gross- structures met in dissection, nervous system, muscular system Flashcards
Order of structures met in dissection
Skin → superficial fascia → deep fascia → muscles → NVB (neuromuscular bundle- nerves, arteries, capillaries, veins not exactly layer, kind of all over the muscle) → lymphatics → bones
2 main layers of skin
epidermis: thinner, outermost layer of skin
- made of keratinized stratified squamous epithelium cells that flatten as they mature and rise to the surface
dermis: deeper, inner layer under the epidermis
- made of connective tissue, which give skin strength and elasticity
- contains blood vessels, nerves, hair follicles, sebaceous glands, and sweat glands
veins always _______ & arteries always _________
drain; supply
4 skin appendages (structures attached to the skin)
1. Nails: keratinized plates on the dorsal surface of the fingers & toes (has root of nail, nail folds, and nail bed)
2. Hair: grows out of follicles that are invaginations of epidermis into the dermis
- hair bulb→ hair grows out of this
- hair papilla → small structure at base of hair bulb that contains blood vessels & nourishes growing hair
- arrector pili → tiny involuntary muscles attached to hair follicles that contract due to cold or fear to create “goosebumps”
3. Sebaceous glands: produce oily sebum to keep hair and skin moisturized
- are present all over the skin except the palms and soles
4. Sweat glands: produce sweat
clinical: sebaceous cyst
small, non-cancerous lump that forms under the skin due to a blocked sebaceous gland
- may be caused by constant combing or an infection
- occurs most frequently on the scalp
2 types of skin grafts
skin grafts: piece of skin taken from one part of body and transplanted to another area
1. Split-Thickness Skin Graft: includes epidermis and part of dermis (not the full dermis)
- used for covering large wounds, burns, or ulcers.
2. Full-Thickness Skin Graft: includes both epidermis and entire dermis.
- sed for smaller areas where cosmetic appearance is important, such as the face
skin creases
parts of the skin over joints that always folds in the same place (skin is thinner at these sites)
- firmly tethered to underlying structures by strong bands of fibrous tissue
langers lines
correspond to natural orientation of collagen fibers in the dermis & are generally perpendicular to orientation of underlying muscle fibers
- surgeons follow these lines when making cuts in order for skin to heal faster and to reduce scarring
4 functions of skin
- Covers and protects the underlying structures
- Acts as a barrier against mechanical, thermal, and physical injuries
- Regulation of body temperature
- Excretion of waste products
fascia + 2 types
fascia: thin, strong layer of connective tissue that surrounds and supports muscles, blood vessels, nerves, and organs
- helps hold everything in place, reduce friction, & provide structural support
1. superficial fascia: just under skin, made of fat (adipose) and loose connective (areolar) tissue
- functions: stores fat to protect body against heat loss, allows skin to move freely over deeper structures, contains blood vessels, nerves, & lymphatic vessels
- denser in places like scalp, palm of hand & sole of foot
- less dense in places with less fat like eyelid, penis, clitoris
2. Deep fascia: denser than superficial fascia, surrounds the muscles, bones, and nerves
- functions: supports & separates muscles to prevent friction, facilitates movement, restricts infections to that one compartment rather than entire limb
- fibrous intermuscular septum & retinacula
- forms aponeurosis, sheaths of muscles/nerves, and capsule
deep fascia: fibrous intermuscular septum & retinacula
Fibrous Intermuscular Septum: thick sheet of connective tissue that goes in b/w muscles & divides them into compartments (e.g., in the arms and legs)
- functions: separates muscle groups to prevent friction, provides attachment points for muscles, helps contain blood vessels and nerves within compartments
Retinacula: hold tendons in place near joints (e.g., wrist, ankle), serves as pulleys around which tendons can move
- ex. flexor retinaculum (wrist- covers the carpal tunnel) & extensor retinaculum (ankle – holds tendons in place over the foot)
cartilage + 3 types
cartilage: type of connective tissue that is firm yet flexible
1. Hyaline Cartilage: most common type of cartilage, found in joints, ribs, nose, trachea, & larynx
2. Fibrocartilage: strongest type of cartilage, contains dense collagen fibers, making it tough and resistant to compression.
- found in intervertebral discs (between spine bones), menisci (knee joint shock absorbers), pubic symphysis (where hip bones meet in front)
3. Elastic Cartilage: most flexible due to elastic fibers in its matrix, allows structures to bend and return to shape
- found in external ear (pinna), epiglottis (flap in throat that prevents food from entering the windpipe)
ligaments + ligament damage
ligament: strong, fibrous band of connective tissue that connects bones to other bones at joints
- provides stability, strength, and support to the joint while allowing movement within a safe range
ligament damage: joint ligaments are very prone to excessive stretching and even tearing/rupture
- healed by blood clots that form at injury and then blood vessels & fibroblasts that invade area and lay down new collagen
bursa
small, closed sac made of fibrous connective tissue and lined internally with a synovial membrane. It is filled with synovial fluid, which acts as a lubricant to reduce friction
- synovial membrane inside bursa secretes viscous synovial fluid that cushions & lubricates tissues
distribution: bursae found in areas that experience a lot of movement & friction, particularly near joints. commonly located where skin rubs against underlying bony structure (over knee, elbow, shoulder, ankle, hip, thigh)
synovial sheath
tubular bursa that surrounds tendon
prevents tendons from mixing up (also reduce friction b/w tendon and its surrounding structures)
supported by mesotendon (chotu that fixes the tendon to its synovial sheath) - allows blood vessels to enter the tendon w/o interfering with its movement
the sheath circles around the tendon and the mesotendon is a little opening ish area
tenosynovitis & bursitis
tenosynovitis: inflammation of the synovial sheath due to overuse, infection, or injury
bursitis: inflammation of a bursa due to excessive friction, injury, or infection
bursae and synovial sheaths are common sites of traumatic or infectious disease
