Lower Limb: Anatomy, Biomechanics, and Neural Control Flashcards
What are the major bones of the legs?
- Trunk: Illium, Pubis
- Leg: Femur, Patella, Tibia/Fibula
- Foot: Tarsals (7), Metatarsals (5), Phalanges (14)
Where does the nerve supply for the legs come from?
Sacral plexus. Arises from Vertebrae L4-S4.
Obturator and femoral nerves arises from L2-L4
Important Innervation of the leg? (4)
Sciatic Nerve L5-S3
Femoral Nerve L1-L4
Common Peroneal N
Tibial N
Muscles that move the thigh? (4 groups)
- Gluteal Group: gluteus maximus, -medius, and -minimus, and tensor fascia latae
- Lateral Rotator Group: obturator, piriformis, gemelles, quadratus femoris
- Adductor Group: adductor longus, -magnus, and -brevis, and pectineus and gracilis
- Iliopsoas Group: Iliacus, psoas
Muscles that move the lower leg: How many flexors and extensors?
Flexors of knee (5): Biceps femoris, semimembranosus, semitendinosus, sartorius, poplitius
Extensors of knee (4): Rectus femoris, vastus lateralis, vastus intermedius, vastus medialis
Muscles that move the foot: How many flexors and extensors?
Flexors (1): Tibialis Anterior
Extensors (6): Gastrocnemius, Soleus, Plantaris, Tibialis Posterior, Peroneus Brevis, Peroneus Longus
Muscles that move the toes: How many flexors and extensors?
Flexors (2): Flexor Digitorum Longus, Flexor Hallucis Longus
Extensors (2): Extensor Digitorum Longus, Extensor Hallucis Longus
What is the bipedal stance?
Ability to remain in upright stance; ability to maintain CoM within the base of support.
CoM - point representing the mean position of matter in the body
Base of support (BoS)- area underneath and between both feet
Mechanical Principles that affect Stability? (4)
- Ability to maintain stability is proportional to the area of the base of support (BoS)
- Stability is directly related to horizontal distance of the CoM from the edge of BoS
- Stability is inversely related to the height of CoM about BoS
- Stability is proportional to the weight of the body
What is CoP? Related to CoM?
CoP - location of the vertical ground reaction force which is equal and opposite to a weighted average of all downward acting forces
CoP location changes according to CoM movement.
Mechanical Model of Quit Stance
Inverted Pendulum Model. Humans are top heavy (2/3 of Mass located 2/3 body height). used for sway angles <8 degrees.
How does the body move during quiet standing? Why important?
Sways back and forth. More sway higher up in the body.
Movement gives sensors that give proprioception. Forced blood to heart.
What are the 3 afferent systems involved in balance stability?
Visual, Vestibular, Proprioceptive
Describe the neural control of balance from the brain?
Two descending paths from higher centers
Recticulospinal tract has 2 parts: medial (Pons - extensor tone) and lateral (Medulla - muscle movement)
Vestibulospinal: inner ear has 2 Otoliths (gravity sensing) and 3 semi-circular canals (rotational acceleration sensing)
What is decerebrate rigidity?
Decerebration removes inhibitory descending drive to reticular formation
What is the vestibulocervical reflex?
Involved in stabilization of head on body, when head rotates/tilts in one direction, neck muscles contract to oppose the motion; uses medial pathway
What is the vestibulospinal reflex?
Involved in stabilizing body, when body rotates/tilts in one direction, ipsilateral extensor muscles contract to counteract; uses lateral pathway
Strategies for Postural Control
-Sensory strategies of how the three systems interact and are organized for controlling posture.
-Sensorimotor strategies reflect how the sensory and motor systems combine to produce a coordinated postural response
-Attentional strategies determine the degree of attention given to a postural task while performing other simultaneous tasks
How can loss of sensory systems can affect postural strategy choice?
- Vestibular loss - rely solely on ankle strategy
- People with distal neuropathies - rely on hip strategy
