The sacrum (pelvic)
The sacrum is roughly triangular in shape and consists of 5 fused vertebrae. It lies at the upper part of the pelvis cavity, with which it articulates. Horizontal ridges indicate the divisions between the fused vertebrae. At the ends of these ridges are openings which allow nerves and blood vessels to pass through.
The Coccyx
The coccyx consists of 4 fused tail vertebrae which are small and have a relatively simple structure. They do not resemble the structure of a typical vertebra. The muscles of the buttocks are attached to the coccyx. It is commonly referred to as the tailbone.
The Sternum (Breastbone)
(Reference of picture http://www.yorku.ca/earmstro/journey/images/sternum.jpg)
The sternum is a long, flat, dagger-shaped bone. It is about 15 - 18 cm long and is found in the centre of the chest region. The broad upper end supports the collar bones. The first seven pairs of ribs are attached to the articulating facets on the sides of the sternum. The 12 thoracic vertebrae, the 12 pair of ribs and the sternum forms the thorax which protects the delicate and vital organs of the thorax, heart and lungs.
Appendicular Skelton
The Appendicular skeleton consists of the girdles and the limbs. The upper (anterior) limbs are attached to the pectoral (shoulder) girdle and the lower (posterior) limbs are attached to the pelvic (hip) girdle.
The Pectoral (Shoulder) Girdle
The Pectoral girdle consists of two shoulder blades (scapulae) and two collar bones (clavicles). These bones articulate with one another, allowing some degree of movement.
(Reference of picture http://en.wikipedia.org/wiki/Image:Illu_pectoral_girdles.jpg)
Shoulder Blades (Scapulae)
The shoulder blade is a flat triangular bone which stretches from the shoulder to the vertebral column at the back. On the back side it has a bony ridge for the attachment of the muscles. The bony ridge forms a prominent projection above the shoulder joint. Beneath the collar bone and just on the inside of the shoulder joint, is another bony projection of the shoulder blade which also serves for the attachment of muscles. The upper outer corner of the shoulder blade ends in the glenoid cavity into which fits the head of the upper arm bone, forming a ball and socket joint.
Collar Bones (clavicle)
Each collar bone is rod-shaped and roughly S-shaped. It lies horizontally and articulates with the upper end of the breastbone, right in the middle and front, just above the first rib. Collar bones serve as a support for the shoulder blades in front and keep the shoulder blades back so that the arms can hang freely at the sides of the body. They prevent the pectoral girdles from getting out of joint easily and ample movement of the shoulders.
The Upper Limbs
The skeleton of the upper limbs or arm may be divided into five main regions: an upper arm bone, the forearm (radius and ulna), the wrist, the palm of the hand and the fingers.
The Upper Arm (Humours)
(Reference of picture www.bartelby.net/107/51.html)
The upper arm is a single long bone. The upper end consists of a semi-circular ball which fits into the socket of the shoulder blade to form the shoulder joint. The lower end of the humours forms a shallow ball and socket joint with the radius and a hinge joint with the ulna in the elbow
The Forearm (Radius and Ulna)
(Reference of picture www.zoology.ubc.ca/.../bonesk/sk04bb01.htm)
The two long bones of the forearm are known as the radius and the ulna. The ulna is the larger of the two bones and is situated on the inner side of the forearm. The upper end of the ulna articulates with the lower end of the humours forming a strong hinge joint in the elbow region. The lower end of the ulna is slender and plays a minor role in the formation of the wrist joint. The radius is situated on the thumb side of the forearm. Its upper end articulates with both the humours and the ulna. The broad, lower end of the radius forms a major part of the wrist joint, where it articulates with the wrist bones (carpals). The radius also allows the forearm to be rotated.
The Wrist
The wrist consists of eight carpal bones. These are small, short bones that are arranged in two rows of four. They have articulating facets which allow them to slide over one another.
The Palm of the Hand
(Reference of picture http://www.dartmouth.edu/~anatomy/assets/bones/wrist-hand/bones2.gif)
The palm is supported by five long metacarpals. The metacarpals articulate with carpals at one end and with the phalanges at the other end.
The Fingers
The fingers are made up of fourteen phalanges. There are three phalanges in each finger but only two in the thumb.
The Pelvic (Hip) Girdle
Female Male
(Reference of picture http://en.wikipedia.org/wiki/Pelvic)
The pelvic girdle consists of two large, sturdy hip bones. Each hip bone consists of three fused bones named the Ilium, ischium and the pubis. The ilium is the largest of the three and forms the upper part of the hip bones. The sacrum fits like a wedge between the two hip bones. The sacrum has a large, flat articular surface on each side for articulation with the ilia. The Ischium forms the inferior part of the hip bone and the pubis the central in front.
The pelvic girdle forms a strong support for the attachment of the limbs. Strong muscles of the back, the legs and the buttocks are attached to it. It protects some of the internal organs. In females it forms a strong basin-like structure for supporting and protecting the developing foetus during child-bearing.
The Lower Limbs or Legs
The skeleton of the lower limb may be divided into five main regions: the upper leg (thigh), the lower leg, the ankle, the arch of the foot and the toes.
The Upper Leg or Thigh
(Reference of picture http://www.allaboutarthritis.com/image/stock_image/hip_anat02b_mmg.gif)
The upper leg has a single long bone, the femur and is the longest bone in the body. The head of the femur is turned slightly inwards and has a large, rounded portion which articulates. At the other end, the femur widens to form two large knobs which form the hinged knee joint with the main long bone (tibia) of the lower leg. On the front side of these two condyle’s, there is an articular surface against which the kneecap (patella) slides. The patella is a small, triangular, flat bone which develops on the tendon of the thigh muscle and is attached by ligaments to the tibia. This enables movement in the knee joint
The Lower Leg
(Reference of picture http://www.patient.co.uk/showdoc/21692493/..%5Cimages%5CI77_L.JPG)
The two bones of the lower leg are the tibia (shinbone) in front and the fibula behind. The tibia is the bigger of the two and extends from the knee to the ankle. The upper end of the tibia has two articulating facets into which the condyle’s of the femur fit to form the knee joint. The lower end of the tibia articulates with one of the tassels to form the ankle joint. The fibula is smaller than the tibia and is on the outside also it is slightly behind the tibia. The upper end articulates with the tibia but does not form part of the knee joint. The lower end forms part of the ankle joint.
The Ankle
(Reference of picture http://www.scoi.com/images/scoi-ankle-main.jpg)
There are seven short, thick tarsal bones, the one is the heel bone, which presses firmly onto the ground when a person stands walks or runs. The calf muscles are attached to the calcenum, allowing the heel to be lifted during movement.
The Arch of the Foot
(Reference of picture http://www.gutenberg.org/files/13910/13910-h/images/fig06-17.png)
The arch is formed partly by some of the tassels but mainly by the five long metatarsals, which extends from the tassels to the toes. The arch is modified for receiving the weight of the body. Some people are born with out arches and it is known as flat feet. They usually wear Orthotic Innersoles (Docpods) to maintain the arch of the foot.
]
The Toes
There are fourteen short phalanges in the toes of each foot. The big toe has two phalanges and the other toes have three in each.
Types of Joints
The human body can bend, swivel, stretch, pivot, and point. Human bodies can perform more than one kind of motion because we have joints.
Fibrous
(Reference of picture http://www.shoppingtrolley.net/images/anatomy/fibrous-joint.jpg)
Fibrous joints connect bones without allowing any movement. The bones of your skull and pelvis are held together by fibrous joints. These joints are also called fixed or immoveable joints, because these joints do not move. This type of joint has no joint cavity and is connected via fibrous connective tissue.
Cartilaginous
(Reference of picture http://www.shoppingtrolley.net/images/anatomy/cartilaginous-joint.jpg)
Cartilaginous joints are joints in which the bones are attached by cartilage.
These joints also have no joint cavity and the bones are connected tightly to each other. These joints only allow a small amount of movement, so are also called partly or slightly moveable joints. The vertebrae are examples of cartilaginous joints.
Synovial
(Reference of picture http://webschoolsolutions.com/patts/systems/capsule.gif)
Most of the joints in the body are synovial joints. These joints are freely moveable and are characterised by being surrounded by an articular capsule which contains the synovial fluid. Bursa sacks contain the synovial fluid. Synovial fluid lubricates the joints, supplies nutrients to the cartilage and it contains cells that remove microbes and debris within the joint cavity. Because of the larger range of movements of this type of joint, there is an increased risk of injury eg dislocations. Synovial joints are located predominantly in limbs.
Different Types of Synovial Joint
Hinge joint
(Reference of picture www.orthoneuro1.com/patiented/elbow.htm)
Hinge - The articular surfaces are moulded to each other in such a manner as to permit motion only in one plane, forward and backwards (movement occurs primarily in a single plane) e.g. elbow, knee, ankle, interphalangeal joints. .
Ball and socket joint
(Reference of picture http://www.stronghealth.com/services/orthopaedics/totaljoint/Ort1935.gif)
Ball and socket - allows movement around 3 axes - flexion / extension, abduction / adduction and rotation, e.g. shoulder, hip. In a ball-and-socket joint, the ball-shaped surface of one bone fits into the cuplike depression of another.
Pivot joint
(Reference of picture http://www.botany.uwc.ac.za/sci_ed/grade10/manphys/images/man/pivot.gif)
Pivot - a ring of bone and ligament surrounds the surface of the other bone - movement in one plane, primarily rotation e.g. between the atlas and axis (i.e. the cervical vertebrae) and the radius and ulna.
Gliding joint
(Reference of picture http://www.shockfamily.net/skeleton/GLIDING.JPG)
Gliding - Flat bone surfaces allow side to side and backwards and forwards movements e.g. between carpals, tarsal, between the sternum and the clavicle and the scapula and the clavicle.
Condyloid joint
(Reference of picture http://en.wikipedia.org/wiki/Image:Gray334.png)
Condyloid - Similar to the ball and socket joint, the condyloid joint allows circular motion. In the condyloid joint, the ball rests up against the end of a bone rather than inside a socket an example is how the carpals of the wrist rest against the end of the radius bone of the forearm
(Reference of picture http://www.hud.ac.uk/hhs/teaching_learning/materials/joints_2004/images/saddle.jpg)
A saddle joint - A saddle joint allows movement back and forth and up and down, but does not allow for rotation like a ball and socket joint an example is the thumb
Muscle structure
All living organisms can move of their own accord or can perform other types of movement. Most living organisms use muscle tissue to get about. Muscle tissue has an ability to relax and contrast so bring about movement and mechanical work in various parts of the body. There are other movements in the body too which are necessary for the survival of the organism such as the heart beat and the movements of the alimentary canal.
Smooth muscle tissue
(Reference of picture http://www.unm.edu/~jimmy/smooth_muscle.jpg)
Smooth muscle tissue is made up of thin-elongated muscle cells, fibres. These fibres are pointed at their ends and each has a single, large, oval nucleus. Each cell has many myofibrils which lie parallel to one another in the direction of the long axis of the cell. They are not arranged in a definite striped pattern, as in skeletal muscles - hence the name smooth muscle . Smooth muscle fibres interlace to form sheets or layers of muscle tissue rather than bundles. Smooth muscle tissue is located in the walls of hollow internal structures such as blood vessels, the stomach, intestines, and urinary bladder. Smooth muscle fibres are usually involuntary and not controlled by the brain, and they are non-striated.
Functions of smooth muscle tissue
- Smooth muscle controls slow, involuntary movements such as the contraction of the smooth muscle tissue in the walls of the stomach and intestines.
- The muscle of the arteries contracts and relaxes to regulate the blood pressure and the flow of blood
Cardiac muscle
(Reference of picture http://www.docfleetwood.net/anatomy/muscular41/cardiac%20muscle.bmp)
Cardiac muscle is the type of muscle found in the heart, and at the base of the vena cava as they enter into the heart. Cardiac muscle is intrinsically contractile but is regulated by autonomic and hormonal stimuli. Cardiac Muscle Tissue shows some of the characteristics of smooth muscle and some of skeletal muscle tissue. Its fibres, like those of skeletal muscle, have cross-striations and contain numerous nuclei. However, like smooth muscle tissue, it is involuntary.
Functions of Cardiac Muscle Tissue
- Cardiac muscle tissue plays the most important role in the contraction of the atria and ventricles of the heart.
- It causes the rhythmical beating of the heart, circulating the blood and its contents throughout the body as a consequence
Skeletal muscle
(Reference of picture http://training.seer.cancer.gov/module_anatomy/images/illu_muscle_structure.jpg)
Skeletal muscle is the most abundant tissue in the vertebrate body. These muscles are attached to and bring about the movement of the various bones of the skeleton, hence the name skeletal muscles. It is striated; that is, the fibres (cells) contain alternating light and dark bands (striations) that are perpendicular to the long axes of the fibres. Skeletal muscle tissue can be made to contract or relax by conscious control (voluntary).
Functions of Skeletal Muscles
- Skeletal muscles function in pairs to bring about the co-ordinated movements of the limbs, trunk, jaws, eyeballs, etc.
- Skeletal muscles are directly involved in the breathing process.
Structure of skeletal muscle
The whole muscle, such as the biceps, is enclosed in a sheath of connective tissue, the epimysium. This sheath folds inwards into the substance of the muscle to surround a large number of smaller bundles, the fasciculi. These fasciculi consist of still smaller bundles of elongated, cylindrical muscle cells, the fibres. Each fibre is a syncytium, i.e. a cell that has many nuclei. The nuclei are oval in shaped and are found at the periphery of the cell, just beneath the thin, elastic membrane (sarcolemma). The sarcoplasm also has many alternating light and dark bands, giving the fibre a striped or striated appearance (hence the name striated muscle). With the aid of an electron microscope it can be seen that each muscle fibre is made up of many smaller units, the myofibrils. Each myofibril consists of small protein filaments, known as actin and myosin filaments. The myosin filaments are slightly thicker and make up the dark band (or A-band). The actin filaments make up the light bands (I-bands) which are situated on either side of the dark band. The actin filaments are attached to the Z-line. This arrangement of actin and myosin filaments is known as a sacromere.
(Reference of picture http://www.life.uiuc.edu/crofts/bioph354/images/sarcom2.JPG)
During the contraction of skeletal muscle tissue, the actin filaments slide inwards between the myosin filaments. Mitochondria provide the energy for this to take place. This action causes a shortening of the sacromeres (Z-lines move closer together), which in turn causes the whole muscle fibre to contract. This can bring about a shortening of the entire muscle such as the biceps, depending on the number of muscles fibres that were stimulated. The contraction of skeletal muscle tissue is very quick and forceful.
Muscle fibre types
All skeletal muscle fibres are not alike in structure or function. For example, skeletal muscle fibres vary in colour depending on their content of myoglobin (myoglobin stores oxygen until needed by mitochondria). Skeletal muscle fibres contract with different velocities, depending on their ability to split Adenosine Triphosphate (ATP). Faster contracting fibres have greater ability to split ATP. In addition, skeletal muscle fibres vary with respect to the metabolic processes they use to generate ATP. They also differ in terms of the onset of fatigue. On the basis of various structural and functional characteristics, skeletal muscle fibres are classified into three types: Type I fibres, Type II B fibres and type II A fibres.
Type I Fibres
These fibres, also called slow twitch or slow oxidative fibres, contain large amounts of myoglobin, many mitochondria and many blood capillaries. Type I fibres are red, split ATP at a slow rate, have a slow contraction velocity, very resistant to fatigue and have a high capacity to generate ATP by oxidative metabolic processes. Such fibres are found in large numbers in the postural muscles of the neck
Type II A Fibres
These fibres, also called fast twitch or fast oxidative fibres, contain very large amounts of myoglobin, very many mitochondria and very many blood capillaries. Type II A fibres are red, have a very high capacity for generating ATP by oxidative metabolic processes, split ATP at a very rapid rate, have a fast contraction velocity and are resistant to fatigue. Such fibres are infrequently found in humans.
Type II B Fibres
These fibres, also called fast twitch or fast glycolytic fibres, contain a low content of myoglobin, relatively few mitochondria, relatively few blood capillaries and large amounts glycogen. Type II B fibres are white, geared to generate ATP by anaerobic metabolic processes, not able to supply skeletal muscle fibres continuously with sufficient ATP, fatigue easily, split ATP at a fast rate and have a fast contraction velocity. Such fibres are found in large numbers in the muscles of the arms.
(Reference used http://www.brianmac.demon.co.uk/muscle.htm)
Sliding filament theory of contraction
The mechanism of filament sliding during contraction of a myofibril.
In the absence of calcium ions, tropomyosin blocks access to the mysosin binding site of actin. When calcium binds to troponin, the positions of troponin and tropomyosin are altered on the the thin flament and myosin then has access to its binding site on actin.
Myosin hydolyzes ATP and undergoes a conformational change into a high-energy state. The head group of myosin binds to actin forming a cross-bridge between the thick and thin filaments. The energy stored by myosin is released, and ADP and inorganic phosphate dissociate from myosin. The resulting relaxation of the myosin molecule entails rotation of the globular head, which induces longitudinal sliding of the filaments.
When the calcium level decreases, troponin locks tropomyosin in the blocking position and the thin filament slides back to the resting state.
References
Blackboard work sheets
Work done in class
http://en.wikipedia.org
