What is Skeletal System 2022, Full Skeletal System Function, How to Nurturing, Function of Bones, Skeleton Parts, Human Skeleton, Bones of the Cranium.
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What is Skeletal System : The structure of the human body is made up of bones. All bones are interconnected. Above the bones are muscles with the help of which the joints of the bones are moved. Bones and muscles protect the internal organs of the body. There are 206 bones found in the human body. The organ that makes up the structure of the human body is called the skeletal system.
The skeleton gives the body a certain shape and size. This gives support to the body. The anatomical structure of vertebrates is made up of skeleton, which provides support to other parts of the body. The soft parts of the body are protected from death. It protects the soft parts of the body from external shocks.
Musculo skeletal system Many parts of the skeleton act as levers, which make it easier for animals to move. The skeleton has a suitable place to attach the muscles. The medullary cavity of the skeleton performs the function of storing fat. Ear bones help to transmit sound vibrations to the inner ear. The living endothelial produces red blood cells (RBCs). Calcium and phosphorus are stored in the skeleton, which is available to the body from time to time when it is needed What is Skeletal System.
Questions for Practice :
- Name the bones of the skull and face.
- Write the functions of chest cavity and vertebral column.
- Write the difference in male and female pelvis.
- Write the functions of bones n human body.
- Draw and label any long and flat bone in upper limb.
Introduction : What is Skeletal System
The skeletal system is made up of different types of bones that make up the skeleton. Voluntary muscles are attached to the skeleton. There are different types of bones that form different joints. The movements in a particular joint depend on the type of joint and the function of the part.
Function of Bones :
- Bones give shape and size to the body.
- They form the basic structure of the body.
- They provide attachment to muscles and tendons
- They are stores of calcium and phosphorus.
- They allow movement of the body in the limbs and as a whole
- Bone produces narrow blood cells.
- Protect by helping to build organs such as the skull, chest, abdomen and pelvis these cavities.
What is Skeletal System Parts : Part of the Skeletal System
- Skull face and cranium
- Vertebral column
- Thoracic cage
- Abdomen and pelvis
- Upper limb
- Lower limb
Human Skeletal System :
Face -13 bones Cranium – 8 bones :
- 1 Vomer
- 1 Maxilla
- 1 Mandible
- 2 Lacrimal
- 2 Nasal
- 2 Zygomatic 2 Temporal
- 2 Paletine
- 2 Inferior conchae
- 1 Occipital
- 1 Sphenoid
- 1 Ethmoid
- 2 Parietal
Skull Skeletal System : what does the skeletal system do
The skull is divided into two parts. The front part is the mouth and the back part is called the cranium. This part of the body contains many important senses such as eyes, nose, ears and tongue. The cranial cavity is filled with the brain.
The bones of the skull are irregular and flat and are attached to each other by fixed suture joints (immovable). The only bone that moves into the skull is the bone of the lower jaw. The skull has several openings through which blood vessels enter the skull and cranial nerves leave the skull which includes the spinal cord.
Face Bones : What is Skeletal System
The number of facial bones is 13. Some of them are in pairs and some are in singles.
- Zygotic Bones (Two) – They form cheek and floor and lateral wall of orbits.
- Maxilla (one) – It is a bone of upper jaw. The maxillary sinus which is a air cavity lined by ciliated mucus membrane opens into the nasal cavity. The maxilla carries the upper teeth.
- Nasal Bones – These are two small flat bones which form superior and lateral part of the bridge of the nose.
- Lacrimal – Bones are two small bones. These (bones) form medial wall of orbit. They are behind (posterior) to nasal bones. The naso-lacrimal duct passes through them the open into nasal cavity.
- Vomer – Is a thin flat bone which forms the hard palate andthe nasal septum. Superiorly it articulates with ethmoid bone.
- Paletine Bones – Are two ‘L’ shaped bones. They form hard palate and lateral wall of nasal cavity and part of orbit.
- Inferior Conchae – are scroll shaped bone which forms lateral wall of the nasal cavity. The superior and middle conchae are above this bone and they are parts of ethmoid bone.
- Mandible – Is the only movable bone of the skull. It is a curved bone which form chin and provide attachment to lower teeth.
- Hyoid Bone – This horse shoe shaped bone is just superior to larynx and below the mandible in the neck. It is attached to styloid process of temporal bone. It provides attachment to the base of the tongue.
Bones of the Cranium :
The cranium is made up of flat and irregular bones joined together by suture joints. The cranium protects brain from injury. Through different holes in cranium bones (foramina) the nerves, blood and lymph vessels pass.
The Frontal Bone – Is the most anterior bone that forms the forehead and part of the orbits (eye-cavity). The bone has two sinuses (cavities filled with air) that open into the nasal cavity. The frontal bone is attached to the parietal, sphenoid, ethmoid, Zygomatic, lacrimal and nasal bones by fibrous joints.
Parietal Bones – Are roof bones of the Cranium and partly form the lateral walls. They are connected to each by suture joints and other bones of the cranium like frontal occipital and temporal bones.
Temporal Bones – Are inferior and lateral bones of the skull. These bones form fixed suture joints with parietal occipital, sphenoid andzygomatic bones. They are also connected to mandible which forms the only moving joint in skull. The external auditory canal lies posterior to this joint.
Occidental Bone : What is Skeletal System
Occidental Bone – lies on backside (posterior) of the cranium and forms posterior wall and base of the skull. It forms fixed joints with parietal temporal and sphenoid bones. The concave part from inside protects cerebellum, and cerebrum. It joints first vertebra ‘Atlas’ of backbone and has a foreman called foreman magnum (large hole). The spinal cord passes through this hole.
Spheroid Bone – Is present in the middle portion of the base of cranium. It joints occidental parietal, temporal and frontal and ethmoid bones. The sinuses in this bone open into nasal cavity. The depression for pituitary gland lies in the middle of the bone called hypophyseal fossa.
Ethmoid Bone – This bone lies in the anterior part of the base of the orbit and nasal cavity. The projections into the nasal cavity on both sides are superior and middle conchie. The air sinuses in the bone open into nasal cavity. The smell sensory nerve fibers from nasal cavity enter through this bone to brain. (Olfactory Nerve)
Air Sinuses : What is Skeletal System
They are present in the bones of the skull. All communicate with the nasal cavity and secrete mucus as they are lined by ciliated mucus membranes. They help with voice resonance and make the skull bones lighter to balance the head at the top of the vertebral column.
Fontanelles of the skull :
These are membranous areas that are not fractured in the bones of the skull at birth. There are anterior and posterior fontanelles. membranes are converted into bones and
Most fontanels are close by around 18 months of age. The presence of fontanelles helps in childbirth by shielding the skull while passing through the birth canal.
Vertebral Column (Back Bone) :
The vertebral column is made up of 33 vertebrae. These are irregular shaped bones. They are strongly linked to each other. These vertebrae together form a column that has limited movement.
The cervical (neck) and lumbar part can move more freely than the thoracic and sacral part. The shape and other features of a vertebral column vary from part to part in the vertebral column. A typical vertebra has got a body, pedicles, Foramen transverse process, spinous process, laminae and articular process. The spinal cord (regions) consists of five parts.
- 7 Cervical
- 12 Thoracic
- 5 Lumbar
- 1 Sacral ( 5 fused vertebrae )
- 1 Coccyx ( 4 fused vertebrae )
Vertebral foreman – They are surrounded by neural arch the spinal cord passes through this foreman.
Inter vertebral foreman – They are present between a pair of vertebrae the nerves, blood vessel and lymph vessels pass through them.
Inter-vertebral disc – It is made up of fibro-cartilage with gelatinous substance, acts as shock absorber.
Ligaments of Vertebral Column :
- Anterior longitudinal ligament
- Transverse longitudinal ligament
- Posterior longitudinal ligament
Functions of the Vertebral Column :
- Protection of spinal cord.
- Protection of spinal nerves, blood vessels and lymph vessels
- Support the skull.
- Attachment to ribs, shoulder pelvis (upper and lower limbs).
- Shock absorption and brain protection.
Movements of the Vertebral Column :
- Lateral flexion
Thoracic Cage :
The bones of thoracic cage are ribs (12 pairs), sternum (1) (breast bone) and thoracic vertebrae (12).
Ribs : What is Skeletal System
The ribs form the anterior and lateral wall of the chest cavity containing the thoracic vertebrae in the back. The superior ten pair is attached to the sternum by coastal cartilage. The last (inferior) two pairs are independent and are called floating ribs. The head of a rib joins with the bodies of two adjacent thoracic vertebrae.
The anterior part of a rib is attached to the sternum by a coastal cartilage (elastic and hyaline). The space between the two ribs is filled with the intercontinental muscles. During inspiration the muscles contract and increase the capacity of the thoracic cavity by lifting the ribs and sternum up and out.
Sternum : What is Skeletal System
It has got the shape of a Roman sword. It is a flat bone and can be seen from the front just under the skin in the middle of the chest. The clavicle and the first rib are attached to the manubrium. The rest of the ribs are attached to the body The sternum.
Typhoid process gives attachment to the diaphragm, the muscles of the anterior abdominal wall, and the linea-alba. Twelve pairs of ribs attach to the thoracic vertebrae in the back and form the thoracic cage.
Peripheral Skeleton : (1) Upper limb and shoulder girdle bones. (2) Lower limb and pelvic girdle bones.
Bones of the Upper Limb With Shoulder :
- Clavicle – Collar Bone
- Scapula – Shoulder
- Humerus – Arm
- Radius – Forearm
- Ulna – Forearm
- Carpal Bones – 8 – in wrist
- Metacarpals – 5 – in palm
- Phalanges – 14 – in fingers
Clavicle or Collar Bone :
It is a long bone with double curve (stretched ‘S’ shape) medially it is connected to sternum and laterally to scapula.
Scapular or Shoulder Blade :
It is a flat and triangular bone. It is on posterior side of chest placed below skin. It is superficial to ribs and muscles are present in between ribs and scapula. It is attached to clavicle and humerus at omicron and glenoid cavity.
Humerus : What is Skeletal System
This is the long bone of upper arm. The head articulate with glenoid cavity of scapula and forms shoulder joints. The lower (distal) end joins with radius and ulna and form elbow joint.
Ulna and Radius :
These are two drum stick like bones of the forearm. The ulna is longer and medial to the radius. When in anatomical position at the upper end they join humerus to form elbow joint. At the lower end they join with carpal bones to form wrist joint. The two bones are parallel and joined together by tough inter – sseous membrane.
Carpal or Wrist Bones – (8) small bones in two rows :
They are irregular in shape –
- Proximal – Scaphoid, lunate (close to midline), triquetral and pisiform.
- Distal – Trapezium Trapezoid (Away from midline) capitate and hamate.
Bones of the metacarpal :
They are five long bones but short in length.They join carpal bones proximal and bones of the fingers distally.
Finger Bones (Phalanges) :
They are 14 small bones. Three in each finger only two in thumb. They joint with each other and metacarpals at the proximal end.
The Pelvic Girdle and Lower Limb :
- Pelvic girdle bones – Hip bones (In-nominate), Sacrum and Coccyx
Hip Bones – The hip is formed after the fusion of three irregular flat bones Ilium, Ischium and pubis. On the lateral and outer surface of pelvis is a deep cavity called acetabulum. The hip joint is formed with spherical end of the femur and the acetabulum. The Ilium is the upper flat part of the bone and has ilia crest which can be palpated below skin.
The pubis is the anterior part of the bone and it joins with opposite pubis bone to form a elastic joint (cartilaginous) called symphonic pubis. The is chium forms the posterior and inferior part of the bone and has a foreman (obturator) through which blood vessels lymph vessels and nerves pass down into lower limb. At the point of union of these three bones the cavity acetabulum is formed.
Pelvis – The two hip bones join vent rally and form syphilis pubis and dorsally at sacroiliac joint.The greater or false pelvis is above the brim of pelvis and lesser or true pelvis is below the brim of pelvis. (The brim of pelvis is at the level of sacral promontory and ileopectineal lines of the hip bones).
Male Pelvis Female Pelvis :
- Narrow (shallow) – Broad (Roomy)
- Strong bones – light bones
- Pubic arch acute – pubic arch wide
- Fixed coccyx – movable coccyx
- Small Heart shaped inlet – Inlet round in shape
Bones of the Lower Limb :
- Thigh bone – femur
- Tibia (or shin bone)
- The patella (Knee cap)
- Tarsal or ankle bones
- Metatarsal bones
Thigh Bone – Femur : What is Skeletal System
This is the strongest and longest bone in human body. The head is almost spherical and joins hip bone into the acetabulum. A small depression on the head of femur is for attachment of the ligament of the head of the femur.
This ligament starts from acetabulum to head of the femur and it contains blood vessels. The femur consists of head, neck, greater and lesser trenchant, shaft and lower end. At the lower end two condyles medial and lateral form joint with tibia and patella.
Tibia (or shin bone) – The tibia is medial bone of the lower leg. Tibia is long bone with two condoles at the proximal end for joining the femur at knee joint. At the lower end (distal) it forms ankle joint with tarsal bone and fibula. Medial malleolus is projection at the lower end and inner side of the tibia.
Fibula – Is a long stick like lateral bone in the leg. The head joins lateral condyle of the tibia. The lower end joins tibia. The outer bony projection at the lower end is called lateral malleolus.
The patella (Knee cap) – This is a triangular bone partly in the tendon of the quadriceps muscle. The posterior surface joins with the patellar surface of femur. It is a sesamoid bone.
Tarsal or Ankle Bones :
- Talus 1
- Calcareous 1
- Navicular 1
- Cuneiform 3
- Cuboid 1
They articulate with tibia and fibula to form ankle joint. The calcaneus is present in heal. At the distal end they join metatarsal bones.
Metatarsal Bones – Metatarsal bone of the foot are five long (short in length) bones. At the proximal end they join tarsal bones and at the distal end they join phalanges.
Phalanges – 14 small bones similar to fingers in upper limb. The great toe has two bones and three in rest of the other toes.
The Arches of the Foot :
- Medial longitudinal Arch
- Lateral longitudinal Arch
- Transverse Arch
Medial Longitudinal Arch – This is the highest of the arches and is formed by calcaneustalus, navicular, three cuneiform and three metatarsal bones. Ideally only the calcaneus andthree metatarsals should touch the floor (ground).
Lateral Longitudinal Arch – This is much less marked andformed by calcaneus, cuboid andtwo lateral metatarsal bones. The bones which touch the ground are calcaneus and metatarsals.
Transverse Arch – They are marked at the level of cuneiform and cuboid. They are better observed in a skeleton.
Common Anatomical Terms Used in Skeletal System :
- Articulation-Joint between the bones.
- Sinus – hollow cavity within a bone.
- Border – ridge separating two surfaces of a bone.
- Condyle – smooth round projection that forms part of the joint.
- Facet – flat and small articulating surface.
- Fissure – A narrow slit.
- Foramen – whole in a bone.
- Fossa – depression on a bone.
- Meatus – tube shaped cavity.
- Septum – partition separating two cavities.
- Spine – a sharp ridge of bone.
- Styloidprocess a sharp downward projection of bone for muscle, ligament attachment.
- Suture is a fixed and immovable joint in skull bones.
- Trochaic is rough bony projection of different sizes for the attachment of ligaments muscle.
- If biggest in size then it is called trochantar. If smallest in size it is called a tubercle. A tuberosity is a medium sized process.
- Articulating surface is the part of a bone which comes close in joint formation.
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