Salient Features and Functions of Bones of Axial and Appendicular Skeletal System : Pharmaguideline -->

Editable Pharmaceutical Documents in MS-Word Format


Salient Features and Functions of Bones of Axial and Appendicular Skeletal System

A vertical axis in the body consists of seven different bones, including all those found in the head, neck, chest, and back.
Axial skeleton
A vertical axis in the body consists of seven different bones, including all those found in the head, neck, chest, and back. Besides protecting brains and spinal cords, lungs and heart are also protected. Moreover, the shoulder, hip, and neck muscles attach to the corresponding head, neck, back, upper arm, and leg muscles. If the limbs are moved, these muscles will also act at the shoulder and hip joints.

Our axial skeleton is made up of 80 bones, which also include our skull, our vertebral column, and our thoracic cage. The skull, however, consists of 22 of those. In addition to seven other bones in the head, there are also three ossicles in each middle ear and the hyoid bone (located in the upper neck). Each vertebra in the vertebral column, plus the fused sacrum and coccyx bones, are called vertebrae. The thoracic cage consists of the ribs, as well as the sternum, the flat, bony organ from which the wings are made.


There are many irregular and flat bones that form the cranium, which protects the brain from external damage. The brain is built up on top of a base and enclosed within a vault. The periosteum forms the outer layer of the dura mater, which lines the inner skull bones. Muscles connect the bones of the mature skull by joints (sutures). Many nerves, blood vessels, and lymph nodes pass through perforations in bones (e.g., foramina, fissures).

Frontal bone
This bone is located on the forehead. A supraorbital margin is a prominent ridge above the eyes forming part of the orbit (eye sockets). Two spaces within the bone are filled with air and covered with ciliated mucous membranes, which direct space to the nasal cavity just above the supraorbital margins. Two bones are originating from the same point in the midline, connected by a suture

Parietal bones
The skull's sides and roof are made up of these bones. A sagittal suture connects them; a coronal suture connects the frontal bone; a lambdoidal suture connects the occipital bone; a squamous suture connects the temporal bones. Brain and blood vessels are accommodated by a concave interior surface.

Temporal bones
These four bones make up the zygomatic, parietal, occipital, and sphenoid bones and form an immovable joint on either side of the head. It has some important characteristics.

Articulation between the squamous part and the parietal bone is called the squamous part. The zygomatic process and the zygomatic bone together are responsible for creating the zygomatic arch (cheeks). The mastoid process, a thickened part behind the ear that can be felt, is located here. The middle ear contains tons of squamous epithelium, in addition to these air sinuses. This part of the skull is home to the spiral organ (the organ of hearing and balance) and contains the sensory organs. A skull's only movable joint, the temporomandibular joint, articulates the temporal bone with the mandible. An articulating surface is immediately behind this section of the bone, followed by the external acoustic meatus (aural canal), which extends into the petrous portion of the bone. A ligament attaches the styloid process of the temporal bone to the articular process since it doesn't articulate with any other bone.

Occipital bone
The skull base and the back of the head are made up of these bones. Parietal, temporal, and sphenoid bones are immovable thanks to their fibrous joints. The inner surface of the cerebrum is deeply concave, and the concavity of the cerebrum is filled with the occipital and cerebellar lobes. Located directly below the atlas, the occiput forms an ankylosed joint with two articular condyles, and the joint is referred to as a condyloid joint. Joints like this allow the head to sway when nodding. A large channel connecting the condyles allows the spinal cord to pass through.

Sphenoid bone
This part of the skull articulates with the temporal, frontal, and parietal bones at the base of the skull, and occupies part of the middle region. In addition, the skull is cross-braced. It joins the facial bones and cranium. It holds the pituitary gland, which lies at the center of a squiggle-shaped depression on the superior surface of the bone. Air sinuses lined with mucous membranes open into the nasal cavity from the body of the bones.

Ethmoid bone
It occupies part of the anterior part of the skull base and is often referred to as the "eye socket." It forms the lateral walls of the nasal cavity as well as the orbital cavity. Conchae, or turbinated processes, enter each nasal cavity at the superior, middle, and inferior levels. Bones of the face, throat, and nose contain many little air sinuses covered with ciliated epithelial cells and containing openings into the nasal cavity. Known as the cribriform plate, this horizontally flattened part of the human body is situated inside the nasal cavity and houses several small foramina through which the olfactory nerve passes between the brain and nasal cavity. Additionally, the upper part of the nasal septum has a very fine plate of bone that forms a perpendicular angle.

Zygomatic (cheek) bones

Zygomatic bones are formed when two bones fuse inside one another before birth. As well as prominences on the cheeks, prominences also line the walls and floors of the orbital cavities.

Maxilla (upper jaw bone)
This bone initially consists of two bones that converge at birth. There is also a maxilla in the eyebrow, and that is the lower jaw, the roof of the mouth, and the lateral wall between the brow and nose. In the upper jaw, the alveolar ridge, or process, protrudes downwards and contains the teeth. There are two major sinuses on each side, the maxillary sinuses, lined with ciliated mucus membranes and openings into the nasal cavity.

Nasal bones
The bones are located on the nasal bridge's superior and lateral surfaces.

Lacrimal bones
Those bones are small, flat and cover a large part of the bridge of the nose, both on the superior and lateral sides. These holes are pierced by a foramen through which the nasolacrimal duct, which carries tears from the eyeball to the nasal cavity, passes.

Cartilage called the vomer forms the majority of the lower portion of the nasal septum and extends upward from the middle of the hard palate. In the superior position, it articulates with the ethmoid bone's perpendicular plate.

Palatine bones
The bones have an L shape. The hard palate is composed of two horizontal parts and two perpendicular parts that project upwards to form lateral walls.

Inferior concha
The lateral wall of the nasal cavity is formed by a shell and a middle shell, which projects forward inside the nasal cavity. Both the superior and middle conchae form part of the ethmoid bone. Each concha increases the surface area of the nasal cavity, allowing for more efficient heating and humidification of the air.

Mandala (lower jaw bone)
There are only two movable bones in the skull, including this lower jaw. The lower jaw comes in two halves that join at the midpoint. Two main parts make up each whole: a curved body consisting of the alveolar ridge and the ramus. In the latter case, the projecting edge is almost at right angles to the body's posterior end. Condylar process, which attaches to the temporal bone and forms the temporomandibular joint, and the coronoid process, which attaches to the muscles and ligaments of the jaw. This point on the ramus where it meets the body is called the jaw angle.

Hyoid bone
Within the soft tissues of the neck, there is a single bone that is located behind the mandible and above the larynx.

Among the main bones of the head are the sphenoid, ethmoids, maxilla, and frontal. A ciliated mucous membrane lines all of these structures, which are located in the nasal cavity. They increase the quality of the voice and make the skull lighter, which makes it easier to carry.

Functions of skull
The skull is made up of different parts, each of which serves a specific function, like protecting the brain from damage. Eye sockets support the eyes and help protect them against injury. They also provide attachments to the muscles that operate them. Temporal bones protect the delicate ear structures. The voice resonates because certain facial bones, including the skull, have sinuses. The skeletal structures of the face make up the walls of the nasal cavities at the back and act as the upper air passages. There are ridges of alveolar ridges in the maxilla and the mandible where the teeth are embedded. During eating, food is chewed with the aid of the mandible, which is controlled by the lower facial muscles.

Vertebral column
Approximately 26 bones are located in the spinal column. It is composed of 24 vertebrae which continue to extend downwards from the occiput. There are 3 to 5 small fused vertebrae separated by the coccyx from the sacrum, which contains five fused vertebrae. A vertebral column consists of different regions. Within the neck are seven vertebrae: the cervical spine. Within the thoracic spine are twelve vertebrae; within the lumbar spine are five vertebrae, with the lowest vertebra hinged to the sacrum. Every vertebra is assigned a number and letter corresponding to the region it is located in the spine.

Intervertebral disc

As the vertebrae are adjacent, intervertebral discs separate the bodies, consisting of an outer rim consisting of fibrocartilage and a central centrifugal core made up of fibrous gelatinous material. Whenever the spinal load is increased, they become thicker towards the lumbar region, starting from the cervical region. The posterior longitudinal ligament is responsible for holding the vertebrae in place. These bones absorb shock, and cartilaginous joints help the vertebral column keep its flexibility.

Intevertabral foramina
Viewed from the side, two adjacent vertebrae from a gap between their pedicles that forms a foramen. Each pair of vertebrae has an intervertebral foramen. These contain spinal nerves, blood vessels, and lymphatic vessels.

Ligaments of the vertebral column
In addition to reducing motion between vertebrae, these ligaments also keep the intervertebral discs stable. An odontoid process attached to the axis is maintained correctly about the atlas by the transverse ligament. Anterior longitudinal ligaments are running along the length of the backbone and covering the vertebral bodies. The posterior longitudinal ligament runs along the length of the vertebral columns and is located directly underneath the posterior surfaces of the vertebral bodies. This connects adjacent vertebrae using the ligament of the Flava Between the occiput and the sacrum, the spinous processes are connected by ligamentnuchae and supraspinous ligament.

Curves of the vertebral column
Observing the spinal column from the side, two primary curves and two secondary curves can be seen. In the uterus, the fetus' head and knees are curled up and touch to some extent. The primary curvature is thus evident. The primary cervical curve occurs at 3 months of age, and secondary lumbar curves appear at 12 - 15 months of age when the child can hold up his head. It is preserved that the thoracic and sacral spines have their primary curves.

Movements of the vertebral column
The vertebral column's bones can only move within relatively limited limits. No matter how you slice it, the spinal column has a variety of motions, more specifically, flexion (bending forward), extension (bending backward), and lateral flexion (bending on the side). More movement occurs in the cervical region and the lumbar region than anywhere else.

As a whole, the vertebral foramina comprise the vertebral canal, an area of bone that surrounds and protects the spinal cord. As the pedicles of adjacent vertebrae meet, they form intervertebral foramina in the spinal cord. Structural support for the spinal cord is provided by the vessels, nerves, and lymphatics of these foramina. All the bones, with their intervertebral disks, function together to allow movement of the spine and the skull is supported by these bones. They protect the brain by dispersing shock waves. Anatomy, the trunk is the axis around which the ribs, shoulder girdle, upper limbs, and pelvic girdle are attached.

A thoracic cage is separated from its lateral walls by twelve pairs of ribs. They are long, curved bone segments that articulate posteriorly with the spinal column. Truly ribs are the ribs that connect directly with the sternum in the anterior area of the body. The third pair of ribs articulate indirectly. In both cases, the ribs and sternum are attached by costal cartilages. The anterior tips of two pairs of ribs are not attached to the sternum at all, instead of extending away from it. These are called floating ribs. Several ribs are connected to the vertebral column by joints. The above rib and the below rib are connected at their bodies by facets on the heads of the vertebrae.

Besides the joint between the tubercle and the transverse process of the lower vertebra of ten of the ribs, there is also a joint between the tubercle and ten of the ribs themselves. A groove runs along the rib's inferior surface, providing a channel for blood vessels and nerves to travel. Breathing is made possible by the intercostal muscles, located between each rib and the one below. A ribcage's arrangement and the amount of cartilage it contains make it a flexible and dynamic structure that can shift in size and shape when it breathes. Inspiration does not cause the first rib to move, as it is firmly attached to the sternum and 1st vertebra. As a result of intercostal muscles contacting the first rib, the entire ribcage is elevated making contact with the first rib.

Located above the sternoclavicular joint and the first two pairs of ribs, the manubrium is the uppermost part of the skeleton. The body is the middle portion and produces rib attachments. An attachment is formed between it and the diaphragm, anterior abdominal wall muscles, and the linea alba.

One of the most important roles in human development is played by the axial skeleton by supporting and protecting the brain, spinal cord, and other organs in the ventral body cavity. In addition to providing a surface to attach muscles that move the head and neck, the scapula also helps regulate the formation of breathing and stabilizes the appendicular skeleton.

Appendicular skeleton
This group of appendicular skeleton bones consists of the limbs, pectoral and pelvic girdles, and the bones connecting the legs to the axial skeleton. Appendicular skeletons consist of 126 bones in adults. Appendicular bones present in the lower skeleton are specialized for stability when walking or running. However, the upper portion of the appendicular skeleton is more mobile and has a greater range of motion, features that allow you to lift objects and carry them.

1. Shoulder girdle and upper limb
Shoulder girdle
Clavicle (collar bone)

Long and S-shaped, the clavicle is part of the head and shoulders. Joints of the sternum articulate with those of the clavicle. Scapular acromion processes form the sternoclavicular joint.

Scapula (shoulder blades)
Skulls are triangular-shaped flat bones surrounding the ribs and lying on a posterior chest wall superficial to it. The scapulae are divided from the ribs by muscles. The shoulder joint, composed of the head of the humerus and the glenoid cavity, is situated at the lateral angle. An asymmetric ridge called the spine runs along the posterior surface of the arm, extending beyond the lateral scapular border but not overhanging the glenoid cavity. At the point where the shoulder blade meets the top of the shoulder, the acromion process is a pronounced overhang visible through the skin. It creates a synovial joint with the clavicle, which allows for shoulder movement. On the upper border of the bone, on the clavicula, are the muscles that attach to the shoulder joint.

Upper limb

It is a bone on the upper arm. According to anatomical definition, the shoulder is made up of the glenoid cavity of the scapula and the head. On the head, the tubercles that are the largest are roughened, and there is a deep groove, called the bicipital groove or intertubular sulcus, that is occupied by one of the biceps' tendons between them. As the elbow joint is formed by the distal end of the bone and the radius and ulna, two surfaces articulate together at the distal end.

Ulna and radius
The forearm consists of these two bones. When the hand is facing forward, that is, with the palm facing forward, the ulna is the longest, lying medially to the radius. It articulates with the humerus at the elbow, and it articulates with the carpal bones at the wrist, and it articulates with the radioulnar joints at the elbow and wrist. Further, interosseous membranes, also called fibrous joints, secure these bones against each other and maintain their relative positions even when force is applied from the wrist or elbow.

Carpel (Wrist bones) bones
Located on each side of the hand are four carpal bones in total. Unlike the bones of the foot or arm, the bones of the arm and foot are closely connected by ligaments. This means they have little freedom of movement. Joints form with the metacarpal bones in the distal row, and with the wrist bones in the proximal row. A strong fibrous band, called the retinaculum, holds the fetuses of the muscles near the bones in the forearm.

Metacarpal (bones of hands)
In the palm, all five of these bones can be found in total. The numbers begin at the thumb side and go inward. Phalanges form the attachment space between the distal and proximal ends, while carpal bones form the attachment space between them.

Phalanges (Finger bones)
A finger has three phalanges, a thumb has two, and there is 14 total. The metacarpal bone meets the hinge joint on each hand, and the two articulate with each other.

2. Pelvic girdle and lower limb
An individual's pelvis is defined as the basin-shaped structure composed of the pelvic girdle and the sacrum that supports it.

Innominate (hip bones)
Three bones make up a hip: the ilium, ischium, and pubis. The acetabulum forms the hip joint by having a deep depression at its lateral side and is located just below the virtually rounded femur head. The ilium extends beyond the iliac crest in addition to having a flattened top, and the curve on the anterior face of the ilium is known as the anterior superior iliac spine. Together with the sacrum, the ilium forms a synovial joint that's strong enough to withstand weight bearing, although it becomes fibrosed over time. There is a cartilaginous joint, the Symphysis pubis, between the pubis of two hip bones, which is the anterior part of the pubis. An ischium is a part of the body located inferiorly and posteriorly. Seating involves the weight of the body resting on the rough projections of the ischia, known as the tubercules of the ischia. During acetabular fusion, the three parts are joined.

Hip bones, sacrum, and coccyx form the pelvis. With the brim of the pelvis dividing the pelvis into upper and lower halves, it is a pyramid-shaped structure composed of the sacrum and iliopectineal lines of the innominate bones. Greater or false pelvis are placed above the brim, whereas lesser or true pelvis is located below.

Lower limb

The body's longest and heaviest bone, the femur is both long and heavy. As the hip joint is formed by the hip bone and the head, the head looks almost spherical. The neck extends outward and downward from the head, with most of its length contained in the hip joint capsule. This area is shaped like a triangular shape and is found in the lower third of the foot. The knee joint is formed by two articular condyles, the tibia, and the patella, located at the distal end of the leg. Using the bones beneath the knee and the foot, the femur carries the weight of the body.

Medial to the femur is the tibia, which is the lower leg's medial bone. In the knee, they form an articulation with the femur through a pair of condyles on the proximal side of the shin. Fibula head and lateral condyle articulate to form the proximal tibiofibular joint. The tibia and talus form the ankle joint, with the fibula and tibia forming the distal extremity. An ankle joint is surrounded by a downward projection of bone called the medial malleolus.

A very long, thin bone belonging to the leg, the fibula has a small head. Anatomically, the proximal tibiofibular joint articulates with the lateral condyle of the tibia at each level. The talus extends beyond the lateral condyle to form the lateral malleolus. Ankle joints are stabilized with this exercise.

Patella (knee cap)
Associated with the knee joint, this sesamoid is roughly triangular. A tendon located in the patellar tendon articulates with the patellar surface of the femur at the knee joint's anterior surface. This tendon is called the quadriceps femoris.

Tarsal (ankle) bones
Among the compounds that make up the anterior part of the foot (ankle) are the talus, the calcaneus, the navicular, the cuboid, and the three cuneiform bones. As the ankle joint conjoins the tibia and fibula, the talus articulates with these bones. It is attached to the heel by the calcaneus bone. There are also articulations between the metatarsals and between the other bones.

Metatarsals (bones of the foot)
From inside out, these five bones make up the greater part of the foot's dorsum. A tarsal bone articulates with its proximal end, and a phalange articulates with its distal end. A ball-shaped portion of the foot is formed by the 1st metatarsal distal head, which is enlarged.

Phalanges (toe bones)
Each of the 14 phalanges is organized similarly to their finger equivalents, namely two at the base of the big toe (the hallux) and three at the ends of each of the other toes.
Get subject wise printable pdf documentsView Here

Ankur Choudhary is India's first professional pharmaceutical blogger, author and founder of, a widely-read pharmaceutical blog since 2008. Sign-up for the free email updates for your daily dose of pharmaceutical tips.
.moc.enilediugamrahp@ofni :liamENeed Help: Ask Question

No comments: Read Comment Policy ▼

Post a Comment

Please don't spam. Comments having links would not be published.

Popular Categories

QA SOPs QC SOPs Micro SOPs HVAC Production SOPs Stores SOPs Checklists Maintenance SOPs HPLC Sterile GLP Validation Protocols Water System GDP Regulatory Maintenance Calibration Warning Letters Education B.Pharmacy
Video Tutorials
Subscribe on Youtube

Submit Guest Posts

Follow Pharmaguideline



Editable Pharmaceutical Documents in MS-Word Format. Ready to use SOPs, Protocols, Master Plans, Manuals and more...




Pharmaceutical Updates

✔ Worldwide Regulatory Updates
✔ Pharmaceutical News Updates
✔ Interview Questions and Answers
✔ All Guidelines in One Place


Recent Posts