Category Human Body

There are three types of muscle in the body. Bones are covered mostly in skeletal muscle, which creates movement by pulling on the bones. Smooth muscle keeps the digestive and other systems moving, while cardiac muscle causes the heart to beat non-stop.

Skeletal muscle

Found in the arms and legs, the long thread-like fibres of skeletal muscles shrink and shorten to move the bones. These are voluntary muscles, which means that we decide to move them.

Smooth muscle

Packed together in layered sheets, smooth muscle lines the walls of the digestive system, the airways, and the bladder. These muscles work automatically, to keep, vital body functions working.

Cardiac muscle

The walls of the heart are formed by cardiac muscle. This must contract continually to keep the heart beating. Cardiac muscle never gets tired, unlike other types of muscle.

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This front view of the skeleton shows the body’s deepest layer of skeletal muscles. Skeletal muscles in the back and neck work to keep the body upright, while those in the arms and legs are used for walking, running, and all kinds of other physical activities.

Sternothyroid

This strap-like muscle at the front of the neck the larynx down.  It is a part of a group of muscles called the infrahyoid muscles. There are four such muscles that are grouped into superficial and deep layers.

Pectoralis minor

This muscle helps to stabilize the shoulder blade when the arm moves. It is one of the anterior axioappendicular (thoracoappendicular) muscles, together with the pectoralis major, subclavius and serratus anterior.

Together with other muscles of the region it produces various movements of the scapula and can be used as an accessory muscle of respiration.

Brachialis

The brachialis helps to bend the elbow. It is fusiform in shape and located in the anterior (flexor) compartment of the arm, deep to the biceps brachii. The brachialis is a broad muscle, with its broadest part located in the middle rather than at either of its extremities.

Intercostal muscles

These muscles between the ribs help with breathing by raising the ribs up and out. The muscles are broken down into three layers, and are primarily used to assist with the breathing process. The three layers are: external intercostal muscles, internal intercostal muscles, and the innermost intercostal muscles.

Posterior rectus sheath

This tissue is formed by the tendons of abdominal muscle. It is an extension of the tendons of the external abdominal oblique, internal abdominal oblique, and transversus abdominis muscles. 

Transversus abdominis

This muscle helps to stabilize the pelvis and lower back when moving. Along with the external abdominal oblique and the internal abdominal oblique, it comprises the lateral abdominal muscles. Combined with the two anterior abdominal muscles (rectus abdominis and pyramidalis), these muscles make up the anterolateral abdominal wall.

Flexor digitorum profundus

This muscle helps to bend the fingers. Flexor digitorum profundus is a fusiform muscle located deep within the anterior (flexor) compartment of the forearm. Along with the flexor pollicis longus and pronator quadratus muscles, it comprises the deep flexor compartment of the forearm.

Gluteus medius

This muscle moves the thigh outwards. Together with the gluteus maximus, gluteus minimus and tensor fasciae latae muscles, it belongs to the muscles of the gluteal region.

Pectineus

This muscle helps to lift the thigh. Fascial compartments of the thigh muscles are specific in that each of them is innervated by a particular nerve. Due to having dual innervation, pectineus is one of a few muscles classified into two compartments at the same time; anterior and medial. The others being adductor longus and adductor magnus.

Adductor compartment of thigh

These muscles bring the thighs together. The adductor magnus is the largest muscle in the medial compartment. It lies posteriorly to the other muscles.

Functionally, the muscle can be divided into two parts; the adductor part, and the hamstring part.

Vastus intermedius

This is one of the four parts of the strong quadriceps muscle at the front of the thigh. Vastus Intermedius is located centrally, underneath Rectus femoris in the anterior compartment of the thigh and on each side of it: Vastus medialis and Vastus Lateralis respectively. It is one of the four muscles that form the quadriceps femoris muscle. Tensor of Vastus Intermedius is a new muscle that is part of the Quadriceps.

Patella (kneecap)

The patella is the kneecap bone. It lies within the quadriceps tendon. This large tendon from the powerful thigh muscles (quadriceps) wraps round the patella and is attached to the top of the lower leg bone (tibia). The quadriceps muscles straighten the knee.

Extensor digitorum longus

This long muscle lifts up the foot and the toes. Besides EDL muscle, this compartment also contains the tibialis anterior, extensor hallucis longus and fibularis (peroneus) tertius muscles.

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Every single movement your body makes is produced by the muscular system. Muscles are layers of hardworking tissue that shape the body, keep it upright, and move it around.

Muscle tissue is made of long cells called fibres, which use energy to contract, or shorten, pulling different parts of the body into position. Movements are controlled by nerve signals from the brain. Sometimes you move your muscles consciously, such as when you sit down, or turn to look at something. But other muscle movements, such as your heartbeat, or when you blink your eyes, hapopen without you thinking about them.

There are three distinct types of muscles: skeletal muscles, cardiac or heart muscles, and smooth (non-striated) muscles. Muscles provide strength, balance, posture, movement and heat for the body to keep warm.

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Bones have different shapes and sizes, depending on their functions. There are five kinds of bone in the human skeleton.

Long bones

These bones are longer than they are wide and are found in the arms, hands, legs, and feet. They support the body’s weight and allow it to move.

Short bones

Roughly cube-shaped bones in the wrist and ankle allow some movement and provide stability to the joints.

Flat bones

Shield-like flat bones protect organs such as the heart and brain.

Irregular bones

These bones have complex shapes, to perform specific roles. For example, the vertebrae allow the back to bend and rotate, and protect the spinal cord.

Sesamoid bones

These small, roundish bones protect tendons and joints from wear and tear. The patella protects the knee joint. It sits inside the tendon that attaches the thigh muscle to the shinbone.

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From the back you can clearly see the complex structure of the spinal column and paired ribs. Each wing-like shoulder blade forms part of the shoulder gridle, where the arm attaches to the axial skeleton.

Suture

Suture lines form where bones of the skull have joined (fused) together.  A tiny amount of movement is permitted at sutures, which contributes to the compliance and elasticity of the skull. These joints are synarthroses. It is normal for many of the bones of the skull to remain unfused at birth.

Parietal bones

A pair of bones makes up the sides of the skull. The parietal bones are marked internally by meningeal blood vessels and externally by the temporal muscles. They meet at the top of the head (sagittal suture) and form a roof for the cranium. 

Occipital bone

This flattish bone forms the back of the skull. The occipital is cupped like a saucer in order to house the back part of the brain. It is one of seven bones that fuse together to form the skull and is directly next to five of the cranium bones.

Atlas

The uppermost vertebra of the spine, this bone supports the head. The atlas does not look like a typical vertebra, with its ring-like structure and the absence of a body, which is actually fused to the axis. Other anatomical landmarks on the atlas include the anterior arch and tubercle, posterior arch and tubercle, vertebral notches, facets, and transverse processes.

Axis

The second bone of the vertebral column allows the head to move from side to side. The axis is somewhat analogous to the other cervical vertebrae in shape, but it differs slightly for two reasons: its spinous process isn’t as obviously bifid, and the presence of the dens. The spinous process serves as the attachment site for many muscles of the spine, particularly those close to the skull, as well as the nuchal ligament.

Cervical vertebrae

These seven bones form the upper part of the spine.  Among the vertebrae of the spinal column, the cervical vertebrae are the thinnest and most delicate bones. Yet, in spite of their size, the cervical vertebrae have the huge jobs of supporting the head, protecting the spinal cord, and providing mobility to the head and neck.

Acromion

This is the highest part of the shoulder blade. It is an important landmark of the skeletal system and a muscle attachment point essential to the function of the shoulder joint. The acromion also forms the acromioclavicular (AC) joint with the clavicle.

Clavicle

This long bone is called the collarbone. The clavicle (collarbone) extends between the manubrium of the sternum and the acromion of the scapula. It is classed as a long bone, and can be palpated along its length. In thin individuals, it is visible under the skin. 

Scapula

Also called the shoulder blade, it connects the arm to the shoulder. In humans they are triangular and lie on the upper back between the levels of the second and eighth ribs. A scapula’s posterior surface is crossed obliquely by a prominent ridge, the spine, which divides the bone into two concave areas, the supraspinous and infraspinous fossae.

Spinal column

Also called the backbone, it is made up of 24 small bones (vertebrae), which protect the nerves.  The Spinal Column is also called the vertebral column. The bones in the spine are called vertebrae (ver-ta-bray). The column starts at the base of the skull and continues to the pelvis. Alternate layers of bone (vertebrae) and cartilage (car-til-ledge, the intervertebral discs) stack vertically one on top of the other in the spinal column. The lattice-like structure of the cancellous bone (cancel-lus, the spongy interior) in a vertebra absorbs external pressure.

Rib

The 12 pairs of curved rib bones protect the heart and lungs. The ribs partially enclose and protect the chest cavity, where many vital organs (including the heart and the lungs) are located. The rib cage is collectively made up of long, curved individual bones with joint-connections to the spinal vertebrae. 

Humerus

This is the upper arm bone. It is located between the elbow joint and the shoulder. At the elbow, it connects primarily to the ulna, as the forearm’s radial bone connects to the wrist. 

Lumber vertebrae

These five bones form the lower part of the spinal column. These vertebrae carry all of the upper body’s weight while providing flexibility and movement to the trunk region. They also protect the delicate spinal cord and nerves within their vertebral canal.

Ulna

This is the inner bone of the forearm. The ulna is located on the opposite side of the forearm from the thumb. It joins with the humerus on its larger end to make the elbow joint, and joins with the carpal bones of the hand at its smaller end.

Ilium

The ilium is one of the bones that makes up the pelvis. In humans, it is divided into two sections: the body and the ala, indicated by a line on the surface of the bone. The other two bones that form the fused pelvis are the ischium and the pubis, which lie below the ilium.

Radius

This is the outer bone of the forearm. It lies laterally and parallel to ulna, the second of the forearm bones. The radius pivots around the ulna to produce movement at the proximal and distal radio-ulnar joints.

Sacrum

This is large, triangular bone that forms the base of the spine. It forms the solid base of the spinal column where it intersects with the hip bones to form the pelvis. The sacrum is a very strong bone that supports the weight of the upper body as it is spread across the pelvis and into the legs. 

Coccyx

Several tiny bones at the end of the spine fuse to form the coccyx.  It is composed of three to five coccygeal vertebrae or spinal bones. The vertebrae may be fused together to form a single bone; however, in some cases, the first vertebra is separate from the others.

Femur

The femur, or thigh bone, is the longest bone in the body. It functions in supporting the weight of the body and allowing motion of the leg. The femur articulates proximally with the acetabulum of the pelvis forming the hip joint, and distally with the tibia and patella to form the knee joint.

Femoral condyles

These rounded, knobbly ends of the femur form part of the knee joint. There are two condyles on each leg known as the medial and lateral femoral condyles. If there is a fracture (break) in part of the condyle, this is known as a fracture of the femoral condyle. Physiotherapy is very important during the rehabilitation following a femoral condyle fracture.

Tibia

The front of this bone is the shin. It forms the knee joint with the femur and the ankle joint with the fibula and tarsus. Many powerful muscles that move the foot and lower leg are anchored to the tibia. 

Fibula

The smaller bone of the lower leg, this is located alongside the tibia. It runs parallel to the tibia, or shin bone, and plays a significant role in stabilizing the ankle and supporting the muscles of the lower leg. Compared to the tibia, the fibula is about the same length, but is considerably thinner.

Heel bone

The largest bone in the foot, this is also called calcaneus. It is situated in the back of the foot, just below the talus, tibia, and fibula bones of the lower leg. Of all of the bones in the foot, the heel bone is the largest.

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The skeleton can be divided into two parts. The axial skeleton (red) forms a central core that supports the upper body and protects important organs. The appendicular skeleton (blue) consists of the arm and leg bones, and the bony gridles that connect them to the axial skeleton.

Axial skeleton

This is made of 80 bones of the skull, vertebrate column, ribs, and breastbone. The bones of the axial skeleton, along with ligaments and muscles, allow the human body to maintain its upright posture. The axial skeleton also transmits weight from the head, trunk, and upper extremities down the back to the lower extremities. In addition, the bones protect the brain and organs in the chest.

Appendicular skeleton

This consists of the 126 bones of the upper and lower limbs, and the shoulder and hip gridles. It includes the bones of the arms and legs, hands and feet, and shoulder and pelvic girdles. The bones of the appendicular skeleton make possible locomotion and other movements of the appendages. They also protect the major organs of digestion, excretion, and reproduction.

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