Discuss the axial and appendicular parts of the skeleton systemExplain the function of joints in bones movementExplain the duty of muscles in locomotion=

The muscular and skeletal systems carry out support to the human body and permit for movement. The skeletal of the skeleton protect the body’s interior organs and support the load of the body. The muscles of the muscular mechanism contract and pull ~ above the bones, enabling for activities as varied as standing, walking, running, and also grasping items.

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Injury or condition affecting the musculoskeletal system can be an extremely debilitating. The most usual musculoskeletal diseases global are resulted in by malnutrition, which have the right to negatively affect breakthrough and maintain of bones and also muscles. Various other diseases influence the joints, such as arthritis, which deserve to make movement difficult and, in advanced cases, completely impair mobility.

Progress in the scientific research of prosthesis architecture has led to the development of artificial joints, through joint replacement surgical treatment in the hips and knees gift the most common. Replacement joints because that shoulders, elbows, and also fingers are likewise available.

Skeletal System

The person skeleton is an endoskeleton that is composed of 206 skeleton in the adult. An endoskeleton develops within the body rather than exterior like the exoskeleton of insects. The skeleton has five main functions: giving support to the body, storing minerals and lipids, producing blood cells, protecting inner organs, and allowing for movement. The skeletal device in vertebrates is divided into the axial skeleton (which is composed of the skull, vertebral column, and rib cage), and the appendicular skeleton (which is composed of limb bones, the pectoral or shoulder girdle, and the pelvic girdle).


Concept in Action

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Explore the human skeleton by city hall the following video clip with digital 3D sculpturing.


The axial skeleton develops the main axis that the body and includes the skeletal of the skull, ossicles of the center ear, hyoid bone the the throat, vertebral column, and also the thoracic cage (rib cage) (Figure 11.25).

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Figure 11.25 The axial skeleton, presented in blue, is composed of the skeletal of the skull, ossicles the the center ear, hyoid bone, vertebral column, and also thoracic cage. The appendicular skeleton, presented in red, consists of the skeletal of the pectoral limbs, pectoral girdle, pelvic limb, and pelvic girdle. (credit: modification of work-related by Mariana Ruiz Villareal)

The skeletal of the skull assistance the frameworks of the face and also protect the brain. The skull consists of cranial bones and facial bones. The cranial bones kind the cranial cavity, i beg your pardon encloses the mind and serves together an attachment website for muscles of the head and also neck. In the adult they room tightly jointed with connective tissue and adjoining bones do not move.

The listening ossicles the the center ear transmit sounds from the air together vibrations to the fluid-filled cochlea. The listening ossicles consist of 2 malleus (hammer) bones, 2 incus (anvil) bones, and also two stapes (stirrups), one on every side. Facial bones carry out cavities for the sense organs (eyes, mouth, and nose), and serve as attachment points for facial muscles.

The hyoid bone lies listed below the mandible in the prior of the neck. The acts together a movable base because that the tongue and also is linked to muscle of the jaw, larynx, and tongue. The mandible creates a joint through the base of the skull. The mandible controls the opening to the mouth and hence, the airway and also gut.

The vertebral column, or spinal column, surrounds and protects the spinal cord, supports the head, and also acts together an attachment suggest for ribs and muscles that the earlier and neck. It is composed of 26 bones: the 24 vertebrae, the sacrum, and also the coccyx. Each vertebral body has actually a huge hole in the facility through i m sorry the spinal cord passes under to the level of the an initial lumbar vertebra. Listed below this level, the hole contains spinal nerves i m sorry exit in between the vertebrae. There is a notch on every side the the hole with which the spinal nerves, can departure from the spinal cord come serve different regions that the body. The vertebral obelisk is around 70 centimeter (28 in) in adults and is curved, which can be seen from a next view.

Intervertebral discs composed of fibrous cartilage lie between surrounding vertebrae from the second cervical vertebra come the sacrum. Each disc helps kind a contempt moveable joint and acts as a cushion come absorb shocks from movements such together walking and running.

The thoracic cage, additionally known together the rib cage consists of the ribs, sternum, thoracic vertebrae, and also costal cartilages. The thoracic cage encloses and protects the organs of the thoracic cavity including the heart and lungs. It additionally provides assistance for the shoulder girdles and also upper limbs and also serves together the attachment suggest for the diaphragm, muscles of the back, chest, neck, and shoulders. Alters in the volume of the thorax enable breathing. The sternum, or breastbone, is a long level bone situated at the anterior the the chest. Choose the skull, that is formed from countless bones in the embryo, i m sorry fuse in the adult. The ribs are 12 pairs of lengthy curved skeleton that attach to the thoracic vertebrae and also curve towards the front of the body, developing the ribcage. Costal cartilages affix the anterior end of most ribs to the sternum.

The appendicular skeleton is created of the bones of the upper and also lower limbs. It likewise includes the pectoral, or shoulder girdle, which attaches the top limbs to the body, and the pelvic girdle, which attaches the reduced limbs come the human body (Figure 11.25).

The pectoral girdle bones transfer pressure generated by muscles exhilaration on the upper limb come the thorax. It consists of the clavicles (or collarbones) in the anterior, and also the scapulae (or shoulder blades) in the posterior.

The top limb consists of bones the the eight (shoulder to elbow), the forearm, and the hand. The humerus is the largest and longest bone the the top limb. It forms a joint through the shoulder and with the forearm in ~ the elbow. The forearm extends native the elbow to the wrist and also consists of 2 bones. The hand has the skeletal of the wrist, the palm, and the bones of the fingers.

The pelvic girdle attaches come the reduced limbs of the axial skeleton. Due to the fact that it is responsible because that bearing the load of the body and for locomotion, the pelvic girdle is securely attached to the axial skeleton by solid ligaments. It likewise has deep sockets with robust ligaments that securely connect to the femur. The pelvic girdle is mostly composed of two huge hip bones. The hip bones join together in the anterior of the human body at a joint referred to as the pubic symphysis and also with the skeletal of the sacrum in ~ the posterior of the body.

The lower limb is composed of the thigh, the leg, and also the foot. The skeleton of the reduced limbs space thicker and stronger than the skeletal of the upper limbs to support the entire weight that the body and also the pressures from locomotion. The femur, or thighbone, is the longest, heaviest, and also strongest bone in the body. The femur and also pelvis type the i know good joint. At its various other end, the femur, together with the shinbone and kneecap, type the knee joint.

Joints and also Skeletal Movement

The suggest at which two or much more bones accomplish is called a joint, or articulation. Joints room responsible for movement, such as the movement of limbs, and also stability, such together the stability uncovered in the skeletal of the skull.

There are two means to classify joints: based upon their structure or based upon their function. The structural group divides joints into fibrous, cartilaginous, and also synovial joints relying on the material composing the joint and the existence or absence of a cavity in the joint. The skeletal of fibrous joints are held together through fibrous connective tissue. Over there is no cavity, or space, present between the bones, so many fibrous joints do not relocate at all, or are only qualified of young movements. The joints in between the skeletal in the skull and also between the teeth and the bone of your sockets are examples of fibrous joints (Figure 11.26 a).

Cartilaginous joints space joints in which the bones are associated by cartilage (Figure 11.26 b). An example is uncovered at the joints between vertebrae, the so-called “disks” of the backbone. Cartilaginous joints permit for very little movement.

Synovial joints are the just joints that have a an are between the adjoining skeleton (Figure 11.26 c). This room is referred to as the share cavity and also is filled with fluid. The fluid lubricates the joint, reducing friction between the bones and enabling for better movement. The ends of the bones space covered v cartilage and the whole joint is surrounding by a capsule. Synovial joints are qualified of the biggest movement of the joint types. Knees, elbows, and shoulders are instances of synovial joints.

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Figure 11.26 (a) Sutures room fibrous joints found only in the skull. (b) Cartilaginous joints space bones connected by cartilage, such as between vertebrae. (c) Synovial joints room the just joints that have actually a room or “synovial cavity” in the joint.

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The wide variety of movement allowed by synovial joints produce different varieties of movements. Angular motions are developed when the angle between the skeletal of a joint changes. Flexion, or bending, occurs once the angle in between the bones decreases. Moving the forearm upward at the elbow is an instance of flexion. Expansion is the opposite of flexion in the the angle between the skeleton of a joint increases. Rotational motion is the movement of a bone together it rotates approximately its very own longitudinal axis. Motion of the head as in speak “no” is an instance of rotation.