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ANATOMY STUDY NOTES
Topics
Work in this topic is divided into three sections:
← Bones and joints
← Muscles and movements
← Movement analysis – which muscles cause which movement at which joint.
ANATOMICAL TERMINOLOGY
When using terminology assume the body is in the anatomical position – standing erect, facing forward, arms by side and palms forward.
|TERM |DEFINITION |EXAMPLE |
|Superior |Toward the head |The head is superior to the trunk |
|Inferior |Toward the feet |The hand is inferior to the elbow |
|Anterior |Front | The nose is on the anterior aspect of the head |
|Posterior |Back |The spine is on the posterior aspect of the back |
|Medial |Toward the midline |The big toe is on the medial aspect of the foot |
|Lateral |Toward the side (outside) |The ears are on the lateral aspect of the head |
|Proximal |Nearer the trunk |The shoulder is at the proximal end of the humerus |
|Distal |Further from the trunk |The fingers are on the distal aspect of the meta- carpals |
|Prone |Face down |A person about to do a push up is prone |
|Supine |Face up |A person about to do a sit up is supine |
|Deep |When a muscle is beneath another |The gluteus minimus is a deep muscle of the hip. |
|Superficial |When a muscle is nearer the skin with respect to |The gluteus maximus is a superficial muscle of the hip. |
| |another | |
BONES AND JOINTS
There are 5 core functions of bone.
1. Movement: Muscles attach to bones. When the muscle contracts it pulls on the bone,
causing movement at the joint.
2. Protection: Some bones surround vital organs or weak points and act as a shield.
Examples include the cranium, ribs, and patella
3. Support: Bones provide us with our structure. They take pressure off our organs and
hold us up.
4. Blood Supply: Long bones of the body make red blood cells in the marrow.
5. Storage: Many of the minerals needed by the body to help it to function are stored in
the bones. Examples are calcium and potassium.
Bones can be classified by their shape. Usually bones of a similar shape have similar function.
1. Long Bones: The long bones of the limbs are obviously used for movement, but they
are also where your blood is produced. Egs – femur, humerus, tibia etc
2. Short Bones: Examples of these include the carpals and tarsals which allow very small
and precise movements.
3. Flat Bones: Bones such as the ribs, scapula, sternum and cranium primary function is
to protect.
4. Irregular Bones These bones tend to be multi-functional eg the bones of the face and
vertebrae protect, provide attachments for muscles and protect nerves and
the spinal cord.
THE SKELETON
There are 206 bones on the human skeleton. The skeleton is divided into two parts:
← The axial skeleton – those bones which form the core of the body. The skull, vertebral column, ribcage and the pelvis.
← The appendicular skeleton – those bones which attach to the axial skeleton. The bones of the shoulder, arms and legs.
There are many bones which have a common name eg collarbone (clavicle), thigh (femur). For assessment purposes you must use the correct name so it is best to start learning them straight away.
[pic]
JOINTS
A joint is defined as a place on the body where two or more bones meet. Just as there are different types of bones there are different types of joint. Joints are classified according to the type of movement that is allowed.
1. Fixed (Fibrous, Immovable) Joints:
No movement allowed. Provides strength and protection. Examples are the sutures in the skull and where the pelvis joins the sacrum.
2. Cartilaginous Joints
Slight amount of movement allowed, so also gives protection, (cartilage acts as a shock absorber), and stability. Examples include where the ribs join to the sternum, and between vertebrae.
3. Synovial Joints
These are freely movable joints and these are the ones we are most interested in because their prime function is to allow movement. Examples include ankle, knee, hip, shoulder etc.
STRUCTURE OF A SYNOVIAL JOINT
The components and their functions are:
The Capsule
A thick sleeve of fibrous tissue which completely surrounds the joint. Its function is to protect the joint by providing stability and by preventing unwanted material to get into the joint.
Cartilage - There are two types of cartilage
1) The ends of the bones are covered by a smooth, white shiny substance called hyaline cartilage. This type of cartilage protects the bones ends by almost eliminating friction as the bones move.
2) Ten percent of synovial joints have a washer-like structure between bone ends called the meniscus. Its purpose is to absorb shock, to stabilize the joint, and to spread synovial fluid.
Synovial Fluid
The joint surface cartilage is well lubricated - more slippery than well-manufactured ball bearings. This is due to the synovial fluid which is manufactured by the synovial membrane (the membrane lining the inside of the capsule)This fluid also provides nutrients for the cartilage and helps to provide a fluid cushion between the bones ends.
Ligaments
Ligaments are strong fibrous bands that join bones ends together. They control the amount of movement allowed at the joint and provide for the primary stability of the joint. Many joints also have internal ligaments that contribute to support, such as the cruciate ligaments of the knee.
THE ANATOMY OF THE KNEE
The knee joint is made up of three bones and a variety of ligaments. The knee is formed by the femur (the thigh bone), the tibia (the shin bone), and the patella (the kneecap). Several muscles and ligaments control the motion of the knee and protect it from damage at the same time. Two ligaments on either side of the knee, called the medial and lateral collateral ligaments, stabilize the knee from side-to-side.
The anterior cruciate ligament (ACL) is one of a pair of ligaments in the centre of the knee joint that form a cross, and this is where the name "cruciate" comes from. There is both an anterior cruciate ligament (ACL) and a posterior cruciate ligament (PCL). Both of these ligaments function to stabilize the knee from front-to-back during normal and athletic activities. The ligaments of the knee make sure that the weight that is transmitted through the knee joint is centred within the joint minimizing the amount of wear and tear on the cartilage inside the knee.
The weight-bearing surfaces of your knees are covered with a layer of cartilage (referred to by doctors as "articular cartilage"). There are also two shock absorbers in your knee on either side of the joint between the cartilage surfaces of the femur and the tibia. These two structures are called the medial meniscus and the lateral meniscus. The menisci are horseshoe-shaped shock absorbers that help to both centre the knee joint during activity and to minimize the amount of stress on the articular cartilage. The combination of the menisci and the surface cartilage in your knee produces a nearly frictionless gliding surface. The knee is an incredible joint. It is strong, flexible, and very tough.
MOVEMENTS AT SYNOVIAL JOINTS
The tables on the following pages provide the anatomical terms that describe how joints move
|MOVEMENT |DEFINITION |EXAMPLES |
| | |1. Trunk Bending forwards |
| |Bending or decreasing the angle between two |(Sideways = lateral |
| |bones |flexion) |
| | |2. Shoulder Moving the arm forward |
|Flexion |[pic] |3. Arm Bending at the elbow |
| | |4. Wrist Bringing the palm toward |
| | |the forearm |
| | |5. Hip Raising the thigh toward |
| | |the trunk |
| | |6. Knee Bending at the knee |
| | |1. Trunk Straightening up |
| |Straightening or increasing the angle between |2. Shoulder Moving the arm backward |
| |two bones |3. Arm Straightening the elbow |
| |[pic] |4. Wrist Taking the palm away from |
|Extension | |the forearm |
| | |5. Hip Moving the leg backward |
| | |6. Knee Straightening the knee |
| | | |
| | |[pic] |
| | |Moving outwards on a star jump |
| | | |
|Abduction |Moving a limb or part of a limb away from the | |
| |midline of the body | |
| | | |
| | |[pic] |
| | |Bringing the limbs back together in a star jump |
| | | |
|Adduction |Moving a limb or part of a limb towards the | |
| |midline of the body | |
| | | |
| | | |
| |A combination of flexion, extension, abduction | |
| |and adduction. |The armstroke |
|Circumduction | |in butterfly |
| |The movement of the limb resembles the shape of| |
| |a cone | |
|MOVEMENT |DEFINITION |EXAMPLES |
| | | |
| | | |
| | |Lateral |
| |Twisting of a limb about its long axis |rotation |
|Rotation | |Medial |
| | |rotation |
| | | |
| | | |
| | | |
| |Movement of the hand into a palm-up position |[pic] |
|Supination |Supination = face down |Turning a card over |
| | |Turning a page in a book |
| | | |
| | |[pic] |
| |Movement of the hand into a palm-down position |Turning a card face down |
|Pronation |Prone = face down |Closing a book |
| | | |
| | |[pic] |
| |Movement of the sole of the foot inward |“A” is inversion |
|Inversion | | |
| | | |
| | |[pic] |
| |Movement of the sole of the foot outward |“B” is eversion |
|Eversion | | |
| | | |
| | | |
| |Movement of the top of the foot upward, closer | |
|Dorsiflexion |to the shin | |
| | | |
| | | |
| | |“B” is dorsiflexion |
| | | |
| | | |
| |Movement of the top of the foot downward. | |
|Plantarflexion | | |
| | | |
| | | |
| | |“A” is plantarflexion |
THE MUSCULAR SYSTEM
Muscles produce movement by pulling the bones in different directions.
All muscles are attached to bone ends by strong tendons. The end of the muscle that is relatively fixed is called the origin, while the end that moves the most is the insertion. The main body of the muscle is called the belly.
When the muscle contracts the origin and insertion are drawn together so that the muscle shortens. The bones attached to the muscle are pulled in the direction of the shortening. This produces movement.
Example: The biceps attaches at the origin to the scapula and inserts to the radius. When the biceps contracts it pulls on the radius, and so the arm flexes at the elbow joint.
Reciprocal Inhibition
Skeletal muscles usually work in pairs. The muscle that causes movement is the agonist. As the agonist contracts, the other muscle in the pair relaxes and lengthens. This muscle is the antagonist.
Examples of an agonist and an antagonist are the triceps and the biceps. For instance, when your elbow extends, the triceps contracts (origin at the scapula and the humerus, and insertion at the ulna). At the same time, the biceps relaxes. The triceps is the agonist and the biceps is the antagonist. For the triceps to cause extension, the biceps must not contract and cause flexion. This process where the agonist contracts and the antagonist relaxes is called reciprocal inhibition.
To control speed of movement the opposing muscles can and do work together - its not a case of one muscle working and the other being completely relaxed. Especially in hard out exercise the antagonist will often begin contracting to help slow down the speed of the bones to prevent injury.
Biceps (agonist) contracts
Biceps (antagonist) relaxes
Triceps (agonist) contracts
Prime Movers
It is very unusual to have only one muscle responsible for causing a movement. Usually other muscles will assist the major muscle in its function.
Gastrocnemius is the major muscle causing planter flexion but it is assisted by soleus.
The most important muscle causing a movement is called the Prime Mover.
Synergists
Synergists are muscles that assist prime movers in producing movement.
Ilio-psoas is the prime mover for hip flexion, and quadriceps is a synergist.
Anterior deltoid is the prime mover for shoulder flexion, and pectoralis is a synergist.
Deltoid
Lattisimus dorsi
Gluteus
medius
Adductor magnus
Semitendonosus Semimembranosus
Gastrocnemius
Soleus
Trapezius
Triceps brachii (long head) Triceps brachii (lateral head)
Brachioradialis
External oblique
Gluteus maximus
Biceps femoris (long head.)
Achilles tendon
Triceps brachii Biceps brachii
Trapezius
Deltoid
Pectoralis major
Latissimus dorsi
Brachioradialis
Extensor carpi radialis longus
Palmaris longus
Quadriceps femoris
Tibialis anterior
External oblique
Rectus abdominus
Iliopsoas
Adductor longus
Gastrocnemius
Soleus
MUSCLE ACTIONS
|JOINT/PART OF THE BODY |MUSCLE |SITE |ACTION |
|Back |Trapezius |Upper back |Elevates and adducts scapula |
| | | |Trunk extension |
| |Erector Spinae |Lower back (medial) | |
|Chest |Pectorals |Upper chest |Flexion, internal rotation and adduction of the |
| | | |shoulder |
|Abdomen |Rectus abdominus |Medial abdomen |Trunk flexion, assists lateral flexion |
| | | |Trunk flexion and rotation |
| |Oblique abdominals |Lateral abdomen | |
|Arm and Shoulder |Deltoid |Above shoulder joint |Flexion, extension, abduction and rotation of |
| | | |the shoulder |
| | | |Adduction of humerus & retraction of scapula |
| |Rhomboids |Upper back |Extension, internal rotation and adduction of |
| | | |the shoulder |
| |Latissimus dorsi |Lower back (extending up to the back |Elbow flexion and supination of the forearm. |
| | |of the armpit) |Elbow flexion |
| | |Anterior upper arm |Elbow extension |
| |Biceps brachii | |Flexion of wrist and fingers |
| | |Beneath the biceps |Extension of wrist and fingers |
| |Brachialis |Posterior upper arm | |
| |Tricep brachii |Anterior forearm | |
| |Wrist flexors |Posterior forearm | |
| |Wrist extensors | | |
|Hip and Leg |Iliopsoas |From mid lumbar vertebrae and pelvis |Hip flexion |
| | |to upper femur | |
| | |Posterior hip | |
| |Gluteals | |Hip extension, external rotation and abduction |
| | |Medial thigh |Hip adduction |
| |Adductors (magnus, longus, and | | |
| |brevis) |Anterior thigh |Knee extension, assists hip flexion |
| |Quadraceps (rectus femoris, vastus | | |
| |lateralis, vastus medialis and vastus| | |
| |intermedius) | | |
| |Hamstrings (biceps femoris, | |Knee flexion, assists hip extension |
| |semimembranosis, semitendonosis) |Posterior thigh | |
| |Tibialis anterior | | |
| |Gastrocnemius | |Dorsiflexion and inversion |
| |Soleus | |Plantarflexion |
| | |Anterior lower leg |Plantarflexion |
| | |Posterior lower leg | |
| | |Beneath gastrocnemius | |
-----------------------
Triceps (antagonist) relaxes
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