Axial skeleton and appendicular skeleton

The bones of the human skeleton are divided into two groups, on the one hand the axial skeleton and on the other the appendicular skeleton. The appendicular skeleton includes all the bones that make up the upper and lower extremities, and the shoulder girdle and pelvic girdle. The axial skeleton includes all the bones along the longitudinal axis of the body. The axial skeleton includes the bones that make up the skull, laryngeal skeleton, spine, and rib cage. The bones of the appendicular skeleton (the limbs and girdles) are “attached” to the axial skeleton. Today in this blog we want to tell you about the axial skeleton and the appendicular skeleton, so that you can recognize where they are in the human body and which are the bones that make them up. So if you want to learn a little more about the human body, it is a good idea that you continue to enjoy all the information that we give you here.

What is the axial skeleton?

The axial skeleton forms the central axis of the body and includes the bones of the skull, the ossicles of the middle ear, the hyoid bone of the throat, the spine, and the rib cage. The role of the axial skeleton is to provide support and protection to the brain, spinal cord, and organs in the ventral cavity of the body. It provides a surface for the attachment of the muscles that move the head, neck, and trunk, performs respiratory movements, and stabilizes parts of the appendicular skeleton.

Skull bones

The bones of the skull support the structures of the face and protect the brain. The skull consists of 22 bones, which are divided into two categories: cranial bones and facial bones. The cranial bones are eight bones that make up the cranial cavity, which encloses the brain and serves as an attachment site for the muscles of the head and neck. The eight cranial bones are the frontal, two parietal, two temporal, occipital, sphenoid, and ethmoid.

auditory hairs

The auditory ossicles in the middle ear transmit sounds from the air as vibrations to the fluid-filled cochlea. The auditory ossicles consist of six bones: two hammer bones, two anvil bones, and two stirrups (one from each bone on each side). These are the smallest bones in the body and are unique to mammals.

Facial bones

Fourteen facial bones make up the face, provide cavities for the sense organs (eyes, mouth, and nose), protect the entrances to the digestive and respiratory tracts, and serve as attachment points for the facial muscles. The 14 facial bones are the nasal bones, the maxillary bones, the zygomatic bones, the palatine, the vomer, the lacrimal bones, the lower nasal turbinates, and the jaw. All of these bones occur in pairs, except the jaw and vomer.

Hyoid bone

Although not found in the skull, the hyoid bone is considered a component of the axial skeleton. The hyoid bone is located under the jaw at the front of the neck. It acts as a movable base for the tongue and is connected to the muscles of the jaw, larynx, and tongue. The jaw articulates with the base of the skull. The jaw controls the opening of the airways and intestine.

Spine

The spinal column surrounds and protects the spinal cord, supports the head, and acts as an attachment point for the ribs and the muscles of the back and neck. The adult spinal column comprises 26 bones: the 24 vertebrae, the sacrum, and the coccyx bones. In the adult, the sacrum is typically made up of five vertebrae that fuse into one. The coccyx is typically 3 to 4 vertebrae that fuse into one. We start life with approximately 33 vertebrae, but as we grow older, several vertebrae fuse together. Adult vertebrae are further divided into 7 cervical vertebrae, 12 thoracic vertebrae, and 5 lumbar vertebrae.

Rib cage

The rib cage is the skeleton of the chest and consists of the ribs, sternum, thoracic vertebrae, and costal cartilages. The rib cage encloses and protects the organs of the chest cavity, including the heart and lungs. It also provides support for the shoulder girdle and upper extremities, and serves as an attachment point for the diaphragm, back, chest, neck, and shoulder muscles. Changes in the volume of the chest allow breathing.

Breastbone

The sternum is a long, flat bone located in the front of the chest. It is made up of three bones that fuse together in the adult. The ribs are 12 pairs of long, curved bones that join the thoracic vertebrae and curve toward the front of the body, forming the rib cage. The costal cartilages connect the anterior ends of the ribs to the sternum, with the exception of the 11th and 12th pairs of ribs, which are free-floating ribs. 

What is the appendicular skeleton?

The bones of the appendicular skeleton make up the rest of the skeleton and are so named because they are appendages of the axial skeleton. The appendicular skeleton is made up of the bones of the upper extremities that function to grasp and manipulate objects, and the lower extremities that allow locomotion. It also includes the pectoral girdle or shoulder girdle, which joins the upper limbs to the body, and the pelvic girdle, which joins the lower limbs to the body.

Pectoral girdle bones

The bones of the pectoral girdle provide the attachment points of the upper extremities to the axial skeleton. The human pectoral girdle consists of the clavicle in the front and the scapula in the back.

Clavicles

The clavicles are S-shaped bones that place the arms on the body. The clavicles are located horizontally along the front of the thorax (chest), just above the first rib. These bones are quite fragile and susceptible to fractures. For example, a fall with the arms extended causes the force to be transmitted to the clavicles, which can break if the force is excessive. The clavicle articulates with the sternum and scapula. The scapulae are flat, triangular bones found at the back of the pectoral girdle. They support the muscles that cross the shoulder joint.

Upper extremity

The upper endIt contains 30 bones in three regions: the arm (shoulder to elbow), the forearm (ulna and radius), and the wrist and hand. A joint is any place where two bones meet. The humerus is the largest and longest bone in the upper limb and the only bone in the arm. It articulates with the scapula at the shoulder and with the forearm at the elbow. The forearm extends from the elbow to the wrist and consists of two bones: the ulna and the radius. The radius is located along the lateral (thumb) side of the forearm and articulates with the humerus at the elbow. The ulna is located on the medial aspect (little finger side) of the forearm. It is longer than the radius. The ulna articulates with the humerus at the elbow. The radius and ulna also articulate with the carpal bones and with each other, which in vertebrates allows a variable degree of rotation of the carpus with respect to the long axis of the limb. The hand includes the eight bones of the carpus (wrist), the five bones of the metacarpus (palm), and the 14 bones of the phalanges (fingers). Each digit consists of three phalanges, except the thumb, when present, which has only two.

pelvic waist

The pelvic girdle attaches to the lower extremities of the axial skeleton. Because it is responsible for supporting body weight and locomotion, the pelvic girdle is firmly attached to the axial skeleton by strong ligaments. It also has deep cavities with sturdy ligaments to securely hold the femur to the body. The pelvic girdle is reinforced by two large hip bones. In adults, the hip bones, or innominate bones, are formed by the fusion of three pairs of bones: the ilium, ischium, and pubis. The pelvis joins in the front of the body at a joint called the pubic symphysis and with the bones of the sacrum at the back of the body.

Lower limb

The lower limb is made up of the thigh, leg, and foot. The bones of the lower limb are the femur, patella, tibia and fibula, tarsus, and metatarsals and phalanges. The bones of the lower extremities are thicker and stronger than the bones of the upper extremities due to the need to support the full weight of the body and the forces resulting from locomotion.

The femur, or femur, is the longest, heaviest, and strongest bone in the body. The femur and pelvis form the hip joint at the proximal end. At the distal end, the femur, tibia, and patella form the knee joint. The patella is a triangular bone that lies anterior to the knee joint. The patella is embedded in the tendon of the femoral extensors (quadriceps).

The tibia, or shin, is a large bone in the leg that sits directly below the knee. The tibia articulates with the femur at its proximal end, with the fibula and tarsal bones at its distal end. It is the second largest bone in the human body and is responsible for transmitting the body’s weight from the femur to the foot. The fibula, or calf bone, is parallel to and articulates with the tibia. It does not articulate with the femur and does not support weight. The fibula acts as a site for the attachment of muscles and forms the lateral part of the ankle joint.

The tarsi are the seven bones of the ankle. The ankle transmits the weight of the body from the tibia and fibula to the foot.

The metatarsals are the five bones of the foot. The phalanges are the 14 bones of the toes. Each toe consists of three phalanges, except for the big toe, which has only two.

I hope you liked all the information that we give you in this blog …