Skeletal System Flashcards
The skeletal system is composed of 2 groups, what are they known as?
Axial skeleton
Appendicular skeleton
Define the Axial Skeleton.
The Axial Skeleton is a group of bones that mainly serve to protect vital organs. They form the main axis or core of the skeletal system.
Describe the cranium and its purpose.
The cranium is made up of hard sheets of bone with fixed joints that protect the brain. At birth, these bones are loose but fuse together at a young age and remain fused for life.
How many cranial and facial bones are there?
There are 8 cranial bones and 14 facial bones. The facial bones help to shape the face.
Describe the thorax and its function.
The thorax comprises of the sternum and 12 pairs of ribs.
It has two primary roles:
Protection for the heart and lungs, and shaping the body.
What are the ribs and what do they do?
The ribs are a series of flat bones positioned closely together in a concave shape around the heart and lungs, providing protection and shape.
Describe the vertebral column.
The vertebral column consists of 33 irregularly shaped bones called vertebrae. These extend from the base of the cranium to the pelvis, providing a central axis for the body.
What is the primary objective of the vertebral column?
Its primary objective is to protect the spinal cord and support the ribcage.
How is the vertebral column held together and what does it allow?
The bones of the vertebral column are held together by powerful ligaments that allow slight movement between adjacent vertebrae, providing considerable flexibility along the length of the spine.
Define cervical vertebrae and state how many there are.
Cervical vertebrae are 7 vertebrae located in the neck. They are designated as C1 through C7.
What are C1 and C2 also known as and why are they special?
C1 is called the “Atlas” and C2 is known as the “Axis.” These are highly specialised vertebrae that form a joint allowing free movement of the head and neck.
Describe the general features of cervical vertebrae C3-C7.
C3-C7 are more typical vertebrae with a body, pedicles, laminae, spinous processes, and facet joints.
What is unique about the cervical vertebrae in terms of anatomical structures?
Cervical vertebrae contain transverse foramen, slight openings that allow vertebral arteries to flow through, supplying blood to the brain.
How does the cervical section of the spine differ in terms of movement?
The cervical spine has the most range of movement compared to other sections of the vertebral column.
Define thoracic vertebrae and how many there are.
Thoracic vertebrae consist of 12 vertebrae located in the thoracic area. They are larger than cervical vertebrae and increase in size from top to bottom.
Define lumbar vertebrae and their characteristics.
Lumbar vertebrae are 5 vertebrae situated in the lower back. They are the largest vertebrae due to their role in supporting the most weight.
Define sacral vertebrae and their unique characteristics.
Sacral vertebrae consist of 5 vertebrae that are fused together, forming the sacrum. This is located below the lumbar spine and forms the back wall of the pelvic girdle.
Define coccygeal vertebrae and describe their features.
Coccygeal vertebrae consist of 4 fused vertebrae that form the coccyx, also known as the tailbone.
List the sections of the spine from top to bottom.
Cervical, Thoracic, Lumbar, Sacral, Coccygeal
How many vertebrae are in the cervical section?
7 vertebrae (C1-C7)
How many vertebrae are in the thoracic section?
12
How many vertebrae are in the lumbar section?
5
How many vertebrae are in the sacral section?
5 (fused)
How many vertebrae are in the coccygeal section?
4 (fused)
Define the role and function of the appendicular skeleton.
The appendicular skeleton is for movement, leverage, shape and blood production. It also provides some protection and comprises the upper and lower limbs and extremities, as well as the pectoral and pelvic girdles.
What bones make up the pectoral girdle?
The pectoral girdle consists of 2 shoulder blades (scapulae) and 2 collar bones (clavicles).
Describe the characteristics and functions of the scapulae.
The scapulae are flat, triangular bones that stretch from shoulder to shoulder, connecting to the vertebral column. They have a bony ridge on the back, forming the acromion and providing muscle attachment points.
What are the functions of the clavicles?
The clavicles extend from the manubrium of the sternum to the acromion of the scapula. They support the shoulder blades and enable free arm movement, while also preventing the pectoral girdles from dislocating easily.
Describe the function of the glenoid cavity.
The upper outer corner of the scapula ends in the glenoid cavity, which forms a ball and socket joint with the head and upper arm bone, allowing for a wide range of movement.
Describe the humerus and its role.
The humerus is a single bone in the upper arm. Its upper end forms a semi-spherical ball that fits into the shoulder blade’s socket, creating the shoulder joint. The lower end forms joints with the radius and ulna at the elbow.
How do the ulna and radius articulate with the humerus?
The lower end of the humerus forms a shallow ball and socket joint with the radius and a hinge joint with the ulna. The ulna’s lower end plays a minor role in wrist joint formation, while the radius is more significant in the wrist and allows forearm rotation.
What bones make up the wrist joint?
The wrist bones, also known as carpals, articulate mainly with the broad, lower end of the radius.
Describe the radio-ulnar joints and their function.
The radio-ulnar joints are pivot joints where the moving bone is the radius. As the head of the radius pivots, the lower end moves around the lower head of the ulna, allowing for forearm rotation.
What bones support the palm and fingers?
The palm is supported by 5 metacarpals, which articulate with the carpals and the phalanges. Fingers are made up of 14 phalanges, 3 in each finger and 2 in each thumb.
Describe the components of the pelvic girdle.
Composed of 2 coxal (hip) bones at the base of the spine, it consists of 3 parts: the iliac, iliac crest, and symphysis pubis. The latter is a cartilaginous joint uniting the left and right pubic bones, allowing for necessary movement in women during childbirth.
What components make up the lower limbs?
The lower limbs consist of the thighs, legs, and feet. The bones are generally larger and stronger than those in the upper limbs to support the body’s weight.
Describe the structure and role of the femur.
The femur, or thigh bone, is the largest and strongest bone in the body. It articulates with the acetabulum in the pelvic bone to form the hip joint, and its lower part forms the knee joint with the tibia and patella.
What is the role of the patella?
Also known as the kneecap, the patella is a flat, rounded but triangular bone that articulates with the femur. It covers the surface of the knee joint and acts as a hinge connecting the femur to the tibia and fibula.
Describe the relationship between the tibia and fibula.
The tibia, or shin bone, is the second longest and strongest bone after the femur. It forms part of the knee and ankle joints. The fibula is the slenderest long bone and is connected at both ends to the tibia but does not form part of the knee joint.
What are the categories of foot bones?
The foot bones are divided into
Tarsals (7 irregularly shaped bones in the ankle)
Metatarsals (5 bones connecting phalanges to tarsals)
Phalanges (toe bones; each toe has 3 except the big toe, which has 2).
What is the general function of synovial joints?
Synovial joints enable a wide range of movements and are formed where 2 or 3 bones meet. There are 6 types, each classified by the degree of movement they allow.
What are pivot joints and where can they be found?
Pivot joints, also known as rotary joints, allow for rotational movement. An example is the joint between the first and second cervical vertebrae (the atlas and axis).
Describe hinge joints and their locations.
Hinge joints allow a swinging motion and are found between the upper and lower arm bones, knees, toes, ankles, and fingers.
What are saddle joints and where are they located?
Saddle joints allow the connected bones to shift in several directions. One example is at the base of the thumb, providing greater flexibility and complexity compared to other fingers.
Explain the structure of gliding joints.
In gliding joints, the opposed surfaces are flat or only slightly curved, allowing the bones to slide against each other in a simple and limited way. They are found in intervertebral joints and many small bones of the wrist and ankle.
What are ball and socket joints and what type of movement do they allow?
Ball and socket joints consist of a rounded or spheroidal surface (ball) of one bone that moves within a cup-shaped depression (socket) of another. They allow greater freedom of movement than any other type of joint.
Describe condyloid joints and their locations.
Condyloid joints occur when an ovoid head of one bone moves in an elliptical cavity of another. They are found at the wrist and at the base of the index finger and permit all movements except axial rotation.
Give the definition and an example of Axial rotation
Definition: The rotary motion of an object or anatomical structure around its own central axis.
Example: Turning the head from side to side involves axial rotation of the cervical vertebrae.
Give the definition and an example of Flexion
Definition: The bending of a joint or limb that decreases the angle between two bones or body parts.
Example: Bending the elbow brings the forearm closer to the upper arm, involving flexion at the elbow joint.
Give the definition and an example of Extension
Definition: The straightening of a joint or limb that increases the angle between two bones or body parts.
Example: Straightening the arm involves extension at the elbow joint.
Give the definition and an example of Lateral rotation
Definition: Rotation away from the midline of the body.
Example: Turning the arm outward involves lateral rotation of the humerus in the shoulder socket.
Give the definition and an example of Medial rotation
Definition: Rotation towards the midline of the body.
Example: Turning the arm inward involves medial rotation of the humerus in the shoulder socket.
Give the definition and an example of abduction.
Definition: The movement of a limb or other body part away from the midline of the body or from another part.
Example: Lifting the arm sideways away from the body involves abduction at the shoulder joint.
Give the definition and an example of Adduction
Definition: The movement of a limb or other body part towards the midline of the body or towards another part.
Example: Lowering the arm back towards the body involves adduction at the shoulder joint.
Define and give examples of Long bones
Definition: These bones are found in the limbs and have a shaft called the diaphysis and two rounded ends known as epiphysis. They act as levers.
Example: Humerus and femur.
Define and give examples of Short bones
Definition: These are small, light, strong, and cube-shaped bones.
Example: Carpals (wrist bones) and tarsals (ankle bones).
Define and give examples of Flat bones
Definition: These bones are thin, flattened, slightly curved, and have a large surface area.
Example: Cranial bones and sternum.
Define and give an example of Sesamoid bones
Definition: These bones develop inside the tendons near the joints of the knees, hands, and feet.
Example: Patella
Define and give examples of irregular bones
Definition: These bones have complex shapes that cannot be classified under any other category.
Example: Vertebrae and sacrum.
Define the Epiphyseal Plate and it’s significance.
Definition: The border between the diaphysis and epiphysis where bones grow in length.
Significance: It’s the region where cartilage continues to grow by mitosis to support body weight as a child grows taller.
What are Chondrocytes and why are they important?
Definition: Cells found in the cartilage near the diaphysis.
Significance: These cells age and degenerate over time, making way for osteoblasts to ossify the matrix and form bone.
What are Osteoblasts and what is their significance?
Definition: Cells that form new bone.
Significance: They move in to ossify the matrix in the region next to the diaphysis, contributing to bone lengthening.
Explain Growth hormones and their significance
Definition: Hormones secreted by glands around the body that stimulate bone growth.
Significance: Mainly produced by the pituitary gland, these hormones are essential for bone lengthening up until maturity.
Explain what is meant by maturity and bone growth and what occurs
Definition: The point where the body has fully matured, typically around the age of 21.
Significance: At this age, the epiphyseal plates harden, and cartilage growth ceases, which is a sign that the bone has reached its maximum length.
Explain Cartilage
Definition
Types
Significance
Definition: Specialised, fibrous connective tissue present in adults and forming the temporary skeleton in embryos.
Types: Hyaline, Elastic and Fibrocartilage.
Significance: Provides support, flexibility, strength and elasticity to various body parts. Acts as a model for bone development.
Explain Organic and Inorganic Components
Definition
Components
Significance
Definition: Bones consist of organic collagen and inorganic minerals.
Components: Calcium phosphate and calcium carbonate.
Significance: These components make bones hard yet flexible.
Explain Cortical Bone and its role
Definition: The outer layer of bone, hard, dense and smooth.
Significance: Provides the primary structural integrity of the skeletal system.
Describe Trabecular Bone and its role
Definition: The inner layer of bone, softer, spongy and honeycomb-like.
Significance: Houses bone marrow and fatty tissues. Important for cushioning and stress absorption.
Explain the Medullary Cavity where it’s positioned and its role.
Definition: Cavity within long bones filled with fatty, yellow bone marrow.
Significance: Runs the full length of long bones and provides storage for fats.
Explain Red Bone Marrow and its significance
Definition: Type of bone marrow where blood cells are produced.
Significance: Vital for the production of blood cells and overall health.
Types of Bones by Composition.
What do short, flat, sesamoid and irregular bones have in common and why are they important?
They all contain thin plates of cortical bone covered by trabecular bone and don’t have well defined cavities for bone marrow.
They are important in supporting and protecting various body structures.
List the 3 types of cells involved in bone development and their individual roles.
Osteoblasts: form bones,
Osteoclasts: break down bones
Osteocytes: maintain bone tissue.
What is the relationship between Cartilage and Chondrocytes
Bone tissue starts as cartilage, formed by specialised cells known as chondrocytes.
Chondrocytes divide and secrete collagen and other proteins to form the cartilage framework for bone formation.
Explain Ossification
Definition: The process of turning cartilage into bone, led by osteoblasts.
Osteoblasts secrete a gelatinous substance and absorb minerals to deposit onto the bone matrix.
Explain the term Resorption
The yearly breakdown and rebuilding of roughly 10% of the skeleton.
Hormone signals direct osteoclasts to break down old bone tissue and redistribute it.
Explain the role of enzymes in resorption
Osteoclasts secrete enzymes like acid phosphatase during resorption.
These enzymes dissolve both the organic collagen and inorganic calcium and phosphorus of the bone.
Explain the role Hormones in the bone remodelling process.
Hormones regulate bone remodelling for maintaining blood calcium levels.
The Parathyroid and thyroid glands signal osteoclasts and osteoblasts to regulate calcium transfer between blood and bones.
Explain how blood calcium levels are maintained via the bone remodelling process.
When calcium levels are low, osteoclasts are triggered. When they are high, osteoblasts are triggered for further ossification, ensuring stable levels of calcium.
Lost the 3 Types of Muscles in the body and their functions.
Cardiac muscles: enable heart function
Skeletal muscles: control body movements
Smooth muscles work involuntarily around organs.
What are cardiac muscles and why are they important?
They are muscles found only in the heart, that perform coordinated contractions to pump blood through the circulatory system.
Explain Skeletal Muscles
They are the muscles responsible for body movements and posture.
They also protect internal organs and tissues from injuries.
Explain smooth muscles
These are found in and around organs and function involuntarily.
Explain Ligaments
More than 20 types of ligaments are found throughout the body.
They hold body parts together and provide stability. They are elastic and can elongate and stretch.
What is the function of ligaments?
Ligaments protect bones during movement and absorb stress.
They ensure steady movement and minimise harm from sudden posture changes.
Explain tendons and their role.
Bands of fibrous tissue that connect muscles to bones.
They transfer force between muscle and bone.
Explain the difference between ligaments and tendons.
Tendons attach muscles to bones for movement.
Ligaments attach bones to each other for stability.
