University of Sheffield IMMS Anatomy 2024-2025 PDF

2024-2025 MBChB Phase 1 Introduction to Medicine and Medical Science (IMMS) Anatomy Name…………………………………… V 1.0  Contents Introduction to Anatomy........................................................................................

2024-2025 MBChB Phase 1 Introduction to Medicine and Medical Science (IMMS) Anatomy Name…………………………………… V 1.0  Contents Introduction to Anatomy.................................................................................................. 4 IMMS Session 1: Introduction to Musculoskeletal Anatomy................................................ 8 Introduction............................................................................................................................ 8 Part 1 - Anatomical Terminology................................................................................................ 9 Part 2 - Joints and Ligaments.................................................................................................. 13 Part 3 - Movement and Muscles............................................................................................... 17 Part 4 - Fundamentals of the Limbs and Vertebral Column......................................................... 21 IMMS Session 2: Introduction to the Nervous System and Neuroanatomy......................... 25 Introduction.......................................................................................................................... 25 Part 1 - Overview of the Nervous System.................................................................................. 26 Part 2 - The Brain and Spinal Cord........................................................................................... 27 Part 3 - The Somatic and Autonomic Nervous Systems............................................................... 32 Part 4 - Cranial Nerves............................................................................................................ 34 Part 5 - Spinal Nerves............................................................................................................. 35 2 Welcome to Anatomy! Welcome to the anatomy component of IMMS. We are looking forward to welcoming you to the Medical Teaching Unit (MTU). In Phase 1, you will study anatomy using various resources including anatomical models, plastinations, and prosections. However, before you work with human tissue, you must understand the regulations that govern activities in the MTU and how you must behave when you are there. You also need to understand some basic concepts in anatomy before we can begin a more detailed study of organs and systems. There are two IMMS anatomy practical sessions and an introductory lecture. The lecture will focus on health and safety and the regulations that govern our work with human tissue in the MTU. It will also include an overview of how anatomy is taught in Phase 1. The IMMS Anatomy practical sessions will take place in the MTU. In these sessions, you will learn some basic concepts in anatomy. You will see and handle real human bones and plastinated human tissue. You will meet some members of the anatomy team and you will be able to familiarise yourself with the MTU and the way anatomy classes run. In the IMMS anatomy sessions, you will work through a series of activities in small groups. The activities are designed to be interactive and exploratory, and we will expect you to be hands-on and proactive. We expect you to prepare for the classes so that you can get the most out of them. You are expected to read the relevant section of this handbook in advance and bring it to the classes. This IMMS anatomy handbook is also available online via Minerva if you wish to access a digital version. There is a lot of information in this handbook, but the purpose of it is to introduce basic concepts, help you in the sessions and to be a resource that you can return to throughout the year, so do not try to learn everything in it immediately. We look forward to welcoming you to the MTU and working with you. Dr Samuel Birks University Teacher and Interim Academic Lead for Anatomy 2024 [email protected] Dr Ellen Ashton Senior University Teacher and Academic Lead for Anatomy [email protected] 3  Introduction to Anatomy What is Anatomy? Anatomy is the study of the structure of the human body. Anatomy encompasses the study of structures that we can see with the naked eye (sometimes called gross anatomy) and the study of structures at a microscopic level (histology). When we talk about anatomy, we will be referring to gross anatomy, but you will study histology during Phase 1 too. Anatomy has always been an integral part of the study of medicine. An understanding of anatomy is important for almost all medical careers – not just for surgery and radiology. Doctors working in emergency medicine, general practice, and many medical specialities such as neurology, anaesthesia, cardiology, and gastroenterology require a sound understanding of anatomy. In your anatomy classes, we will mostly concentrate on ‘normal’ anatomy, but we will touch on common and important relevant clinical pathologies too. Anatomy Teaching Staff We are fortunate to have a diverse team of anatomy teachers (also known as ‘anatomy demonstrators’) to support your learning. In your anatomy classes, teaching and learning is a partnership between us. The role of the anatomy teachers is to guide and encourage you and to help you when you need it, but they will not do the work for you. This way of learning may be new to you, but if you can embrace it then you will thrive in the sessions. The demonstrators will help you to develop and deepen your understanding of anatomy, they will ask you questions and will encourage you to do the talking. You will work with different demonstrators throughout the year so that you can benefit from different teaching styles. The Medical Teaching Unit (MTU) The MTU is a unique, lively, and interesting place to study, and we hope you enjoy your time studying there. However, the MTU is unlike any other study space as all activities undertaken within it are done so in accordance with the Human Tissue Act (HTA) 2004. There are also health and safety regulations that you must be aware of, and rules that you MUST follow. The most fundamental aspect of our work in the MTU is that the dignity of the deceased must never be compromised. You must respect this in everything that you do and say, both within and outside the MTU. You must always behave professionally in the MTU, and human tissue (prosections and plastinations) must ALWAYS be handled carefully and discussed respectfully. If you behave in a manner that is deemed inappropriate, you will be asked to leave the MTU, and further action may be taken. In the introductory lecture, you will be given a more detailed overview of the rules and regulations that you must comply with when working in the MTU. 4 The Practical Classes In anatomy practical classes, you will work in small groups on a series of activities, using various resources. Preparation for anatomy classes is essential as we will cover a lot in each session. We expect you to come to classes prepared, with a basic understanding of the topics we will be covering and ready to start the activities. This is important because you will not have a demonstrator with your group all the time. If you are prepared for the class, you can start to undertake the activities independently. You should read the relevant section of the anatomy handbooks in advance of the class. This will help you to get the most out of the sessions - the demonstrators will expect you to have read the relevant section in advance. Bring your handbook to the practical classes too, as the activities will refer to content within them. You should watch the recommended sections of Acland’s Video Atlas of Human Anatomy in preparation too. These videos will help you to visualise anatomical structures and appreciate the spatial relationships between structures. Your anatomy handbooks contain information about which videos to watch ahead of each session and the length of each video is given in brackets. Acland’s Video Atlas is available online via the university library: https://aclandanatomy-com.sheffield.idm.oclc.org/ - you will be asked to sign in with your university account details. Alternatively, you can access it via MUSE > StarPlus > enter ‘Acland’s Video Atlas of Human Anatomy’ in the search box and then follow the links to access. You can access the relevant videos via the volumes and subheadings, or you can simply enter the video number in the search box. The activities that you will work through in the practical sessions will be made available on Minerva, but copies will be provided at your table in the sessions, so you do not need to print them out. Electronic Devices are NOT permitted in the during classes Although we appreciate that many of you will use electronic devices such as laptops, tablets or mobile devices to aid your learning, you are NOT permitted to use them in the MTU. This is because there is a risk of students using devices to take unauthorised photographs of the cadaveric human material in the MTU, which is prohibited. This means your devices (including your mobile phone) MUST remain in your bag when you come to class. If a student is seen using their mobile device in the class, they will be told to leave the class. If a student is found to have taken a photograph within the MTU, they will be subject to disciplinary proceedings. 5  What you need to bring to class Your handbook - it contains core information and helpful illustrations. Something to write with if you want to make notes – electronic devices are not permitted. Working with Human Tissue Our ability to offer you the opportunity to work with human tissue depends solely upon the huge generosity of our donors and their families. However, we understand that not everyone will feel comfortable working with human tissue, but we do expect you to engage with the classes as a mark of respect to our donors. We know that many students look forward to working with human tissue, but that some have mixed emotions and may feel anxious, nervous, or worried about it. All these feelings are normal, and it is important to acknowledge them – it does not mean that you will not enjoy anatomy or that you are not ‘cut out’ for the course. The IMMS anatomy sessions will give you time to familiarise yourself with the MTU and give you the opportunity to see and handle human tissue before we start systems-based teaching. When you come to the IMMS anatomy sessions, please talk to staff about how you feel. Think ahead about what you might do if you feel overwhelmed or upset in the MTU – you are allowed to leave the MTU if you need to, and you do not need to ask permission. Working with human tissue can be particularly upsetting for anyone who is coping with bereavement or serious illness. Please contact the Dr Birks (the Academic Lead for Anatomy) ([email protected]) if you are dealing with personal circumstances that you feel will make attending anatomy classes difficult or impossible. Sometimes students ‘feel bad’ about working with human tissue. Always remember that it was a donor’s wish to bequeath their body to your education and that respect for the donor is of paramount importance, so as long as you handle the tissue with care and discuss it with respect, you should not feel bad about working with human tissue. Key Resources Anatomy is a vast subject, and a common difficulty for students is knowing how much detail to go into when learning anatomy. Your Phase 1 examinations assess your knowledge and understanding of the material covered in Phase 1. Therefore, your key resources are: Your practical sessions – you should attend your sessions and engage with them: get involved, complete the activities, and ask questions. Prepare in advance to get the most out of the sessions. The specimens, models, your peers (i.e. your group) and demonstrators are key resources. 6  Your anatomy handbooks – these contain the core information and have been written specifically for your course. All the material in the anatomy handbooks is examinable. There are two key reasons for providing you with a handbook, rather than recommending other resources: o Many resources contain more information than is needed at this stage of the course. This can leave students feeling overwhelmed, trying to figure out what to learn, and how much to learn. o Resources (books, websites, apps) often say slightly different things about the same structure, which can be confusing when you are first starting out. Therefore, the handbooks should remove any guesswork about what you need to know, and how much detail to go into. Anatomy formative assessments and practice exam questions will be made available on Blackboard throughout the year as you progress through the teaching blocks. Once these have been made available to you, they will remain available for the rest of the year, and you can complete them as many times as you like. The purpose of the formative assessments is to allow you to gauge your understanding of the material covered in the anatomy handbooks and practical sessions. Because they are for your own learning, we will not monitor whether you complete these assessments, and your grades will not be recorded. The recommended textbook for further reading is Gray’s Anatomy for Students (Drake, Vogl and Mitchell). This is a good all-round anatomy text with clear illustrations. The library holds print copies of the 5th edition (2023). The 4 th edition (2019) is available online via the university library. You can access it via MUSE > StarPlus > enter ‘Gray’s Anatomy for Students’ in the search box and then follow the links to access. Supplementary Resources We hope you enjoy anatomy and want to learn more. If you would like to widen your study of anatomy, supplement your learning, or use a variety of resources, there are many different options available that include: Anatomy textbooks - these generally contain text and illustrations. Although we recommended Gray’s Anatomy for Students, it is important to choose a book that you like and find easy to use. There are many undergraduate anatomy textbooks in the university libraries, and they will differ in the style of writing, amount of text and type and quality of images. Feel free to choose a book that appeals to you – there will be little variation in the content between different textbooks. Anatomy atlases - these contain labelled images and little, if any, text. The images may be diagrams or images of prosections. Online resources - these include websites, videos, and apps. Many are free, with optional, paid-for extras (such as access to tests, questions, or e-learning modules). Anatomy flashcards - these generally contain brief text and images, which some students find helpful for revision. Some students like to make their own too. Anatomy colouring books - these contain black and white image templates for you to colour in. They can help with visualising structures and pathways and make a refreshing change from text-based resources. 7  IMMS Session 1: Introduction to Musculoskeletal Anatomy Introduction The study of the musculoskeletal system does not simply mean knowing the names of all the muscles and bones. It also includes understanding their functions, their composition, and the diseases that affect them. An in-depth understanding of musculoskeletal anatomy is vital in specialities such as orthopaedic surgery, rheumatology, general practice and emergency medicine. We will look at muscles and bones in detail throughout the year. In this IMMS session we will start by learning the anatomical terminology we use in anatomy and by exploring the basic structure and function of muscles and joints. Learning Outcomes 1. Identify parts of the body using anatomical terminology. 2. Describe the anatomical position and use anatomical terminology to describe the location of a part of the body in relation to another. 3. Identify the coronal, sagittal and transverse planes. 4. Distinguish between the axial and appendicular skeleton. 5. Describe the histological classification of joints and give an example of each type. 6. Describe the different types of synovial joints and give an example of each type. 7. Use anatomical terminology to describe the movements of parts of the body. 8. Describe the histological classification of muscles. 9. Describe the difference between muscles, tendons, and ligaments. 10. Describe the different shapes of skeletal muscles. 11. Appreciate the similarities and differences between the gross anatomy of the upper and lower limbs. 12. Describe the gross anatomy and function of the vertebral column, identify the main features of a vertebra and distinguish between cervical, thoracic, and lumbar vertebrae. Recommended Videos from Acland’s Video Atlas 3.3.1. The vertebral column, features of a typical vertebra (4:45). 8 Part 1 - Anatomical Terminology Parts of the Body In anatomy and medicine, we use specific terms to describe parts of the body. Many of these terms are used in everyday language too, but they often have a different meaning in a medical context. For example, in everyday language, when we say ‘arm’ we usually mean the whole upper limb, but in anatomy, the arm is the region between the shoulder and the elbow. Some important anatomical definitions of parts of the body are listed in the table below. Part Description Torso / The main central part of the body including the thorax, abdomen, and pelvis. Trunk Not including the neck, head, or the upper or lower limbs. The upper part of the torso from the bottom of the neck to the diaphragm (an internal muscular sheet that separates the thorax from the abdomen). The Thorax thorax houses the lungs and heart and is surrounded by the ribs. The term ‘chest’ is often used to mean the thorax, but this is less accurate, as some may use it to refer to the front of the thorax only. The central part of the torso between the diaphragm and top of the pelvic bones. The abdomen contains most of the organs of digestion including the Abdomen stomach, intestines, and liver. In everyday conversation, people often refer to the entirety of the abdomen as the ‘stomach’. The lowest part of the torso, between the abdomen and the start of the lower limbs. The pelvis contains the final part of the digestive tract, the bladder, and the reproductive organs. Pelvis The bony skeleton of the pelvic region is also called the pelvis, so the term ‘pelvis’ is used to describe both the entirety of the pelvic region (including organs and blood vessels) and the bones of the pelvic region. A poorly descriptive term. Anatomically, the ‘back’ refers to the entire posterior Back surface of the torso, however, in everyday conversation people may use this term to refer to the vertebral column / spine. The upper part of the upper limb (from the shoulder to the elbow). This is Arm where the biceps muscle is located. In everyday conversation, people usually refer to the entire upper limb as the ‘arm’. Forearm The middle part of the upper limb (from the elbow to the wrist). Thigh The upper part of the lower limb (from the hip to the knee). The middle part of the lower limb (from the knee to the ankle). Leg In everyday conversation, people usually refer to the entire lower limb as the ‘leg’. 9  The Anatomical Position and Positional Descriptions We must be able to describe the position of one part of the body relative to another, or the location of an injury or skin lesion, to another health professional, without ambiguity. We use specific anatomical terms to describe where something (e.g. an organ or an injury) is located relative to other structures. These specific terms should be used when talking to other health professionals but when talking to patients, it will usually be more appropriate to use everyday vocabulary. These anatomical terms, however, are only accurate if all professionals use them in the context of the ‘anatomical position’. In the anatomical position, a person is standing up with their feet flat on the floor, facing forward, arms by their sides with their palms facing forwards. We always describe the location of structures and injuries in the context of the anatomical position. Figure 1.1 The Anatomical Position Image by OpenStax (2016). Anatomy and Physiology. Licenced under CC 4.0. https://openstax.org/details/books/anatomy-and-physiology. 10 The table below lists the anatomical terms that we use to describe the location of structures or parts of the body, relative to each other. Descriptor Meaning Example Superior Above The brain is superior to the heart. Inferior Below The pelvis is inferior to the thorax. Anterior / Front (in front of) The nose is anterior to the ears. Ventral Posterior / Back (behind) The spine is posterior to the sternum. Dorsal Medial Closer to the centre line The big toe is medial to the little toe. Further away from the centre Lateral The thumb is lateral to the palm. line Proximal Closer to the origin The elbow is proximal to the wrist. Distal Further away from the origin The toes are distal to the knee. The right arm and right leg are Ipsilateral The same side of the body ipsilateral to each other. The right arm and left leg are Contralateral The opposite side of the body contralateral to each other. Deep Further away from the surface The heart is deep to the sternum. Superficial Closer to the surface The skin is superficial to muscle. Supine Lying down on one’s back, With the patient supine, they are (position) facing up facing the ceiling. Prone Lying down on one’s front, With the patient prone, they are (position) face down facing the floor. Cranial* Towards the head The brain is cranial to the spinal cord. Caudal* Towards the ‘tail’ The pelvis is caudal to the abdomen. The frontal lobe of the brain is rostral Rostral* Towards the face to the occipital lobe. *The terms cranial, caudal, and rostral are mainly used when discussing neuroanatomy and embryology. 11  Let’s look at an example of how these terms are used in practice. Consider the following scenario: an A&E doctor seeing a patient with a laceration (cut) might describe the injury over the phone to another doctor as follows: “The patient has sustained a 15cm oblique (diagonal) laceration to their right anterior forearm. It starts approximately 3cm proximal to the lateral aspect of the wrist skin crease and extends to the medial border of the middle third of the forearm.” This probably seems very wordy, but it gives the person receiving the referral a very precise picture of exactly where the injury is, without seeing it for themselves. Over time, you will learn how to use these terms and using them will become second nature. Anatomical Planes The body can be ‘cut’ or viewed in cross-section. Seeing structures in cross-section can be confusing at first, but it helps us to appreciate the 3D nature of the body and the spatial relationships between structures. In clinical practice, the interpretation of radiological images (CT, MRI, ultrasound, and X-rays) depends on being able to recognise anatomical structures and relationships in different planes. There are three anatomical planes to know and recognise: Coronal (also called ‘frontal’) = ‘face-on’. A coronal incision cuts a structure into an anterior and a posterior part. Sagittal = ‘side-on’. A midline sagittal incision cuts a structure into a left and a right side. Transverse (also called axial or horizontal) = ‘end-on’. An axial incision cuts a structure into a superior and an inferior part. These terms are used in relation to the whole body, regions, and individual organs. Figure 1.2 Anatomical Planes Image by OpenStax (2016). Anatomy and Physiology. Licenced under CC 4.0. https://openstax.org/details/books/anatomy-and-physiology. 12 The Skeleton The skeleton is the bony scaffolding of the body. We can divide it into axial and appendicular parts. Axial = central, or core, parts: the skull, vertebral column, ribs, and sternum. Appendicular = the bones of the limbs, including the shoulder blades (scapulae), collarbones (clavicles) and the hip bones. Figure 1.3 Axial (white) and Appendicular Skeleton (blue) Image by Mariana Ruiz Villarreal, 2009. Image free for use in the public domain. The skeleton is made of bone and cartilage. Whilst bone is hard and rigid, cartilage is flexible. In babies, much of the skeleton is cartilage which ossifies (becomes bone) as they grow. Some cartilage remains in the adult skeleton. For example, the anterior parts of the ribs are made of cartilage. Part 2 - Joints and Ligaments A joint is formed where two bones meet and the two bones articulate with each other. For example, the femur and tibia articulate at the knee joint. Joints are classified according to their histological structure and their biomechanical structure. Not all joints move. Histological Classification of Joints The word ‘histological’ refers to the cellular and structural composition of tissues. There are three different histological types of joints. 13  Synovial joints are the most common type of joint. A very narrow synovial cavity separates the articular surfaces of the bones. The cavity contains lubricating synovial fluid, which is enclosed in a joint capsule. The joint capsule has two layers: an outer fibrous capsule, and an inner synovial membrane. The articular surfaces are covered with articular ‘hyaline’ cartilage. Synovial joints usually allow a great deal of movement. Examples: the shoulder, knee, and wrist joints. Fibrous joints connect two bones together via strong fibrous tissue. There is no cavity and no fluid. There is usually very little (if any) movement at fibrous joints. Example: the joints between the individual bones of the skull (called ‘sutures’). Cartilaginous joints are like fibrous joints, but the articular surfaces are separated by cartilage instead of fibrous tissue. There are two subtypes: Primary cartilaginous joints are connected to each other by hyaline cartilage, which allows some flexibility. Example: where the ribs meet the sternum (sternocostal joints). Secondary cartilaginous joints are connected to each other by fibrocartilage, plus a layer of hyaline cartilage covers the articular surfaces of the bones. They are flexible but strong and can support a lot of weight. Example: the intervertebral discs between the vertebrae in the spine. Figure 1.4 Synovial joint (top left), fibrous joint (top right), primary cartilaginous joint (bottom left) and secondary cartilaginous joint (bottom right) Illustration by Dr Sam Birks. Reproduced here with permission. 14 Biomechanical Classification of Synovial Joints Synovial joints permit movements in different planes and to different degrees, depending on the shape of the articular surfaces and other factors such as surrounding ligaments and muscles. There are six types of synovial joints. Ball and socket joint – the end of one bone is shaped like a ball which fits into a rounded, bowl-shaped socket on another bone e.g. the shoulder joint and the hip joint. These joints are mobile and allow a significant range of movement in all directions, including rotation. How stable these joints are is dependent on the fit between the ball and socket - the better the fit, the more stable the joint but the less mobile it is (e.g. the hip). With a poorer fit comes better mobility but less stability and greater risk of dislocation (e.g. the shoulder). Hinge joint – just like a hinge on a door, they allow a significant range of movement, but only in one plane e.g. the elbow and knee joints allow only flexion and extension. Pivot joint – the best example is found at the top of the spine where the first and second cervical vertebrae articulate with each other. The first vertebrae (C1, the atlas) at the base of the skull pivots around the peg of the second vertebrae (C2, the axis). It allows rotational movement only, allowing us to turn our head left and right. Saddle joint – these joints are shaped like a rider sitting in a saddle, and permit movement in two planes. The best example is the joint at the base of the thumb, where the metacarpal of the thumb articulates with one of the small carpal bones in the wrist (the carpometacarpal joint of the thumb). Condyloid joint – like a ball and socket joint, but the joint surfaces are oval-shaped. They have a good range of movement but only in two planes e.g. the wrist joint and the metacarpophalangeal joints of the fingers (the knuckles) allow flexion and extension, and abduction and adduction. Plane joint – the articular surfaces are almost flat and glide against each other. The range of movement is usually limited and dictated by the neighbouring bones and surrounding ligaments. Examples include the joints between the small carpal bones of the wrist and the acromioclavicular joint at the top of the shoulder. 15  Figure 1.5 Types of Synovial Joint Image by OpenStax (2016). Anatomy and Physiology. Licenced under CC 4.0. https://openstax.org/details/books/anatomy-and-physiology. Ligaments A ligament is a band of fibrous connective tissue that attaches bone to bone. Ligaments stabilise joints and limit their movement. They can stretch and, over time, can be stretched to allow greater joint mobility. The commonly used term ‘double-jointed’ is a misnomer – people who appear to be ‘double-jointed’ have ligaments that are stretchy enough to allow their joints a greater degree of mobility (‘hypermobility’). A sprain occurs when a ligament is overstretched and injured. The most often sprained ligaments are those of the ankle, caused by ‘going over’ on the ankle. Over-stretched and torn ligaments are painful. They may not return to their original shape. When joints dislocate, the ligaments may be stretched so much that they become permanently lax, leading to joint instability and in some cases, recurrent dislocation. 16 Part 3 - Movement and Muscles Describing Movements We also use specific terms to describe movements of the body when talking to other healthcare professionals. We use these terms instead of everyday terms like ‘bending’ or ‘straightening’. Descriptor Meaning Flexion Bending (decreasing the angle between the two parts). Extension Straightening (increasing the angle between the two parts). Lateral flexion Unique to the vertebral column: bending sideways. Abduction Movement away from the midline. Adduction Movement towards the midline. Rotating (around an axis) towards the midline (also known as Internal rotation medial rotation). Rotating (around an axis) away from the midline (also known as External rotation lateral rotation). Unique to the forearm: internal rotation of the radius, so that the Pronation palm faces posteriorly (our forearm and hand are pronated when we type using a keyboard). Unique to the forearm: external rotation of the radius, so that the Supination palm faces anteriorly (i.e. the anatomical position). Unique to the thumb and little finger: flexion and rotation of the Opposition thumb or little finger so that each one can reach the other. Combination of flexion, extension, abduction, and adduction such Circumduction that the appendage traces a circular or conical pattern. Unique to the ankle: the foot and toes move superiorly towards the Dorsiflexion shin (pointing the foot and toes ‘up’). Unique to the ankle: the foot and toes move inferiorly (pointing the Plantarflexion foot and toes ‘down’). Unique to the foot: flexing inwards so that the sole of the foot faces Inversion medially. Unique to the foot: flexing outwards so that the sole of the foot Eversion faces laterally. Unique to the scapula and mandible: moving the scapula or Protraction mandible anteriorly (e.g. moving our upper limb out in front of us to push open a door). Unique to the scapula and mandible: moving the scapula or Retraction mandible posteriorly (e.g. ‘squaring’ the shoulders). Unique to the scapula and mandible: moving the scapula or Elevation mandible superiorly (e.g. shrugging shoulders, closing the mouth). Unique to the scapula and mandible: moving the scapula or Depression mandible inferiorly (e.g. returning the shoulders after elevation, opening the mouth). 17  Figure 1.6 Types of body movements Image by OpenStax (2016). Anatomy and Physiology. Licenced under CC 4.0. https://openstax.org/details/books/anatomy-and-physiology. 18 Histological Classification of Muscles Muscles are classified histologically according to their cellular and structural composition. There are three different types. Skeletal muscle is found throughout the body. Skeletal muscles provide support for the body and move the joints and some soft tissues, such as the eyeball and tongue. They are under voluntary control (i.e. we can consciously control them). The muscle fibres are described as striated as they have a striped appearance under a microscope. Smooth muscle is found in the walls of blood vessels and internal organs such as the intestine. Smooth muscle is involuntarily controlled by the autonomic nervous system – we cannot consciously control its activity. Smooth muscle fibres are not striated. Cardiac muscle is unique to the heart. It is involuntarily controlled. Cardiac muscle cells contract in response to electrical impulses that are spontaneously generated by specialised cells within the heart. The autonomic nervous system influences these specialised cells and can speed up or slow down the heart rate. Cardiac muscle fibres are striated. Skeletal Muscles and Tendons Skeletal muscles are attached to bone or soft tissues by tendons, which are composed of strong connective tissue. Many tendons are rounded (like a cord) but some form thin, flat, sheets called aponeuroses (singular = aponeurosis). Aponeuroses are found in the scalp and abdominal wall. The muscle between tendons is often referred to as the muscle belly. To move joints, muscles or tendons must cross the joint. When a muscle contracts, one of the structures it is attached to moves, whilst the other structure does not. The bone or part that does not move is called the origin, and the bone or part that does move is called the insertion. Skeletal muscles have Latin names – some are long and difficult to pronounce. However, their names are descriptive, relating to their shape, size, position, length, the bone (or structure) they are attached to or a combination of these characteristics. For example, the names of many small muscles in the hand and foot contain the word ‘brevis’ - meaning ‘short’. Shapes of Skeletal Muscles Skeletal muscles come in many different shapes and sizes. The fibres of skeletal muscles are arranged in various ways to allow them to exert force or achieve specific movements. There are four main orientations of skeletal muscle fibres. Parallel – the muscle fibres are aligned parallel to each other. They can shorten significantly and quickly but are relatively less powerful than pennate muscles. There are two subtypes: o Fusiform muscles often have a long tendon at each end, and the muscle belly bulges out in the middle. Example: biceps brachii in the arm. o Strap muscles are belt-shaped and relatively uniform in width at the belly. Examples: sartorius in the thigh and rectus abdominis in the abdominal wall. 19  Convergent – these muscles are fan-shaped and have a very broad attachment at one end, with fibres converging onto a much smaller attachment at the other. Example: pectoralis major on the anterior thoracic wall. Circular – the muscle fibres are arranged in concentric rings around a structure and are often called sphincters. When they contract, they close the aperture they surround. Example: the muscles around the eyes and lips. Pennate – the muscle fibres are arranged at an angle to the direction in which the muscle acts. They cannot shorten as much as parallel muscles, but they are powerful. There are three subtypes: o Unipennate – the fibres are arranged diagonally in relation to their tendon and insert onto one side of the tendon only (like a feather, but with fibres on only one side of the central spine). Example: extensor digitorum longus in the leg. o Bipennate – the fibres are arranged in a V-shape and insert onto both sides of the tendon; they look like a feather. Example: rectus femoris in the thigh. o Multipennate – these muscles look like multiple bipennate muscles (or multiple feathers) side-by-side, all converging onto one tendon. Example: deltoid in the shoulder. Figure 1.7 Shapes and orientation of fibres within skeletal muscle Illustration by Dr Sam Birks. Reproduced here with permission. 20 A motor unit is composed of a single motor neuron, its axon, and the muscle fibres it supplies. There is great variation in the size of motor units within muscles. In the small muscles that move the eyeball, a single motor nerve axon may supply only a few muscle fibres, allowing fine control of eye movements. In contrast, in the large thigh muscles, a motor unit may comprise thousands of muscle fibres, giving the muscle more power but less precision. Part 4 - Fundamentals of the Limbs and Vertebral Column The Limbs The upper and lower limbs both comprise three parts: the arm, forearm and hand in the upper limb and the thigh, leg, and foot in the lower limb. Bones and joints are smaller and more numerous in the distal parts of the limbs. The gross anatomy of the upper and lower limbs is very similar. We find: a ball and socket joint where the limbs meet the torso (the shoulder and hip joints). one large bone in the proximal part (humerus and femur). a hinge joint separates the proximal and middle parts (elbow and knee joints). two bones in the middle part (radius and ulna, tibia and fibula). a collection of small bones at the start of the distal part (carpal bones, tarsal bones). five digits (fingers and toes). one digit significantly larger than the others (thumb, great toe). most of the muscle mass concentrated proximally (arm and thigh). The upper limb has evolved primarily for dexterity and is therefore more mobile: the shoulder joint has a shallow socket and relatively lax ligaments which allow a significant range of movement for positioning the hand. the fingers are long and perform complex movements. Conversely, the lower limb has evolved for bipedal locomotion and to support the weight of the body: the hip joint has a deep socket and strong ligaments, so it is very stable but less mobile than the shoulder joint. the foot and toes are adapted for weight-bearing rather than dexterity. 21  Figure 1.8 Comparison between the upper and lower limbs Illustration by Dr Sam Birks. Reproduced here with permission. The Vertebral Column The vertebral column (also known as the spine or spinal column) spans from the base of the skull to the coccyx. The spine supports the head, neck, and torso, protects the spinal cord, provides an attachment for muscles, and allows movement. There are 33 vertebrae divided into 5 ‘sections’: Cervical - 7 cervical vertebrae in the neck (C1 - C7) Thoracic - 12 thoracic vertebrae in the thorax (T1 - T12) Lumbar - 5 lumbar vertebrae in the abdomen (L1 - L5) Sacral - 5 sacral vertebrae in the pelvis (S1 - S5) which are fused into the sacrum Coccygeal - 4 coccygeal vertebrae in the pelvis (Co1 - Co4) which are fused into the coccyx. The vertebral column is not straight. Instead, it is curved which helps to absorb mechanical forces. The cervical and lumbar segments curve anteriorly, forming a cervical lordosis and a lumbar lordosis. The thoracic and sacral segments curve posteriorly, forming a thoracic kyphosis and a sacral kyphosis. 22  Figure 1.9 The parts and curvatures of the vertebral column Image by Anatomy Standard (anatomystandard.com). Licenced under CC BY-NC 4.0. Labels added. Small synovial facet joints, intervertebral discs, and several groups of ligaments connect the vertebrae to each other. The intervertebral discs between the vertebrae support the weight of the body and absorb shock. Movements between individual vertebrae are small, but collectively allow the vertebral column significant movement. Each vertebra has a broadly similar shape with named parts, projections, and facets for articulation with adjacent vertebrae. Figure 1.10 Superior (left) and lateral (right) views of a vertebra Illustrations by Dr Sam Birks. Reproduced here with permission. 23  Although most vertebrae look broadly similar, those in the cervical, thoracic, lumbar, and sacral spine have different features that are specific to their function, and some even possess unique parts. The following table summarises the key differences between the vertebrae of the different regions of the vertebral column. We will come back to these again later in the year. Vertebrae and Superior view Lateral view their distinguishing features Cervical (C1-C7): have bifid (‘two- pronged’) spinous process, holes in the transverse processes (transverse foramen) and oval-shaped bodies. The vertebral foramen (the hole for the spinal canal) is triangular. The first two (C1 and C2) are uniquely modified for rotation of the head. Thoracic (T1-T12): have long, sharp, downward-sloping spinous processes that overlap the vertebra below, additional articular facets for the attachment of ribs and heart- shaped bodies. The vertebral foramen is round. Lumbar (L1-L5): have short, blunt spinous processes and extra-large, oval-shaped bodies to support the weight of the body. The vertebral foramen is triangular. Sacral (S1-S5): fused into the sacrum, a triangular-shaped bone that sits in the posterior midline. It articulates with the left and right hip bones to form the bony pelvis. Coccygeal (Co1-Co4): fused to form the coccyx, which is a vestigial remnant of what used to be a tail located at the bottom of the sacrum. (Anterior view) Figure 1.11 Cervical, thoracic, lumbar and sacral vertebrae Illustrations by Dr Sam Birks. Reproduced here with permission. 24 IMMS Session 2: Introduction to the Nervous System and Neuroanatomy Introduction The aim of this session is to provide an overview of the structural and functional organisation of the nervous system. Neurological conditions are extremely common, and many patients present to general practice and the emergency department with neurological signs and symptoms, such as headache, weakness, sensory disturbance, visual disturbance, seizures or poor balance and coordination. You will study the brain in more detail later in the academic year. In this IMMS session, we will start by exploring the gross anatomy of the brain. We will also learn about the functional divisions of the nervous system. Neuroanatomy can be difficult so do not worry if you do not quite understand all the information in this section of the handbook. You will return to it later when we study neuroanatomy in more detail. Learning Outcomes 1. Understand the terms rostral and caudal. 2. Understand the difference between the anatomical and functional divisions of the nervous system. 3. Identify the major features of the brain and spinal cord. 4. Understand the terms ventricles, cerebrospinal fluid, and meninges. 5. Describe the location of the Circle of Willis and understand the term ‘anastomosis’. 6. Describe the difference between the somatic and autonomic nervous systems. 7. Describe the divisions of the autonomic nervous system, the broad functions of these divisions and their basic anatomical organisation. 8. Understand the general role of cranial nerves and where they originate from. 9. Describe the general role of spinal nerves and their composition. 10. Appreciate the concept of dermatomes and myotomes. Recommended Videos from Acland’s Video Atlas 4.7.1. Brain: initial overview (44s) 4.7.2. Lining of the cranial cavity (3:02) 4.7.3. The meningeal layers (3:45). 25  Part 1 - Overview of the Nervous System Our nervous system controls everything we do. From the most fundamental functions, such as consciousness and sleep-wake cycles, to the most complex, such as speech and language, judgement, reasoning, personality, emotion and self-awareness. Let us start with what you might already know about the nervous system. The brain, spinal cord and all nerves are part of the nervous system. The skull protects the brain, and the vertebral column protects the spinal cord. The nervous system is composed of neurons (nerve cells) and supporting cells. Neurons have a cell body and projections called axons and dendrites that allow them to communicate with other neurons. Axons are bundled together to form nerves. Our nervous system operates on both a conscious, voluntary level and on an unconscious, involuntary level. Terminology In neuroanatomy, we use three additional anatomical terms that are not really used for other systems (except when discussing embryological development). These are cranial (‘towards the head’), caudal (‘towards the tail’) and rostral (‘towards the face’). Figure 2.1 Anatomical direction and relations of the brain Illustrations by Dr Sam Birks. Reproduced here with permission. 26 Organisation of the Nervous System Anatomically, the nervous system is subdivided into two parts: the central nervous system (CNS) = brain and spinal cord the peripheral nervous system (PNS) = all nervous tissue outside the CNS, primarily nerves: o cranial nerves (arise from the brain) o spinal nerves (arise from the spinal cord) o autonomic nerves Functionally, the nervous system is subdivided into two parts: Somatic nervous system = controls voluntary activities; under conscious control. Autonomic nervous system (ANS) = controls involuntary activities; not under conscious control. We will come back to the somatic and autonomic systems later. Part 2 - The Brain and Spinal Cord The brain is protected by the skull and is anatomically divided into three main parts: the cerebrum the cerebellum the brainstem The Cerebrum The cerebrum is the largest part of the brain. It is composed of masses of neurons and other cells that support them. It is composed of the left and right cerebral hemispheres, which are connected to each other. The surface of the cerebrum is called the cerebral cortex. It contains neuron cell bodies, which gives it a grey appearance, hence the term grey matter. Information is processed in the grey matter. The cerebral cortex is folded. The folds are called gyri (singular: gyrus), and the grooves between the folds are called sulci (singular: sulcus). Deep to the cerebral cortex, within the cerebral hemispheres, we find: o masses of axons. They have a pale appearance in comparison to the cortex and collectively comprise white matter. Information is transmitted through bundles of fibres in the white matter. o collections of cell bodies called nuclei. They look grey in comparison to the surrounding white matter (nucleus = a collection of cell bodies within the CNS). Each cerebral hemisphere is divided anatomically into four lobes, named after the bones of the skull that cover them. They are the frontal, parietal, occipital, and temporal lobes. The large frontal lobe is located anteriorly, and the small occipital lobe is located posteriorly. The parietal and temporal lobes are located between the frontal and occipital lobes. 27  Figure 2.2 The lobes and main sulci of the brain Illustrations by Dr Sam Birks. Reproduced here with permission. The Cerebellum Meaning ‘little brain’, the cerebellum is located inferior to the posterior part of the cerebrum. Like the cerebrum, the cerebellum: is composed of left and right hemispheres that are connected to each other. has a highly folded cortex. contains white matter and nuclei deep to the cortex. The cerebellum is attached to the brainstem. The cerebellum functions in balance, coordination, and movement, but operates beyond our conscious control. We will learn more about the cerebellum in the Neuroanatomy block. The Brainstem The brainstem is composed of three parts: the midbrain, pons, and medulla. It is located inferior to the cerebrum and anterior to the cerebellum (and is attached to both). The brainstem is complex and carries out vital functions. It: relays information between the cerebrum, spinal cord and cerebellum. gives rise to most of the cranial nerves. contains ‘centres’ that regulate breathing and consciousness. 28 The Spinal Cord The spinal cord is continuous with the medulla of the brainstem and is protected by the vertebral column. The spinal cord is shorter than the vertebral column; the cord ends around the level of the first and second lumbar vertebrae (L1 - L2). The neuron cell bodies that are located within the cord constitute the grey matter, which is roughly shaped like an ‘H’ in a transverse cross-section. The grey matter is surrounded by white matter which contains tracts; bundles of axons that connect different parts of the CNS to each other. Tracts in the spinal cord cannot be seen with the naked eye. Thirty-one pairs of spinal nerves are attached to the spinal cord. Each pair of nerves corresponds to a spinal cord segment, and they carry information between the spinal cord (CNS) and periphery (e.g. skin, muscles). We will learn more about the spinal cord in the Neuroanatomy block. The Ventricles and Cerebrospinal Fluid The brain is not completely solid but has cavities inside it called ventricles. The ventricles are continuous with each other and filled with cerebrospinal fluid (CSF), which is produced by specialised cells within the ventricles. CSF leaves the ventricles through small openings and surrounds the brain and spinal cord. It: provides nutrients to the brain. protects the brain by providing a cushion against trauma. prevents delicate nerves and vessels from being compressed between the brain and the internal surface of the skull. There are four interconnected ventricles (with specific names) within the brain and a narrow, CSF-filled channel within the spinal cord. We will learn more about the ventricles and CSF production, circulation, and reabsorption when we study the brain in more detail. Figure 2.3 Lateral (left) and superior (right) views of the ventricular system Image by BodyParts3D. Licenced under CC 2.1. Labels added. 29  The Meninges Three membranes (thin layers of tissue) are located between the brain and spinal cord and the bones that protect them. Collectively, these membranes are the meninges. The three meningeal layers are the dura mater, arachnoid mater, and pia mater. The dura mater lines the inner surface of the skull and vertebral column. It is thick and strong. Extensions of the dura (dural folds) project into the cranial cavity. The arachnoid mater is deep to the dura. It is thin and loosely encloses the brain and spinal cord. The pia mater is deep to the arachnoid. It is adhered to the surface of the brain and spinal cord. It is very thin and cannot be seen with the naked eye. The meninges protect the brain and provide a scaffold for blood vessels. The meninges and the spaces between them are clinically relevant. Figure 2.4 The meningeal layers Labelled meninges image by Dr Sam Birks. Reproduced here with permission. Original design by National Cancer Institute. Labels, colours, and vector adapted. 30 The Blood Supply to the Brain Two pairs of arteries supply the brain: the left and right internal carotid arteries and the left and right vertebral arteries. Both pairs of arteries ascend through the neck to the brain. On the inferior surface of the cerebrum these arteries give rise to branches that form an interconnected ring called the Circle of Willis. The Circle of Willis is an example of an anastomosis - where branches from otherwise separate arteries unite with each other. Such an arrangement allows for the blood supply to an area to be maintained if one of the vessels supplying it becomes blocked. The Circle of Willis gives rise to three cerebral arteries on each side (which supply the cerebral hemispheres), cerebellar arteries (which supply the cerebellum), and arteries that supply the brainstem and spinal cord. Communicating arteries connect the cerebral arteries with each other. Figure 2.5 Inferior view of the brain showing the Circle of Willis Image by OpenStax (2016). Anatomy and Physiology. Licenced under CC 4.0. https://openstax.org/details/books/anatomy-and-physiology. Each artery supplies a particular region, or territory, of the brain, cerebellum, or brainstem. Because different regions of the brain serve different functions, the functional deficits seen when an artery is blocked is dependent on which artery is involved (blockage of an artery leading to death of brain tissue is called a stroke). Veins drain blood from the brain. There are deep veins within the brain and superficial veins on the surface of the brain. There are also large veins enclosed within the dura mater called dural venous sinuses. 31  Part 3 - The Somatic and Autonomic Nervous Systems Functionally, the nervous system is subdivided into the somatic nervous system and the autonomic nervous system (ANS). The somatic nervous system controls voluntary activities. It has a motor and sensory component. The motor component controls the voluntary contraction of skeletal muscle. For example, it controls the movement of our limbs, trunk, and face. The sensory component carries information about peripheral stimuli from the sensory receptors in the body to the CNS, which reaches our conscious perception (e.g. touch, pain, temperature). The autonomic nervous system (ANS) controls involuntary activities such as heart rate, blood pressure, respiration, digestion, and sexual arousal. Like the somatic system, the ANS has a motor and sensory component. The motor component of the ANS controls smooth muscle, glands, and cardiac muscle. It is subdivided into two parts: the sympathetic nervous system = ‘flight and fight’ the parasympathetic nervous system = ‘rest and digest’. The sensory component of the ANS conveys sensory information about the internal environment from the viscera (organs) to the CNS, but it does not reach our conscious perception. An example is blood pressure monitoring. The Sympathetic and Parasympathetic Systems Sympathetic and parasympathetic nerves are motor to smooth muscle, glands, and cardiac muscle. They are also called visceral efferent nerves, as they leave the CNS (‘efferent’ means to travel away from something). They have generally opposite but coordinated actions. The sympathetic system prepares the body for the four F’s: ‘fight, flight, fright and freeze’: Heart rate increases and the bronchi dilate. Peripheral blood vessels constrict and divert blood away from the skin and gut to the skeletal muscles in preparation for activity. The pupils dilate, hair stands on end and sweat glands are stimulated. The parasympathetic system prepares the body for ‘rest and digest’: Heart rate decreases and the bronchi constrict. Glands are stimulated (e.g. salivary glands, digestive secretions) and gut activity (peristalsis) is stimulated. The pupils constrict. The sympathetic and parasympathetic systems share the same basic anatomical arrangement, but with some important differences. In both systems, there are two neurons in the pathway from the CNS to the target organ (effector). 32  The cell bodies of the first neurons are located in the CNS: o sympathetic neuron cell bodies are located in the thoracic and upper lumbar segments of the spinal cord (T1 - L2/3). o parasympathetic neuron cell bodies are located in the brainstem and sacral part of the spinal cord (S2 - S4). Their axons leave the CNS and synapse with a second neuron, whose cell body is located in a ganglion (a collection of cell bodies outside the CNS). For this reason, the first neuron is called a preganglionic or presynaptic neuron, and the second neuron is called a postganglionic or postsynaptic neuron. The postganglionic fibres travel to target organs. Figure 2.6 Organisation of the neurons and autonomic ganglia in the sympathetic and parasympathetic divisions of the autonomic nervous system. Graphic by Dr Ellen Ashton. Reproduced here with permission. Sympathetic ganglia are located closer to the CNS than to target organs, so their preganglionic axons are short, and their postganglionic axons are long. Parasympathetic ganglia are located very close to target organs (or even within them) so their preganglionic axons are long, and their postganglionic axons are short. Although both systems innervate the thoracic, abdominal, and pelvic viscera, the sympathetic system is far more widely distributed than the parasympathetic system. Because sympathetic nerves innervate sweat glands, smooth muscle in blood vessel walls and hair follicles (the arrector pili muscles), they reach every part of the body. 33  Sensory Component of the Autonomic Nervous System The sensory component of the autonomic nervous system carries sensory information from the organs to the CNS, but it does not usually reach our conscious perception. Sensory autonomic fibres are also called visceral afferent fibres, as they bring information back to the CNS. Visceral afferents travel back to the CNS along the paths of the sympathetic and parasympathetic nerves. Sensory autonomic fibres send information about our internal environment back to the CNS (e.g. blood pressure, levels of carbon dioxide in our blood). These sensory inputs elicit reflex (automatic, unconscious) responses, which constantly maintain our internal environment. These fibres also convey information to the CNS about distension, stretch, spasm or ischaemia of the viscera, which may cause pain or discomfort that does reach consciousness. The distribution and course of visceral afferents is clinically important and relevant to the phenomenon of referred pain. We will learn more about referred pain later in the course. Part 4 - Cranial Nerves Cranial nerves arise from the cerebrum and brainstem. There are twelve pairs which are numbered I - XII and individually named. Their names are descriptive and relate to the nerve’s function, course, or structure(s) it supplies. Figure 2.7 Inferior view of the brain and cranial nerves Illustration by Dr Sam Birks. Reproduced here with permission. 34 The brainstem contains collections of cell bodies associated with the cranial nerves called cranial nerve nuclei (singular = nucleus). Cranial nerves leave the CNS and travel into the periphery, so they are part of the peripheral nervous system (except cranial nerves I and II). The 12 cranial nerves mainly serve the head and neck. Cranial nerves exit the skull by passing through holes in the base of the skull called foramina (singular = foramen). The cranial nerves carry different types of nerve fibres. Cranial nerves may be purely sensory, purely motor, or both sensory and motor. Some cranial nerves contain fibres that serve the special senses (vision, hearing, taste and smell). Some cranial nerves also carry parasympathetic fibres. Cranial nerves do not contain sympathetic fibres. Part 5 - Spinal Nerves Thirty-one pairs of spinal nerves are attached to the spinal cord. A pair of spinal nerves corresponds to each segment of the spinal cord. We have: 8 pairs of cervical spinal nerves (C1 - C8) 12 pairs of thoracic spinal nerves (T1 - T12) 5 pairs of lumbar spinal nerves (L1- L5) 5 pairs of sacral spinal nerves (S1 - S5) 1 pair of coccygeal spinal nerves (Co1). (We have eight cervical spinal cord segments and eight pairs of cervical spinal nerves, but only seven cervical vertebrae). The spinal nerves are mixed nerves and carry: somatic motor fibres from the CNS to the body (voluntary control of muscles). somatic sensory fibres from the body to the CNS (conscious sensation). sympathetic (i.e. autonomic motor) fibres from the CNS to the body (to involuntarily activate the ‘fight or flight’ responses around the body). The vertebral column protects the spinal cord. Spinal nerves pass through the gaps formed between adjacent vertebrae called intervertebral foramina. Somatic Motor Fibres The cell bodies of the motor neurons are located in the ventral horn of the spinal cord. The axons leave the cord via the ventral (motor) root of the spinal nerve. These motor fibres stimulate the voluntary contraction of skeletal muscle. Somatic Sensory Fibres The cell bodies of peripheral sensory neurons are located in the dorsal root ganglia (DRG) which are visible with the naked eye as small ‘swellings’ on the dorsal roots. Instead of a single axon, these neurons have two processes, one that projects peripherally into the spinal nerve and one that projects centrally into the dorsal horn of the spinal cord. 35  Sensory information travels from peripheral receptors (e.g. in the skin) towards the DRG via the spinal nerve and then from the DRG to the dorsal horn via the dorsal rootlets. Figure 2.8 Spinal cord segment and spinal nerves Illustration by Dr Sam Birks. Reproduced here with permission. Sympathetic Fibres All 31 pairs of spinal nerves contain sympathetic fibres, which stimulate sweat glands and the contraction of smooth muscle in peripheral blood vessels and the hair follicles as part of the ‘fight or flight’ response. Dermatomes and Myotomes Dermatomes and myotomes are important concepts in anatomy and medicine as they are assessed as part of a nervous system examination. Testing dermatomes and myotomes can give us important information about spinal nerves and their corresponding spinal cord segments. A dermatome is the area of skin innervated by a single spinal nerve. Dermatome maps, like the one on the next page, show us the cutaneous territories of each spinal nerve. For example, sensation over the thumb is served by the C6 spinal nerve. 36  Figure 2.9 The dermatomes of the upper limb Illustration by Dr Sam Birks. Reproduced here with permission. When examining sensation, we assess the patient’s ability to sense touch, pain, temperature, vibration, and joint position sense (proprioception) because these different sensory modalities travel up the spinal cord via different pathways. A myotome is the group of muscles innervated a single spinal nerve. In clinical practice, we assess the myotomes by asking the patient to move the joint associated with that muscle group and nerve. We will come back to dermatomes and myotomes in more detail later in the year. Remember! The IMMS sessions of anatomy introduce you to fundamental anatomical concepts and terminology that you must know to understand the more detailed sessions later in the year. This handbook includes a lot of new content, concepts, and structures, but not in very much detail. We will come back to study much of this content in greater detail in the specific musculoskeletal and neuroanatomy sessions next year. 37