Applied Anatomy and Physiology
Joints, movements and muscles
The skeletal system
The skeleton is a shaping framework for the body giving protection for internal organs,
blood cell production site and a mineral store
It provides attachment for the muscular system, acts as levers and pivot points
Types of bones:
Flat bones – protect internal organs and suitable for muscular attachment e.g.,
sternum, ribs, cranium and pelvis
Long bones – levers for movement and sites for blood cell production e.g., femur,
humerus, tibia, radius
Irregular bones – vertebrae which protects the spinal cord
Short bones – carpals and tarsal bear weight effectively
Sesamoid bones – ease joint movement and resist compression e.g., patella
Joints: A place in the body where two or more bones articulate to allow movement to occur.
Categories of joints:
Fixed joint – no movement between bones e.g., cranium or pelvis
Cartilaginous joint – slightly moveable joint, allows some movement e.g., the thoracic
and lumbar sections of the vertebrae
Synovial joint – a freely moveable joint
Synovial joints:
Ball and socket joints – movement in all directions
Hinge – movement along one plane forward and backward
Condyloid – movement along two ‘planes’. Forward, backward and side-to-side
Pivot – movement ‘around’ an axis
Joint name Type of joint Articulating bones
Shoulder Ball and socket Scapula, Humerus
Elbow Hinge Humerus, Radius, Ulna
Wrist Condyloid Radius, Ulna, Carpals
Neck Pivot Vertebrae, Atlas and Axis
Radio-ulnar Pivot Radius, Ulna
Hip Ball and socket Pelvis, Femur
Ankle Hinge Tibia, Fibula, Talus
Knee Hinge Femur, Tibia
Spine Cartilaginous Vertebral discs
Features of a synovial joint:
Common Features Structure Function
Ligament Tough band of connective Support – attaches bone to
tissue. bone
Synovial fluid Lubricating liquid contained Movement – allows friction
within the joint cavity. free movement
Articular cartilage Smooth, tough tissue that Protection – prevents bones
covers the end of bones. rubbing against each other
Joint capsule Fibrous, tough sac with an Protection – prevents impact
inner membrane that to tissue in the joint
surrounds the joint.
,Bursa Fluid filled sac located Support – ensure joint
between tendons and bones functions effectively
to ensure they don’t rub.
Movements (how the joints move away from ‘anatomical position’):
Flexion = Movement forwards from anatomical position
Extension = Movement backwards from anatomical position
Abduction = Movement away from the midline
Adduction = Movement towards the midline
Horizontal flexion = Occurs when a limb is parallel to the ground and the articulating
bone at a joint moves closer to the midline of the body
Horizontal extension = Moves the articulating bone closer to the midline of the body
Rotation = Body part turns about its ‘long axis’. Medial rotation – turns inwards, lateral
– turns outwards.
Pronation = Palms down
Supination = Palms up (in anatomical position).
Dorsiflexion = Point toes up (decreases the joint angle)
Plantarflexion = Point toes down (increases the joint angle)
Lateral flexion = Bending the spine sideways.
Planes of movement
Sagittal plane – Vertical line that separates the left and right sides of the body
Frontal plane – Vertical line that divides the body into anterior (front) and posterior
(back) parts
Transverse plane – Horizontal line that divides body into upper and lower parts.
Joint type Name Plane of movement Movement pattern
Ball and Socket Shoulder, hip Sagittal Flexion & Extension
Frontal Abduction & adduction
Transverse H Flex, H Ext, M Rot, L
Rot
Hinge Elbow, knee, ankle Sagittal Flexion, extension,
dorsiflexion,
plantarflexion
Condyloid Wrist Sagittal Flexion & extension
Frontal Abduction &
Adduction
Pivot Radio-ulna Transverse Supination and
Pronation
,The Muscular System
Movements of the skeleton system are created by the muscles that are attached to bones.
Muscles are attached to bones via tendons which come in two forms;
The origin tendon – connection to a bone that remains stable during muscular
contraction.
The insertion tendon – connection to a bone that moves lots during muscular
contraction.
Antagonistic muscle action
Muscles work as antagonistic pairs. To create movement, muscles have one of three
roles:
▫ Agonist – a muscle that contracts or shortens to create movement. The prime mover.
▫ Antagonist – a muscle that relaxes or lengthens to allow movement.
▫ Fixator – a muscle that stabilises one part of a body while another causes movement. It
works to stabilise the origin.
Muscles will work as an agonist to create the movement or as an antagonist to allow
the movement.
All muscles work as pairs across paired movements
Movement Agonist Antagonist
Wrist Flexion Wrist flexors Wrist extensors
Extension Wrist extensors Wrist flexors
Radio-ulna Pronation Pronator teres Supinator
Supination Supinator Pronator teres
Elbow Flexion Biceps brachii Triceps brachii
Extension Triceps brachii Biceps brachii
Shoulder Flexion Anterior deltoid Posterior deltoid
Extension Posterior deltoid Anterior deltoid
Abduction Middle deltoid Latissimus dorsi
Adduction Latissimus dorsi Middle deltoid
Hor Flexion Pectoralis major Trapezius
Hor Extension Trapezius Pectoralis major
Lat Rotation Teres major Infraspinatus
Med Rotation Infraspinatus Teres major
Hip Flexion Iliopsoas Gluteus maximus
Extension Gluteus maximus Iliopsoas
Abduction Gluteus Medius Adductor group
Adduction Adductor group Gluteus Medius
Lat Rotation Gluteus maximus Gluteus Medius
Med Rotation Gluteus Medius Gluteus maximus
Knee Flexion Biceps femoris Rectus femoris
Extension Rectus femoris Biceps femoris
Ankle Dorsiflexion Tibialis anterior Gastrocnemius
Plantarflexion Gastrocnemius Tibialis anterior
Spine Flexion Rectus Abdominus Erector Spinae
Extension Erector Spinae Rectus Abdominus
Lat flexion Obliques Obliques
Rotation Obliques Obliques
, Muscle Contraction
Isometric contraction – where there is muscle tension but no change in length
Isotonic contraction – where there is muscle tension and a change in length
Concentric – muscle shortens in length
Eccentric – muscle increases in length
Agonist = concentric
Antagonist = eccentric
Fixator = isometric
The motor unit and skeletal muscle contraction
1. Nerve impulse initiated in the motor neuron cell body
2. Nerve impulse conducted down the axon of the motor neuron by a nerve action
potential to the synaptic cleft
3. Neurotransmitter called acetylcholine is secreted into the synaptic cleft to conduct the
nerve impulse across the gap
4. If the electrical charge is above a threshold, the muscle fibre will contract
5. This happens in an ‘all-or-none' fashion
Motor neuron = a nerve cell which conducts a nerve impulse to a group of muscle
fibres
Motor unit = Motor neurons and a group of muscle fibres
Action potential = Positive electrical charge inside the nerve and muscle cells which
conducts the nerve impulse down the neuron and the muscle fibre.
Neurotransmitter = A chemical (acetylcholine) produced and secreted by a neuron
which transmits the nerve impulse across the synaptic cleft to the muscle fibre.
All-or-none law = Depending on whether the stimulus is above a threshold, all muscle
fibres will give a complete contraction or no contraction at all.
Muscle Fibre Types
Smooth muscle – works automatically and with no conscious control I.e., in the
intestines and blood vessels
Cardiac muscle – Muscle of our heart and works autonomously without tiring
