The developmental growth pattern of skin follows _____
Blaschkos lines
The skin is made up of ______
2 main layers: the epidermis and the dermis
also contains appendages such as hair follicles, glands, blood vessels, lymphatics and nerves
The epidermis is an outer layer of stratified cellular epithelium and the dermis is a deeper layer of connective tissue
What are the 4 layers of the epidermis?
basal layer
prickle cell layer
granular cell layer
keratinocyte layer
basal layer is making new cells which move up and up till they start to lose nucleus and die in keratinocyte layer
Describe the basal cell layer?
- The basal layer is one cell thick and contains lots of intermediate filaments such as keratin, it is highly metabolically active as cells are constantly being made and moved up from the basement membrane
Describe the prickle cell layer?
- The prickle cell layer contains larger polyhedral cells and lots of desmosomes for anchorage and support
Describe the granular cell layer?
- In the granular cell layer, lipids and lipid hydrolases are synthesized and secreted by lamellar bodies (AKA Odland bodies) to form a water tight intercellular bi-layer
- These lamellar bodies also produce abundant amounts of pro-filaggrin which is converted to filaggrin in the outer layer, filaggrin has a dual role in holding moisture within cells and as a component of the tough protein cell envelope
- As cells move outwards they are beginning to lose their nuclei and die
Describe the keratinocyte layer?
- The keratin layer is made up of overlapping e-nucleated cell remnants and forms a tight waterproof barrier
Keratinocytes make up 95% of the epidermis but what are 3 other cell types? Describe them?
1) Melanocytes: these contain melanosomes which convert tyrosine to melanin which is transferred into surrounding keratinocytes to give protection against UV radiation. Variation in melanin production NOT melanocyte number is what causes racial differences in skin colour
2) Langerhan’s Cells: These are specialised dendritic cells of the skin derived from the bone marrow, they are found in the prickle cell layer, the dermis and the lymph nodes, they play a key role in antigen presentation and immunoregulation
3) Merkel Cells: These are mechanocreceptors and play a role in sensation (they are numerous on fingertips and in the oral cavity). They are found in the basal layer between keratinocytes and nerve fibres.
Epidermis is from _____ and dermis from _____
epidermis = ectoderm
dermis = mesoderm
What does the dermis contain?
- It contains a range of cells: fibroblasts, mast cells, lymphocytes, dermal dendritic cells, langerhan’s cells and macrophages, it also contains blood and lymphatic vessels, nerves, muscle and appendages e.g. glands
Brachial plexus is made up of _________
- Roots – C5-T1
- Trunks – superior, middle and inferior
- Divisions – anterior and posterior
- Cords – lateral, posterior, medial
- (Terminal) Named Nerves – musculocutaneous, axillary, radial, median, ulnar
- Really tired drink coffee now
Nerves that come off roots of the brachial plexus and what do they supply?
- Dorsal scapular nerve – supplies rhomboids major and minor
- Long thoracic nerve – supplies serratus anterior
Nerves that come off trunks of the brachial plexus and what do they supply?
- Off the superior trunk
- Nerve to subclavius
- Suprascapular nerve – supplies infraspinatus and supraspinatus in the rotator cuff
Nerves that come off the lateral cord?
- Lateral pectoral nerve – pectoralis muscles
- Musculocutaneous nerve terminally
- Makes up half of the median nerve
Nerves that come off the posterior cord?
- Radial nerve terminally
- Axillary nerve terminally
- Thoracodorsal nerve – supplies latissimus dorsi
- Lower suprascapular nerve – supplies teres major
- Upper suprascapular nerve – supplies part of subscapularis
Nerves that come off the medial cord?
- Makes up half of the median nerve
- Ulnar nerve terminally
- Medial pectoral nerve – supplies pectoral muscles
- Medial cutaneous nerve of the forearm
- Medial cutaneous nerve of the arm
Musculocutaneous nerve is what roots?
C5-C7
What does the musculocutaneous nerve supply?
- Anterior compartment of the arm: biceps brachii, corachobrachialis and brachialis
- Sensory to Lateral forearm
Axillary nerve is what roots?
C5-C6
What does the axillary nerve supply?
- Deltoid
- Teres minor
- Innervates the shoulder joint
- Sensory innervation to the badge patch
The radial nerve is what roots?
C5-T1
What does the radial nerve supply?
- Posterior compartment of arm: triceps brachii
- Posterior compartment of the forearm
- Sensory innervation to skin on the posterior forearm, lateral aspect of the dorsum of the hand and dorsal surface of lateral three and half digits
What does the median nerve supply?
- Innervates all the muscles of the anterior compartment of the forearm EXCEPT flexor carpi ulnaris and the 4th and 5th digits of flexor digitorum profundus
- Innervates the lateral 2 lumbricals and thenar muscles
- Sensory innervation to lateral three digits on palm
The median nerve is what roots?
C6-T1
