Human Anatomical Variations And Anomalies: An Essay On Development.

Skull Flat Bones and its Parts

Describe about the Human Anatomical Variations and Anomalies.Developmental?

The skull flat bones is the bony structure forming the head of the skeleton. It has two parts, the facial skeleton and the neurocranium. The former is composed of bones and the latter forms a cranial cavity. The bones of the skull are joined by synarthrodial joints. The flat bones in the skull includes occipital, parietal, frontal, nasal, lacrimal and vomer bones.

The skull supports the face structure and forms a cavity for the brain. It protects the brain from injuries. The flat bones gives protection or broad surfacre for muscle attachment.

The spine is made of a series of bones packed like blocks with cushions called discs in between. The spine is present from the base of the skull till the pelvis.

The spine is the pillar of support for the weight of the body and it protects the spinal cord.

The vertebral column is composed up of cortical bones. It is surrounded by a connective tissue membrane and below the cortical bone layer is the layer of spongy cancellous bone. The vertebral column is divided into different regions which are named according to the region of spine. These are cervical spine, lumbar spine, thoracic spine, sacrum and coccyx. The medullary cavity lies within this that has an inner core of bone marrow.

These bones function in skeletal mobility and are subjected to load during activities of daily life (Notebaert, 2014).

These are synarthrodial or immovable joints and are a kind of fibrous joints. These are formed by bony ossification. The Sharpey’s fibres permit some level of flexibility. Little movement in the suture contributes to elasticity and compliance of the skull.

This is a kind of fibrocartilaginous joint. The joint lies between adjacent vertebrae. The joints allow slight movement of the vertebrae. Moreover, it acts as the ligament for holding the vertebrae together. They too have a role as shock absorbers.

This is a kind of synovial joint. They achieve movement at the point of contact of the articulating bones. The movements possible with synovial joints are adduction, abduction, flexion, extension and rotation. Abduction refers to the movement away from the mid-line of the body. Adduction is the movement toward the mid-line of the body. Extension is the straightening limbs at a joint and flexion refers to the bending of limbs at a joint. Rotation is the circular movement around the fixed point.

Function of Skull and Flat Bones

The synovial joint is the movable type of joints in human body. Its structure  consist of synovial cavity, joint capsule and articular cartilage.

Synovial cavity- It has space between bone filled with synovial fluid.

Joint capsule- It consist ofs outer fibrous membrane containing ligaments and inner synovial membrane secreting synovial fluid. The synovial fluid lubricates the joint and acts as a shock absorber.

Articular cartilage- It is a layer of hyaline cartilage lining the epiphyses of joint with smooth surfaces. It acts as a shock absorber and prevents friction during movement.

This is the Tendon tissue. It is a band of  fibrous connective tissue which attaches muscle to bones. It is composed of collagen and attaches to the connective tissue layer called periosteum.

Function- Its main function is to attach bones to muscles and enable flexible movement in the body. Movements like running, jumping, lifting and other physical actions occurs because of tendon tissue. Longer than average tendons in calf muscles or back of heel is advantageous for long distance runners.

This is the structure of ligament. It is a dense band of fibrous connective tissue made of  collagen fibres which connects one bones to other bones to form joints. The fibres of connective tissues are arranged irregularly or in parallel starns. Irregular fibrous connective tissue is found in dermis of skin and regular fibrous connective tissue is found in tendons and ligaments.

Function- It provides stability to joints and prevent those movement that might damage joints. It ensures proper alignment of bones during movement. It different range of motion control for different joints. For example it prevents elbow joints from extending backward.

This is the Articular cartilage. It is the specialized connective tissue of diarthrodial joints. The cartilage is repsonisble for facilitating load transmission with reduced friction and giving a lubricated surface for articulation. It does not have lymphatics, nerves and blood vessels and has a low capacity for intrinsic healing and repair.

The 3 types of muscle tissue are cardiac, smooth, and skeletal. Cardiac muscle cells are found in the walls of the heart where they appear striated, and have involuntary control. Smooth muscle fibers are present in the walls of hollow visceral organs, apart from the heart. They  appear as spindle-shaped, and are under involuntary control. Skeletal muscle fibers are present  in muscles attached to the skeleton. They are striated in appearance and are under voluntary control (Lindstedt, 2016).

The Spine and its Functions

A nerve impulse at neuromuscular junction stimulates release of Acetylcholine. It lead sto depeolarization of motor end plate which travel throughout the muscle by transverse tubules. It causes the release of Ca+ ions from sarcoplasmic reticulum.

In the presence of high Ca+ ions, the ions binds to Troponin and changes the shape. This results in moving Tropomypsin from the active site of the Actin. The next step is attachment of myosin filaments to the Actin and formation of a bridge.

When ATP is broken down it causes release of energy and enables the myosin to pull the actin filaments inwards. This shortenes the muscle.

Detachment of myosin from actin takes place and this leads to the break of the cross-bridge when a molecule of ATP binds to myosin. When the ATP is broken, the myosin head is again attached to the actin binding site.

The process of contraction takes place till there is sufficient ATP and Ca+ stores. When the impulse stops, Ca+ ions is pumped back to sarcoplasmic reticulum and actin returns to resting positon causing the muscles to leghten and relax again (Rall, 2014).

The biceps and the triceps are the antagonistic muscles. The elbow joints is responsible for the movement of the forearm. The biceps refers to the front of the upper arm and the triceps refers to the back of the upper arm. When the triceps muscle contracts, there is a downward movement of the forearm whereas when the biceps muscle contracts, upper movement of the forearmtakes place. For the foreaem to lift, the biceps contracts and the triceps relaxes. For lowering the forearm, the triceps undergoes contraction and the biceps undergo relaxation (Jarmey, 2013).

There are numerous risks associated with poor posture. Poor posture can impede the ability of the lungs to expand. Posture, when correct, helps to increases one's ability to breathe, and allows muscles to work at optimum capacity. Bad posture causes physical and mental heath complications iuncluding depression and stress. Poor posture is also a main risk factor in many injuries. They also develop poor breathing as it restricts blood and oxygen flow. Neck pain and back pain are very common. People may be suffering from headaches (Diogo & Wood, 2016).

Imporper lifting techniques can cause injuries. Muscle injuries occur when a person getting out of lifting outs a great amount of stress on the lower back muscle and the demand on the muscle is high. Disc injuries can also occur when injuries occur to the invertebral discs. There are many joints where bones come in contact with each other in the back. Usually they are capable of handling the stresses related to lifting. However, inappropriate lifting techniquescan irritate the joints and may cause them to become "locked” (Isa et al., 2014).

The pain and discomfort of arthritis can make it difficult to sleep. Many people with feel irresistable fatigue and a lack of energy. In some cases, flare-ups leads toshort-term fever. Lack of appetite can contribute to poor overall health. The organs mostly effected are circulatory system, mouth, eyes and skin, respiratory system and immune system. The complications with skin are rashes and nodule formation. Complication arises with thinning of bones. Scarring, inflammation, and drying are the possible effects o the eyes. Lungs are effected in that they get scarred and inflamed. Atherosclerosis and stroke may be some other potential complications. Blood clots, anemia, Felty syndrome, compressed or pinched nerves  are some other negative impacts on a person’s health (Wilcox et al., 2014). Arthritis affects normal movement of human body. The protective cartilage and fluids inside joints breakdown due to wearing down of tissues or  injury. It makes the movement of affected joints difficult and painful. When bones rub against each other, it causes acute pain. Continuor painful friction may also lead to inflammation in knees, hips, spine and hand. The intensity of pain varies from person to person.

References

Diogo, R., & Wood, B. (2016). Origin, Development, and Evolution of Primate Muscles, with Notes on Human Anatomical Variations and Anomalies.Developmental Approaches to Human Evolution, 167-204.

Isa, H., Kamat, S. R., Rohana, A., Saptari, A., &Shahrizan, M. (2014, June). Analysis of Muscle Activity using Surface Electromyography for Muscle Performance in Manual Lifting Task. In Applied Mechanics and Materials (Vol. 564, pp. 644-649).

Jarmey, C. (2013). The concise book of muscles. North Atlantic Books.

Lindstedt, S. L. (2016). Skeletal muscle tissue in movement and health: positives and negatives. Journal of Experimental Biology, 219(2), 183-188.

Netter, F. H. (2014). Atlas of Human Anatomy, Professional Edition: including NetterReference. com Access with Full Downloadable Image Bank. Elsevier Health Sciences.

Notebaert, A. (2014). Student use of pictures on text-based examination questions in an undergraduate human anatomy course (530.6). The FASEB Journal, 28(1 Supplement), 530-6.

Rall, J. A. (2014). Birth of the sliding filament model of muscular contraction: proposal. In Mechanism of Muscular Contraction (pp. 29-57). Springer New York.

Wilcox, S., Schoffman, D. E., Dowda, M., & Sharpe, P. A. (2014). Psychometric Properties of the 8-Item English Arthritis Self-Efficacy Scale in a Diverse Sample. Arthritis, 2014.