Muscle and Joint Anatomy Lecture Notes

Here are some notes about muscle and joint anatomy: - **Joints are classified by structure and function.** - **Structural classification** is based on the type of material holding the joint together. There are three types of structural classifications: - **Fibrou...

Here are some notes about muscle and joint anatomy: - **Joints are classified by structure and function.** - **Structural classification** is based on the type of material holding the joint together. There are three types of structural classifications: - **Fibrous:** The joint is held together by fibrous connective tissue. - **Cartilaginous:** The joint is held together by hyaline or fibrocartilage. - **Synovial:** Many structures hold the joint together. - **Functional classification** is based on how much movement is produced at the joint. There are three types of functional classifications: - **Synarthrosis:** Little to no movement. - **Amphiarthrosis:** Some movement. - **Diarthrosis:** Freely moveable. - There are several types of fibrous joints: sutures, syndesmoses, and gomphoses. - **Sutures** are found between the bones of the skull and are synarthrodial, meaning there is no movement at the joint. - **Syndesmoses** are found between two bones that are connected by fibrous connective tissue, such as between the ulna and radius. These joints are amphiarthrodial, meaning they allow some movement. - **Gomphoses** are the joints between teeth and their sockets (alveoli), and are synarthrodial. - **Cartilaginous joints are classified into two types**: synchondroses and symphyses. - **Synchondroses** are primary cartilaginous joints, meaning the bones are connected by hyaline cartilage. This type of joint is often temporary because it ossifies with age. - **Symphyses** are secondary cartilaginous joints because fibrocartilage joins the bones. They are strong, slightly movable joints (amphiarthrodial). - **Synovial joints are freely movable joints** that contain several components including the synovial membrane, synovial cavity, synovial fluid, articular cartilage, and accessory ligaments. - **Synovial joints** can also contain intra-articular discs and menisci. - **Intra-articular discs** are fibrocartilaginous discs found at joints under high stress, such as the TMJ and sternoclavicular joint. - **Menisci** are fibrocartilaginous discs found between the femur and tibia at the knee. - **There are six types of synovial joints:** planar, hinge, pivot, condyloid, saddle, and ball and socket. - **Planar joints** consist of two relatively flat surfaces that allow gliding and sliding motions. They have one degree of freedom, allowing for uniaxial movement in only one plane. - **Hinge joints** are similar to a door hinge, with a cylindrical surface fitting into a cylindrical groove. They allow for uniaxial movement in one degree of freedom. - **Pivot joints** have a projection that fits into a ring. They have one degree of freedom, allowing for uniaxial movement. - **Condyloid joints** have an oval-shaped projection that fits into an elliptical hole. These joints have two degrees of freedom, allowing for biaxial movement including flexion/extension and adduction/abduction. - **Saddle joints** have opposing surfaces that are reciprocally concave-convex. These joints have two degrees of freedom, allowing for biaxial movement including flexion/extension and adduction/abduction. - **Ball-and-socket joints** consist of a spherical surface fitting into a bowl-shaped socket. They allow for triaxial movement in three degrees of freedom, including flexion/extension, adduction/abduction, and rotation. - **Ligaments are connective tissue structures that connect bone to bone.** They play a crucial role in stabilizing joints and limiting certain movements. - **Joints receive blood supply from articular arteries and have a rich nerve supply** that provides sensory information about proprioception and pain. - There are three types of muscle tissue: skeletal, cardiac, and smooth. - **Skeletal muscle tissue** is voluntary and primarily attached to bones. Its main functions include movement of the body and movement at joints. - **Cardiac muscle tissue** is involuntary and forms the wall of the heart, responsible for pumping blood. - **Smooth (visceral) muscle tissue** is involuntary and is found in the walls of organs (viscera). Its functions include movement of food through the gastrointestinal system and secretion of fluids from glands. - **Skeletal muscles are voluntarily controlled muscles that make up the muscular system.** - Muscles are responsible for allowing bones to move or change position, due to their unique ability to contract actively and produce tension. - It is important to understand the origin, insertion, action, and nerve innervation of each muscle. - Skeletal muscles have specific attachment sites: origin and insertion. - **The origin** is typically the less moveable point of attachment. - **The insertion** is the point of attachment that moves when the muscle contracts. - There are three types of muscular actions: isometric, concentric, and eccentric. - **Isometric contractions** occur when the muscle contracts and produces force but does not change length. - **Concentric contractions** occur when the muscle shortens while contracting, producing acceleration of body segments. - **Eccentric contractions** occur when the muscle lengthens while contracting, decelerating body segments and providing shock absorption. - Muscles play different roles in the body, including agonist/prime mover, antagonist, synergist, and stabilizer/fixator/supporter. - **The agonist/prime mover** is the primary muscle producing a joint motion. - **The antagonist** is the muscle with the opposite action of the agonist. - **The synergist** contracts at the same time as the agonist, assisting in the movement. - **The stabilizer/fixator/supporter** contracts isometrically to stabilize a limb during movement. - Skeletal muscles are named based on characteristics like fiber direction, size, shape, action, number of origins, location, and attachment sites. - **Tendons and aponeuroses are extensions of connective tissue that attach muscle to bone or other muscles.** - **A tendon** is a cord of dense connective tissue. - **An aponeurosis** is a broad, flat tendon. - **Tendon sheaths** are tube-like structures that wrap around tendons at the wrist and ankle to protect them. - There are two types of fascia: superficial and deep. - **Superficial fascia** is loose connective tissue found beneath the skin. - **Deep fascia** is dense irregular connective tissue that wraps around muscles. - **Nerves are bundles of dendrites or axons.** Sensory nerves receive sensory stimuli, while motor nerves stimulate muscle contraction. - Spinal nerves come from the spinal cord and innervate skeletal muscles. Cranial nerves come from the brain and innervate head and neck muscles. Please note that this response is entirely based on the provided excerpts from the lecture notes. It is recommended to refer to the complete lecture notes for a more comprehensive understanding of the subject matter. What are the three structural classifications of joints? The three structural classifications of joints are: **Fibrous:** The joint is held together by fibrous connective tissue.12 **Cartilaginous:** The joint is held together by cartilage (hyaline or fibrocartilage).12 **Synovial:** Many structures hold the joint together.12\ Three Structural Classifications of Joints The three structural classifications of joints are: **Fibrous joints**: These joints are held together by fibrous connective tissue12. There are three types of fibrous joints: sutures, syndesmoses, and gomphoses.23 ○ Sutures are found between the bones of the skull.2 They are synarthrodial, meaning there is no movement at the joint.2 ○ Syndesmoses are amphiarthrodial joints, meaning they allow some movement.3 They consist of two bones connected by fibrous connective tissue, such as the joint between the ulna and radius.3 ○ Gomphoses are synarthrodial joints that are found between the teeth and their sockets (alveoli).3 **Cartilaginous joints**: These joints are held together by cartilage.12 There are two types of cartilaginous joints: synchondroses and symphyses.3 ○ Synchondroses are primary cartilaginous joints because the bones are connected by hyaline cartilage.3 These are often temporary joints that ossify with age, like the epiphyseal growth plate.3 ○ Symphyses are secondary cartilaginous joints in which the bones are joined by fibrocartilage.3 Symphyses are strong, slightly movable joints.3 An example of a symphysis is the intervertebral disc (IVD) between the vertebrae.3 **Synovial Joints**: These joints have many structures involved in holding the joint together.2 They are also known as diarthrodial joints, which are freely moveable joints.2 Examples of synovial joints include the plane, hinge, pivot, condyloid, saddle, and ball-and-socket joints.4567 You have previously asked about the types of muscular actions. While this is related to the function of joints, it does not pertain to your current query about the structural classifications of joints. What are the three types of muscular actions? The three types of muscular actions are: **Isometric:** In an isometric action, the muscle contracts and produces force, but there is no movement at the joint. The muscle acts to provide stability.1 **Concentric:** In a concentric action, the muscle shortens while contracting. This results in the acceleration of body segments.1 For example, when you lift a weight, your biceps muscle performs a concentric contraction to bend your elbow. **Eccentric:** An eccentric action involves the muscle lengthening while contracting. This type of contraction is used to decelerate body segments and can provide shock absorption.1 An example of this is when you lower a weight back down; your biceps muscle lengthens while still contracting to control the descent. What are the three types of muscle tissue? There are three types of muscle tissue: **skeletal muscle tissue**, **cardiac muscle tissue**, and **smooth muscle tissue**1. **Skeletal muscle tissue** is primarily attached to bones, and is responsible for the movement of the body and movement at joints1. Skeletal muscles are under **voluntary control** meaning that you can consciously control their contractions1. Each skeletal muscle is supplied by a motor and sensory nerve1. Skeletal muscles are also known as the **muscular system**2. **Cardiac muscle tissue** is only found in the wall of the heart1. Cardiac muscle is responsible for the beating of the heart to pump blood1. This muscle type is under **involuntary control**, meaning that you cannot consciously control its contractions1. **Smooth muscle tissue**, also known as visceral muscle tissue, is located in the walls of internal organs or viscera1. Smooth muscle is responsible for a variety of functions, such as moving food through the gastrointestinal system and secreting fluids from glands1. Similar to cardiac muscle, smooth muscle is also under **involuntary control**1. copy\_all thumb\_up thumb\_down keep\_pinSave to note What is the difference between an agonist and an antagonist muscle? Here is an explanation of the difference between an agonist and an antagonist muscle, based on the provided source: An **agonist**, also called a **prime mover**, is the main muscle responsible for producing a specific movement at a joint1. It actively contracts to produce concentric, isometric, or eccentric contractions1. For example, when you bend your elbow, the biceps muscle is the agonist. An **antagonist** is a muscle that opposes the action of the agonist muscle2. It typically relaxes or elongates passively while the agonist contracts, allowing for smooth and controlled movement2. In the example of bending the elbow, the triceps muscle is the antagonist. The source also describes other muscles that are involved in movement: **Synergist**: A synergist muscle assists the agonist in performing the movement. It may have an action similar to the agonist or help to stabilize the joint during the movement. **Stabilizer/Fixator/Supporter**: These muscles contract isometrically to fix or stabilize a body part, allowing the agonist to work more efficiently. The source focuses primarily on the structure and classification of joints and different types of muscle tissue. While it provides definitions for agonist and antagonist muscles, it does not provide detailed examples of how these muscle groups work together to produce different movements. It\'s important to note that the interaction between agonist and antagonist muscles is crucial for coordinated and controlled movement. They work in a balanced way, with one muscle contracting while the other relaxes or lengthens, to produce a smooth, purposeful action. copy\_all thumb\_up thumb\_down keep\_pinSave to note Describe the two types of cartilaginous joints and give an example of each. Types of Cartilaginous Joints The two types of cartilaginous joints are **synchondroses** and **symphyses**1. **Synchondroses**: These are **primary cartilaginous joints** because the bones are connected by **hyaline cartilage**. Synchondroses are often **temporary joints**, meaning they will typically ossify with age1. A common example of a synchondrosis is the **epiphyseal growth plate**, also called the metaphyseal area, which is found in growing long bones1. **Symphyses**: These are **secondary cartilaginous joints** where the bones are joined by **fibrocartilage**1. Symphyses are **strong, slightly movable joints**, also known as **amphiarthrodial joints**12. An example of a symphysis is the **intervertebral disc (IVD)** located between the vertebrae of the spine1. copy\_all thumb\_up thumb\_down keep\_pinSave to note What are the three types of muscle tissue and where are they located? Here is information from the sources regarding the three types of muscle tissue and their locations: **Skeletal muscle tissue** is primarily attached to **bones**.1 This type of muscle tissue is also attached to skin or fascia.1 Skeletal muscle is responsible for the movement of the body and movement at joints.1 Skeletal muscle is under **voluntary control**.1 The **muscular system** is made up of the voluntarily controlled muscles.2 **Cardiac muscle tissue** makes up the wall of the **heart**.1 It is responsible for the heart beating to pump blood.1 Cardiac muscle is under **involuntary control**.1 **Smooth muscle tissue** is found in the walls of **viscera** (internal organs).1 Smooth muscle is also called **visceral muscle tissue**.1 It is responsible for functions like moving food through the gastrointestinal system and secreting fluids from glands.1 Like cardiac muscle, smooth muscle is under **involuntary control**.1 copy\_all thumb\_up thumb\_down keep\_pinSave to note How do muscles play a role in stability? Here is information from the sources on how muscles contribute to stability: **Isometric muscle contractions** play a key role in stability. During an isometric contraction, the muscle contracts and generates force but does not change length, so there is no movement at the joint.1 This type of contraction is essential for maintaining posture and resisting external forces. For example, when you stand upright, your core muscles, including your abdominal and back muscles, are constantly engaged in isometric contractions to keep your spine stable. Muscles act as **stabilizers, fixators, or supporters** to keep a limb or body part from moving when other muscles contract.2 They accomplish this by contracting isometrically. The **origin and insertion** of a muscle also contribute to stability. The origin of a muscle is typically attached to a bone that doesn\'t move during the muscle\'s contraction, while the insertion attaches to the bone that is moved by the contraction.3 This arrangement helps to ensure that the force generated by the muscle is transmitted effectively to the bone, contributing to stability. **Ligaments** are connective tissue structures that connect bones to bones and help stabilize joints.4 They work in conjunction with muscles to limit excessive movement and prevent injury. **Tendons** are strong cords of dense connective tissue that attach muscles to bones.5 They transmit the force generated by the muscle to the bone, enabling movement and providing stability. The sources do not explicitly state how the fiber direction of a muscle belly contributes to stability. However, based on my general knowledge of anatomy and physiology, which is not from the provided sources, the direction of muscle fibers influences the line of pull of the muscle, which can affect the stability of the joint. You may want to independently verify this information. For example, a muscle with fibers that run parallel to the bone will primarily produce a pulling force, while a muscle with fibers that run obliquely can also provide some rotational stability. copy\_all thumb\_up thumb\_down keep\_pinSave to note What are the three types of fibrous joints and their characteristics? Here is information from the sources regarding the three types of fibrous joints and their characteristics: **Fibrous Joints** Fibrous joints are held together by fibrous connective tissue. The three types of fibrous joints are: **Sutures:** Sutures are found between the bones of the skull. These joints are **synarthrodial**, meaning they allow for **no movement**. Sutures are an example of a **synarthrosis**, which is a joint classification based on function.1 **Syndesmoses:** Syndesmoses consist of two bones connected by fibrous connective tissue. These joints are **amphiarthrodial**, meaning they allow for **some movement**. They are classified functionally as **amphiarthroses**. An example of a syndesmosis is the joint between the tibia and fibula or the joint between the radius and ulna.12 **Gomphoses:** A gomphosis is a joint between a tooth and its socket (alveolus). This type of joint is **synarthrodial** because there is **no movement** between the tooth and the socket. Gomphoses are also **synarthroses**.2 copy\_all thumb\_up thumb\_down keep\_pinSave to note What are the four types of muscle roles in the body? Here is information from the sources describing the four types of muscle roles in the body: Muscle Roles in the Body **Agonist/Prime Mover:** The agonist, also called the prime mover, is the primary muscle responsible for producing a specific movement at a joint. It actively contracts to produce concentric, isometric, or eccentric contractions1. For example, when you flex your elbow, the biceps brachii is the agonist1. **Antagonist:** The antagonist is the muscle that has the opposite action of the agonist muscle at a particular joint. It typically does not assist or resist the movement but passively elongates or shortens to allow the motion to occur2. In the example of elbow flexion, the triceps brachii is the antagonist to the biceps brachii2. **Synergist:** A synergist is a muscle that contracts simultaneously with the agonist muscle to help execute a movement. The action of the synergist may be the same or very similar to the action of the agonist muscle2. Synergists can also help to stabilize the joint or modify the direction of movement. **Stabilizer/Fixator/Supporter:** A stabilizer, also known as a fixator or supporter, is a muscle that contracts isometrically to hold a limb or body part steady while the agonist muscle contracts2. This stabilization allows the agonist to work more efficiently. For example, the muscles of the core stabilize the spine during movements of the limbs. The sources focus primarily on the structure and classification of joints, different types of muscle tissues, and how muscles are named. The sources provide definitions for the different roles of muscles, but do not give detailed examples for synergist and stabilizer muscles. copy\_all thumb\_up thumb\_down keep\_pinSave to note What is the difference between the origin and insertion of a muscle? Here is information from the sources regarding the origin and insertion of a muscle: Origin and Insertion **Skeletal muscles** attach to structures like bones, skin, or fascia. Skeletal muscles shorten, or contract, which generates force that pulls on the structures they are attached to.12 **The origin of a muscle** is typically attached to a structure that does not move when the muscle contracts. The origin is usually attached to a bone, but can also be attached to another muscle.2 **The insertion of a muscle** is attached to the structure that moves when the muscle contracts. The insertion is attached to skin, bone, or another muscle.2 The **belly** of the muscle is the fleshy portion that is located between the origin and insertion.2 Muscles pull with **equal force** at both the origin and the insertion.3 The direction of the pull is determined by the direction of the muscle fibers in the belly.3 **Example:** The biceps brachii is a muscle in the arm. The **origin** of the biceps brachii has two heads that attach to the scapula, a bone in the shoulder. The scapula generally does not move when the biceps brachii contracts. The **insertion** of the biceps brachii is on the radius, a bone in the forearm. The radius moves when the biceps brachii contracts. When the biceps brachii contracts, it pulls on both the scapula and the radius with equal force. Because the scapula is more stable than the radius, the force of the contraction is translated to movement at the radius, which flexes the elbow. The information in the sources primarily focuses on the definitions of the origin and insertion. There are no detailed examples of origins and insertions for specific muscles other than what has been provided above. copy\_all thumb\_up thumb\_down keep\_pinSave to note What are the three types of synovial joints? While the sources provide an overview of the six types of synovial joints, they do not categorize them into three distinct groups. The sources describe the structural classification of joints and list six types of synovial joints: plane, hinge, pivot, condyloid, saddle, and ball-and-socket joints.1234 copy\_all thumb\_up thumb\_down keep\_pinSave to note What is the function of ligaments in joints? Here is information from the sources regarding the function of ligaments in joints: Function of Ligaments in Joints **Ligaments** are connective tissue structures that attach bone to bone.1 Ligaments play an important role in **stabilizing joints** and can **limit certain movements** within the joint.1 For example, in our conversation history, we discussed how muscles function as stabilizers to keep a joint from moving during muscle contraction. Ligaments also contribute to the stability of the joint, but they are passive structures, unlike muscles. Ligaments are classified by their anatomical relationship to the **joint capsule:**1 ○ **Capsular ligaments** blend with the joint capsule or are a thickening of the joint capsule. Capsular ligaments increase the strength of the capsule. ○ **Extracapsular ligaments** are located outside of the joint capsule but function to stabilize the joint near the capsule. ○ **Intracapsular ligaments** are located within the joint capsule and act to reinforce the connection between the articulating surfaces. The sources primarily focus on the structural classification of joints, the different types of muscle tissues, and how muscles are named. The sources do not provide detailed information on the specific functions of ligaments in different types of joints. Today\'s lecture will focus on the joints of the vertebral column and a little bit of the thoracic cage. Our vertebra are stacked up against each other, and they\'re going to form two joints as they articulate with other vertebra in the spine.\ \ **Anterior Intervertebral Joint**\ The first joint that we\'re going to talk about exists between two vertebral bodies and the corresponding intervertebral disc because the intervertebral disc is made up of cartilage, this is an amphiarthrodial joint, so it\'s slightly mobile. It offers a little bit of mobility to the spine, but also offers some flexibility and shock absorption as the spinal column moves.\ Whenever we have two vertebral bodies and the disc in between that represents what\'s known as our anterior intervertebral joint, because it sits on the anterior side of the spine.\ \ \ We know that all joints are going to be separate or supported by ligaments. Let\'s have a look at some of the ligaments that support this joint.\ ***The Anterior Longitudinal Ligament* (ALL)** this is a continuous ligament that runs up and down the spinal column, connecting vertebral bodies, intervertebral discs so on and so forth. It\'s a strong, dense ligament, and it goes all the way from the skull, specifically the Occipital, all the way down at the base of the spine, which is our sacrum.\ This ligament restricts movement specifically, it\'s helping to restrict backwards bending, i.e. extension. We can also call that hyper extension.\ If we slide to the back of the vertebra and of this joint, we will see another structure, this is known as ***The Posterior Longitudinal Ligament (PLL)*** that connects the posterior aspect of the vertebral bodies as well as the intervertebral disc. But unlike the ALL it does not really help to provide our motion primarily, it has a low tensile strength, its job is to allow vessels to pass between vertebra to vertebra. It doesn\'t really restrict forward bending, and it also doesn\'t really protect the backside of the joint.\ \ **Disc Herniation**\ So bear that in mind, because we\'re going to talk of the disc and disc herniations next. The intervertebral discs are found throughout all of the mobile segments in the spine that have a vertebral body. So bear that in mind, any segment that doesn\'t have a vertebral body, I\'m talking about the Atlas or the axis, they're not the same intervertebral disc here. The disc is responsible for adding height to the column - about 20 to 25% of your overall column height, and it also helps to protect the intervertebral discs and absorb shock as it\'s traveling up and down.\ \ The outer base of the disc is known as the **annulus fibrosis,** and the annulus fibrosis is responsible for keeping the center core of the disc in place, and it helps to restrict access movement between the corresponding vertebra, okay, this little guy here, it\'s almost like the center of a jelly donut. This is known as the **nucleus pulposus**, okay, this is gelatinous in nature, and this is actually the portion of the disc that helps to **resist compressive forces as they\'re traveling up and down the spine - especially with bad posture.**\ What can happen is that the annular fibers begin to degrade. And when they begin to degrade and erode and degenerate, they fail to contain the nucleus or keep the nucleus in place. Eventually, what can happen is, if the annulus fails to contain the nucleus, the nucleus will push its way out of place, and that is a disc herniation. Most classically, disc herniations occur in the posterior and lateral direction. That should make sense, because we just talked about the fact about the that the PLL, the posterior ligament, doesn\'t really do a great job of containing or supporting the back of this joint, so that this is able to push in this posterior lateral direction. When they do that, they are going to compress this spinal nerve root, on the same side of the body that they herniate.\ \ \ \ Joint 2 - The second joint is also referred to as an intervertebral joint, but typically we call this a **posterior intervertebral joint,** because it\'s located on the posterior aspect of the spine. This joint has several names:\ - zygapophysial joint\ - facet joint\ And both of these joints are synovial joints. So we know that if we have a synovial joint, that tells us that there\'s going to be movement that\'s permitted at these surfaces. These two facets, which are found on the articular processes of vertebra, these come together and they form planar synovial joints, which allow individual slide glide between vertebra. Every vertebra is going to form these facet joints superiorly and inferiorly, with its corresponding segments above and below.\ \ A screenshot of a computer showing a diagram of the spine Description automatically generated So typically we\'ll say that each vertebral segment will form two superior facet joints and two inferior facet joints for a total of four planar joints at every single segment in the spine.  These joints are synovial, so they are going to be protected by a capsular membrane. And these capsules are fairly loose in the cervical spine because the cervical spine permits the most amount of mobility. Note: Even though individually, these joints permit slide and glide, globally, these joints work together to permit the overall motion of the spine. So if you look at your cervical spinal column, it doesn\'t just slide and glide. It flexes, it extends, it laterally flexes on both sides, and it can do a little bit of rotation. All of that is happening at these Z joints or these facet joints that are permitting individual slide and glide motion. So up next, once we talk about the joint, we have to talk about the ligaments that support the joint. So the ligaments that support the joint are found close to and around the joint, helping to restrict access motion.\ The first ligament which is inside the spinal canal is known as our **ligamentum flavum.** It runs from lamina to lamina of adjacent vertebra, so we are now sitting behind or on the posterior aspect of the spinal canal (Talking about the plane and the direction we are looking at the vertebrae. On the anterior aspect of the spinal canal, you would see your posterior longitudinal ligament, and there is a space between these two ligaments and that space is the spinal canal.\ \ We will find our ligamentum flavum running from our second cervical vertebra, C2, all the way down to the S1, the first vertebra of the sacrum. So every single segment in the spine where we have these Z -joints or these zygapophysial joints, we will find this ligamentum flavum supporting the joint. - It helps to preserve upright posture after you have flexed the spine. So when you bend forward and then you come back to your neutral anatomical position, this ligament is helping these joints resume that position. **Supraspinous Ligament** So we have supraspinous ligament. This ligament is going to run all the way up and down the spine, going from the tip or apex of the spinous process to the tip/apex of the next spinous process all the way from the bottom, the sacrum, up to the seventh cervical vertebra. A diagram of a bone structure Description automatically generated\ \ \ \ In addition to the supraspinous ligament, we have **The Interspinous Ligament** that fills the gap or the spaces between the spinous processes (SP to SP).\ \ **Intertransverse Ligament** helps to support the Z -joints and goes TVP to TVP. So for our Z -joints, we have four ligaments. Ligamentum flavum, supraspinous, interspinous, intertransverse. transverse. Every facet joint or Z joint, is going to receive support from these four ligaments.  **Ligamentum Nuchae**\ If we slide all the way up to the cervical spine, we need to have sort of a broader form of support as the cervical spine has the most amount of mobility. When we get to our seventh cervical vertebra - the largest cervical vertebra hence the largest cervical spinous process we call this the vertebral prominence. And what this does is this signifies a little bit of a difference in the ligaments supporting the SPs in this region.\ We have something called the ligamentum nuchae, which is a very thick broad ligament where the supraspinous ligaments have now blended into this very broad dense structure **in addition** to our supraspinous and interspinous ligaments because we have an additional amount of mobility in the cervical spine and we need to hold the head up against the force of gravity. In the cervical spine we have the thin supraspinous ligaments, and we still have the interspinous ligaments, okay, here and here and here, but in addition to these two structures, we also have this broad nuchal ligament, okay, because we are restricting excess motion in this region and also holding up the skull and the neck against the force of gravity. A diagram of the neck and back of a person Description automatically generated **Specialty Vertebra and their joints**\ \ **Craniovertebral Joints**\ If we slide all the way up to the very, very top, we have two specialized vertebra, the atlas, which is C1, and the axis C2. The Atlas does not have a body. The axis has this specialized extension on it referred to as the dens or the adontoid process. Because of the specialized anatomy of these two vertebral segments, they are going to have specialized set of joints. So we typically refer to these generally as cranial vertebral joints because these are the joints that are sitting between the cranium skull and the first few cervical vertebra.\ **- Atlanto-axial joints.**  **Lateral** They are synovial gliding joints that slide and glide individually. They\'re made up of facet surfaces, and they add to the overall mobility of the cervical spine. The difference here is they\'re made up of the lateral masses of the atlas and the superior articular process of the axis. So remember that the axis behaves a little bit more like a normal cervical vertebra, but the atlas is quite unique. **Medial** The medial joint here is quite unique. It exists between the dens, or the adontoid process, and the anterior aspect of C1, the anterior arch of C1. This joint is a pivot synovial joint, so it is going to permit rotation. 50% of rotation that occurs in the cervical spine occurs at this joint alone. The rest is supported by the remainder of the joints in the cervical spine, but that\'s a lot of motion to be happening at this one particular segment or joint. **Supporting Ligaments in Atlantoaxial joints** Travelling directly behind the dens is your spinal cord. So we do not want this dens to move out of place. We want to ensure that this dens stays in place. So as we\'re going to see in a moment, there are a lot of supporting ligaments at this joint that are going to reinforce the connection between the atlas and the axis. - **Anterior Atlantoaxial Ligament** Starting off with the two ligaments that reinforce the joint capsules, we have the anterior atlantoaxial joint ligament. It runs from the atlas to the axis. So it\'s going to run from the anterior arch of the atlas to the body of the axis, reinforcing the connection between these two structures. Bones of the human skull Description automatically generated - **Posterior Atlantoaxial Ligament**\ Up next, we have the posterior atlantoaxial ligament, which is going to run from the posterior arch of the atlas to the lamina of the axis, which is the posterior aspect of the axis.\ In the case of the atlas, we don\'t have a lamina. So we go from posterior arch to lamina of axis. Both of these are going to reinforce the anterior and posterior sides of this joint.\ \  **The Transverse Ligament** of the Atlas\ \ If we take off these ligaments (**Posterior and Anterior Atlantoaxial Ligaments)** and look at the inside of the joint we see a structure which also has a superior and inferior extension and is called **The Transverse Ligament** of the Atlas.\ The broad portion of this ligament runs left to right because it\'s running in the transverse plane.\ This is a thick, broad ligament that wraps right around the posterior aspect of the dens, and it\'s going to anchor the dens to the anterior arch of the atlas. So, it\'s going to go from one side of the anterior arch to the other side of the anterior arch, anchoring it to the lateral mass, which is formed on the anterior side of the atlas. This arrangement will hold the dens firmly against the anterior arch of the atlas. Very important. If you look at this picture down here, the ligament will be going from here to here because that\'s where our lateral masses are, and it\'s going to be wrapping around the back of the dens. In addition to anchoring, it on either side of the atlas, the ligament is also going to have these little extensions. So **the superior longitudinal band** is going to anchor the dens to the occiput, and the **inferior longitudinal band** is going to anchor or reinforce the dens, hold it to the body of the axis. Now although the dens is a part of the axis, we still have a ligament that reinforces and holds everything in place here. So when all three of these guys are in place, the transverse, the superior band, and the inferior band, they form this cross -like structure across the dens known as the cruciate ligament of the atlas.\ **Cruciate Ligament**\ So although this says cruciate ligament as if it\'s a singular structure, it\'s made up of three distinct structures. The superior longitudinal band, the transverse ligament, and the inferior longitudinal band. Each of these is holding the dens in a particular manner and anchoring it. When all of them are in place, they form the cruciate ligament.\ \ **LIGAMENTS CONNECTING THE AXIS WITH THE OCCIPITAL BONE:\ The tectorial membrane** sits on top of all of the smaller ligaments that support the dens, and is a continuation of the PLL, helping to secure posterior aspect, and it runs all the way up to the skull. So it\'s covering that whole structure we just talked about above\ \ So this is a deep picture, and if I were to go more superficial, I get the picture on top. **ALAR ligaments**\ Final series of ligaments that we want to look at here, there\'s a lot of ligaments supporting this end because of the fact that we don\'t want it to move, we want it to stay in place. We have these two ligaments on the side of the dens that are called the ALAR ligaments.\ The ALAR ligaments are going to prevent any sort of side -to -side rocking of the dens because they anchor the side of the dens to the side of the occiput, preventing any side -to -side rocking. Note that the **ligamentum nuchae** will further reinforce this joint by connecting the SPs and the posterior aspect of the axis of the atlas. The ligamentum nuchae goes from C7 all the way up to the skull (vertebral column with the cranium) and has an ability to protect the atlas/axis orientation. axial ligaments **ATLANTOOCCIPITAL JOINT**\ We have one more joint to look at with respect to the cranium and that is the atlantooccipital joint. This is where the atlas is going to form a connection with the base of the skull, which is our occiput, hence the name atlantooccipital. **The articular capsules** surround the condyles of the occipital bone and connect them with the superior articular surfaces of the lateral masses of the atlas. they are thin and loose.* *The capsule that is going to be supporting this joint is a synovial joint. In this case, it\'s going to be a condyloid joint.\ Remember that condyloid joints are egg -shaped surfaces that articulate with each other. So that means that we\'re going to see that this joint permits biaxial movements.  Synovial membrane here is going to be reinforced by two important ligaments. **Anterior Atlantooccipital membrane** that\'s going to reinforce the anterior aspect of the joint. It runs from the base of the skull to the anterior surface of the atlas.\ It passes between the anterior margin of the foramen magnum **above**, and the upper border of the anterior arch of the atlas **below**\ \ Contrasting that we have the **Posterior Atlantooccipital membrane** which is going to run from the base of the skull to the posterior aspect of the atlas. These two membranes are going to help reinforce the joint capsule and do a little bit to permit or restrict excess movement.\ \ Atlantooccipital joint is biaxial because it is condyloid in shape therefore it\'s going to permit flexion and extension which is nodding your head "yes". It will also permit a little bit of side bending like "I don\'t know". The rotation component of this joint is very minimal. Typically we\'ll say that this joint permits up and down yes and then side to side because as we just learned the majority of rotation is happening at that Atlantoaxial joint.\ \ **UNCOVERTIBLE JOINTS (or cleft of Luschka\'s joints)** Uncovertible joints (**or cleft of Luschka\'s joints**) formed between the uncinate processes - the little cat ear extensions on the vertebra and form a joint with the vertebra superior to it.\ They exist between C3 and C7 because those are our classic cervical vertebra and they are synovial planar joints that help to permit additional action of flexion and extension. So they allow a little bit more flexion and extension in the cervical spine but they limit lateral flexion.\ Typically when somebody gets cervical spine degeneration these are usually the joints that where osteoarthritis and degeneration begins because of their limitation in lateral flexion. Cervical Joints **COSTOVERTEBRAL JOINT**\ These are the joints between the thoracic vertebra and the ribs. The head of the rib articulate with the thoracic vertebra and form this costovertebral joint. \ In this case the head of the rib is going to articulate with two vertebral bodies and the intervertebral disc in between. For example, the seventh rib is going to articulate with the vertebral body of the same level T7 and the vertebral body above it T6. This is the same arrangement except for the following levels T1, T10, T11, T12 all form a costovertebral joint with a single vertebra of the same level.\ \ So rib 1 with T1, rib 10 with T10, rib 11 with T11, and rib 12 with T12. That has to do with the unique anatomical characteristics at those levels. So those are the exceptions.\ \ **The radiate ligament of the rib:** Every other costovertebral joint will have this particular arrangement where one rib articulates with two corresponding vertebral bodies. The ligaments that support these ribs are the radiate ligament of the rib, which runs from the head of the rib over the vertebral bodies. So it\'s going to completely support and reinforce the connection with the rib in both vertebra. **Intra-Articular Ligament of head of rib** helps the rib head hold itself against the intervertebral disc, specifically the crest. The ligament reinforces the connection between the crest of the rib against the intervertebral disc.\ Remember that little point? It\'s going to anchor that in against the actual intervertebral disc. So you have the ligament on top, which is reinforcing the capsule, holding the rib against both vertebral bodies and the disc. The next joint that\'s formed, if we slide along the rib, is a costotransverse joint. **COSTOTRANSVERSE JOINTS**\ These joints are with the tubercle of the rib and the facet on the transverse process. Remember that the transverse process has a costal facet. This is another synovial joint that\'s formed, adding to the overall mobility of the thoracic ribcage. So we have a synovial joint here at the costovertebral and we have a synovial joint here at the costotransverse. This joint will be reinforced by the following ligaments:\ **\ The Superior Costotransverse Ligaments** They run from the neck of the rib to the transverse process immediately above it. So this is holding the rib up in place because the ribs have an angle here. **The Costotransverse Ligament** reinforces the connection between the neck of the rib and the TDP - it almost fills the space in between the neck of the rib and the transverse process.\ \ **The Lateral Costotransverse** supports the posterior aspect here, between the TDP and the non -articular portion of the rib tubercle. Superior costotransverse holds it up.\ Costotransverse fills the gap.\ Lateral costotransverse reinforces the posterior aspect. **JOINTS OF THORACIC CAGE**\ \ \ So when we\'re talking about the posterior articulation of how ribs meet vertebra, this summary rings true:\ - [Each rib articulates with 2 vertebral bodies and 1 transverse process]. It\'s always going to articulate with the vertebral body of the same level and the one above. It will also articulate with the TDP at the same level. Remember the exceptions. T1, T10, T11, T12 are only articulating with rib 1, rib 10, rib 11, 12 at their vertebral bodies.\ That\'s very important.\ \ **STERNOCOSTAL AND COSOCHONDRAL JOINTS**\ Sliding around the rib to the front, we have how the ribs form attachments with the sternum and also with their corresponding costal cartilages. So when we look at these joints, what\'s interesting is that from rib 2, 3, 4, 5, 6, 7, so 2 - 7, the ribs are going to form these sternocostal joints and they are synovial which means they offer a little bit of mobility.\ A diagram of the spine Description automatically generated The top joint -- rib 1 - there is no synovial joint. There are 2 bones connected by piece of hyaline cartilage. This, in essence, is a **synchondrosis**. Even though the hyaline cartilage is a primary cartilaginous joint, it is an example of one of those that does not ossify after skeletal maturity and remains cartilaginous. This is because we need the flexibility here so that the rib permits flexible motion. We do not want it to ossify because it would restrict motion of the rib cage during breathing.\ So rib 1 forms a **synchondrosis** attachment for stability of the rib cage.\ Ribs 2 - 7 form **synovial joints**, which offer slide glide mobility of the rib cage on the sternum. **Radiate Ligaments**\ In addition, ligaments that are going to help to reinforce this connection known as radiate ligaments because they have this radiating pattern that run from the end of the rib, specifically the costal cartilage, on top of the sternum, helping to reinforce the connection. We find these bands at all of these sternum costal joints **CostoChondral Joints\ **where the rib meets its corresponding costal cartilage known as costohondral joints and they are also synchondrosis type of joint so this is another example where we have a bone connecting to hyaline cartilage which i previously told you these guys ossify but these are the exceptions to the rule where cartilage doesn\'t ossify. We don\'t want this cartilage ossifying after skeletal maturity.\ **\ **These joints permit flexibility to the rib cage.\ - the sternocostal joints which have a synovial cavity permit mobility. - the costochondral permit flexibility okay as well as this first rib attachment here. **Joint Movement:** when we put all of these joints together we get the overall motion of the rib cage. Remember each of these joints all the way along here has been individual slide glide but as we learned earlier today that when you have individual slide glide motions, you can add those motions together and get what\'s called **global mobility of the area**. We saw that in the vertebral column with the vasectoids.\ \ When our **sternocostal** **+ costotransverse + costovertebral joints** are working together we have an attachment at the sternum and then these attachments at the spine the rib is going to be able to move around these attachment points as if it was the handle of a bucket if you think about how a **bucket handle** moves right the front and the back move together for the handle to go up and down so when you breathe in the ribs are going to move in a superior and lateral direction using the motion at these joints okay it would be the opposite when you breathe out.\ \ \ So if I move in a superior and lateral direction okay i am expanding the rib cage this way creating more room for the lungs to inflate that\'s bucket handle.\ A diagram of a human body Description automatically generated\ In addition at the sternocostal joint, the ribs can also via their pull on the sternum they can pull the sternum anteriorly and superiorly so this is going to cause the chest to expand or grow in this direction (downward arrow pink) Because the sternum moves up and down in a single unit fashion this represents or looks like when you\'re using like a **pump handle** of an old well so sternum moves superiorly when you in and inferiorly when you breathe out.\ The combination of bucket handle and pump handle motion is how the chest wall **expands when you breathe in** and **contracts when you breathe out.\ \ ** **Summary** - **Anatomy of the Vertebral Column and Thoracic Cage** [1:16](https://otter.ai/u/zLCU-8MEh7fpl9BDIIqVJtAby0s?tab=summary&t=76s) - Speaker 1 introduces the second asynchronous lecture on EMS anatomy, focusing on the anatomy of the vertebral column and the thoracic cage. - The lecture covers the joints of the vertebral column, starting with the anterior intervertebral joint, which is slightly mobile and offers flexibility and shock absorption. - The anterior longitudinal ligament (ALL) is described, running from the skull to the sacrum, helping to restrict backward bending. - The posterior longitudinal ligament (PLL) is mentioned, connecting the posterior aspects of vertebral bodies but not restricting forward bending. - **Intervertebral Discs and Herniations** [3:56](https://otter.ai/u/zLCU-8MEh7fpl9BDIIqVJtAby0s?tab=summary&t=236s) - The intervertebral discs are discussed, responsible for adding height to the column and protecting the spine from shock. - The annulus fibrosis and nucleus pulposus are explained, with the annulus fibrosis keeping the nucleus in place and the nucleus resisting compressive forces. - Over time, the annulus fibers can degrade, leading to disc herniations where the nucleus pushes out of place, typically in the posterior and lateral directions. - The posterior intervertebral joint, also known as the facet joint, is introduced, allowing individual slide-glide between vertebrae. - **Facet Joints and Ligaments** [7:20](https://otter.ai/u/zLCU-8MEh7fpl9BDIIqVJtAby0s?tab=summary&t=440s) - The facet joints, also known as zygapophyseal joints, are described as synovial joints, forming between the articular processes of vertebrae. - Each vertebral segment forms two superior and two inferior facet joints, allowing for overall spine mobility. - The ligamentum flavum, supraspinous ligament, interspinous ligament, and intertransverse ligament are discussed as supporting the facet joints. - The cervical spine, with the most mobility, requires additional support, including the broad nuchal ligament and the ligamentum nuchae. - **Specialty Vertebrae and Cranial Vertebral Joints** [14:02](https://otter.ai/u/zLCU-8MEh7fpl9BDIIqVJtAby0s?tab=summary&t=843s) - The Atlas (C1) and Axis (C2) are introduced as specialized vertebrae, with the Atlas having no body and the Axis having the dens or odontoid process. - The atlantoaxial joint is described, including the lateral masses of the Atlas and the superior articular processes of the Axis, forming synovial gliding joints. - The medial atlantoaxial joint, a pivot synovial joint, allows for 50% of cervical spine rotation, with the dens being held in place by several ligaments. - The anterior and posterior atlantoaxial ligaments, transverse ligament of the axis, and tectorial membrane are discussed as reinforcing the atlantoaxial joint. - **Atlanto-Occipital Joint and Oncocervical Joints** [23:36](https://otter.ai/u/zLCU-8MEh7fpl9BDIIqVJtAby0s?tab=summary&t=1416s) - The atlanto-occipital joint is introduced, connecting the Atlas to the base of the skull (occiput), forming a condyloid joint that permits flexion, extension, and side bending. - The anterior and posterior atlanto-occipital membranes reinforce the joint capsule, allowing for axial movements. - Oncocervical joints, formed between the uncovertebral processes, exist between C3 and C7, allowing for additional flexion and extension while limiting lateral flexion. - These joints are often sites of degeneration and osteoarthritis due to their limited mobility. - **Costo-Vertebral and Costo-Transverse Joints** [27:29](https://otter.ai/u/zLCU-8MEh7fpl9BDIIqVJtAby0s?tab=summary&t=1649s) - The costo-vertebral joint is described, where the head of the rib articulates with two vertebral bodies and the intervertebral disc in between, except for T1, T10, T11, and T12. - The radiate ligament of the rib and the intra-articular ligament of the head of the rib are mentioned as reinforcing the costo-vertebral joint. - The costo-transverse joint is introduced, formed between the tubercle of the rib and the facet on the transverse process, allowing for additional mobility. - The superior, intercostal, and lateral costo-transverse ligaments are discussed as reinforcing the costo-transverse joint. - **Sternocostal and Costochondral Joints** [33:26](https://otter.ai/u/zLCU-8MEh7fpl9BDIIqVJtAby0s?tab=summary&t=2007s) - The sternocostal joints, formed between the second to seventh ribs and the sternum, are synovial and offer mobility. - The first rib forms a synchondrosis attachment with the sternum, allowing for flexibility and stability of the rib cage during breathing. - The costochondral joints, where the ribs meet their corresponding costal cartilages, are also synchondrosis, remaining cartilaginous to allow for flexibility. - These joints, along with the sternocostal joints, contribute to the overall mobility of the rib cage during respiration. - **Overall Motion of the Rib Cage** [37:32](https://otter.ai/u/zLCU-8MEh7fpl9BDIIqVJtAby0s?tab=summary&t=2252s) - The combination of sternocostal, costo-transverse, and costochondral joints allows for the rib cage to move like a bucket handle and a pump handle during respiration. - The rib cage expands superiorly and laterally during inhalation, and contracts during exhalation. - The sternum moves superiorly and anteriorly during inhalation, contributing to the expansion of the chest. - The lecture concludes with a practical exercise for students to feel the movement of their ribs and sternum during breathing.