Anatomy Flashcards
What are the 2 main groups of back muscles
Extrinsic: trapezius, lattismus dorsi, elevator scapulae, rhomboids, serratus posterior
Intrinsic (superficial layer, intermediate layer and deep) - these muscles produce movement and maintain posture inc erector spinae
Innervation of intrinsic back muscles
Posterior rami of spinal nerves
3 groups of intrinsic back muscles
Superficial: splenius, cervicis, splenius capititis)
Intermediate: erector spinae
Deep: transversospinal, semispinalis,
What are the different curvatures of the back
Lordosis (secondary curve- neck and lower back)
Kyphosis (primary curve - upper back and gluteus region)
What is cauda equine syndrome
Rare and severe type of spinal stenosis where all of the nerves in the lower back suddenly become severely compromised
Where are the adrenals located
Superior to the kidneys in the renal fascia and posterior to parts of the diaphragm
Right is posterior to the liver and IVC
Left is posterior to the stomach and pancreas
Right is pyramidal in shape; left is semilunar and slightly larger
What are the 3 layers of the outer cortex of the adrenal gland
- embryological origin (mesoderm) similar to gonads
- secretes steroid hormones with cholesterol precursors
- secretion controlled by pituitary
Mineralocorticoids eg aldosterone (RAAS system)
Glucocorticoids eg cortisol and corticocosterol (ACTH from pituitary)
Androgenic steroids
Describe the inner medulla of the adrenal gland
- Embryology from neural crest (similar to sympathetic nervous system)
- Neuroendocrine
- secretes catecholamines: adrenaline and noradrenaline
- secretion is under SNS control - augments the SNS response (rapid)
What are the zones of the Cortex
Zona glomerulosa (mineralcorticoids) - blobs
Zona fasiculata (glucocorticoids) - strings
Zona reticularis (androgens) - networks
Blood supply of the adrenals
Arteries: 3 suprarenals each side
- superior (from phrenic)
- middle (from AA)
- inferior (from renal arteries)
Veins: 1 each side
- right - IVC
- left - left renal vein
Drainage of adrenals
Arterioles from capsular arteries give rise to sinusoidal capillaries which drain into a medullary vein
What is secretion of the adrenals controlled by
Preganglionic neurons
The secretory cell is functionally equivalent to the postganglionic neurons of the SNS. Therefore secretions can be quickly released
Pathology of the cortex
Hypoadrenalism: Addison’s disease (no secretion of any hormones)
Hyperadrenalism: oversecretion Mineralcorticoids: conn’s syndrome Glucocorticoids: Cushing’s syndrome Malignant tumour: all 3 hyperstimulated Neuroendocrine lung tumour: XS glucocorticoids
What is phaeochromocytoma
Rare cause of secondary hypertension
Mostly benign adrenal tumour of neuroectodermal origin
Produces excessive catecholamines, causing hypertension which is continuous or sporadic
Can be dangerously high
Can cause lethal disease due to cardiovascular complications eg during surgical and obstetric procedures
Symptoms: headache, excessive sweating and palpitations
Diagnosis: urinary catecholamines or metabolites (not usually plasma)
Describe location of pelvis
Inferoposterior to abdomen
Part of the trunk
Area of transition between trunk and lower limbs
Compartment surrounded by bony pelvis
2 areas of the pelvis
Greater (false) pelvis - superior to pelvic inlet
Lesser (true) pelvis - runs between pelvic inlet and outlet - provides Bony framework for peritoneum
What is the pelvic girdle
Connects vertebral column to 2 femurs
Made of 3 bones
What is the subpubic angle
Defined by 2 bones either side (ischio pubic rami)
Degree of angle differs between males and females
Surface landmarks of bony pelvis
Iliac crest L4
Posterior superior iliac spine
2 dimples overlying sacrum (triangular region)
Coccyx
Characteristic features of male pelvis
Pelvic girdle is heavier and thicker and more prominent bony landmarks
Greater pelvis (superior to pelvic inlet) is quite deep
Lesser pelvis is quite deep and narrow
Sacral promontry will stick out and is quite narrow
Obturator foramen has a more rounded shape
Acetabulum is larger
Characteristic features of female pelvis
Greater pelvis is quite shallow
Lesser pelvis is shallow and wide
Pelvic inlet is oval, rounded and wide in the female- sacral promontry sticks out less than in males
Pelvic outlet larger (due to childbirth)
Sub pubic angle is wider (above 80 degrees)
Obturator foramen is more oval in shape
What are the endocrine parts of the pancreas
Islets of langerhans
Why does pancreas only comprise 1-2% of volume but receives 20% of blood supply
This disproportion is because of the high capillary network needed for hormone uptake
What are the exocrine parts of the pancreas
Duct cells that secrete aqueous NaHCO3 solution and acinar cells that secrete digestive enzymes
What are the islets of the pancreas
Evenly distributed throughout the organ
25% in head, 25% in uncinate process, 20% in body, 30% in tail
Each islet has up to 3 arterioles, expanding into an extensive network of fenestrated capillaries draining into up to 6 venules
What do the different cell types secrete
Beta - insulin and amylin (70%)
Alpha - glucagon (20%)
Delta - somatostatin (5-10%)
PP cells - containing pancreatic polypeptide (1-2%) sometimes called F cells
Not distinguishable from each other except via immunostaining
How does the pancreas develop embryonically
Embryonic duodenum and endoderm come together by rotation of the GI tract that brings bile duct round
Embryonic ductal epithelium can differentiate into endocrine or exocrine part
Blood supply of the pancreas
Splenic and superior and inferior pancreaticoduodenal arteries
Veins tributaries of splenic and superior mesenteric portal
Innervation of the pancreas
Sympathetic (abdominopelvic splanchic)
Parasympathetic (vagal)
Why is the pancreas vulnerable for injury
Not very well protected
Has a soft consistency
Not easily accessible for surgery
Why is pancreatic cancer so serious and life threatening
Difficult to reach for surgery
Doesn’t show symptoms early on
Close proximity to kidney and spleen (spread) due to extensive blood and lymph supply
What are the different chains of an insulin molecule
A chain (21 aa) B chain (30 aa) C peptide (31aa)+ 4 when connected to a and b
Where is insulin synthesised
B cells
Half life of 5-9 mins
Initially as proinsulin which has 86 aa in humans
Function of C peptide
Links A and B chain but has no biological activity however emerging research data suggests otherwise
What is the main physiological regulator of insulin
Blood glucose >5mM - rise in ATP : ADP ratio results in closure of ATP sensitive K + channels, membrane depolarisation, leading to opening of voltage gated Ca2+ channels - increased insulin resistance
Glucose is metabolised, phosphate is added to ADP to make high energy ATP
Neural control of insulin release
Sympathetic NS- B-adrenoceptor increases IR ; a2-adrenoceptor decreases IR
Parasympathetic NS - muscarinic receptors increase IR
Action of insulin
Promotes growth and development (particularly intrauterine)
Promotes cellular uptake of K+ via Na+-K_ ATPase pump
Promotes uptake and utilisation of glucose in skeletal muscle and adipose
Promotes fuel storage ( anabolic) - increases rate of synthesis and storage of energy reserves and of protein
What is glucagon
A peptide hormone , synthesised in islet a cells
Release is stimulated by low blood glucose (<3.5mM)
Para and sympathetic NSs (both branches) and aa
Inhibited by high blood glucose, insulin and somatostatin
Actions: opposite to those of insulin
Main actions of glucagon
Raise blood glucose
Stimulate hepatic glycogenolysis
Stimulate hepatic gluconeogenesis
Stimulate lipolysis (triglyceride synthesis)
What happens when there is a rise in blood glucose
Stimulation of B cells to increase insulin and inhibition of a cells to decrease glucagon which then decreases blood glucose to normal
What happens when there is a decrease in blood glucose
Stimulation of a cells which leads to an increase in glucagon and inhibition of B cells to decrease insulin which then increases blood glucose back to normal
What is somatostatin
Peptide hormone
Synthesised in islet gamma cells (14aa) also in CNA and GIT (28aa)
Inhibits both glucagon and insulin secretion by a paracrine mechanism
What are the roles of adrenaline, cortisol and GH in fuel metabolism
Adrenaline - provision of energy for emergencies and exercise
Cortisol - mobilisation of fuels during adaptation to stress
GH - promotion of growth (normally smaller role in metabolism)
What are the 2 types of diabetes
Type 1 : insulin deficiency
Type 2: impaired B cell function and or loss of insulin sensitivity (insulin resistance)
Symptoms of both T1 and T2 diabetes
Glucosuria (glucose in urine - large glucose load in filtrate so is excreted in urine)
Polyuria ( glucose holds water with it leading to frequent urination)
Thirst (due to diuresis)
Fatigue and malaise ( high glucose but lacked insulin means glucose cant be used properly)
Blurred vision (due to chronic hyperglycaemia)
Infections eg candidiasis (glucose provides optimum conditions for bacteria)
Symptoms of ONLY T1
Weight loss (less anabolic effects of insulin - lose fats and muscle)
Ketoacidosis (N&V, acetone breath- due to body trying to deal with acidosis)
Symptoms of only T2
Complications (secondary)
Altered mental status (due to chronic hyperglycaemia)
What are the glucose levels for making a diagnosis
Fasting > 7.0 mmol/L
Random > 11.1 mmol/L
Plasma glucose concentration > 11.1 mmol/L, 2h after 75g glucose in an oral glucose tolerance test
Or HbA1c > 48 mmol/mol (or 6.5%) normal = 20-42mmol/mol 4-6%
What is the HbA 1c test
Glycated or glycosylated haemoglobin
- indicator of glycaemic control during the previous 2-3 months
How do you diagnose ‘pre diabetes’ / impaired glucose tolerance
Impaired glucose tolerance:
Fasting <7 mmol/L
Random or OGTT >7.8 but < 11.1 mmol/L
Impaired fasting glycaemia
Fasting >6.1mmol/L but <7mmol/L
Risk categories for future diabetes and / or CVD ‘pre diabetes’ HbA1c :42-47 mmol/mol
What is type 1 diabetes
An autoimmune condition (autoantibodies may be detected)
Progressive destruction of islet B cells
0.6% of uk population
Onset usually <40 years
Rapid onset
No complications at diagnosis
Weight - normal or loss
Tendency to ketosis
Treatment with insulin, regular exercise, healthy diet
What is ketogenesis
Synthesis of ketone bodies by the liver from fatty acid breakdown products
2x acetyl CoA = acetoacetate
B-hydroxybutyrate and acetone
Normally a small amount in the blood but in starvation and type 1 DM -> ketosis -> metabolic acidosis (decrease in blood pH )
Sources of insulin
Animal: porcine , bovine
Human: semi-synthetic - enzymatically modified human insulin
Recombinant E. coli , yeast
Insulin is classified according to duration of action
Different types of insulin
Short acting
- soluble
Intermediate acting
- isophane (complexed with protamine, NPH)
Long acting
- insulin zinc suspension
- analogues (glargine, detemir)
Biphasic (pre mixed)
- mix of short and intermediate acting insulin’s
Why should you rotate the injection site
To avoid lipodystrophy which leads to erratic insulin absorption of that part of the skin and altered fat distribution under the skin
When are iv insulin injections used
Short acting soluble insulin for urgent treatment
For fine control in serious illness In diabetic ketoacidosis In surgery (peri operative)
What is cell replacement therapy
Islet transplantation from human cadaver
Requirement for immunosuppressive to prevent rejection
Limited supply of islets for transplantation
What is type 2 diabetes
Relative insulin deficiency (impaired B cell function) and / or insulin deficiency
5.4% of population
Onset usually >40 years
Gradual onset
Complications present in 25% of patients at time of diagnosis
Usually overweight
No ketones in urine (only at really advanced)
Secondary causes of DM
Endocrine: Cushing’s (excess cortisol), acromegaly (excess GH), phaeochromocytoma (excess adrenaline)
Pancreatic disease
- chronic pancreatitis, surgery, cystic fibrosis, tumour either via loss of function or loss of tissue
Genetic disorders: Down’s syndrome, prader willi
Drug induced: steroids, beta blockers, diuretics
Lifestyle changes to help diabetes
Diet - healthy (weight loss if necessary 5-10%)
Lifestyle
Exercise - improves insulin sensitivity and weight loss
Smoking cessation - decreases CV risk
Strategy of treatment for T2 DM
Diet / lifestyle interventions
Metformin (caution in renal impairment) or SU or DPP-4i or pioglitazone or SGLT-2i
Then dual therapy (2 drugs)
Then triple therapy (start insulin)
Then intensify insulin regime or add drugs
Mode of action of metformin
Not clear
Is thought to Activates AMP kinase
Decreases gluconeogenesis and increase glucose utlilisation
Mode of action of sodium glucose co transporter 2 (SGLT-2) inhibitors
Eg dapaglifozin, canagliflozin
Inhibit renal glucose reabsorption
- reversible inhibit SGLT-2 in renal PCT to reduce glucose reabsorption and increase urinary glucose excretion - decrease in blood glucose
Describe the pituitary gland
1cm bean shaped gland
Located in a cavity of the sphenoid bone (sella turcica)
Under the control of the hypothalamus
2 parts: anterior and posterior have different embryological origins
Why is the pituitary in 2 separate pieces
Because it forms from an ectodermal upgrowth (rathke’s pouch) from the roof of the primitive mouth and an neuroectodermal downgrowth of the brain
Describe the posterior lobe of the pituitary gland
Neural tissue (growth down from the hypothalamus) and attached to it via the pituitary stalk
Secretes 2 hormones:
ADH and oxytocin
Synthesised in the cell bodies of the neuron and stored in the terminal ends of the axons
Secreted by nuerosecretion
Acts on non endocrine tissues
Blood supply from middle and inferior hypophyseal arteries
Describe the anterior lobe of the pituitary Gland
Glandular tissue growing up from the embryological epithelium of the roof of the mouth (rathkes pouch)
Main bulk of the anterior pituitary is called the pars distalis
Curls around the pituitary stalk (pars tuberalis)
The pars intermedia is the piece next to the posterior pituitary and can be separated from the rest by the vestiges of rathkes pouch. It secretes melanocyte stimulating hormone
What are chromophobes of the pituitary gland
Immature with only a few hormones
Recently released most of their hormones
Waiting in reserve so don’t have a lot of hormones
(Either one of these or all)
In the anterior pituitary what colours are the different cells
Acidophils - pink
Basophils - purple
Chromophobes - pale
Interspersed with plentiful capillaries
Ultrastructure of the anterior pituitary
Presence of prominent storage granules, nucleus with nucleolus, mitochondria, endoplasmic reticulum
What are chromophils
Actively secreting cells
2 different types of acidophils of the pituitary and what they secrete
Somatotrophs - GH
Lactotrophs - prolactin
2 different types of basophils
Corticotrophs - ACTH + others
Thyrotrophs - TSH
Describe secretion from the anterior pituitary
Mediated by hypothalamic releasing hormones from the median eminence of the hypothalamus
Blood supply from super hypophyseal arteries (internal carotids)
Via the pituitary portal system - external plexus collects from hypothalamus
This carries stimulating hormones directly from the hypothalamus to the cells of the anterior pituitary
Pituitary hormones are secreted into the lower capillary bed and drain into the hypophyseal veins
Blood supply enters via the pituitary stalk (can be damaged in head injury)
Clinical relevance of pituitary tumours
Relatively common they are frequently benign but cause problems because of pressure on surrounding structures
What is bilateral hemianopia
Temporal field of view lost (peripheral vision)
Describe tumours of the pituitary gland
Relatively common
Almost all are benign and do not spread (adenoma)
Size of an orange
Dangerous as can compress parts of the brain
Pituitary is relatively accessible by nasal cavity and saphenoid bone
What hormone is oversecreted in a pituitary tumour
Growth
What is the levator ani
Has a number of subdivisons which are defined as individual muscles in most textbooks but are difficult to distinguish
Why are the testes outside the pelvis
Because sperm production is optimal at temperatures 2-4c below body temperature
What is the perineum
The area on the outside of the pelvic floor
Region between vulva / scrotum and perineal body and anal region
Perineal membrane is part of the perineum divides the region of the urogenital triangle into a superficial and a deep pouch
Blood supply and nerves in the pelvis
Supply to pelvic organs via branches of internal iliac vessels
Other branches of the internal iliac go to glutei
The veins of the pelvic organs form interlinked plexus resulting in Portocaval anastomoses via the superior rectal vein
Lymph vessels follow blood vessels although the direction of pelvic lymph flow is towards the nodes around the common iliac vessels
Pelvic organs are innervated by the plexus of the autonomic nervous system
