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MUSCULOSKELETAL SYSTEM ANATOMY AND PHYSIOLOGY REVIEW

The ⚡ musculoskeletal system ⚡ consists of bones, joints, ligaments, muscles, and tendons. The skeleton gives shape to the body, provides physical support and protection for the organs, stores minerals, is responsible for blood cell formation, and provides sites for muscle attachment. The action of muscles holds the skeleton upright and creates physical movement of the body. First figure depicts the bones of the skeleton. Next figures illustrate the major muscles of the body. Any disease or disorder of this system greatly affects activities of daily living.

Skeleton

FIGURE. Skeleton (anterior view)

The skeletal system consists of bones formed from osseous tissue that provide structure and function to the overall body. Also included in the skeletal system is the cartilage that forms the joints between bones and the ligaments that hold bones together at the joints. Bones can be subdivided into long bones (arms, legs, hands, and feet), short bones (wrist, ankles, and knee caps), flat bones (ribs, sternum, shoulder blades, hip bones, and cranial bones), and irregular bones (vertebrae and facial bones).

Anterior view of muscles

FIGURE. Anterior view of muscles

The adult skeletal system has two divisions: the axial skeletal system and the appendicular skeletal system. The axial skeleton is the center portion of the body and includes the bones of the skull, hyoid bone, bones of the middle ear, vertebral column, and rib cage. The appendicular skeleton is composed of the bones of the appendages or limbs and includes the bones of the arms and legs, the shoulders, and the pelvic girdle.

Posterior view of muscles

FIGURE. Posterior view of muscles

There are two types of bone: compact and spongy. Compact bone is the dense, hard tissue found in the shafts of long bones. Yellow marrow, which is composed of fat, is stored in these bones. Spongy bone, or cancellous bone, is less dense and is found at the ends of long bones and in the other bones of the body.

The muscular system holds the body upright and moves the skeletal system. Muscles have specialized cells for contraction wherein they shorten and pull a bone to produce movement. Muscle movement creates heat that helps to regulate body temperature.

There are three types of muscles:

  1. Skeletal muscle is also called voluntary muscle because it is attached to the skeleton and its movement is consciously controlled. The cells of this type of muscle are elongated and have the ability to stretch and return to their previous shape.
  2. Smooth muscle is also called involuntary or visceral muscle because it is found in the walls of organs and its function is not consciously controlled. This type of muscle has shorter cells with tapered ends and cannot stretch as much as skeletal muscle.
  3. Cardiac muscle is found only in the heart. This muscle is a combination of skeletal and smooth muscle. It is involuntarily controlled but has the ability to contract.

Video: Anatomy and Physiology of Skeletal System

Video: Anatomy and Physiology of Muscular System

The musculoskeletal system review

Key terms

Term Meaning
Musculoskeletal system The body system that provides support, stability, shape, and movement to the body
Joint The point at which two (or more) bones meet.
Cartilage Soft connective tissue found between joints
Ligaments Connective tissue that attaches bone to bone at a joint
Tendons Connective tissue that attaches muscle to bone
Voluntary muscle Muscle that can be consciously controlled
Involuntary muscle Muscle that is controlled by the autonomic nervous system (not consciously controlled)
Striated muscle Muscle tissue that has a striped appearance due to its fiber composition

The musculoskeletal system

In the musculoskeletal system, the muscular and skeletal systems work together to support and move the body.

The bones of the skeletal system serve to protect the body’s organs, support the weight of the body, and give the body shape. The muscles of the muscular system attach to these bones, pulling on them to allow for movement of the body.

The human skeleton

The human skeleton performs several major functions. It protects the internal organs, supports and gives shape to the body and allows for movement. It also is the site of blood cell production, which occurs in the marrow of some bones.

The skeleton

The human skeleton is divided into two parts: the axial skeleton and the appendicular skeleton.

Diagram labeling the axial and appendicular skeletons of the human body

The axial skeleton consists of:

  • the skull, which protects the brain and supports facial structure
  • the vertebral column (spine), which surrounds and protects the spinal cord and support the head
  • the thoracic (rib) cage), which surrounds and protects the organs within the chest (including heart and lungs)

The appendicular skeleton consists of:

  • the pectoral girdle (shoulders)
  • upper and lower limbs (arms and legs)
  • the pelvic girdle (hip bones) and lower limbs (legs)

Joints, cartilage, ligaments, and tendons

Diagram of a synovial joint, illustrating the various connective tissues (tendons, ligaments, cartilage)

The musculoskeletal system also contains connective structures and tissues that support the body and allow for its movement.

Cartilage acts as a shock absorber to reduce friction. Ligaments help stabilize the joint, keeping it from moving outside of its intended range of motion. Tendons connect the skeletal system to the muscular system by attaching muscle to bone. When muscle contracts, the tendon acts on the bone, causing movement.

Comparison of three types of joints: suture joints in the skull (fixed), cartilaginous vertebral discs (slightly movable), and a synovial joint (freely movable): (a) Suture joint – fixed; (b) Vertebral discs – slightly movable; (c) Synovial joint – freely movable. Image from OpenStax, CC BY 4.0

Joints, the point at which two or more bones connect, can be fixed, slightly movable, or freely movable.

Muscles

The body contains three types of muscle tissue: skeletal muscle, smooth muscle, and cardiac muscle.

Comparison of the three types of muscle – skeletal, smooth, and cardiac: (a) Skeletal muscle; (b) Smooth muscle; (c) Cardiac muscle.

Skeletal muscle is voluntary and striated. These are the muscles that attach to bones and control conscious movement. Smooth muscle is involuntary and non-striated. It is found in the hollow organs of the body, such as the stomach, intestines, and around blood vessels. Cardiac muscle is involuntary and striated. It is found only in the heart and is specialized to help pump blood throughout the body.

Muscle contraction

When a muscle fiber receives a signal from the nervous system, myosin filaments are stimulated, pulling actin filaments closer together. This shortens sarcomeres within a fiber, causing it to contract.

Musculoskeletal System

Introduction

The musculoskeletal system is composed of two systems – the muscular system and the skeletal system – but is commonly referred to as ‘musculoskeletal’ because of the main common functions of the said two systems, which are, movement and support.

The musculoskeletal system is made up of hard and soft tissues. The hard tissue includes bones and cartilages (articular cartilages), while the soft tissues are the muscles, tendons, synovial membranes, joints capsule and ligaments.

Primarily, the roles of the musculoskeletal system are movement and support, but the system also performs the following functions:

  • Protection of vital structures
  • Provision of body forms
  • Stability
  • Storage of salts (e.g., calcium)
  • Formation and supply of new blood cells

Essentially the skeletal part of the system pertains to the arrangement of bones, and how they join to one another to form joints which permit and limit specific movements. This part also outlines the factors that influence stability of some of those joints. For example, a joint with good bony congruence (joint with bones fitting well together) is most likely to be more stable than one with poor bony congruence. On the other hand, the muscular portion of the musculoskeletal system primarily describes the movements produced at joints, which as a basic principle, is based on the location of a muscle in relation to the joint and attachment to bones forming the joint. For example, a muscle lying anterior to two or more bones, and also crossing the joint formed by those bones anteriorly will produce the movement – “flexion” at that joint when it is contracted.

Muscles

Muscles are the largest soft tissues of the musculoskeletal system. The muscle cells – muscle fibres – produce contractions that move body parts, including internal organs. Associated connective tissue binds muscle fibres into fascicles or bundles, and these associated connective tissues also convey nerve fibres and blood vessels (capillaries) to the muscle cells.

Muscle bundles – histological slide

Functions

Include:

  • Production of movement
  • Support of the body
  • Stability of joints
  • Production of body heat
  • Provision of form to the body

Types

Muscles can be grouped into the following three types:

  • Skeletal muscle, which move bones and other structures (e.g., the eyes)
  • Cardiac muscle, which forms most of the walls of the heart and adjacent great vessels, such as the aorta
  • Smooth (Visceral) muscle, which forms part of the walls of most vessels and hollow organs, move substances through viscera such as the intestine, and controls movement through blood vessels

However, the basic histological classification of muscles is into two types:

  • Striated
  • Non-striated

Based on this classification, skeletal and cardiac muscles are grouped as striated muscles, while the visceral muscle is non-striated. This structural characteristic (striation) is due to the way the filaments of actin and myosin are arranged in each of the classes of muscles.

Striations – histological slide

Tendons and Ligaments

tendon is a tough, flexible band of fibrous connective tissue that connects muscles to bones. The extracellular connective tissue between muscle fibres binds to tendons at the distal and proximal ends, and the tendon binds to the periosteum of bones at the muscle’s proximal attachment to bone (origin) and distal attachment (insertion). As muscle contracts, tendon transmits the force to the bones, pulling on them and causing movement.

Tendon of flexor digitorum longus muscle – medial view

Tendons and ligaments are made of dense fibrous connective tissue (DFCT) which has an abundance of collagen fibre bundles arranged in parallel, creating a high tensile strength (resistance to longitudinal force). Tendons and ligaments appear white because their fibrous connective tissues are made up of collagen, and collagen is white. They also appear white because they have very poor blood supply. Nutrients reach those structures by diffusion.

Tendons are generally rounded cords and thick. Ligaments are flatter in shape than tendons and attach a bone to another bone. They have more elastic fibres and thus are slightly stretchier than tendons.

Joint Capsule and Synovial Membrane

Synovial membranes line the synovial cavity and secrete synovial fluid that lubricates most joints where they are found (synovial joints) in order to reduce friction. The fluid secreted by a synovial membrane also serve as a source of nutrients for tendons and ligaments, as well as to articular cartilages.

Joint capsules are very strong and surround a joint, particularly synovial joints. They are composed of dense fibrous connective tissue. Ligaments are usually found by thickenings of the joint capsule, for example, the medial and lateral thickenings of the joint capsule at the knee joint, forms the medial and lateral collateral ligaments of the knee joint.

Skeletal System

This system is composed of bones and cartilages, and makes up the hard tissue of the musculoskeletal system. Functions of the skeletal system include:

  • support for the body
  • shock absorption
  • storage for salts
  • production of blood cells
  • production of vital organs
  • mechanical basis for movement

The skeletal system consists of two main parts, the axial skeleton and the appendicular skeleton. The axial skeleton consists of the bones of the head, neck and trunk. The appendicular skeleton consists of the bones of the limbs, including those forming the pectoral and pelvic girdles.

Hard tissues of the musculoskeletal system will be discussed further under the headings – bones, cartilages, and joints.

Femur – ventral view

Bones

Bones are made up of a superficial layer, compact bone, and a deeper layer of spongy bone, except where the latter is replaced by a medullary (marrow) cavity. Within this cavity in the adult bone, and between the spicules of spongy bones, blood cells are formed.

A typical bone (especially long bones) has a head, neck and body or shaft. It also possesses some markings and formations that gives passage and attachments to soft tissues like ligaments and tendons. Some of those features (markings) include:

  • Condyle – rounded articular area (e.g. lateral femoral condyle)
  • Crest – ridge of bone (e.g. iliac crest)
  • Epicondyle – eminence superior to a condyle
  • Facet – smooth, flat area, usually covered with cartilage
  • Foramen – passage through a bone

Classification of Bones

Bones can be classified according to their shapes as follows:

  • Long bones – These are bones longer than they are wide. They are tubular (e.g. the humerus in the arm)
  • Short bones – These bones are roughly cube-like or round. Examples include the tarsals and carpals
  • Flat bones – these types of bones are mostly thin, flattened and usually curved. They mostly serve protective functions. Examples include most of the skull bones – protecting the brain, and the ribs – protecting the thoracic viscera
  • Irregular bones – These are bones that do not fit into any of the other types of bones. Generally, irregular bones will have a foramen through them. A very good example is the hip bone

Cartilages

Cartilages line the articulating surfaces of bones. Thus, cartilages are usually found deep within a joint. They are great for weight bearing and are extremely slippery to reduce the friction inside a joint (movable joint like synovial joint). Synovial joints possess hyaline cartilage.

Joints

Joints are formed where two or more bones meet. They promote movements of body parts, however, movement is not a necessary attribute of a joint as some joints do not move, e.g. joints between bones of the skull. The integrity or stability of a joint is guaranteed by several factors including the bony congruence (fit of bones), and other structures which cross the joint.

Joints can be classified broadly by the connective tissues found between the bone ends. The following are three categories based on their structures:

  • Fibrous joints – The tissues between the bone ends of this class of joints is dense fibrous connective tissue (DFCT). The bones are held together firmly and the joint allows little or no movement. Examples are the sutures of the skull
  • Cartilaginous joints – The tissue between the bones forming this category of joints is cartilage. The bones are firmly held together by these, but movement is also allowed. An example is the joints between the bodies of the vertebrae
  • Synovial joints – These joints have the potential to allow movement through a wide range – far more than fibrous or cartilaginous joints. There are no direct bone to bone attachment by tissues at the bone ends, instead they are held together by a connective tissue sleeve – the joint capsule, attached at the margins of the joint.

There is a potential space called synovial cavity between the bone ends, allowing easy movements. Cartilage is also found on the articular surfaces of the bones. Synovial membrane is found in this joint, and covers structures within the synovial cavity other than those covered with articular cartilage. Hence, synovial membrane is the inner lining of the joint capsule.

Other classification of joints includes:

Based on Axis:

  • Uni-axial joints
  • Bi-axial joints
  • Multi-axial joints

Based on Shape (Synovial joints):

  • ball and socket joints (e.g. hip joint)
  • condylar joints (e.g. knee joint)
  • hinge joints (e.g. elbow joint)
  • pivot joints (e.g. radio-ulnar joints)
  • ellipsoid joints (e.g. 2nd – 5th metacarpal-phalanx joints)
  • plane joints (e.g. joints between the carpal bones)

Clinical Correlation

There is a variety of conditions that affect the muscles, bones, and joints. Disorders of the musculoskeletal system may range from diseases to minor physical disabilities. The following are some clinical conditions of the musculoskeletal system:

Osteoporosis

Osteoporosis is a condition that affects bone strength (the word osteoporosis literally means “porous bones”). It is a condition in which the bones become fragile and brittle, leading to a higher risk of fractures than in normal bone. As a result, even a minor bump or accident can cause serious fractures.

Osteoporosis is the “bone of the old”, especially, in women. The hard, rock-like quality of bone is dependent upon calcium. When too much calcium is dissolved from bones or not enough is replaced, bones lose density and are easily fractured. Estrogen, the female sex hormone, helps maintain proper calcium levels in bones. Once the ovaries stop producing the hormone, women are at higher risk of developing osteoporosis. A collapse of bony vertebrae of the spinal column results in loss of height and stooped posture. Hip fractures are a common occurrence.

Sarcopenia

Sarcopenia is a syndrome characterized by progressive and generalized loss of skeletal muscle mass and strength with a risk of adverse outcomes such as physical disability, poor quality of life and death.

Arthritis

Arthritis is a group of conditions affecting the joints. These conditions cause damage to the joints, usually resulting in pain and stiffness due to aging. Arthritis can affect many different parts of the joint and nearly every joint in the body.

As an individual ages, the joint tissues become less resilient to wear and tear and start to degenerate. This degeneration manifest as swelling, pain, and often-times, loss of mobility of joints. Changes occur in both joint soft tissues and the articulating bones, a condition called osteoarthritis. A more serious form of disease is called rheumatoid arthritis. The latter is an autoimmune disease wherein the body produces antibodies against joint tissues causing chronic inflammation resulting in severe joint damage, pain and immobility.

Muscular Dystrophy

Muscular dystrophy is a group of muscle diseases that weaken the musculoskeletal system and hamper locomotion. Muscular dystrophies are characterized by progressive skeletal muscle weakness, defects in muscle proteins, and the death of muscle fibres (muscle cells) and tissue.

It is a group of inherited diseases in which the muscles that control movement progressively weaken. The prefix, dys-, means abnormal, while the root, -trophy, refers to maintaining normal nourishment, structure and function. The most common form in children is called Duchenne muscular dystrophy and affects only males. It usually appears between the ages of 2 to 6 and the afflicted live typically into late teens to early 20s.

Other conditions involving the musculoskeletal system include:

  • Lupus erythematosus
  • Myasthenia gravis
  • Rotator cuff tear
  • Tendonitis
  • Carpal tunnel syndrome
  • Osteomalacia

Bones

Anatomy

Bones make up the skeletal system of the human body and are responsible for somatic rigidity, storage of different micronutrients, and housing bone marrow. They also produce red blood cells and the various forms of white blood cells and provide structural outline and movement.

Of the two hundred and six bones in an adult human body, there are several types that are grouped together due to their general features, such as shape, placement and additional properties.

What is a Bone?

bone is a somatic structure that is comprised of calcified connective tissue. Ground substance and collagen fibers create a matrix that contains osteocytes. These cells are the most common cell found in mature bone and responsible for maintaining bone growth and density. Within the bone matrix both calcium and phosphate are abundantly stored, strengthening and densifying the structure.

Bone matrix – histological slide

Each bone is connected with one or more bones and are united via a joint (only exception: hyoid bone). With the attached tendons and musculature, the skeleton acts as a lever that drives the force of movement. The inner core of bones (medulla) contains either red bone marrow (primary site of hematopoiesis) or is filled with yellow bone marrow filled with adipose tissue.

Bone marrow – histological slide

The main outcomes of bone development are endochondral and membranousforms. This particular characteristic along with the general shape of the bone are used to classify the skeletal system. The main shapes that are recognized include:

  • long
  • short
  • flat
  • sesamoid
  • irregular

Types of Bone

Long bones

These bones develop via endochondral ossification, a process in which the hyaline cartilage plate is slowly replaced. A shaft, or diaphysis, connects the two ends known as the epiphyses (plural for epiphysis). The marrow cavity is enclosed by the diaphysis which is thick, compact bone. The epiphysis is mainly spongy bone and is covered by a thin layer of compact bone; the articular ends participate in the joints.

Humerus – ventral view

The metaphysis is situated on the border of the diaphysis and the epiphysis at the neck of the bone and is the place of growth during development. This group of bones includes the:

  • humerus
  • ulna
  • radius
  • fibula
  • tibia
  • femur
  • metacarpal bones
  • phalanges

Short bones

thin external layer of compact bone covers vast spongy bone and marrow, making a shape that is more or less cuboid. The carpal bones and tarsal bones fall into this category.

Hamate bone – ventral view

Flat bones

Two layers of compact bone cover both spongy bone and bone marrow space. They grow by replacing connective tissue. Fibrocartilage covers their articular surfaces. This group is compiled of the:

  • skull bones
  • ribs
  • sternum
  • scapulae

Sternum – ventral view

Irregular bones

thin layer of compact bone covers a mass of mostly spongy bone. This group is not categorized by shape, but by bone content and includes the

Vertebral column (Fourth cervical vertebra) – ventral view

Sesamoid bones

Sesamoid bones are embedded within tendons. They are found at the end of long bones in the limbs, where the tendons cross, for example the patella bone in the knee. Sesamoid bones protect the tendons from excess wear by reducing friction.

Patella – lateral-right view

Clinical Aspects

Common bone diseases often affect the bone density, e.g. in young children due to malnutrition. For example, rickets is a bone deformity seen in young children who lack vitamin D. Their legs are disfigured and they have trouble walking. The damage is irreversible though surgery may help. Osteomalacia and osteoporosis are diseases seen mainly in adulthood.

Osteomalacia is the improper mineralisation of bone due to a lack of available calcium and phosphate. The bone density decreases and the bones become soft. Osteoporosis has been noted in all ages but mostly in postmenopausal and elderly women. A progressive decrease in bone density increases the risk of fracture. Patients who are on long-term steroid medication are in particular risk.

What Is an Erectile Dysfunction Pump?

Overview

An erectile dysfunction pump is a device used to help achieve and maintain an erection by drawing blood into the penis via air suction. It’s not a cure for erectile dysfunction (ED), but can help increase your ability to have sexual intercourse. This device is sometimes called a penis pump or vacuum pump. It’s a noninvasive treatment that can be used alone or with other ED treatments or oral medications.

What Does an ED Pump Look Like?

The ED pump is made up of three separate parts:

  • A clear plastic tube that is placed over your penis.
  • A pump that is attached to the tube and powered by hand or battery.
  • A band (sometimes called a constriction ring) that fits around the base of the erect penis.

How Do You Use an ED Pump?

First, apply water-soluble jelly to the base of the penis to create a water-tight seal. Then place your penis in the tube and pump the air out slowly. This causes your penis to fill with blood. (Note: It takes an average of 10 to 20 minutes to achieve a full erection, according to Weill Cornell Medical College.)

Next, place the band around the base of your penis to maintain your erection. The band comes in several sizes and tensions. Trial and error may be necessary to determine which band size is the most comfortable for you. Once the ring is in place, you can remove the pump and start sexual relations.

Most men can keep an erection for about 30 minutes. However, the band can cut off blood flow and cause injury if worn for longer, according to the Mayo Clinic. Remember to remove the band after intercourse.

Who Can Use an ED Pump?

The ED pump should be used by men with ED. It’s an especially good option for men who can’t take oral ED medications.

According to Weill Cornell, men who have the following conditions should use caution before using an ED pump:

  • history of prolonged erection
  • history of bleeding disorders or use of blood thinning medications such as warfarin (Coumadin) and
  • clopidogrel (Plavix)
  • diminished penile sensation
  • spinal cord injury
  • curvature of the penis

You should see your doctor before using a pump. ED can be a symptom of a variety of underlying, and sometimes serious, medical conditions. Treatment for those conditions can often correct ED.

Where Can You Get an ED Pump?

Talk to your doctor. Some ED pumps are available without prescription, but your doctor can make a recommendation based on your specific condition. Be sure to tell your doctor about any other illnesses or injuries you may have had and any medications you are taking, including any other ED treatments you have already tried.

Some ED pumps sold online and in magazines may not be safe or effective. Try to choose a model with a vacuum limiter — this will prevent the pressure from building too high and causing injury.

What Are the Benefits of Using an ED Pump?

It may take a bit of practice, but most men are able to have sexual intercourse using an ED pump.

Other benefits include the following:

  • lower risk of complications than with other ED treatments
  • minimal cost after initial purchase
  • noninvasive treatment
  • it can be combined with other ED treatments, such as oral medications

What Are the Risks of Using an ED Pump?

The ED pump can interfere with spontaneity, and some men find it uncomfortable or awkward. Some men also find that they have to shave their pubic hair at the base of the penis in order to maintain a good seal.

The ED pump is generally considered to be safe, but can cause increased bleeding in men who:

  • take blood thinners
  • have sickle cell anemia
  • have any blood disorder that causes bleeding or interferes with clotting

Potential side effects include:

  • red dots caused by bleeding under the skin’s surface, called petechiae
  • numbness or coldness
  • bluish-colored skin
  • bruising
  • pain
  • painful ejaculation

Can an ED Pump Enlarge the Penis?

Some advertisers claim that ED pumps can make your penis larger. While an ED pump will help maintain size and shape, especially after surgery, it won’t make your penis bigger. Using an ED pump in an attempt to make your penis bigger may even result in injury, warns the Mayo Clinic.

Is the ED Pump Covered by Insurance?

With proper, detailed medical documentation, some health insurance providers will cover the expense of an ED pump in certain circumstances. However, it’s unlikely that you’ll be covered if you purchase one without seeing a doctor or receiving a diagnosis. Before purchasing an ED pump, check with your insurance provider to see if you’re covered and, if so, what documentation is required.

Can an Erectile Dysfunction Ring Treat Impotence?

What is erectile dysfunction?

Erectile dysfunction (ED), once referred to as impotence, is defined as difficulty getting and maintaining an erection long enough to perform sexual intercourse. ED doesn’t mean a reduced desire for sex.

According to the National Institutes of Health (NIH), ED affects men of all ages, but men are likely to experience it as they get older. The prevalence of ED is as follows:

  • 12 percent of men under 60
  • 22 percent of men in their 60s
  • 30 percent of men 70 and older

There are many treatments for ED. Some involve lifestyle changes, psychotherapy, medication, surgery, or assistance from a device. An ED ring is a common device that can help treat ED.

Causes of ED

How erections work

When a man is sexually aroused, the brain causes blood to flow to the penis, making it larger and firmer. Getting and maintaining an erection requires healthy blood vessels.

They let blood flow into the penis and then close off, keeping blood in the penis during sexual arousal. They then open up and let blood flow back when sexual arousal ends.

Physical causes of ED

Many diseases and medical conditions can cause physical damage to arteries, nerves, and muscles, or can affect blood flow, which may all lead to ED. The conditions include:

  • high blood pressure
  • diabetes
  • heart disease
  • kidney disease
  • high cholesterol
  • clogged arteries
  • hormonal imbalance

Neurological disorders like back and brain surgeries, Parkinson’s disease, and multiple sclerosis affect nerve signals and can also cause ED. Many men also experience ED after surgical treatment for prostate cancer.

Other factors that make maintaining an erection difficult can include:

  • surgeries and injuries to the penis or organs around the penis
  • overuse of alcohol, recreational drugs, and nicotine
  • side effects of prescription drugs
  • low testosterone

Other causes of ED

Physical and medical conditions aren’t the only sources of ED. Stress, anxiety, depression, low self-esteem, and relationship issues can all have negative effects on reaching and maintaining an erection.

Once an episode of ED occurs, the fear of it happening again can block a man’s ability to achieve a subsequent erection. Previous sexual trauma like rape and abuse also can lead to ED.

Medications for ED

During just about every television event there are prescription drug commercials advertising ED treatments that include drugs such as Cialis, Viagra, and Levitra. These oral medications work by inducing dilation of the blood vessels in the penis, facilitating blood flow to the penis and helping cause an erection if the man is sexually aroused.

Other prescription treatments like Caverject and Muse are injected or inserted into the penis. These medications also increase blood flow to the penis and will cause an erection with or without sexual arousal.

ED rings

Prescription medications don’t help all cases of ED. They can also cause unwanted side effects like flushing, headaches, or changes in vision. Most prescription medications for ED can’t be used if you have a history of heart problems or are taking certain medications.

When prescription medications aren’t appropriate, medical devices may help ED. However, surgically-inserted penile implants may not appeal to all men, and some may find vacuum pumps embarrassing or difficult to handle. In those cases, an ED ring might be a good option.

How ED rings work

An ED ring is placed around the base of the penis to slow the flow of blood back from your penis to help maintain an erection. Most are made of flexible material like rubber, silicone, or plastic, and some are made of metal.

Some ED rings have two parts, one circle that fits around the penis, and one that constricts the testicles. Most users find the ring helps an erection last long enough for intercourse.

As ED rings prevent blood from flowing back while the penis is erect, they work best when a man can achieve a partial or full erection but has difficulty maintaining it.

ED rings can also be used with a pump or ED vacuum that fits over the penis and gently pulls blood into the penis by the vacuum created. ED rings are sold on their own or along with pumps and vacuums.

Using an ED ring

When an erection beings, gently stretch the ring over the head of the penis, down the shaft, and to the base. Some tips to keep in mind:

  • be careful to avoid catching pubic hairs
  • lubricant can help ease the ring on and off
  • wash the ED ring gently before and after each use with warm water and a small amount of mild soap

Precautions

Men with blood-clotting disorders or blood problems such as sickle cell anemia should not use an ED ring, and men on blood-thinning medications should talk to their doctor before using one.

Most manufacturers recommend removing the ring after having it on for 20 minutes. Some men may be sensitive to the material of the ring. Also, men should stop using it if irritation develops in either partner and then see a doctor. Don’t sleep with the ring on, as it may affect blood flow to the penis.

Also, some users find that orgasm with an ED ring isn’t as powerful.

Outlook

The probability of experiencing ED increases with age, and it’s a common issue, yet sometimes difficult to discuss. Most men will need to try different treatments before discovering what’s right for them. In some cases, more than one approach may be necessary over time.

An ED ring is a good option for healthy men who achieve some erection or who use a penis pump or vacuum to start an erection. ED rings are available from many sources and don’t require a doctor’s prescription. As always, talk to your doctor about any questions or concerns you have about ED rings and stop using them if any irritation or other issues develop.

Erectile Dysfunction (ED): Causes, Treatment, and More

What is erectile dysfunction (ED)?

Erectile dysfunction (ED) is the inability to get or keep an erection firm enough to have sexual intercourse. It’s also sometimes referred to as impotence.

Occasional ED isn’t uncommon. Many men experience it during times of stress. Frequent ED can be a sign of health problems that need treatment. It can also be a sign of emotional or relationship difficulties that may need to be addressed by a professional.

Not all male sexual problems are caused by ED. Other types of male sexual dysfunction include:

  • premature ejaculation
  • delayed or absent ejaculation
  • lack of interest in sex

What are the symptoms of ED?

You may have erectile dysfunction if you regularly have:

  • trouble getting an erection
  • difficulty maintaining an erection during sexual activities
  • reduced interest in sex

Other sexual disorders related to ED include:

  • premature ejaculation
  • delayed ejaculation
  • anorgasmia, which is the inability to achieve orgasm after ample stimulation

You should talk to your doctor if you have any of these symptoms, especially if they’ve lasted for two or more months. Your doctor can determine if your sexual disorder is caused by an underlying condition that requires treatment.

What causes ED?

There are many possible causes for ED, and they can include both emotional and physical disorders. Some common causes are:

  • cardiovascular disease
  • diabetes
  • hypertension
  • hyperlipidemia
  • damage from cancer or surgery
  • injuries
  • obesity or being overweight
  • increased age
  • stress
  • anxiety
  • relationship problems
  • drug use
  • alcohol use
  • smoking

ED can be caused by only one of these factors or several. That’s why it’s important to work with your doctor so that they can rule out or treat any underlying medical conditions.

What causes an erection?

An erection is the result of increased blood flow into your penis. Blood flow is usually stimulated by either sexual thoughts or direct contact with your penis.

When a man becomes sexually excited, muscles in their penis relax. This relaxation allows for increased blood flow through the penile arteries. This blood fills two chambers inside the penis called the corpora cavernosa. As the chambers fill with blood, the penis grows rigid. Erection ends when the muscles contract and the accumulated blood can flow out through the penile veins.

ED can occur because of problems at any stage of the erection process. For example, the penile arteries may be too damaged to open properly and allow blood in.

How does age affect incidence of ED?

Up to 30 million American men are affected by ED, according to the National Institute of Diabetes and Digestive and Kidney Diseases. The prevalence of ED increases with age. ED affects:

  • 12 percent of men younger than 60
  • 22 percent of men in their 60s
  • 30 percent of men 70 or older

Although the risk of ED increases with age, ED is not inevitable as you get older. It may be more difficult to get an erection as you age, but that doesn’t necessarily mean you will develop ED. In general, the healthier you are, the better your sexual function.

ED can also occur among younger men. A 2013 study found that one in four men seeking their first treatment for ED were under the age of 40. The researchers found a stronger correlation between smoking and illicit drug use and ED in men under 40 than among older men. That suggests that lifestyle choices may be a main contributing factor for ED in younger men.

An analysis of research on ED in men under 40 found that smoking was a factor for ED among 41 percent of men under the age of 40. Diabetes was the next most common risk factor and was linked to ED in 27 percent of men under 40.

How is ED diagnosed?

Your doctor will ask you questions about your symptoms and health history. They may do tests to determine if your symptoms are caused by an underlying condition. You should expect a physical exam where your doctor will listen to your heart and lungs, check your blood pressure, and examine your testicles and penis. They may also recommend a rectal exam to check your prostate. Additionally, you may need blood or urine tests to rule out other conditions.

Nocturnal penile tumescence (NPT) test

An NPT test is done using a portable, battery-powered device that you wear on your thigh while you’re sleeping. The device evaluates the quality of nocturnal erections and stores the data, which your doctor can later access. Your doctor can use this data to better understand your penis function and ED.

Nocturnal erections are erections that occur while you’re sleeping, and they’re a normal part of a healthily functioning penis.

What treatments are available?

Treatment for ED will depend on the underlying cause. You may also need to use a combination of treatments, including medication, lifestyle changes, or therapy.

ED medications

Your doctor may prescribe medication to help manage your symptoms of ED. You may need to try several medications before you find one that works. These medications can have side effects. If you’re experiencing unpleasant side effects, talk to your doctor. They may be able to recommend a different medication.

The following medications stimulate blood flow to your penis to help treat ED:

  • alprostadil (Caverject)
  • avanafil (Stendra)
  • sildenafil (Viagra)
  • tadalafil (Cialis)
  • testosterone (Androderm)
  • vardenafil (Levitra)

Natural remedies and herbs for ED

For some men, natural remedies may help treat ED. Talk to your doctor before trying a new supplement or herb.

You should also use caution when buying supplements and herbs. Many aren’t regulated, which means they may contain additional ingredients not listed on the labels. Ask your doctor to recommend reputable brands and avoid purchasing supplements online.

The following herbs and supplements have been shown to have varying degrees of success for the treatment of ED:

  • L-arginine
  • DHEA
  • ginseng
  • yohimbe
  • Asparagus racemosus

Talk therapy

Psychological factors are a common cause of ED, including:

  • stress
  • anxiety
  • post-traumatic stress disorder (PTSD)
  • depression

If you’re experiencing psychological ED, you may benefit from talk therapy. Therapy can help you manage your mental health. You’ll likely work with your therapist over several sessions, and your therapist will address things like major stress or anxiety factors, feelings around sex, or subconscious conflicts that could be affecting your sexual well-being.

If ED is affecting your relationship, you may also consider speaking with a relationship counselor. Relationship counseling can help you reconnect emotionally with a partner, which may also help your ED.

Alternative treatments

If your ED is caused by stress, yoga and massage may help if you find these activities relaxing.

Prostatic massage

Some men use a form of massage therapy called prostatic massage. Practitioners massage the tissues in and around your groin to promote blood flow to your penis. There are limited studies on the efficacy of this type of massage.

Acupuncture

Acupuncture may help treat psychological ED, though studies are limited and inconclusive. You’ll likely need several appointments before you begin to notice any improvements. When choosing an acupuncturist, look for a certified practitioner who uses disposable needles and follows U.S. Food and Drug Administration guidelines for needle disposal and sterilization.

Pelvic floor muscle exercises

A small study of 55 men saw improvement to penile function after three months of regular pelvic floor muscles exercises, and after six months, 40 percent of men had regained normal erectile function.

Kegel exercises are a simple exercise you can use to strengthen your pelvic floor muscles. Here’s how you do them:

  1. Identify your pelvic floor muscles. To do this, stop peeing midstream. The muscles you use to do this are your pelvic floor muscles. Your testicles will also rise when you contract these muscles.
  2. Now that you know where these muscles are, contract them for 5 to 20 seconds. Then release them.
  3. Repeat this exercise 10 to 20 times in a row, three to four times a day.

Lifestyle changes and diet

Healthy lifestyle habits may prevent ED, and in some situations reverse the condition:

  • Exercise regularly.
  • Maintain a low blood pressure.
  • Eat a balanced, nutritious diet.
  • Maintain a healthy weight.
  • Avoid alcohol and cigarettes.
  • Reduce your stress.

ED is often related to problems with your blood flow, so maintaining your blood vessel health through exercise and a healthy diet may help reduce your risk for ED.

Change your medications

In some cases, medications used to treat other conditions may cause ED. Talk to your doctor about medications you’re taking and whether they could be causing your symptoms. There may be other medications you can take instead.

Don’t stop taking medications without first talking to your doctor.

Is ED reversible?

In many cases, you can improve your symptoms of ED. Many medications and treatments are available. As well, certain devices, like an erectile dysfunction pump or erectile dysfunction ring, may help temporarily manage symptoms of ED so that you can continue to engage in sexual intercourse.

ED is a common condition, and it has many possible causes. Discuss your symptoms with your doctor early so that they can rule out underlying causes and begin a treatment plan.

Peripheral Nervous System

Together the CNS and the PNS provide three general functions: sensory, integrative, and motor. The sensory function consists of receptors that monitor the body both externally and internally. The sensory receptors convert their information into nerve impulses, which are then transmitted via the PNS to the CNS, and the signals are integrated. They are brought together, creating sensations and helping to produce thoughts and perceptions. As a result, we make decisions and use motor functions to act on them. The PNS includes the cranial and spinal nerves as well as the ANS.

Cranial Nerves

Twelve pairs of cranial nerves come from the brain. They are named both by Roman numeral and name. The Roman numeral partially identifies the cranial nerves’ location in the brain. Refer to Table for a summary of the cranial nerves and their function.

Table. Cranial Nerves

NUMBER AND NAME FUNCTION(S)
I Olfactory • Sense of smell
II Optic • Sense of sight
III Oculomotor • Movement of the eyeball• Constriction of pupil in bright light or for near vision
IV Trochlear • Movement of eyeball
V Trigeminal • Sensation in face, scalp, and teeth• Contraction of chewing muscles
VI Abducens • Movement in the eyeball
VII Facial • Sense of taste• Contraction of facial muscles

• Secretion of saliva

VIII Acoustic (vestibulocochlear) • Sense of hearing• Sense of equilibrium
IX Glossopharyngeal • Sense of taste• Sensory for cardiac, respiratory, and blood pressure reflexes

• Contraction of pharynx

• Secretion of saliva

X Vagus • Sensory in cardiac, respiratory, and blood pressure reflexes• Sensory and motor to larynx (speaking)

• Decreases heart rate

• Contraction of alimentary tube (peristalsis)

• Increases digestive secretions

XI Accessory • Contraction of neck and shoulder muscles• Motor to larynx (speaking)
XII Hypoglossal • Movement of the tongue

Spinal Nerves

Thirty-one pairs of spinal nerves branch from the spinal cord. There are 8 pairs of cervical nerves (C1–C8), 12 pairs of thoracic nerves (T1–T12), 5 pairs of lumbar nerves (L1–L5), 5 pairs of sacral nerves (S1–S5), and 1 pair of coccygeal nerves. Each set of nerves has a specialized task.

The spinal cord and spinal nerves

FIGURE. The spinal cord and spinal nerves. The distribution of spinal nerves is shown only on the left side. The nerve plexuses are labeled on the right side. A nerve plexus is a network of neurons from several segments of the spinal cord that combine to form nerves to specific parts of the body. For example, the radial and ulnar nerves to the arm emerge from the brachial plexus. (From Scanlon, VC, and Sanders, T: Essentials of Anatomy and Physiology, ed 5. FA Davis, Philadelphia, 2007, p 173, with permission.)

Spinal Cord Function and Anatomy

The spinal cord is a cylindrical shaped bundle of nerve fibers that is connected to the brain at the brain stem. The spinal cord runs down the center of the protective spinal column extending from the neck to the lower back. The brain and spinal cord are the major components of the central nervous system (CNS). The CNS is the processing center for the nervous system, receiving information from and sending information to the peripheral nervous system. Peripheral nervous system cells connect various organs and structures of the body to the CNS through the cranial nerves and spinal nerves. Spinal cord nerves transmit information from body organs and external stimuli to the brain and send information from the brain to other areas of the body.

Illustration of spinal cord cross-section.

Spinal Cord Anatomy

Spinal cord anatomy

The spinal cord is composed of nervous tissue. The interior of the spinal cord consists of neurons, nervous system support cells called glia, and blood vessels. Neurons are the basic unit of nervous tissue. They are composed of a cell body and projections that extend from the cell body that are able to conduct and transmit nerve signals. These projections are axons (carry signals away from the cell body) and dendrites (carry signals toward the cell body). The neurons and their dendrites are contained within an H-shaped region of the spinal cord called gray matter. Surrounding the gray matter area is a region called white matter. The white matter section of the spinal cord contains axons that are covered with an insulating substance called myelin. Myelin is whitish in appearance and allows electrical signals to flow freely and quickly. Axons carry signals along descending and ascending tracts away from and toward the brain.

Neurons

Neurons are classified as either motor, sensory, or interneurons. Motor neurons carry information from the central nervous system to organs, glands, and muscles. Sensory neurons send information to the central nervous system from internal organs or from external stimuli. Interneurons relay signals between motor and sensory neurons. The descending tracts of the spinal cord consist of motor nerves that send signals from the brain to control voluntary and involuntary muscles. They also help to maintain homeostasis by assisting in the regulation of autonomic functions such as heart rate, blood pressure, and internal temperature. The ascending tracts of the spinal cord consist of sensory nerves that send signals from internal organs and external signals from the skin and extremities to the brain. Reflexes and repetitive movements are controlled by spinal cord neuronal circuits that are stimulated by sensory information without input from the brain.

Spinal Nerves

The axons that link the spinal cord to the muscles and the rest of the body are bundled into 31 pairs of spinal nerves, each pair with a sensory root and a motor root that make connections within the gray matter. These nerves must pass between the protective barrier of the spinal column to connect the spinal cord to the rest of the body. The location of the nerves in the spinal cord determine their function.

Spinal Column

Human Spine Blueprint. This is a detailed blueprint of a human spine showing the side view with different regions and vertebrae labeled. wetcake/Getty Images

The spongy spinal cord is protected by the irregular shaped bones of the spinal column called vertebrae. Spinal vertebrae are components of the axial skeleton and each contain an opening that serves as a channel for the spinal cord to pass through. Between the stacked vertebrae are discs of semi-rigid cartilage, and in the narrow spaces between them are passages through which the spinal nerves exit to the rest of the body. These are places where the spinal cord is vulnerable to direct injury. The vertebrae can be organized into sections, and are named and numbered from top to bottom according to their location along the backbone:

  • Cervical vertebrae (1-7) located in the neck
  • Thoracic vertebrae (1-12) in the upper back (attached to the ribcage)
  • Lumbar vertebrae (1-5) in the lower back
  • Sacral vertebrae (1-5) in the hip area
  • Coccygeal vertebrae (1-4 fused) in the tail-bone

Spinal Cord Segments

The spinal cord is also organized into segments and named and numbered from top to bottom. Each segment marks where spinal nerves emerge from the cord to connect to specific regions of the body. Locations of spinal cord segments do not correspond exactly to vertebral locations, but they are roughly equivalent.

  • Cervical spinal nerves (C1 to C8) control signals to the back of the head, the neck and shoulders, the arms and hands, and the diaphragm.
  • Thoracic spinal nerves (T1 to T12) control signals to the chest muscles, some muscles of the back, and parts of the abdomen.
  • Lumbar spinal nerves (L1 to L5) control signals to the lower parts of the abdomen and the back, the buttocks, some parts of the external genital organs, and parts of the leg.
  • Sacral spinal nerves (S1 to S5) control signals to the thighs and lower parts of the legs, the feet, most of the external genital organs, and the area around the anus.

The single coccygeal nerve carries sensory information from the skin of the lower back.

Spinal Cord Injury

The consequences of a spinal cord injury vary depending on the size and severity of the injury. A spinal cord injury may cut off normal communication with the brain that can result in a complete or incomplete injury. A complete injury results in a total lack of sensory and motor function below the level of injury. In the case of an incomplete injury, the ability of the spinal cord to convey messages to or from the brain is not completely lost. This type of injury enables a person to maintain some motor or sensory function below the injury.

Divisions of the Brain

The brain is a complex organ that acts as the control center of the body. As a component of the central nervous system, the brain sends, receives, processes, and directs sensory information. The brain is split into left and right hemispheres by a band of fibers called the corpus callosum. There are three major divisions of the brain, with each division having specific functions. The major divisions of the brain are the forebrain (prosencephalon), midbrain (mesencephalon), and hindbrain (rhombencephalon).

Forebrain (Prosencephalon)

The forebrain is by far the largest brain division. It includes the cerebrum, which counts for about two-thirds of the brain’s mass and covers most other brain structures. The forebrain consists of two subdivisions called the telencephalon and diencephalon. The olfactory and optic cranial nerves are found in the forebrain, as well as the lateral and third cerebral ventricles.

Telencephalon

A major component of the telencephalon is the cerebral cortex, which is further divided into four lobes. These lobes include the frontal lobes, parietal lobes, occipital lobes, and temporal lobes. The cerebral cortex contains folded bulges called gyri that create indentations in the brain. Functions of the cerebral cortex include processing sensory information, controlling motor functions, and performing higher order functions such as reasoning and problem-solving.

  • Frontal Lobes: The prefrontal cortex, premotor area, and motor area of the brain. These lobes function in voluntary muscle movement, memory, thinking, decision-making, and planning.
  • Parietal Lobes: Responsible for receiving and processing sensory information. These lobes also contain the somatosensory cortex, which is essential for processing touch sensations.
  • Occipital Lobes: Responsible for receiving and processing visual information from the retina.
  • Temporal Lobes: Home of the limbic system structures including the amygdala, and hippocampus. These lobes organize sensory input, as well as aid in auditory perception, memory formation, and language and speech production.

Diencephalon

The diencephalon is the region of the brain that relays sensory information and connects components of the endocrine system with the nervous system. The diencephalon regulates a number of functions including autonomic, endocrine, and motor functions. It also plays a major role in sensory perception. Components of the diencephalon include:

  • Thalamus: A limbic system structure that connects areas of the cerebral cortex that are involved in sensory perception and movement with other parts of the brain and spinal cord. The thalamus also plays a role in the control of sleep and wake cycles.
  • Hypothalamus: Acts as the control center for many autonomic functions including respiration, blood pressure, and body temperature regulation. This endocrine structure secretes hormones that act on the pituitary gland to regulate biological processes including metabolism, growth, and the development of reproductive system organs. As a component of the limbic system, the hypothalamus influences various emotional responses through its influence on the pituitary gland, skeletal muscular system, and autonomic nervous system.
  • Pineal Gland: This small endocrine gland produces the hormone melatonin. Melatonin production is vital to the regulation of sleep-wake cycles and also influences sexual development. The pineal gland converts nerve signals from the sympathetic component of the peripheral nervous system into hormone signals, thereby linking the nervous and endocrine systems.

Midbrain (Mesencephalon)

The midbrain is the area of the brain that connects the forebrain to the hindbrain. The midbrain and hindbrain together compose the brainstem. The brainstem connects the spinal cord with the cerebrum. The midbrain regulates movement and aids in the processing of auditory and visual information. The oculomotor and trochlear cranial nerves are located in the midbrain. These nerves control eye and eyelid movement. The cerebral aqueduct, a canal that connects the third and fourth cerebral ventricles, is also located in the midbrain. Other components of the midbrain include:

  • Tectum: The dorsal portion of the midbrain that is composed of the superior and inferior colliculi. These colliculi are rounded bulges that are involved in visual and auditory reflexes. The superior colliculus processes visual signals and relays them to the occipital lobes. The inferior colliculus processes auditory signals and relays them to the auditory cortex in the temporal lobe.
  • Cerebral peduncle: The anterior portion of the midbrain consisting of large bundles of nerve fiber tracts that connect the forebrain to the hindbrain. Structures of the cerebral peduncle include the tegmentum and crus cerebri. The tegmentum forms the base of the midbrain and includes the reticular formation and the red nucleus. The reticular formation is a cluster of nerves within the brainstem that relay sensory and motor signals to and from the spinal cord and the brain. It aids in the control of autonomic and endocrine functions, as well as muscle reflexes and sleep and awake states. The red nucleus is a mass of cells that aids in motor function.
  • Substantia nigra: This large mass of brain matter with pigmented nerve cells produces the neurotransmitter dopamine. The substantia nigra helps control voluntary movement and regulates mood.

Hindbrain (Rhombencephalon)

The hindbrain is composed of two subregions called the metencephalon and myelencephalon. Several cranial nerves are located in this brain region. The trigeminal, abducent, facial, and vestibulocochlear nerves are found in the metencephalon. The glossopharyngeal, vagus, accessory, and hypoglossal nerves are located in the myelencephalon. The fourth cerebral ventricle also extends through this region of the brain. The hindbrain assists in the regulation of autonomic functions, maintaining balance and equilibrium, movement coordination, and the relay of sensory information.

Metencephalon

The metencephalon is the upper region of the hindbrain and contains the pons and cerebellum. The pons is a component of the brainstem, which acts as a bridge connecting the cerebrum with the medulla oblongata and cerebellum. The pons assists in the control of autonomic functions, as well as states of sleep and arousal.

The cerebellum relays information between muscles and areas of the cerebral cortex that are involved in motor control. This hindbrain structure aids in fine movement coordination, balance and equilibrium maintenance, and muscle tone.

Myelencephalon

The myelencephalon is the lower region of the hindbrain located below the metencephalon and above the spinal cord. It consists of the medulla oblongata. This brain structure relays motor and sensory signals between the spinal cord and higher brain regions. It also assists in the regulation of autonomic functions such as breathing, heart rate, and reflex actions including swallowing and sneezing.