Exam 2 Guide - Integumentary System PDF

Chapter 5: The Integumentary System =================================== Melanocytes vs. keratinocytes - What substance does each cell produce **Melanocytes:** Located in basale layer (deepest) and produces melanin. **Keratinocytes:** major cell in epidermis and produce fibrous keratin, - Wha...

Chapter 5: The Integumentary System =================================== Melanocytes vs. keratinocytes - What substance does each cell produce **Melanocytes:** Located in basale layer (deepest) and produces melanin. **Keratinocytes:** major cell in epidermis and produce fibrous keratin, - What is the purpose of these substances **Melanin** helps protect the skin from UV and gives pigmentation. More sun = more melanin. **Keratin** helps strengthen/protect skin. Four layers of the epidermis (ignore the 5^th^ layer the stratum lucidum) - Know each layers' location in the epidermis (deep vs. middle vs. superficial) - Unique characteristics of each layer o What kind of cells are found in the layer o Are these cells alive or dead o In each layer -- what are the cells doing, or what is their function - alternate name if the layer has one 1. **Stratum Corneum:** most superficial. Has 20-30 layers of cells (most). They are anucleated, keratinized dead cells that are shed easily. 2. **Stratum Granulosum:** second layer. One-five cells thick. LAST layer of LIVE cells. Keratinocytes flatten, nuclei and organelles disintegrate, and keratinization takes place. The prekeratin filaments bind together with keratinohyaline granules to form keratin. The keratin and glycolipids secrete a water-resistant glycolipid making this water-resistant. 3. **Stratum Spinosum:** third layer. ["Spikey"] because the keratinocytes in this layer seem to have little spikes. Several layers thick of filaments containing pre-keratin, keratinocytes, and dendritic (immune) cells scatter among the keratinocytes. 4. **Stratum Basale:** Also known as [stratum germinativum]. It is base layer, closest to dermis, smallest layer too. Consists of a single layer of stem cells that are in active mitosis. Keratinocytes arise from here (basale layer and move up, die as they do so). Contains melanocytes as well. Layers of the dermis - Thickness of each layer and their skin features associated with them. **Papillary:** superficial layer of areolar connective tissue with collagen fibers and elastic fibers. Many small blood vessels and lymphatic vessels. Contains dermal papillae: fingerlike extensions that project into epidermis. In thick skin, [dermal papillae] lie on dermal ridges which are called [epidermal ridges], collectively known as frictional ridges for gripping and sense of touch. **Reticular:** Deeper dermis. Accounts for \~80% thickness. Coarse, dense fibrous irregular connective tissue. Collagen fibers = strength. Elastic = stretch/recoil. Contains network of blood vessels known as dermal vascular plexus. Also has [cleavage lines] which help doctors know where to place incisions because they heal better. And [flexure lines] near joint areas. Secretions of the sweat glands and sebaceous glands - There a few kinds of sweat glands -- be familiar with their names [Two main types of sweat glands:] Apocrine, Eccrine (merocrine). **Eccrine (merocrine):** most abundant but mostly on palms, feet, and forehead. Ducts end at pores on skin surface. Help with thermoregulation. **Apocrine:** Limited to axillary (armpit) and anogenital (involving genitals) areas, secreting sweat and fatty substances/proteins that lead to odor. Larger than eccrine and found deeper. The ducts empty INTO hair follicles. **Sebaceous (oil) glands:** everywhere BUT thick skin. Most develop from hair follicles and secrete oil INTO hair follicles. Activate due to puberty and secrete sebum (oily holocrine secretion, softens skin and hair). Table 5.1 Summary of Cutaneous Glands. The table shows comparison of Eccrine Sweat Glands, Aporcrine Sweat Glands and Sebaceous Glands. The comparison is as follows: Functions: Eccrine Sweat Glands: Temperature control, Some antibacterial properties, Aporcrine Sweat Glands: May act as sexual scent glands, Sebaceous Glands: Lubricate skin and hair, Help prevent water loss, Antibacterial properties. Type of Secretion: Eccrine Sweat Glands: Hypotonic filtrate of blood plasma, Aporcrine Sweat Glands: Filtrate of blood plasma with added proteins and fatty substances, Sebaceous Glands: Sebum (an oily secretion). Method of Secretion: Eccrine Sweat Glands: Merocrine (exocytosis), Aporcrine Sweat Glands: Merocrine (exocytosis), Sebaceous Glands: Holocrine. Secretion Exits Duct At: Eccrine Sweat Glands: Skin surface, Aporcrine Sweat Glands: Usually upper part of hair follicle; rarely, skin surface, Sebaceous Glands: Usually upper part of hair follicle; sometimes, skin surface. Body Location: Eccrine Sweat Glands: Everywhere, but especially palms, soles, forehead, Aporcrine Sweat Glands: Mostly axillary and anogenital regions, Sebaceous Glands: Everywhere except palms and soles. Alterations in skin color that can indicate disease **Cyanosis:** blueish from lack of oxygen in hemoglobin. **Jaundice:** yellowish from liver disease. **Erythema:** redness from fever, hypertension, allergy, or inflammation. **Pallor:** paleness from fear, blood loss/low blood pressure, anemia. Hair - What is hair made of Flexible strands of [dead keratinized cells]. - Where is it produced Everywhere **[BUT]** palms, soles of feet, lips, nipples, and some areas of external genitalia. - How does it grow **Hair matrix** where cells actively divide to produce more new hair cells. - What factors influence hair growth Nutrition and hormones. - Main types of hair found on the body **Vellus:** pale, fine hair seen on children and adults. T**erminal:** coarse, longer hair. - What dictates hair color Melanocytes (melanin). Nails - What are nails made of Modifications of the epidermis containing [hard keratin.] - Blood supply to nails, how does this contribute to nail appearance Underlying [capillaries] give nails their pinkish appearance. - Be familiar with the following nail structures: hyponychium, free edge, lunule, nail matrix **Free edge:** what hangs off and is white. **Hyponychium:** skin under the nail where dirt accumulates. **Lunule:** the white crescent moon at top of nail (thickened nail matrix). **Nail matrix:** the formation site of reproducing cells for the nail growth. Metabolic functions of skin Skin cancer -- be familiar with the 3 major types - Defining characteristics of each type (presentation on skin, level of metastasis, are they curable, other unique things mentioned about each type, etc.) **Basal cell carcinoma:** least malignant and most common. They slowly invade the dermis and hypodermis, rarely metastasize. Mostly seen on sun exposed regions. **Squamous cell carcinoma:** Second most common and can metastasize. Involves keratinocytes in stratum spinosum and are reddened papules. **Melanoma:** worst case possible. They are cancer of melanocytes and are highly resistant to treatments meaning most deadly. [ABCD rule for melanoma spotting:] A: asymmetry; the two sides of the pigmented area do not match B: border irregularity; exhibits indentations C: color; contains several colors (black, brown, tan, sometimes red or blue) D: diameter; larger than 6 mm (size of pencil eraser) Burns - What is the main concern when treating a person who has been burned, how do clinicians assess this concern The main concern when treating a person who has been burned is **dehydration and electrolyte imbalance.** Infections are also a big concern but not the immediate. - Distinguish a first-degree vs. second-degree vs. third degree burn (what skin layers are involved with each type) **First degree** affects the epidermal layer. Localized redness, swelling, and some pain. **Second degree** affects the epidermal and upper dermal layer. Blisters occur here. **Third degree** is a full thickness burn (affects all). Loss of sensation because nerves are burned are common. Skin turns gray-white, cherry red or blackened. No edemas (swelling). Skin grafting is essential. Chapter 6: Bones and Skeletal Tissue ==================================== Growth of cartilage -- appositional vs interstitial growth **Appositional:** Chondroblasts in perichondrium secrete ne wmatric against external surface of existing cartilage. (On surface of cartilage) **Interstitial:** Chondrocytes within lacunae divide and secrete new matrix, expanding cartilage from within. (INterstitial = made INside catrilage). Types of cartilage: **Hyaline cartilage:** flexibility, support, and resilience. Contains collagen fibers ONLY. Found in articular joints, costal ribs, respiratory parts, and nasal cartilage. **Elastic cartilage:** like hyaline but with elastic fibers. Only on external ear and epiglottis. **Fibrocartilage:** Parallel rows of chondrocytes alternating with thick collagen fibers; great tensile strength and resists compression (spine uses and menisci of knee). Structure of a typical long bone \- Gross anatomy (4 PowerPoint slides, focus on structures presented in bold type on these slides) **Compact and spongy bone:** Compact (lamellar) is dense outer layer that appears white and solid. It is sandwiched between 2 connective tissue membranes: periosteum (outside portion) and endosteum (inside portion). Spongy is sponge-like internal portion of compact bone. The needle-like flat pieces are trabeculae which are filled with marrow. Thin plates cover this (diploe). Structure of gross anatomy parts: **Short:** Vary in size and structure. Cube-like are in wrist and ankle. Sesamoid bones form within tendons. **Irregular:** Complicated shapes such as vertebrae or hip bones. **Flat:** Thin, flat, slightly curves. Such as sternum, scapulae, ribs, and most skull bones. **Long:** Longer than wide. Such as limb bones (humerus, femur, radius, etc). Strucure of long bones specifically: **Shaft:** diaphysis. Made of compact bone surrounding internal cavity of yellow marrow in adults. **Bone ends:** epiphyses. Consist of compact bone externally and spongy internally. (Articular cartilage covers articular surfaces). Between epiphysis and diaphysis is an [epiphyseal line] which is the remnant of childhood [epiphyseal plate] (growth plate) meaning that there is no more growth once ossified. \- Microscopic anatomy -- focus on the canals and canaliculi **5 major cell types:** osteoclast (cleaners), osteoblast (bone forming), Osteocyte (bone cell), Osteogenic cells (stem cells), bone lining cells (help maintain matrix). Lamellar (compact) bone consists of osteon (haversian system), canals and cananiculi, interstitial and circumferential lamellae. **Canals and canaliculi:** ***[Central (Haversian) canal]*** runs through the core of each osteon containing blood vessels and nerve fibers. [ ***Perforating (Volkmann's) canals***] lined with endosteum occur at right angles to central canal. They connect blood vessels and nerves of periosteum, medullary cavity, and central canal. They contain [lacunae] (small cavities that contain osteocytes) and [canaliculi] (tiny canals that connect lacunae to each other and to the central system). Hematopoietic tissue in bones (there is one slide in the chapter 6 PowerPoint that is specific to hematopoietic tissue, be familiar with all information presented on the slide) **Hematopoietic tissue** is the blood forming tissue (red blood marrow). It is found in [medullary cavities of diaphysis] and all spongy bone in infants. In adults, it is found more in [flat bones] because yellow takes over the infant places. Endochondral ossification -- in general what is happening during endochondral ossification **Endochondral ossification** forms most of the skeleton inferior to the skull. Forms by replacing hyaline cartilage model. Bone becomes endochondral bones. Begins at primary ossification center in the center of cartilage shaft. 1. Bone collar forms around diaphysis of hyaline cartilage bone. 2. Cartilage calcifies in the center of the diaphysis and then develops cavities. 3. Periosteal bud invades the internal cavities of spongy bone forms. 4. Diaphysis elongates and medullary cavity forms. Secondary ossification occurs in epiphyses. 5. Epiphyses ossify. When ossification is complete, hyaline cartilage remains only in epiphyseal plates and articulate cartilages. Postnatal bone growth -- interstitial vs appositional growth **Interstitial growth** requires epiphyseal cartilage in epiphyseal plate. This allows bone to grow [lengthwise.] **Appositional growth** causes bones to [widen]. Osteoblasts in periosteum secrete bone matrix on external bone surface and allow bone to build wider. Hormonal regulation of bone growth -- 3 hormones are mentioned, be familiar with their importance and how they impact bone growth during infancy, childhood, or adolescence **Growth hormone:** Stimulates epiphyseal plate activity in infancy to childhood. **Thyroid hormone:** Modulates growth hormone, ensuring proper proportions to skeleton during growth. **Estrogens:** stimulate adolescent growth spurt. Bone remodeling -- cells involved in bone deposit vs. those involved in bone resorption **Remodeling units**: adjacent osteoblasts (deposit) and osteocytes (resorption). **Osteocytes are cell eaters.** They dig grooves in bone and break down matrix as they move on. Secrete lysosomal enzymes which digest matrix with their acid. Activation involves parathyroid hormone and immune T cell proteins. **Osteoblast form bones.** Begin as osteoid seam, unmineralized bone matrix. Then calcification front to transition osteoid seam and older mineralized bone. Then Calcification of new bone matrix. Hormonal control of bone remodeling (bone deposit and bone resorption) -- there are 2 hormones mentioned, be familiar with how these hormones impact bone remodeling **Hormonal control (negative feedback loop):** involves parathyroid hormone. Controls the Ca2+ levels (calcium needed for nerve impulses and muscle contraction). **Mechanical stress response:** mechanical and gravitational forces trigger bone remodeling where bone needs to be strengthened. Stages of bone fracture repair 1. **Hematoma formation:** blood vessels hemorrhage, forming a hematoma (clot). 2. **Fibrocartilaginous callus formation:** capillaries grow into hematoma to sipply phagocytes to clear up the debris. Fibroblasts secrete collagen fibers as a mesh and these all begin reconstruction of bone. 3. **Bony callus formation:** 1-week post fracture, new trabeculae appear in the fibrocartilaginous callus due to spongy bone. Bony callus continues until firm union forms and repeats until endochondral ossification. 4. **Bone remodeling:** begins during the bony callus time. Excess material is removes and compact bone is laid down to reconstruct shaft walls. Chapter 7: The Skeleton ======================= Bone markings -- know the description for each of the following: - **Foramen:** Round or oval opening through a bone. - **Notch:** indentation at the edge of a structure. - **Tuberosity:** large, rounded projection. - **Tubercle**: Small rounded projection or process. - **Fossa:** Shallow depression in a bone, often serving as an articular surface. - **Process:** Any body prominence. Like spinous process, the sharp projection. - **Condyle:** Rounded articular projection often articulates with a fossa. Bones of the axial skeleton vs. the appendicular skeleton **Axial**: skull, vertebrae, thoracic cage. **Appendicular:** appendages; limbs. Note - for all the bones listed after this: - Know where they are located - If they are commonly known by another name be familiar with that name (example: the scapulae are more commonly known as the shoulder blades) Cranial bones - **Occipital bone** (2 important bone features mentioned in the PowerPoint): Most of the skulls posterior wall (back) and [posterior cranial fossa]. Also has the [foramen] [magnum] meaning "great hole" for the brain connecting to spinal cord. Flared by a pair of occipital condyles (little nubs) that articulate with the atlas (1^st^ vertebrae). - **Frontal bone:** Forehead. Forms anterior portion of cranium. - **Temporal bones** (what part of the skull do they make): Make up the inferolateral aspects of skull and parts of the cranial base, complicated shape. Makes up: [Squamous] (zygomatic processes articulates with zygomatic bones to form zygomatic arch (cheekbones)). [Tympanic:] surrounds external acoustic meatus (external ear canal). [Petrous:] Houses middle and inner ear canals. (Makes up middle cranial fossa. Includes mastoid and styloid processes: areas for attachment of several neck and tongue muscles). - **Sphenoid bone** (what makes this cranial bone unique, 2 important bone features mentioned in the PowerPoint): Bat-shaped bone. Keystone bone that articulates with all other cranial bones. Body includes sella turcica prominence that includes hypophyseal fossa are that encloses the pituitary gland. - **Ethmoid bone** (what makes this cranial bone unique): Deepest skull bone, complex shape, lies between sphenoid and nasal bones. Superior part is formed by paired horizontal [cribiform plates] (helps form roof of nasal cavity and floor of anterior canal fossa). [ Crista galli] is superior triangular process (attachment of dura mater). [Perpendicular plate] (forms superior form of nasal septum that divides nasal caity into L/R). [Orbital plates] (contribute to medial wall of orbits). Facial bones: what does each bone listed here form in the face - Mandible: Lower jaw bone. - Zygomatic bone: cheekbone and inferolateral margins of orbits. Articulate with zygomatic processes of temporal, frontal, and maxillary bones. - Maxillary bone: Upper jaw. Articulates with zygomatic processes at zygomatic bones (cheekbones). - Lacrimal bone: Forms medial walls of orbits. Articulates with frontal, maxillary, and ethmoid bones. - Hyoid: what makes this bone unique Not a skull bone. It is the anterior neck bone inferior to the mandible. ONLY bone that does not articulate with another. Acts as movable base for tongue and attachment for muscles for swallowing and speech. Vertebral column: location of each in the vertebral column Cervical = top 7. Concave posteriorly Thoracis = middle 12. Convex posteriorly Lumbar = lower back 5. Concave (inward) posteriorly Sacral = bottom. Convex (outward) posteriorly - **First cervical vertebrae:** Atlas. No spinous process. Has 2 masses known as occipital condyles. Move for nodding "yes" - **Second cervical vertebrae:** Axis. Has body adn processes like others. Feature dens that pivot for rotation to allow shaking "no" - **Thoracic vertebrae** (what do they articulate with): articulate with ribs. T1-T12 - **Lumbar vertebrae:** L1-5. Receive most stress so they are the largest. - **Sacrum** (what forms the sacrum): one bone made of 5 fused vertebrae. Articulates with hip. - **Coccyx:** fused of 3-5 vertebrae. Thoracic cage - Sternum, in addition to its location know: - **What forms the sternum** "Breast bone" in middle of chest. Sternum and costal cartilages anteriorly. Thoracis vertebrae posteriorly. Ribs laterally. - **Important anatomical landmarks** **Manubrium:** [ ] superior portion like a shield that articulates with clavicular notches and ribs 1 and [2. Jugular notch:] central indentation in superior border of manubrium. [Sternal angle]: horizontal ridge across front of sternum. **Body:** midportion that articulates with costal cartilages 2-7. **Xiphoid process:** inferior end that is site of muscle attachment. [Xiphisternal joint:] point where sternal body and xiphoid process fuse. - True ribs vs. false ribs vs. vertebral (floating) ribs **True:** 1-7, attach directly to sternum by individual costal cartilages. **False:** 8-10, attach indirectly to sternum by joining costal cartilage of rib above. **Floating:** 11-12, no attachment. Bones that make the pectoral girdle **Pectoral girdle** = shoulder girdle. Clavicles anteriorly, scapulae posteriorly. Upper limb - **Humerus:** Upper arm. Largest and longest of the upper arm lib. Articulates with glenoid and scapula superiorly and inferiorly to radius and ulna through trochlea. - **Ulna** (bone features, joint that it is a major part of): Medial forearm bone. Proximal end connects to humerus elbow joint and distal to radius as radioulnar joint. Interosseous membrane connects radius and ulna. **Features:** [olecranon and] [coronoid process] (grip trochlea of humerus forming hinge joint for flexion). [Radial notch] (articulates with head of radius at proximal end). - **Radius** (what bone is it connected to and what connects them together): Lateral forearm bone. Proximal end with humerus and ulna. Distally ulna at radioulnar joint. FORMS MAJOR PORTION OF WRIST. **Features:** [Head] (articulates with capitulum of humerus and radial notch of ulna). [Radial tuberosity] (anchors biceps). [Ulnar notch] (articulates with ulna at distal end). - **Carpal bones:** Wrist bones. [ONLY] scaphoid, lunate, and triquetrum form the wrist. - **Metacarpals:** Palm. 5 metacarpals. [Bases] articulate with carpals; [heads] articulate with proximal phalanges. Bones that make the pelvic girdle - What is the purpose of the pelvic girdle - How does the pelvic girdle differ between males and females **Pelvic girdle** = hip girdle. Keep slower limbs attached to axial skeleton (trunk) via strong ligaments. Also transmits weight and supports pelvic organs. [Females] pelvic girdle is adapted for childbearing; wide, shallow, light. Lower limb - **Femur:** Upper leg bone. Largest and the strongest. Articulates proximally with acetabulum of hip. Articulates distally with tibia and patella. **Features:** [greater and lesser trochanter] at top (like little horns). [Lateral and medial condyles] at distal end (to articulate with tibia). [Medial and lateral] [epicondyles] (side little protrusions for muscle attachment). [Patellar surface] (smooth little pads on bottom). - **Patella**: Kneecap. Sesamoid bone in quadriceps tendon that protects knee. - **Tibia** (what is its purpose, is it medially or laterally located): Medial that receives the weight of body from femur. - **Fibula** (what is its purpose, what bone(s) does it articulate with, is it medially or laterally located): Laterally located parallel to tibia. NOT weight bearing. NO articulation with femur. Articulates proximally and distally to tibia. Tib/Fib are connected by [interosseous membranes] too. - **Calcaneus**: Heel. Body weight is PRIMARILY carried by talus and calcaneus. - **Metatarsals:** Pad of foot. 5 metatarsal bones (big to little toes (hallux = big toe). Chapter 8: Joints ================= Joint classifications - how movable are the following joint classes: - **Synarthroses:** Immobile. - **Amphiarthroses:** Somewhat moveable. - **Diarthroses:** Freely moving. Joint cavity: which type of joint (fibrous vs. cartilaginous vs. synovial) have a joint cavity and which do not have a joint cavity **Fibrous:** No joint cavity. Most are immovable (depends on length of fibers). 3 types: sutures, syndesmoses, and gomphoses. **Cartilaginous:** No cavity. Not highly moveable. 2 types: synchondroses (hyaline cartilage, most are synarthrotic (immovable)), and symphyses (fibrocartilage, amphiarthrotic). **Synovial:** Almost all limb joints. All diarthrotic (free to move) and separates by a fluid-filled joint cavity. Fibrous joints: know the 3 types and examples for each type **Sutures:** rigid, interlocking joints of skull. Ex: cranial sutures like coronary suture. They are closed immovable sutures known as **[synostoses.]** **Syndesmoses:** Bones connected by ligaments. The fiber length impacts the joint movement (longer=more movement). Ex: ligament in tibia/fibula. **Gomphoses:** peg-in-socket joints. Teeth are the only example. Synovial joints: - Associated structures that help to reduce friction **Synovial joint cavity:** contains fluid only for synovial joints. - Are synovial joints synarthroses, amphiarthroses, or diarthroses? **Diarthroses** - In general, are they stable or unstable (do they dislocate)? **Quite stable** due to shape of articular surface, ligament number/location, and muscle tone. - Six general features of all synovial joints 1. **Articular cartilage:** hyaline cartilage covering bone ends to prevent crushing. 2. **Joint (synovial) cavity:** fluid-filled space. 3. Outer **fibrous layer of articular capsule:** dense irregular connective tissue lining. 4. Inner **synovial membrane of articular capsule**: loose connective tissue, makes synovial fluid to lubricate and nourish articular cartilage. 5. Different **reinforcing ligaments:** capsular (thickened part of fibrous layer), extracapsular (outside capsule), intracapsular (deep to capsule, covered by synovial membrane). 6. **Nerves and blood vessels**: Nerves detect pain, monitor position/stretch. Capillary beds supply filtrate for synovial fluid. - For the following categories of synovial joints be familiar with examples of each (see Focus Figure 8.1): o **Condylar joint:** Biaxial. Allows flexion, extension, adduction, and abduction. It has oval articular surfaces that fit together like knuckle joints (metacarpophalangeal). - **Pivot joint:** Uniaxial. Involves rotation like radius and ulna. - **Hinge joint:** uniaxial. Cylinder and trough type joint. Allows flexion and extension like the joint between humerus and ulna. - **Saddle joint:** Biaxial. Articulates with a concave and a convex (a little saddle and someone sitting on it). Allows adduction, abduction. Slexion, and extension. o **Plane joint:** nonaxial, only gliding like between vertebrae. Movements at synovial joints: - **Flexion:** Decrease the angle of the joint. (Like bowing forward.) - **Extension:** Increase angle of the joint. (Like tilting head back.) - **Hyperextension:** Movement beyond anatomical position. - **Dorsiflexion:** Bending the foot and shin. - **Plantar flexion:** Pointing toes (like ballet). - **Circumduction:** Involves flexion, abduction, extension, and adduction. Describes a cone of space (like little arm circles). - **Abduction:** along frontal plane (like jumping jacks), away from midline. - **Adduction:** along frontal plane (like jumping jacks), towards midline. - **Lateral rotation:** Rotation away from the midline (rotation between C1/C2 vertebrae). For the following synovial joints: where is each located, what type of joint is it (hinge, pivot, ball-and-socket, etc.), their level of stability (prone/not prone to dislocation), range of motion and movements allowed at the joint (flexion, extension, circumduction, etc.). Which joint is the most complex. - **Temporomandibular joint:** Jaw joint where mandibular condyle articulates with temporal bone. It\'s a [modified hinge joint]. Two movements: gliding (molars) and hinge (depression/elevation). Most EASILY dislocated. - **Glenohumeral joint:** Shoulder joint. Ball-and-socket joint = free movement, but less stable. Head of humerus fits into the shallow glenoid cavity of scapula. The articular capsule is thin and lose (giving range of motion). - **Elbow joint:** Hinge joint. Flexion and extension ONLY. Primarily by trochlear notch of ulna articulating with trochlea of humerus. - **Coxal joint:** Hip joint. Ball-and-socket joint (free mover, limited by deepness of socket but stabler). Head of femur fits into a deep socket (acetabulum). - **Knee joint:** Most complex. Hinge joint allowing for flexion, extendsion, and some rotation when partly flexed. It consists of 3 joint cavities surrounded by a single cavity. Femoropatellar joint (Plane joint allowing only for gliding motion during knee flexion), Lateral/Medial joint forms tibiofemoral joint (it is femoral condyles and lateral/medial menisci of tibia articulating). Knee joint -- know how each of these ligaments contribute to supporting and stabilizing the knee joint: - **Tibial collateral ligaments:** prevent rotation when knee is extended. - **Oblique popliteal ligaments:** Stabilizes posterior knee joint. - **Patellar ligament:** works with the quadriceps tendon and quadriceps muscles to straighten the knee when extended. Doctors tap this to test knee-jerk reflex. - **Cruciate ligaments:** Anterior cruciate ligament (ACL) attaches to anterior of tibia. Prevents the forward sliding of tibia and stops hyperextension of knee. Posterior cruciate ligament (PCL) attaches to posterior tibia and prevents backward sliding of tibia and forward sliding of femur. Common [knee injuries] involve which ligaments: Collateral ligaments Cruciate ligaments (ACL/PCL) Cartilages (menisci)