Topic 1 - Body Structure/Embryology 1+2 PDF

🐒 Topic 1 - Body Structure/Embryology 1+2 Lecture 0 - Introduction to Anatomy Describe/State the Anatomical Position Plane(s) Axial = Transverse = Horizonal In the midline, the sagittal plane is...

🐒 Topic 1 - Body Structure/Embryology 1+2 Lecture 0 - Introduction to Anatomy Describe/State the Anatomical Position Plane(s) Axial = Transverse = Horizonal In the midline, the sagittal plane is known as median sagittal while any plane parallel to the median sagittal plane is known as parasagittal Superior means toward the head and inferior/caudal means toward the feet. Ventral/anterior = front Dorsal/posterior = back Medial = towards midline Lateral = away from midline Superficial = on the surface Topic 1 - Body Structure/Embryology 1+2 1 Topic 1 - Body Structure/Embryology 1+2 2  Thorax, Abdomen, Pelvis locations Define Distal + Proximal Distal – situated away from the centre of the body or from the point of attachment. Proximal - situated nearer to the centre of the body or the point of attachment. Flexion and extension Flexion - movement that decreases angle between 2 body parts. Extension - increasing angle between 2 body parts. Topic 1 - Body Structure/Embryology 1+2 3  Abduction + Adduction abduction - movement away from the midline adduction - movement towards the midline Topic 1 - Body Structure/Embryology 1+2 4  medial + lateral rotation Medial rotation is a rotational movement towards the midline. It is sometimes referred to as internal rotation. Lateral rotation is a rotating movement away from the midline. elevation + depression Elevation refers to movement in a superior direction. Topic 1 - Body Structure/Embryology 1+2 5  depression refers to movement in an inferior direction. Supination + Pronation turn your hand onto its back, palm up. This is the supine position, and so this movement is supination. flip your hand onto its front, palm down. This is the prone position, and so this movement is named pronation. These terms also apply to the whole body – when lying flat on the back, the body is supine. When lying flat on the front, the body is prone Dorsiflexion + Plantarflexion They refer to the two surfaces of the foot; the dorsum (superior surface) and the plantar surface (the sole). Topic 1 - Body Structure/Embryology 1+2 6  Dorsiflexion refers to flexion at the ankle, so that the foot points more superiorly. Plantarflexion refers extension at the ankle, so that the foot points inferiorly. Inversion + Eversion Inversion involves the movement of the sole towards the median plane – so that the sole faces in a medial direction. Eversion involves the movement of the sole away from the median plane – so that the sole faces in a lateral direction. Opposition and Reposition Opposition brings the thumb and little finger together. Reposition is a movement that moves the thumb and the little finger away from each other, effectively reversing opposition. Topic 1 - Body Structure/Embryology 1+2 7  Circumduction Protraction and Retraction Lecture 1 - Embryology I what it the most important time of pregnancy 3-8 weeks, mother does not know she is pregnant, she could therefore expose the embryo to teratogens (agent/factor causing malformation of an embryo, results in congenital abnormalities.) Embryology overall for the first 4 weeks Week 1 - fertilisation, cleavage, compaction, blastocyst formation + cavitation, Hatching Wek 2 - implantation Topic 1 - Body Structure/Embryology 1+2 8  Week 3 - Gastrulation Week 4 - neurulation, segmentation, folding The First Week Day 1 = fertilisation, zygote forms in fallopian tubes Day 2-3 = Cleavage Following fertilisation, cellular division occurs of blastomeres, with the initial one cell dividing on through the process of mitosis = CLEAVAGE - 2^n divisions Day 4 = Compaction: 8 cell → 16 cell morula → Totipotency is lost and differentiation occurs. Day 5 = Blastocyst formation + cavitation morula continues to divide and becomes known as the blastocyst. cavitation Cavitation - fluid pumped into an early blastocyst Topic 1 - Body Structure/Embryology 1+2 9  (Blastocoel = Blastocyst cavity which eventually becomes Yolk sac) The blastocyst - spherical shape, made up of approximately 100 cells. These blastocyst cells differentiate into two cell lines: the trophoblast and the embryoblast (ICM). The outer cell mass (trophoblast) - makes contact with the endometrium of the uterus and causes implantation —> formation of the placenta The inner cell mass (embryoblast) —> development of the embryo itself. Hatching zona pellucida breaks open to release the blastocyst Topic 1 - Body Structure/Embryology 1+2 10  The Second Week Implantation The trophoblast differentiates —> syncytiotrophoblast layer and cytotrophoblast layer. The embryoblast differentiates —> epiblast and the hypoblast (bilaminar disk) Amniotic cavity forms within the epiblast (closed sac containing the amniotic fluid) Around day 6, the syncytiotrophoblast invades into the endometrium and digests the mucus of the uterus, allowing maternal blood vessels to invade into it, forming the the placenta. Blastocyst cavity (Blastocoel) → primary yolk sac- It is important for blood supply, and provides nutrition till the placenta develops Topic 1 - Body Structure/Embryology 1+2 11  What is the clinical relevance to implantation of an embryo? In placenta praevia, implantation of the embryo occurs in the lower uterine segment (instead of in the normal position of the upper posterior uterine wall). A low-lying placenta → more susceptible to haemorrhage → due to a defective attachment to the uterine wall.. Third week Gastrulation Topic 1 - Body Structure/Embryology 1+2 12  Gastrulation = the two cell layers (bilayer) become three germ cell layers (triminar), and the bodily axes observed in the mature adult are created. Gastrulation occurs through The primitive streak → a groove in the midline of the epiblast which appears during the third week. Cells of the epiblast layer break off and migrate toward the primitive streak. Here, they detach and penetrate through the epiblast layer to form three new germ cell layers: Endoderm, Mesoderm, Ectoderm Topic 1 - Body Structure/Embryology 1+2 13  Endoderm, Mesoderm, Ectoderm Endoderm The endoderm becomes the internal layer of the body and forms: The lining of internal organ systems and specialised cells (Pancreas, Liver, Thyroid) Mesoderm The mesoderm becomes the supportive tissues of internal structures: Cardiac muscle, Skeletal muscle, Smooth muscle, connective tissue Ectoderm Epidermal skin cells, Neurones Lecture 2 - Embryology II 4th to 8th Week Topic 1 - Body Structure/Embryology 1+2 14  what is the notochord The mesoderm layer is responsible for creating the notochord - a linear structure along the dorsal (back) side of the embryo where the spine will form. induces thickening of the ectoderm + starts process of neurulation what is the neural tube comes off the ectoderm forms the CNS Explain the neurulation process (week 4) Lateral edges of ectoderm become elevated, forms the neural fold. - The pressed mid region = neural groove - Neural plate = neural groove + neural fold - Neural folds fuse together -> occurs cranially + cordally -> forms neural tube. - Outer part of ectoderm begins to move down and surrounding the endoderm + mesoderm. neural plate → neural groove → neural tube Topic 1 - Body Structure/Embryology 1+2 15  3rd image: View of neurulation from the top of the neural plate failure of notochord development may cause (2) vertebral column abnormalities (spina bifida, scoliosis) What are Somites Somites (part of mesoderm) give rise to vertebrae, ribs, skeletal muscles, skin & dermis Somites are paraxial mesoderm. Paraxial means they are parallel to the axial line, defined when the notochord first appeared 3 components of Somites Topic 1 - Body Structure/Embryology 1+2 16  Sclerotome - vertebrae + ribs Myotome - skeletal muscle development Dermatome - Skin + Dermis segmentation organisation of somites to form repeating structures. somites, which are mesoderm blocks alongside the neural tube, also called paraxial mesoderm. somites derive into the 3 components (SMD) Somites closely associate with the neural tube, leading to specific spinal nerves and levels of the neural tube. This connection explains how spinal nerves innervate muscles and skin in adults. Cephalocaudal folding + lateral folding Folding shapes the trilaminar disk into an embryo. Two types of folding occur: head-to-tail (cephalocaudal) and side-to-side (lateral). The neural tube has already formed from the neural plate. In lateral folding, the sides of the ectoderm come together, forming a tube with ectoderm outside and endoderm inside. This process pinches off part of the yolk sac, which becomes the embryo's GI tract. Cephalocaudal folding creates the head and tail of the embryo. The GI tract remains connected to the umbilical cord during this folding. Topic 1 - Body Structure/Embryology 1+2 17  What is primary curvature Spine exhibits one continuous C-shaped curve What is visible in the 4th week of development (+ diagram with labels) embryo is cylindrical c-shape Topic 1 - Body Structure/Embryology 1+2 18  What is visible in the 5th week of development (+ diagram) Growth of head due to rapid growth of brain Branchial arches → mandible Upper limb bud → upper limb What is visible in the 6th week of development Limbs show regional development Especially upper limbs Elbow and wrist identifiable What is visible in the 7th week of development Topic 1 - Body Structure/Embryology 1+2 19  Upper limbs bent at elbows Fingers and thumb are distinct but webbed What is visible in the 8th week of development fingers and toes are distinct and separated Eyelids evident ears appear external genitalia start appearing Topic 1 - Body Structure/Embryology 1+2 20