Lower Limb - Anatomy, Biomechanics, Neural Control of Standing Flashcards
What are the major bone of the trunk connected to the legs?
Ilium (hip Bone)
Pubis
What are the major bones in the legs?
femur (thigh)
Patella (knee cap)
Tibia/Fibula (Lower Leg)
What are the major bones in the foot?
tarsals (ankle bones - 7)
metatarsals (5)
Phalanges (in toes - 14)
What are the bones of the lower limb?
Where does the Sacral Plexus arise from?
vertebrae L4-S4
Where do the Obturator and Femoral nerves arise from
Vertebrae L2-L4
What are the main nerves that are involved in the nervous Innervation of the Leg
Femoral Nerve L1-L4
Sciatic Nerve L5-S3
Common Peroneal Nerve
Tibial Nerve
What are the main groups of muscles that move the Thigh?
Gluteal group
Lateral Rotator group
Adductor group
Iliopsoas group
What are the Gluteal Muscles and their nerves?
Gluteus Maximus - inferior Gluteal Nerve
Gluteus Medius - Superior Gluteal Nerve
Glutes Minimus - Superior Gluteal Nerve
tensor Fasciate Latae - Superior Gluteal Nerve
What are the muscles in the Lateral Rotator Group and their nerves?
Obturator - Branch of Sciatic Plexus
Piriformis - Branch of Sciatic Plexus
Gemelles - branches of Sciatic Plexus
Quadratus Femoris - Branch of Sciatic Plexus
What are the muscles and their nerves in the Adductor group?
Adductor Longus - Obturator
Adductor Magnus - Tibial Portion of Sciatic
Adductor Brevis - Obturator
Pectineus - Femoral
Gracilis - Obturator
What are the muscles and their nerves of the Iliopsoas group?
Iliacus - femoral
Psoas - femoral
What are the flexors of the Knee?
Biceps Femoris - sciatic tibial portion (long head) and Common peroneal of Sciatic ( short head)
Semimbranosus - Sciatic Tibial portion
Semitendinosus - Sciatic Tibial portion
Sartorius - Femoral
Poplitius - tibial nerve
What are the extensors of the Knee
Quadriceps
- Rectus Femoris
- Vastus Lateralis
- Vastus Intermedius
- Vastus Medialis
Nerve: Femoral
What are the flexors of the ankle?
Tibialis Anterior - Deep Peroneal
What are the Extensors of the Ankle
Gastronemius (medial and lateral) - Tibial
Soleus - Tibial
Plantaris - Tibial
Tibialis Posterior - Tibial
Peroneus (Fibularis) brevis - Superficial peroneal
peroneus (Fibularis) longus - Superficial Peroneal
What are the flexors of the Toes?
Flexor Digitorum Longus - Tibial
Flexor hallucis Longus - Tibial
What are the Extensors at the Toes
Extensor Digitorum Longus - Deep peroneal
Extensor hallucis Longus - Deep peroneal
What is needed to maintain an upright position in Humans?
Centre of mass of the body must remain within the confines of the base of support
What is the base of support in humans?
The area underneath and between the feet or the feet and cane/crutch
What Mechanical principles Affect Stability?
- Ability of the body to maintain stability against disturbing external forces is proportional to the area of the base of support
- Stability is directedly related to horizontal distance of the center of mass from the edge of the base of support
- Stability is inversely related to the height of the Centre of mass above the base of support
- stability is proportional to the weight of the body
What is the centre of pressure?
the location of the vertical ground reaction force which is equal and opposite to a weighted average of the locations of all downward acting forces (weight of the body and the inertial effect of body movement)
Why does the location of the Center of pressure changes?
Center of pressure location changes according to CofM movement and distribution of muscle forces required to control or produce that movement
Why are humans generally less stable than Quadripeds?
2/3rd of the mass of the body is located at 2/3rds of the body height above the ground and this makes up more unstable
What does the inverted pendulum model tell us for sway angle of more than 8 degrees?
The model predicts that the difference between the CofP and CofM is proportional to the horizontal acceleration of the CofM
Formula for the inverted pendulum model
CoP – CoM = -Ix/Wd = -Kx
I = Moment of inertia of the total
body about the ankle in the direction
of interest
x = Horizontal acceleration of the
CoM in the direction of interest
d = Vertical distance from the ankle
joints to the CoM
W = Total body weigh above the
ankle joints
What are the afferent Systems involved in balance stability?
visual
vestibular
proprioceptive
What pathways make of the medial system?
Reticulo-spinal
vestibulo-spinal
What is the purpose of the medial system?
This system is involved in controlling posture
What are the two parts of the Reticulospinal Tract?
Medial
- arises in Pons
- responsible for extensor tone (decerebrate Rigidity)
Lateral
- arises in Medulla
- more involved in muscle movement
What is Decerebrate Rigidity
Decerebrate rigidity is a condition that occurs when there is damage to the brain, specifically to certain areas that control movement and coordination. This damage leads to increased muscle stiffness and a specific posture where the limbs are extended and rigid. It’s a neurological response indicating a lack of normal inhibitory control over muscle tone.
What is Inhibitory Descending Drive
The brain has a system that sends signals (or “drive”) to control and inhibit certain activities in the spinal cord. This control is important for maintaining balanced and coordinated movements.
What is Reticular Formation
The reticular formation is a part of the brainstem that plays a crucial role in regulating various bodily functions, including consciousness, arousal, and motor control.
What are Descending Noradrenergic and Serotonergic Neuromodulatory Axonal Projections
refers to nerve pathways that carry signals using neurotransmitters like noradrenaline (noradrenergic) and serotonin (serotonergic). These pathways start in the brain (from the nuclei) and travel down (descending) to the spinal cord. They act as modulators, influencing and adjusting the activity of other nerve cells in the spinal cord.
What are Excitatory Neuromodulatory Axonal Projections
The signals carried by these pathways are “excitatory,” meaning they increase the activity of the nerve cells they interact with. In the context of motor control, this increased activity can enhance the transmission of signals that lead to muscle contractions and movement.
What is the difference between Decerebrate and Decorticate Postures?
Decerebrate posture result from damage to the upper brainstem. The arms are adducted and extended, with the wrist pronated and the fingers flexed. the legs are stiffly extended with plantar flexion of the feet
Decorticate posture results from damage to one of both corticospinal tracts. the arms are adducted and flexed, with the wrist and gingers flexed on the chest. the legs are stiffly extended and internally rotated, with plantar flexion of the fee
What are the components of the Vestibulospinal pathway
Vestibular Apparatus (Inner Ear)
is comprised on two Otoliths
(gravity sensing) and three
semi-circular canals (rotational
acceleration sensing)
What is the purpose of the parts of the vestibulospinal pathway components
lateral tract - involved in stabilization of body
medial tract - involved in stabilization of head
What is the vestibulocercical Reflex
-Involved in stabilization of head on body. Uses Medial Vestibulospinal pathway.
- When the head rotates or tilts in one direction, contract neck muscles to oppose
the motion.
- Also, biomechanical components of the head have a characteristic resonance frequency of 2-3 Hz which oscillation would likely occur and this reflex will help dampen
What is the vestibulospinal Reflex?
- Involved in stabilizing body.
Uses Lateral Vestibulospinal pathway. - When body rotates or tilts in
one direction, contract ipsilateral extensor
muscles to counteract.
Types of Strategies for Postural Control
- Sensory strategies of how the three systems (visual, vestibular
and proprioceptive) interact and are organized for controlling posture.
Enviromental conditions can have large effects on type of postural
strategies used. - Sensorimotor strategies reflect how the sensory and motor
systems combine to produce a co-ordinated postural response. - Attentional strategies determine the degree of attention given
to a postural task while performing other tasks simultaneously.
Can be modified depending on the degree of anticipation of upcoming
disturbances, and on previous postural conditions (postural set)
How does the lost of a sensory system affect postural Strategy choice?
Vestibular Loss - tend to rely solely on ankle strategy
People with Distal Neuropathies (loss of sensation from proprioceptors) - tend to rely on hip strategy
Different sensory inputs can weight the type of postural strategy chose
