Anatomy LC3: Lower Limb, Back, and Spinal Cord (PDF)

ANATOMY LC3- SKELETAL SYSTEM: VERTEBRAL COLUMN AND THE LOWER LIMBS...

ANATOMY LC3- SKELETAL SYSTEM: VERTEBRAL COLUMN AND THE LOWER LIMBS DR. BOLISLIS | 08/19/2024 COURSE OUTLINE The superior and inferior aspects of the vertebral body are lined with hyaline cartilage. I. VERTEBRAL COLUMN Adjacent vertebral bodies are separated by a A. Structure of the Vertebrae fibrocartilaginous intervertebral disc. B. Classifications of the Vertebrae C. Joints and Ligaments II. BONES OF THE LOWER LIMB A. FEMUR B. PATELLA C. TIBIA D. FIBULA E. BONES OF THE FOOT 1. Tarsals 2. Metatarsals 3. Phalanges Figure 2. General structure of a vertebrae. III. JOINTS OF THE LOWER LIMB A. HIP JOINT II. VERTEBRAL ARCH B. KNEE JOINT Forms the lateral and posterior aspect of each C. PROXIMAL AND DISTAL vertebrae. TIBIOFIBULAR JOINTS Forms an enclosed hole – the vertebral D. ANKLE JOINT foramen. The foramina of all the vertebrae line E. SUBTALAR JOINT up to form the vertebral canal, which encloses the spinal cord. I. VERTEBRAL COLUMN The vertebral arches have several bony Series of approximately 33 bones called prominences, which act as attachment sites for vertebrae, which are separated by intervertebral muscles and ligaments: discs. Divided into 5 different regions, with each ATTACHMENT SITES region characterized by a different vertebral Spinous Each vertebra has a single spinous structure. processes process, centered posteriorly at the point of the arch. Transverse Each vertebra has two transverse processes processes, which extend laterally and posteriorly from the vertebral body. In the thoracic vertebrae, the transverse processes articulate with the ribs. Pedicles Connect the vertebral body to the transverse processes. Lamina Connect the transverse and spinous processes. Articular Form joints between one vertebra processes and its superior and inferior counterparts. Figure 1. Vertebral Column. Located at the intersection of the laminae and pedicles. 4 MAIN FUNCTIONS Protection Encloses and protects the spinal cord within the spinal canal. Support Carries the weight of the body above the pelvis. Axis Forms the central axis of the body. Movement Has roles in both posture and movement. Figure 3. Superior view of a lumbar vertebrae, showing its A. STRUCTURE OF THE VERTEBRAE characteristic features. All vertebrae share a basic common structure. They each consist of an anterior vertebral B. CLASSIFICATIONS OF THE VERTEBRAE body, and a posterior vertebral arch. I. CERVICAL VERTEBRAE I. VERTEBRAL BODY The most proximal region. Forms the anterior part of each vertebrae. There are 7 cervical vertebrae in the human body. It is the weight-bearing component, & vertebrae Found in the neck region. in the lower portion of the column have larger They have three main distinguishing features: body than those in the upper portion (to better support the increased weight). BATCH 2028 1A 1  ANATOMY LC 3: SKELETAL SYSTEM - THE LOWER LIMB, BACK, AND SPINAL CORD Dr. BOLISLIS, M. D. 08/19/2024 MAIN DISTINGUISHING FACTORS III. LUMBAR VERTEBRAE Bifid spinous The spinous process bifurcates at Third region of the vertebral column, located in process its distal end. the lower back between thoracic and your vertebral segments. EXCEPTIONS There are five lumbar vertebrae in most C1 No spinous process humans. The largest in the vertebral column. Spinous process is Structurally specialized to support the weight of C7 longer than that of the torso. C2-C6 and may not Main function as a weight bearing structure. bifurcate Lumbar vertebrae have very large vertebral bodies, which are kidney shaped. Transverse An opening in each transverse They lack the characteristic features of other foramina process, through which the vertebrae, with no transverse foramina, costal vertebral arteries travel to the facets, or bifid spinous processes. brain. They have a triangular-shaped vertebral foramen Triangular Triangular shape of the vertebral like the cervical vertebrae. vertebral foramen. Their spinous processes are shorter than those of foramen thoracic vertebrae and do not extend inferiorly below the level of the vertebral body. NICE TO KNOW Their size and orientation permit needle access to C1 - AKA "Atlas" the spinal canal and spinal cord. C2 - AKA "Axis" o Epidural anesthesia. C7 - AKA "Vertebral Prominens" o Lumbar puncture. Two cervical vertebrae that are unique. C1 and C2 are specialized to allow for the movement of OTHER FEATURES OF A TYPICAL VERTEBRAE the head. Transverse Are long and slender C7 or “Vertebral Prominens” because it is the processes most prominent spinous process that can be felt Articular Have nearly vertical facets in the neck processes Spinous Are short and broad processes Accessory Can be found on the posterior processes aspect of the base of each transverse process. They act as sites of attachment for deep back muscles. Mammillary Can be found on the posterior Figure 4. Characteristic features of a cervical vertebrae processes surface of each superior articular process. They act as sites of II. THORACIC VERTEBRAE attachment for deep back There are 12 thoracic vertebrae. muscles Medium-sized, and increase in size from superior to inferior. Their specialized function is to articulate with ribs, producing the bony thorax. Each thoracic vertebra has two ‘demi facets’. o Superiorly and inferiorly placed on either side of its vertebral body. o Articulate with the heads of 2 different ribs. On the transverse processes of the thoracic vertebrae, there is a costal facet for articulation with the shaft of a single rib. Figure 6. Superior view of a lumbar vertebrae The spinous processes of thoracic vertebrae are oriented obliquely inferiorly and posteriorly. JOINTS The vertebral foramen of thoracic vertebrae is The joints of the lumbar vertebrae are supported circular, in contrast to the cervical vertebrae. by several ligaments. They can be divided into two groups: 1. Those present throughout the vertebral column. 2. Those unique to the lumbar spine. o The lumbosacral joint (between L5 and S1 vertebrae) is strengthened by the Iliolumbar ligaments. o Fan-like ligaments radiating from the Figure 5. Lateral view of a thoracic vertebrae transverse processes of the L5 vertebra to the ilia of the pelvis BATCH 2028 1A 2  ANATOMY LC 3: SKELETAL SYSTEM - THE LOWER LIMB, BACK, AND SPINAL CORD Dr. BOLISLIS, M. D. 08/19/2024 COMPONENTS OF INTERVERTEBRAL DISC ANATOMICAL RELATIONSHIPS Annulus Type I collagen Throughout the vertebral column, the spinal cord fibrosus Consist of an outer ring of collagen travels through the vertebral canal (made up by of fibrocartilage arranged in a the foramina of all vertebrae) circle-like configuration. At around the level of L1, the spinal cord This arrangement of fibers limits terminates and the cauda equina begins rotation between vertebrae. Bundle of lumbar, sacral and coccygeal nerve Nucleus Type II collagen roots pulposus Fills the center of the intervertebral Spinal nerves exit the vertebral canal through the disc, is gelatinous, and absorbs intervertebral foramina. compression forces between vertebrae. IV. SACRUM A collection of 5 fused vertebrae PATHOLOGY Described as an inverted triangle, with the apex pointing inferiorly. Abnormal displacement of the nucleus results in a On the lateral walls of the sacrum are facets for herniated disc. articulation with the pelvis at the sacroiliac joints. A sudden Increase In the compression load on the vertebral column causes the nucleus pulposus V. COCCYX to flatten; o However, the resilience of the surrounding Or tailbone annulus fibrosus accommodates the resulting A small bone which articulates with the apex of outward bulging of the nucleus. the sacrum. Sometimes, the outward thrust of the nucleus is Recognised by its lack of vertebral arches. Due too great for the anulus fibrosus and it ruptures, to the lack of vertebral arches, there is no allowing the nucleus pulposus to herniate and vertebral canal. protrude into the vertebral canal, where it may press on spinal nerve roots, a spinal nerve. or even the spinal cord. Figure 7. Diagram of the sacrum and coccyx, articulating with the pelvic bones. C. JOINTS AND LIGAMENTS The mobile vertebrae articulate with each other via joints between their bodies and articular facets. Left and right superior articular facets articulate with the vertebra above. Left and right inferior articular facets articulate with the vertebra below. Figure 9. Intervertebral disc Vertebral bodies indirectly articulate with each other via the intervertebral discs. Figure 10. Ligaments of the lumbar vertebrae 2 LIGAMENTS THAT STRENGTHEN THE VERTEBRAL BODY JOINTS ALL Anterior Longitudinal Ligament Figure 8. a. L3 and L4 vertebrae: posterior b. Lumbar vertebrae, articulated: left lateral view Thick and prevents hyperextension of the vertebral column. The vertebral body joints are cartilaginous joints, PLL Posterior Longitudinal Ligament designed for weight-bearing. Weaker and prevents hyperflexion The articular surfaces are covered by hyaline, and Runs the full length of the vertebral column. are connected by the intervertebral disc. BATCH 2028 1A 3 ANATOMY LC 3: SKELETAL SYSTEM - THE LOWER LIMB, BACK, AND SPINAL CORD Dr. BOLISLIS, M. D. 08/19/2024 FACET JOINTS Inter- A ridge of bone that runs in an Joints between the articular facets are being trochanteric inferomedial direction on the supported by several ligaments. line anterior surface of the femur, spanning between the two LIGAMENTS trochanters After it passes the lesser trochanter Ligamentum Extends between lamina of on the posterior surface pectineal flavum adjacent vertebrae. line > pectineal line. Interspinous & Join the spinous processes of Anterior attachment of the hip joint supraspinous adjacent vertebrae. The capsule. ligament interspinous ligaments attach Inter- Ridge of the bone that connects the between processes, and the trochanteric two trochanters supraspinous ligaments attach crest Located on the posterior surface of to the tips. the femur Intertransverse Extends between transverse ligaments processes. Allow for some gliding motions between the FRACTURES vertebrae Intra Occurs within the capsule of the hip capsular joint. II. BONES OF THE LOWER LIMB It can damage the medial femoral circumflex artery and cause avascular necrosis of the femoral head. A. FEMUR Extra Blood supply to the head of femur is The femur is the only bone in the thigh. capsular intact, so avascular necrosis is a rare It is the longest bone in the body. complication Acts as the site of original and attachment of many muscles and ligaments B. SHAFT Divided into three parts: Proximal, Shaft and Distal. The shaft of the femur descends in a slight medial direction. This brings the knees closer to the body’s center of gravity, increasing stability. LINEA ASPERA Latin for rough line. These are roughened ridges on the posterior surface of the femoral shaft. Figure 11. Anterior & Posterior Image of the Femur Splits distally to form the medial and lateral supracondylar lines and the flat popliteal A. PROXIMAL REGION surface lies between them. Articulates with the acetabulum of the pelvis to Proximally, the medial border of the linea form the hip joint. aspeara become the pectineal line. ○ The lateral border becomes the gluteal PROXIMAL LANDMARKS tuberosity. Distally, the linea aspera widens and forms the Head Articulates with the acetabulum of floor of the popliteal fossa. the pelvis to form the hip joint. ○ Medial and lateral borders form the medial Has smooth surface covered with and lateral supracondylar lines. articular cartilage ○ The medial supracondylar line ends at the ○ Except for a smaller depression: adductor tubercle. The fovea where ligamentum teres attaches Neck Connects the head of the femur with the shaft Cylindrical, projecting in a superior and medial direction Greater Most lateral palpable projection of trochanter the bone that originated from the anterior aspect, just lateral to the neck Site of attachment for many of the muscles in the gluteal region Lesser Smaller than the greater trochanter. trochanter It projects from the posteromedial side of the femur, just inferior to the neck-shaft junction. Figure 12. Posterior surface of the right femoral shaft. BATCH 2028 1A 4 ANATOMY LC 3: SKELETAL SYSTEM - THE LOWER LIMB, BACK, AND SPINAL CORD Dr. BOLISLIS, M. D. 08/19/2024 C. DISTAL REGION B. POSTERIOR SURFACE The distal end of the femur is characterized by Articulates with the femur, and is marked by the presence of the medial and lateral condyles two facets which articulates with the tibia and patella to form the knee joint. Medial facet Articulates with the medial condyle of the femur Medial and Rounded areas at the end of the Lateral facet Articulates with the lateral Lateral femur. condyle of the femur Condyles Posterior and Inferior surfaces articulate with the tibia and menisci of the knee. The anterior surface articulates with the patella. Medial and Bony elevations on non-articular Lateral areas of the condyles. Epicondyles Medial epicondyle is larger. Inter- Deep notch on the posterior Condylar surface of the femur, between 2 Figure 15. Anterior and Posterior Surface of the patella. Fossa condyles. Has 2 facets for attachment of FUNCTIONS intracapsular knee ligaments: ACL Leg Enhances the leverage that the & PCL. extension quadriceps tendon can exert on the femur, increasing the efficiency of the muscle. Protection Protects the anterior aspect of the knee joint from physical trauma. C. TIBIA Also known as the shin. It is the main bone of the lower leg. Expands at its proximal and distal ends. Figure 13. Anterior and Posterior surface of the right femur. Articulating at the knee and ankle joints, respectively. B. PATELLA Second largest bone in the body. Also known as the kneecap. Key weight-bearing structure. It is located at the front of the knee joint within the Some sources say that both the tibia and fibula patellofemoral groove of the femur. are weight bearing bones, but for this discussion, Its superior aspect is attached to the quadriceps the tibia is the only weight bearing bone between tendon and inferior aspect to the patellar ligament. the two. Classified as a sesamoid type bone. ○ It is the largest sesamoid bone in the body. The patella has a triangular shape, with anterior and posterior surfaces. Figure 14. The Figure 16. Overview of the tibia. position of the patella within the lower limb. A. PROXIMAL REGION The proximal tibia is widened by the medial and lateral condyles, which aids in weight bearing. A. ANTERIOR SURFACE The condyles form a flat surface known as the tibial plateau. Situated inferiorly & is connected to Articulates with the femoral condyles to form the Apex the tibial tuberosity by the patellar key articulation of the knee joint. ligament Forms the superior aspect of the INTERCONDYLAR EMINENCE Base bone Located between the condyles. Attachment for quadriceps tendon Projects upwards on either side as the medial and lateral intercondylar tubercles. BATCH 2028 1A 5 ANATOMY LC 3: SKELETAL SYSTEM - THE LOWER LIMB, BACK, AND SPINAL CORD Dr. BOLISLIS, M. D. 08/19/2024 Main site of attachment for the ligaments and the LATERALLY menisci of the knee joint Fibular notch, where the fibula is bound to the Intercondylar tubercles of the tibia articulate with tibia – forming the distal tibiofibular joint. the intercondylar fossa of the femur. FRACTURES High Energy Occurs predominantly in the Trauma younger population Low Energy AKA insufficiency fractures Trauma occurs predominantly in the elderly. These fractures are classified using the Schatzker classification, and if very displaced will likely require operative management. D. FIBULA Figure 17. The tibial plateau. The fibula is a bone located within the lateral aspect of the leg. Its main function is to act as an B. SHAFT attachment for muscles, and not as a The shaft of the tibia is prism-shaped, with three weight-bearer. borders and three surfaces; anterior, posterior and lateral. Anterior Palpable subcutaneously down the border anterior surface of the leg as the shin Proximal aspect of the anterior border is marked by the tibial tuberosity Attachment site for the patella ligament Posterior Marked by a ridge of bone known as surface soleal line Site of origin for part of the soleus muscle, and extends inferomedially, blending with the medial border of the tibia Figure 18. Overview of the fibula within the leg. Lateral Interosseous border border Gives attachment to the interosseous ARTICULATIONS membrane Proximal Articulated with the lateral condyle Tibiofibular of the tibia Joint Distal Articulates with the fibular notch of Tibiofibular the tibia. Joint Ankle Joint Articulated with the talus bone of the foot. LANDMARKS OF FIBULA PROXIMAL At the proximal end, the fibula has an enlarged head, which contains a facet for articulation with the lateral condyle of the tibia. SHAFT Has three surfaces: anterior, lateral Figure 18. Bony Landmarks of the Tibial Shaft. and posterior. The leg is split into 3 compartments, C. DISTAL and each surface faces its respective compartment (e.g anterior surface The distal end of the tibia widens to assist the faces the anterior compartment of the weight-bearing leg.) MEDIAL MALLEOLUS DISTAL Distally, the lateral surface continues inferiorly, and is called the lateral Bony projection continuing inferiorly on the medial malleolus. aspect of the tibia. Lateral malleolus: More prominent Articulates with the tarsal bones to form part of than the medial malleolus the ankle joint. ○ Can be palpated at the ankle on On the posterior surface of the tibia, there is a the lateral side of the leg. groove through which the tendon of tibialis posterior passes. BATCH 2028 1A 6 ANATOMY LC 3: SKELETAL SYSTEM - THE LOWER LIMB, BACK, AND SPINAL CORD Dr. BOLISLIS, M. D. 08/19/2024 A. PROXIMAL ROW The proximal tarsal bones are the talus and the calcaneus. These comprise the hindfoot, forming the bony framework around the proximal ankle and heel. TALUS Most superior of the tarsal bones Main function: It transmits the weight of the entire body to the foot. It has three articulations: ARTICULATIONS Figure 19. Anatomical landmarks of fibula. Superiorly Ankle joint: between the talus and the bones of the leg (the tibia E. BONES OF THE FOOT and fibula). Inferiorly Subtalar joint: between the talus and calcaneus. Anteriorly Talonavicular joint: between the talus and the navicular. Main function: Transmits forces from the tibia to Figure 20. Overview of the bones of the foot. the heel bone (known as calcaneus). Bones of the foot can be divided into 3 groups Wider anteriorly compared to posteriorly which and 3 regions. provides additional stability to the ankle. Numerous ligaments attach to the talus, no muscles originate from or insert onto it. 3 GROUPS ○ There is a high risk of avascular necrosis as Tarsals A set of seven irregularly shaped the vascular supply is dependent on fascial bones; situated proximally in the structures. foot in the ankle area. Metatarsals Connect the phalanges to the CALCANEUS tarsals. Largest tarsal bone Five in number: one for each digit Lies underneath the talus where it constitutes the Phalanges The bones of the toes. heel. It has two articulations: Each toe has three phalanges: Proximal, Intermediate, and Distal ARTICULATIONS ○ Except the big toe, which only has two phalanges. Superiorly Subtalar (talocalcaneal) joint: The bones of the foot provide mechanical support between the calcaneus and the for the soft tissues; helping the foot withstand the talus. weight of the body whilst standing and in motion. Anteriorly Subtalar joint: between the talus and calcaneus. 3 REGIONS Protrudes posteriorly and takes the weight of the Hindfoot Talus and calcaneus body as the heel hits the ground when walking. Midfoot Navicular, cuboid, and cuneiforms The posterior aspect of the calcaneus is marked by calcaneal tuberosity, to which the Achilles Forefoot Metatarsals and phalanges. tendon attaches. 1. TARSALS The tarsal bones of the foot are organized into three rows: proximal, intermediate, and distal. Figure 22. Calcaneus bone. Figure 21. Tarsal bones of the foot. BATCH 2028 1A 7 ANATOMY LC 3: SKELETAL SYSTEM - THE LOWER LIMB, BACK, AND SPINAL CORD Dr. BOLISLIS, M. D. 08/19/2024 B. INTERMEDIATE ROW The intermediate row of tarsal bones contains one bone, the navicular. Positioned medially, it articulates with: ○ The talus posteriorly ○ All three cuneiform bones anteriorly ○ The cuboid bone laterally. On the plantar surface of the navicular, there is a tuberosity for the attachment of part of the tibialis posterior tendon. Figure 25. Cuneiform bones 2. METATARSALS The metatarsals are located in the forefoot, between the tarsals and phalanges. They are numbered I-V (medial to lateral). They are convex dorsally and consist of a head, neck, shaft, and base (distal to proximal). ARTICULATIONS Figure 23. Navicular bone. Proximally Tarsometatarsal joints: between the metatarsal bases and the tarsal bones C. DISTAL ROW Laterally Intermetatarsal joint(s): between the In the distal row, there are four tarsal bones – metatarsal and the adjacent the cuboid and the three cuneiforms. These metatarsals. bones articulate with the metatarsals of the foot. Distally Metatarsophalangeal joint: between The cuboid is most lateral: the metatarsal head and the proximal o Lying anterior to the calcaneus and behind the phalanx fourth and fifth metatarsals. o The inferior (plantar) surface of the cuboid is marked by a groove for the tendon of fibularis longus. Figure 26.. Metatarsal bones. Figure 24. Cuboid bone. 3. PHALANGES The three cuneiforms (lateral, intermediate (or The phalanges are the bones of the toes. middle) and medial) are wedge shaped bones. The second to fifth toes all have proximal, o Articulate with the navicular posteriorly, and the middle, and distal phalanges. metatarsals anteriorly. The great toe has only 2; proximal and distal o The shape of the bones helps form a phalanges. They are similar in structure to the metatarsals, transverse arch across the foot. each phalanx consists of a base, shaft, and head. o They are also the attachment point for several muscles: Medial Tibialis anterior, (part of) tibialis cuneiform posterior, and fibularis longus. Lateral Flexor hallucis brevis cuneiform Figure 26. Phalanges of the foot. BATCH 2028 1A 8 ANATOMY LC 3: SKELETAL SYSTEM - THE LOWER LIMB, BACK, AND SPINAL CORD Dr. BOLISLIS, M. D. 08/19/2024 III. JOINTS OF THE LOWER LIMB Ischiofemoral Spans between the body of the ischium and greater trochanter of the femur, reinforcing the capsule A. HIP JOINT posteriorly. The hip joint is a ball and socket synovial joint, Has a spiral orientation and formed by an articulation between the pelvic prevents hyperextension and acetabulum and the head of the femur (similar to holds the femoral head in the glenohumeral joint of upper extremity). acetabulum. STRUCTURES OF THE HIP JOINT ARTICULATING SURFACES The hip joint consists of an articulation between the head of the femur and the acetabulum of the pelvis. ACETABULUM A cup-like depression located on the inferolateral aspect of the pelvis. Its cavity is deepened by the presence of a Figure 28. The extracapsular ligaments of the hip joint. fibrocartilaginous collar – the acetabular labrum. The head of the femur is hemispherical, and fits MOVEMENTS AND MUSCLE completely into the concavity of the acetabulum. The movements that can be carried out at the hip joint are listed below, along with the principle muscles responsible for each action: MOVEMENTS AND MUSCLE Flexion Iliopsoas, rectus femoris, sartorius, pectineus Figure 27. Articulating Extension Gluteus maximus; surfaces of the hip joint. semimembranosus, semitendinosus and biceps femoris (the hamstrings) Abduction Adductors longus, brevis and LIGAMENTS magnus, pectineus and gracilis The ligaments of the hip joint act to increase Lateral Biceps femoris, gluteus maximus, stability. They can be divided into two groups – (external) piriformis, assisted by the intracapsular and extracapsular: rotation obturators, gemilli and quadratus femoris. INTRA Ligament of head of femur Medial Anterior fibres of gluteus medius CAPSULAR Runs from the acetabular fossa to (internal) and minimus, tensor fascia latae the fovea of the femur rotation Encloses a branch of the obturator Circumduction Multiple muscles artery (artery to head of femur), a minor source of arterial supply to The degree to which flexion at the hip can occur the hip joint. depends on whether the knee is flexed – this EXTRA There are three main extracapsular relaxes the hamstring muscles, and increases the CAPSULAR ligaments, continuous with the range of flexion. outer surface of the hip joint Extension at the hip joint is limited by the joint capsule. capsule and the iliofemoral ligament. o These structures become taut during EXTRACAPSULAR LIGAMENTS extension to limit further movement. Iliofemoral Arises from the anterior inferior ligament iliac spine & then bifurcates before B. KNEE JOINT inserting into the intertrochanteric The knee joint is a hinge type synovial joint mainly line of the femur. allows flexion and extension (and small degree of Has a ‘Y’ shaped appearance, & medial and lateral rotation) prevents hyperextension of the hip joint. Strongest of the three ligaments. Pubofemoral Spans between the superior pubic rami and the intertrochanteric line of the femur, reinforcing the capsule anteriorly and inferiorly. Has a triangular shape, and prevents excessive abduction and Figure 29. The femur, tibia extension. and patella of the knee joint. BATCH 2028 1A 9 ANATOMY LC 3: SKELETAL SYSTEM - THE LOWER LIMB, BACK, AND SPINAL CORD Dr. BOLISLIS, M. D. 08/19/2024 ARTICULATING SURFACES BURSA The knee joint consists of two articulations - In knee joint is the synovial fluid filled sac, found tibiofemoral and patellofemoral. between moving structures in a joint - with the aim The joint surfaces are lined with hyaline cartilage of reducing wear and tear on those structures and are enclosed within a single joint cavity. BURSAE ARTICULATING SURFACES Suprapatellar Located between the quadriceps Tibiofemoral Medial and lateral condyles of the bursa femoris and the femur. femur articulate with the tibial Prepatellar Located between the apex of the condyles. bursa patella and the skin. Major weight-bearing component Infrapatellar Split into deep and superficial. of the knee joint bursa o Deep bursa - lies between the Patellofemoral The anterior aspect of the distal tibia and the patellar ligament. femur articulates with the patella. o Superficial - lies between the Allows the tendon of quadriceps patella ligament and the skin femoris (knee extensor) to be Semi- Located posterior to the knee inserted directly over the knee membranosus joint, between semimembranosus extensor) to be inserted directly bursa muscle and medial head of the over the knee gastrocnemius. Figure 30. The inferior surface of the femur and superior surface of the tibia is shown. Figure 33. Sagittal view of the knee joint, showing the major MENISCI bursae. The medial and lateral meniscus are fibrocartilage structures in the knee that serve two functions: LIGAMENTS ○ To deepen the articular surface of the tibia, The major ligaments in the knee joint are: thus increasing the stability of the joint ○ To act as shock absorbers by increasing Patellar A continuation of the quadriceps surface area to further dissipate forces ligament femoris tendon distal to the patella. It ○ C shaped and attached at both ends to the attaches to the tibial tuberosity. intercondylar area of the tibia. Collateral Two strap-like ligaments. They act to ligaments stabilize the hinge motion of the knee, preventing excessive medial or lateral movement A. Medial collateral ligament Wide and flat ligament, found on the medial side of the joint. Proximally, it attaches to the medial epicondyle of Figure 31. the femur, distally it attaches to the Posterior view of the knee joint, with the joint medial condyle of the tibia. capsule removed. B. Lateral collateral ligament Thinner and rounder than the medial collateral ligament. It attaches Medial The medial meniscus is also fixed to proximally to the lateral epicondyle of meniscus the medial collateral ligament and the femur and distally to a depression the joint capsule on the lateral surface of the fibular Lateral Smaller and is more mobile head. meniscus o The most common meniscus Cruciate These two ligaments connect the affected in athletes (tear) ligament femur and the tibia. A. Anterior cruciate ligament (ACL) Attaches at the anterior intercondylar region of the tibia where it blends with the medial meniscus. It ascends posteriorly to attach to the femur in the intercondylar fossa. It prevents anterior dislocation of the Figure 32. The menisci of the knee joint. tibia onto the femur. Superior surface of the tibia. BATCH 2028 1A 10 ANATOMY LC 3: SKELETAL SYSTEM - THE LOWER LIMB, BACK, AND SPINAL CORD Dr. BOLISLIS, M. D. 08/19/2024 B. Posterior cruciate ligament (PCL) Attaches at the posterior intercondylar region of the tibia and ascends anteriorly to attach to the anteromedial femoral condyle. It prevents posterior dislocation of the tibia onto the femur. Figure 35. Posterior view of the left proximal tibiofibular joint. B. DISTAL (INFERIOR) TIBIOFIBULAR JOINT Consists of an articulation with the fibular notch of the distal tibia and fibula An example of a fibrous joint where the joint surfaces are bound by tough fibrous tissue The distal tibiofibular joint is supported by: Interosseous A fibrous structure Figure 34. Anterior view of the knee joint, showing some of the major ligaments. membrane spanning the length of the tibia and fibula. Anterior and posterior MOVEMENTS inferior tibiofibular Extension Produced by the quadriceps ligaments femoris, which inserts into the Inferior transverse A continuation of the tibial tuberosity. tibiofibular ligament posterior inferior Flexion Produced by the hamstrings, tibiofibular ligaments gracilis, sartorius and popliteus. Lateral rotation Produced by the biceps femoris. Medial Produced by five muscles: rotation Semimembranosus, Semitendinosus, Gracilis, Sartorius, and Popliteus Lateral and medial rotation can only occur when the knee is flexed (if the knee is not flexed, the medial/lateral rotation occurs at the hip joint). Proximal and distal tibiofibular joints C. PROXIMAL AND DISTAL TIBIOFIBULAR Figure 36. The left distal tibiofibular joint, supported by the JOINTS interosseous membrane and the anterior inferior tibiofibular ligament A. PROXIMAL TIBIOFIBULAR JOINT D. ANKLE JOINT Formed by an articulation between the head of The ankle joint (talocrural joint) is a synovial joint the fibula and the lateral condyle of the tibia. formed by the tibia and fibula and the foot. A plane type synovial joint; where the bones glide Functionally, it is a hinge type of joint, permitting over one another to create movement. dorsiflexion and plantarflexion of the foot. Articular surface of the proximal tibiofibular joint is The ankle joint can be felt between tendons on lined with hyaline cartilage and contained within a the anterior surface of the ankle as a slight joint capsule depression The joint capsule receives additional support from: Anterior and posterior Span between the superior tibiofibular fibular head and lateral ligaments tibial condyle Lateral collateral ligament of the knee joint Provides reinforcement Biceps femoris as it inserts onto the fibular head. Figure 37. The bones of the ankle joint: tibia, fibula and talus. BATCH 2028 1A 11 ANATOMY LC 3: SKELETAL SYSTEM - THE LOWER LIMB, BACK, AND SPINAL CORD Dr. BOLISLIS, M. D. 08/19/2024 ARTICULATING SURFACES LIGAMENTS Formed by three bones; the tibia and fibula of the There are two main sets of ligaments, which leg, and the talus of the foot. originate from each malleolus The tibia and fibula are bound together by strong Known as deltoid ligament tibiofibular ligaments. Attached to the medial malleolus. Together, they form a bracket shaped socket, o A bony prominence projecting from covered in hyaline cartilage. Medial the medial aspect of the distal tibia. o This socket is known as a mortise. ligament Consists of four ligaments, which fan The body of the talus fits snugly into the mortise out from the malleolus, attaching to formed by tibia and fibula. the talus, calcaneus and navicular The articulating part of the talus is wedge-shaped bones. - it is broad anteriorly, and narrow posteriorly. Primary action: resist over-eversion of the foot The anterior part of the talus is Originates from the lateral malleolus held in the mortise, the joint is (bony prominence projecting from the more stable. Lateral lateral aspect of the distal fibula) and The grip of the malleoli on the ligament resists over-inversion of the foot. trochlea is strongest during Composed of 3 distinct and separate Dorsiflexion dorsiflexion because this ligaments. movement forces the wider anterior part of the trochlea 3 DISTINCT LATERAL LIGAMENTS posteriorly between the malleoli, Anterior Spans between lateral malleolus spreading the tibia and fibula talofibular and lateral aspect of the talus. slightly apart. Posterior Spans between the lateral The posterior part of the talus is talofibular malleolus and the posterior held in the mortise, the joint is less aspect of the talus stable. Calcaneofibular Spans between the lateral Plantarflexion If the mechanism of injury is malleolus and the calcaneus dorsiflexion of the ankle, usually it’s a fracture. If there is excessive Over-eversion - foot outwards plantarflexion, the mechanism of Inversion - foot innerside, cause of tripping injury is in its location. If the mechanism of injury is dorsiflexion of the ankle, usually it’s a fracture. If there is excessive plantarflexion, the mechanism of injury is in its location. Figure 40. Bones and Ligaments of the Foot. MOVEMENTS AND MUSCLES INVOLVED The ankle joint is a hinge type of joint, with movement permitted in one plane. Figure 38. X-ray of a normal ankle joint. Note the bracket shaped socket formed by the tibia and fibula. Eversion and Inversion are produced by the subtalar joint. Produced by the muscles in the posterior compartment of the leg Plantar flexion o Gastrocnemius o Soleus o Plantaris o Posterior Tibialis Produced by the muscles in the anterior compartment of the leg Figure 39. The talus. It is broad anteriorly, which strengthens the Dorsiflexion o Tibialis anterior joint during dorsiflexion. o Extensor hallucis longus o Extensor digitorum longus BATCH 2028 1A 12 ANATOMY LC 3: SKELETAL SYSTEM - THE LOWER LIMB, BACK, AND SPINAL CORD Dr. BOLISLIS, M. D. 08/19/2024 E. SUBTALAR JOINT STABILITY Articulation between two of the tarsal bones in the The subtalar joint is enclosed by a joint capsule, foot - the talus and calcaneus. which is lined internally by synovial membrane The joint is classified structurally as a synovial and strengthened externally by a fibrous layer. joint, and functionally as a plane synovial joint. The capsule is also supported by three ligaments: 1. Posterior talocalcaneal ligament ARTICULATING SURFACES 2. Medial talocalcaneal ligament The subtalar joint is formed between two of the 3. Lateral talocalcaneal ligament tarsal bones: An additional ligament: the interosseous talocalcaneal ligament o Acts to bind the talus and calcaneus together. Posterior Talar Inferior surface of the body Articular Surface of the talus It lies within the sinus tarsi (small cavity between talus and calcaneus), and is Posterior Calcaneal Superior surface of the particularly strong; providing the majority of Articular Facet calcaneus the ligamentous stability to the joint. As a typical synovial joint, these surfaces are covered by articular cartilage MOVEMENTS Note: Some text refers to the talocalcaneal part of The subtalar joint is formed on an oblique axis the talocalcaneonavicular joint as being part of the and is therefore the chief site within the foot for subtalar joint. generation of eversion and inversion movements. This movement is produced by: Lateral Compartment Eversion of the leg Tibialis Anterior muscle Inversion Subtalar joints won’t contribute to plantar or dorsiflexion of the foot. Figure 41. The subtalar joint and interosseous talocalcaneal ligament. Reference(s): Bolislis, M.D. (2024). Osteology of the Vertebral Column Wineski, L. E. (2019). Snell’s Clinical Anatomy By Regions (10th ed.). Philadelphia (PA): Wolters Kluwer. TeachMeAnatomy. (2024). Bones of the Lower Limbs. https://teachmeanatomy.info/lower-limb/bones/ BATCH 2028 1A 13