondyle of humerus. Insertion: Flexor retinaculum and palmar aponeurosis. Action: Weakly flexes hand at wrist joint.

Flexor carpi ulnaris

Origin: Medial epicondyle of humerus. Insertion: Pisiform, hamate, and base of 5th metacarpal. Action: Flexes and addutcs the hand.

Orbicularis oculi

Origin: Medial wall of orbit. Insertion: Circular path around orbit. Action: Closes eye.

Orbicularis oris

Origin: Mm fibers surrounding opening of mouth. Insertion: Skin at corners of mouth. Action: Closes and protrudes lips(puckers), compresses them against teeth, shapes lips for speech.

Trapezius

Origin: Occipital bone and 7th cervical and all thoracic vertebrae. Insertion: Clavicle, acromion, spine of scapula. Actions: Elevate scapula and head. Adduct scapula. Depress scapula. Rotate scapula.

Rectus Abdominis

Origin: Pubic crest and pubic symphysis. Insertion: Cartilage of 5th - 7th ribs and xiphoid process. Action: flexes and compresses abdomen.

Adductor brevis.

Origin: Pubis Insertion: Linea aspera

Gracilis

Origin: Pubis Insertion: Medial tibia

Adductor longus

Origin: Pubis Insertion: linea aspera

Pectineus

Origin: Pubus Action: adducts thigh

Biceps brachii

Origin: Scapula Insertion: Radial tuberosity Action: flexes at shoulder and elbow & supinates at radioulnar joint

Erector spinae

Origin: Several origins including iliac crest, ribs, vertebrae. Insertion: Several insertions including skull bones, vertebrae, ribs. Action: Chief extensor of v.c.. Unilateral flexion of v.c.

Sternocleidomastiod

Origin: Sternum and clavicle. Insertion: Mastoid process of skull Action: Flexes the cervical vertebrae and laterally flexes the neck and rotates face in opposite direction.

Temporalis

Origin: Temporal bone. Insertion: Mandible- coronoid process and ramus. Action: Elevates and retracts mandible.

Brachioradialis

Origin: humerus Insertion: Radius Action: flexes elbow

Triceps brachi

Origin: scapula & lateral heads from humerus. Insertion: Ulna. Action: Extends elbow & shoulder joints.

Adductor magnus

Origin:Pubis Insertion:

Antagonist

Relaxes and yields to prime mover

Bell's Palsy

Bell's palsy, also known as facial paralysis, is a unilateral paralysis of the muscles of facial expression. It is due to damage or disease of the facial (VII) nerve. Possible causes include inflammation of the facial nerve due to an ear infection, ear surgery that damages the facial nerve, or infection by the herpes simplex virus. The paralysis causes the entire side of the face to droop in severe cases. The person cannot wrinkle the forehead, close the eye, or pucker the lips on the affected side. Drooling and difficulty in swallowing also occur. Eighty percent of patients recover completely within a few weeks to a few months. For others, paralysis is permanent. The symptoms of Bell's palsy mimic those of a stroke.

Prime mover (agonist)

Contracts to cause the desired action

Synergists:

contract to stabilize nearby joints to prevent unwanted movement (extensors stabilize wrist during flexion of digits)

Origin

is the bone that does not move when muscle shortens (Normally Proximal)

Insertion

is usually the movable bone (usually distal)

3 muscles of hamstring

semimembranosus, semitendinosus, biceps femoris

Fixator

stabilizes the origin of the prime mover. ( scapula held steady so deltoid can raise arm)

Fascicles

A contraction muscle shortens to about 70% of its length. Fascicular arrangement represents a compromise b/w force power (force of contraction) and range of motion. Muscles w/ long fibers have a great range of motion. The greater the cross section, the greater the power. Pennation increases the cross section, and thus increases power.

Inguinal Hernia

A hernia (HER-nē-a) is a protrusion of an organ through a structure that normally contains it, which creates a lump that can be seen or felt through the skin's surface. The inguinal region is a weak area in the abdominal wall. It is often the site of an inguinal hernia, a rupture or separation of a portion of the inguinal area of the abdominal wall resulting in the protrusion of a part of the small intestine. A hernia is much more common in males than in females because the inguinal canals in males are larger to accommodate the spermatic cord and ilioinguinal nerve. Treatment of hernias most often involves surgery. The organ that protrudes is "tucked" back into the abdominal cavity and the defect in the abdominal muscles is repaired. In addition, a mesh is often applied to reinforce the area of weakness.

Pulled Hamstrings***

A strain or partial tear of the proximal hamstring muscles is referred to as pulled hamstrings or hamstring strains. Like pulled groins (see Exhibit 11.Q), they are common sports injuries in individuals who run very hard and/or are required to perform quick starts and stops. Sometimes the violent muscular exertion required to perform a feat tears away a part of the tendinous origins of the hamstrings, especially the biceps femoris, from the ischial tuberosity. This is usually accompanied by a contusion (bruising), tearing of some of the muscle fibers, and rupture of blood vessels, producing a hematoma (collection of blood) and sharp pain. Adequate training with good balance between the quadriceps femoris and hamstrings and stretching exercises before running or competing are important in preventing this injury.

Intramuscular (IM) injection

An injection that penetrates the skin and subcutaneous layer to enter a skeletal muscle. Common sites are the deltoid, gluteus medius, and vastus lateralis muscles.

Injury of Levator Ani and Urinary Stress Incontinence

During childbirth, the levator ani muscle supports the head of the fetus, and the muscle may be injured during a difficult childbirth or traumatized during an episiotomy (a cut made with surgical scissors to prevent or direct tearing of the perineum during the birth of a baby). The consequence of such injuries may be urinary stress incontinence, that is, the leakage of urine whenever intra-abdominal pressure is increased—for example, during coughing. One way to treat urinary stress incontinence is to strengthen and tighten the muscles that support the pelvic viscera. This is accomplished by Kegel exercises, the alternate contraction and relaxation of muscles of the pelvic floor. To find the correct muscles, the person imagines that she is urinating and then contracts the muscles as if stopping in midstream. The muscles should be held for a count of three, then relaxed for a count of three. This should be done 5-10 times each hour—sitting, standing, and lying down. Kegel exercises are also encouraged during pregnancy to strengthen the muscles for delivery.

Dysphagia

Dysphagia (dis-FĀ-jē-a; dys- = abnormal; -phagia = to eat) is a clinical term for difficulty in swallowing. Some individuals are unable to swallow while others have difficulty swallowing liquids, foods, or saliva. Causes include nervous system disorders that weaken or damage muscles of deglutition (stroke, Parkinson's disease, cerebral palsy); infections; cancer of the head, neck, or esophagus; and injuries to the head, neck, or chest.

Golfer's elbow

Golfer's elbow is a condition that can be caused by strain of the flexor muscles, especially the flexor carpi radialis, as a result of repetitive movements such as swinging a golf club. Strain can, however, be caused by many actions. Pianists, violinists, movers, weight lifters, bikers, and those who use computers are among those who may develop pain near the medial epicondyle (medial epicondylitis).

Impingement Syndrome***

One of the most common causes of shoulder pain and dysfunction in athletes is known as impingement syndrome, which is sometimes confused with another common complaint, compartment syndrome, discussed in Disorders: Homeostatic Imbalances at the end of this chapter. The repetitive movement of the arm over the head that is common in baseball, overhead racquet sports, lifting weights over the head, spiking a volleyball, and swimming puts these athletes at risk. Impingement syndrome may also be caused by a direct blow or stretch injury. Continual pinching of the supraspinatus tendon as a result of overhead motions causes it to become inflamed and results in pain. If movement is continued despite the pain, the tendon may degenerate near the attachment to the humerus and ultimately may tear away from the bone (rotator cuff injury). Treatment consists of resting the injured tendons, strengthening the shoulder through exercise, massage therapy, and surgery if the injury is particularly severe. During surgery, an inflamed bursa may be removed, bone may be trimmed, and/or the coracoacromial ligament may be detached. Torn rotator cuff tendons may be trimmed and then reattached with sutures, anchors, or surgical tacks. These steps make more space, thus relieving pressure and allowing the arm to move freely.

Deltoid:

Origin: Acromial end of clavicle, acromion, spine of scapula. Insertion: Deltoid tuberosity of the humerus. Action: Lateral fibers adduct. Posterior fibers extend arm.

Rotator cuff injury

Rotator cuff Refers to the tendons of four deep shoulder muscles (subscapularis, supraspinatus, infraspinatus, and teres minor) that form a complete circle around the shoulder; they strengthen and stabilize the shoulder joint. is a strain or tear in the rotator cuff muscles and is common among baseball pitchers, volleyball players, racquet sports players, and swimmers due to shoulder movements that involve vigorous circumduction. It also occurs as a result of wear and tear, aging, trauma, poor posture, improper lifting, and repetitive motions in certain jobs, such as placing items on a shelf above your head. Most often, there is tearing of the supraspinatus muscle tendon or the rotator cuff. This tendon is especially predisposed to wear and tear because of its location between the head of the humerus and acromion of the scapula, which compresses the tendon during shoulder movements. Poor posture and poor body mechanics also increase compression of the supraspinatus muscle tendon.

Shin Splint Syndrome ***

Shin splint syndrome, or simply shin splints, refers to pain or soreness along the tibia, specifically the medial, distal two-thirds. It may be caused by tendinitis of the anterior compartment muscles, especially the tibialis anterior muscle, inflammation of the periosteum (periostitis) around the tibia, or stress fractures of the tibia. The tendinitis usually occurs when poorly conditioned runners run on hard or banked surfaces with poorly supportive running shoes. The condition may also occur with vigorous activity of the legs following a period of relative inactivity or running in cold weather without proper warmup. The muscles in the anterior compartment (mainly the tibialis anterior) can be strengthened to balance the stronger posterior compartment muscles.

Strabismus

Strabismus (stra-BIZ-mus; strabismos = squinting) is a condition in which the two eyeballs are not properly aligned. This can be hereditary or it can be due to birth injuries, poor attachments of the muscles, problems with the brain's control center, or localized disease. Strabismus can be constant or intermittent. In strabismus, each eye sends an image to a different area of the brain and because the brain usually ignores the messages sent by one of the eyes, the ignored eye becomes weaker; hence "lazy eye," or amblyopia, develops. External strabismus results when a lesion in the oculomotor (III) nerve causes the eyeball to move laterally when at rest, and results in an inability to move the eyeball medially and inferiorly. A lesion in the abducens (VI) nerve results in internal strabismus, a condition in which the eyeball moves medially when at rest and cannot move laterally. Treatment options for strabismus depend on the specific type of problem and include surgery, visual therapy (retraining the brain's control center), and orthoptics (eye muscle training to straighten the eyes).

Carpal Tunnel Syndrome***

The carpal tunnel is a narrow passageway formed anteriorly by the flexor retinaculum and posteriorly by the carpal bones. Through this tunnel pass the median nerve, the most superficial structure, and the long flexor tendons for the digits (see Figure 11.18f). Structures within the carpal tunnel, especially the median nerve, are vulnerable to compression, and the resulting condition is called carpal tunnel syndrome. Compression of the median nerve leads to sensory changes over the lateral side of the hand and muscle weakness in the thenar eminence. This results in pain, numbness, and tingling of the fingers. The condition may be caused by inflammation of the digital tendon sheaths, fluid retention, excessive exercise, infection, trauma, and/or repetitive activities that involve flexion of the wrist, such as keyboarding, cutting hair, or playing the piano. Treatment may involve the use of nonsteroidal anti-inflammatory drugs (such as ibuprofen or aspirin), wearing a wrist splint, corticosteroid injections, or surgery to cut the flexor retinaculum and release pressure on the median nerve.

Groin Pull

The five major muscles of the inner thigh function to move the legs medially. This muscle group is important in activities such as sprinting, hurdling, and horseback riding. A rupture or tear of one or more of these muscles can cause a groin pull. Groin pulls most often occur during sprinting or twisting, or from kicking a solid, perhaps stationary object. Symptoms of a groin pull may be sudden or may not surface until the day after the injury; they include sharp pain in the inguinal region, swelling, bruising, or inability to contract the muscles. As with most strain injuries, treatment involves PRICE therapy, which stands for protection, rest, ice, compression, and elevation. After the injured part is protected from further damage, ice should be applied immediately, and the injured part should be elevated and rested. An elastic bandage should be applied, if possible, to compress the injured tissue.

Back Injuries and Heavy Lifting

The four factors associated with increased risk of back injury are amount of force, repetition, posture, and stress applied to the backbone. Poor physical condition, poor posture, lack of exercise, and excessive body weight contribute to the number and severity of sprains and strains. Back pain caused by a muscle strain or ligament sprain will normally heal within a short time and may never cause further problems. However, if ligaments and muscles are weak, discs in the lower back can become weakened and may herniate (rupture) with excessive lifting or a sudden fall, causing considerable pain. Full flexion at the waist, as in touching your toes, overstretches the erector spinae muscles. Muscles that are overstretched cannot contract effectively. Straightening up from such a position is therefore initiated by the hamstring muscles on the back of the thigh and the gluteus maximus muscles of the buttocks. The erector spinae muscles join in as the degree of flexion decreases. Improperly lifting a heavy weight, however, can strain the erector spinae muscles. The result can be painful muscle spasms, tearing of tendons and ligaments of the lower back, and herniating of intervertebral discs. The lumbar muscles are adapted for maintaining posture, not for lifting. This is why it is important to bend at the knees and use the powerful extensor muscles of the thighs and buttocks while lifting a heavy load.

Intubation during Anesthesia

When general anesthesia is administered during surgery, a total relaxation of the muscles results. Once the various types of drugs for anesthesia have been given (especially the paralytic agents), the patient's airway must be protected and the lungs ventilated because the muscles involved with respiration are among those paralyzed. Paralysis of the genioglossus muscle causes the tongue to fall posteriorly, which may obstruct the airway to the lungs. To avoid this, the mandible is either manually thrust forward and held in place (known as the "sniffing position"), or a tube is inserted from the lips through the laryngopharynx (inferior portion of the throat) into the trachea (endotracheal intubation). People can also be intubated nasally (through the nose).