It acts as an intermediary between the trunk and the lower limb. Transmits weight of the body to the limbs and absorbs stress of muscular activity when in an erect position.
What are the spinal levels of the nerve to obturator internus?
L5, S1, S2
Which spinal level(s) innervate obturator internus?
L5, S1
List five mechanisms that increase the efficiency of the human gait, the associated mechanism/anatomy and how that anatomy functions in its energy-saving role
1) lateral pelvic tilting action: Gmed, Gmin & tensor fasciae latae pull laterally on the stance side pelvis, which prevents drop on the swing side pelvis thereby reducing the need for muscular input to maintain the pelvis & CofM on the correct trajectory
2) valgus knee angle: places knees close to midline of body, reducing the tendency to shift laterally and therefore the need to use muscular energy to keep the body over the CofM
3) transverse pelvic tilting action: with the long femur, elongates the stride, which reduces overall energy use during locomotion by increasing the length of each stride taken per unit energy spent
4) knee flexion during stance phase: associated with entire lower limb, prevents over rise in CofM on swing side, thereby keeping the pelvis on the correct, energy efficient trajectory
5) prevention of flexion at the hip at initial contact: G. max and the long hamdstrings (LH of biceps femoris, Semitensinosus, semimembranosus, and HS portion of adductor magnus) pull backward on the pelvis from their insertions during initial contact and loading response of the walking gait so that we don't fall forward, which would necessitate large extension moments from these moments to correct
What are the biomechanical advantages to bipedal locomotion of having a short and broad pelvis?
1) brings the vertebral column closer to the hip joint which increases stability by lowering the center of gravity
2) increases the mechanical advantage of the muscles that pull the trunk onto the supporting leg
List the bones that participate in the hip joint
ilium
ischium
pubis
femor (proximal portion)
Describe the functions of the sacrotuberous and sacrospinous ligaments.
1) they convert the greater and lesser sciatic notches into the greater and lesser sciatic foramina, respectively.
2) they help prevent over anterior rotation of the sacrum relative to the ilium.
True or false: the fibrous joint capsule of the hip joint reflects back onto itself. If false, provide the correct information.
FALSE. The synovial membrane of the hip joint reflects back onto itself.
Which structure(s) converts the inferior aspect of the acetabulum into a foramen?
The transverse acetabular ligament.
Describe the histology, gross structure, and function of the iliofemoral ligament?
Histology: because it is a ligament we know that it is dominated by collagen fibers, but also has a significant component of elastic fibers in it. The fiber orientation is somewhat more random than that of tendons, reflecting the multi-directional forces acting on the structure.
Gross structure: the iliofemoral ligament is located anteriorly, blending with and reinforcing the fibers of the joint capsule. It is a V-shaped ligament with the vertex attaching at the acetabular margin, immediately inferior to the anterior inferior iliac spine and traveling laterally over to the proximal femur. There are two arms to the ligament: the superior arm attaches along the superior aspect of the intertrochanteric line and the inferior arm attaches along the more inferior margin of intertrochanteric line.
Function: all ligaments function to hold structures together, be it bone and bone, bone and cartilage, or cartilage to cartilage. This one has the specific function of reinforcing the joint capsule of the hip. When we are standing erect, the fibers are pulled taught, there by further stabilizing the hip joint and reducing the muscular energy needed to maintain an erect posture.
True or false: both anterior and posterior rami contribute nerve fibers to the lumbosacral plexus. If false, correct the statement.
FALSE: somatic nerve plexuses receive fibers from anterior rami only.
True or False: the lumbar plexus is composed of nerves ONLY from spinal levels L1 to L3. If false, correct the statement.
False: most of the anterior rami of L4 also contributes to the lumbar plexus and in 50% of people, T12 also contributes.
Derive the primary blood supply of the gluteus maximus muscle back to the abdominal aorta through the anterior trunk. Do not include landmarks.
True or false: in general, the superior and inferior gluteal nerves both enter the gluteal region inferior to piriformis. If false, provide the correct information.
FALSE: in general, piriformis divides the greater sciatic notch into a superior and inferior passage, and the nerves take either the superior (superior gluteal nerve) or the inferior (inferior gluteal nerve) path.
What are the two major branches of the sciatic nerve and what are their respective spinal levels?
Common fibular (L4, L5, S1, S2) and tibial (L4, L5, S1, S2, S3) nerves
What are the spinal levels of the genitofemoral nerve?
L1 and L2
Trace the efferent innervation of the obturator internus muscle between the appropriate place in the spinal cord and the target muscle. Do not include landmarks.
anterior grey horn @ L5&S1 / anterior white column @ L5&S1 / anterior root @ L5&S1 / spinal nerves @ L5&S1/ anterior rami converge to form nerve to obturator internus /nerve to obturator internus
Trace the somatic efferent impulse path of obturator internus between the appropriate place in the spinal cord and the target. Indicate the start and the end points, the path of the structure, and include the relevant nerve transitions.
Start point: anterior grey horns @ L5 and S1/ anterior white columns @ L5 and S1/ anterior roots @ L5 and S1/ spinal nerves @ L5 and S1 (exit through their respective intervertebral formaina) / anterior rami @ L5 and S1 / (converge to form the) nerve to obturator internus (this occurs within the pelvis on the deep/anterior surface of piriformis) / obturator internus (passes through the inferior passage of the greater sciatic notch and enters the muscle on the deep surface, end point)
True or false: L4 contributes to the lumbar plexus, the lumbosacral trunk and the sacral plexus
TRUE
At which spinal levels do sympathetic impulses leave the CNS?
T1-L2
True or false (if false, explain your answer): all symphyses are located a) in the postcrania and b) in the midline of the body. Provide the correct information, if false.
FALSE. All are found in the midline of the body, and most are found postcranially. But the mandibular symphysis is found in the cranium.
What contributes to the energetically efficient bipedal mode of locomotion practiced by humans?
3) the valgus angle of the femur, placing the knees in the midline of the body
4) knee flexion during full stance
5) trunk extension during initial contact and loading response
If the lumbosacral trunk has a lesion on it after the convergence of the anterior rami fibers that make up the trunk and before the separation of any discrete nerves, rending it non-functional, would lateral pelvic tilting action still be able to occur? Explain your answer.
Essential information: Possibly, but it will most likely be seriously compromised. GMedius, GMinimus, and Tensor fasciae latae are responsible for lateral pelvic tilting action. They are innervated by spinal contributions from L4, L5 and S1. The lumbosacral trunk is composed of fibers from the inferior half of L4 and L5. So if it was no longer able to conduct impulses, the three muscles responsible for lateral pelvic tilting action would lose contributions from two of their three spinal levels, so the action may be possible, but it is highly likely that it will be seriously compromised.
Potential additional information:Possibly, but it will most likely be seriously compromised. GMedius, GMinimus, and Tensor fasciae latae are responsible for lateral pelvic tilting action. They are innervated by the superior gluteal nerve which receives spinal contributions from L4, L5 and S1, primarily by L4 and L5. The lumbosacral trunk is comprised of fibers from the inferior portion of L4 and L5. So if it was unable to conduct impulses, the three muscles responsible for lateral pelvic tilting action would lose contributions from two of their three spinal levels, though they may still receive impulses from S1, so the action may be possible, but it is highly likely that it will be seriously compromised.
Which gluteal muscles would be affected if the genitofemoral nerve no longer functioned? Explain your answer.
Essential information: None of them would be affected. Genitofemoral is sensory only.
Non-essential: None of them would be affected. Genitofemoral is a) sensory only and b) supplied by L1 and L2, whereas the gluteal muscles are supplied by L4 - S2.
Which gluteal muscles does the tibial branch of the sciatic nerve innervate? Explain your answer.
None of them. The tibial branch of the sciatic nerve innervates muscles in the posterior compartment of the thigh and leg and in the sole of the foot.
If spinal levels L5, S1, and S2 were entirely unable to conduct impulses, would muscles in the gluteal region still be able to laterally rotate the thigh at the hip? Explain your answer (being sure to reference specific relevant muscles, nerves and spinal levels).
Yes, some would. Most of the muscles in the gluteal region that laterally rotate the thigh at the hip are innervated by fibers from spinal levels L5, S1, and/or S2 (Gmax, piriformis, superior & inferior gemelli, quadratus femoris). But the posterior fibers of GMedius and GMinimus are also able to laterally rotate the thigh at the hip and are innervated by L4, L5, and S1. As long as L4 is functional, lateral rotation will most likely still occur.
If the anterior trunk of the internal iliac artery were completely blocked, which gluteal muscles would lose their primary arterial supply?
True or false (if false, provide the correct answer): Elastic cartilage may act as a secondary shock absorber in primary weight bearing joints of the lower limb. If false, explain why it is false.
FALSE, elastic cartilage is found only in the head and neck in structures associated with vibration but it is not involved with lower limb joints.
True or false (if false, provide the correct information): Hyaline cartilage covers the entire interior surface of the articulating bones of the hip joint.
FALSE. The accetabular fossa and the fovea of the head of the femur are not covered in hyaline cartilage.
The following statement(s) is/are true about synovial joints (multiple answers may be true):
A)
Select the option(s) that best describes blood circulation to the tissues:
A) If the primary arterial path is blocked, it is likely that the tissue will be unable to obtain the nutrients necessary for function
B) Anastomoses tend to result in blockages due to the intersection of opposing circulatory pathways
C) The function of blood is to deliver nutrients and oxygen to the tissues of the body
D) Blood is a connective tissue
E) A muscle is likely to have two primary blood sources, but joints have to have more than four
C&D
Describe the function of tensor fascia lata during the walking gait, making sure to include:
A) the phases in which it is active
B) its function during each phase, and
C) other muscles with which they are acting
A) Initial contact, loading response, mid-stance & terminal stance
b) lateral pelvic tilting action
c) GMedius and GMinimus
TRUE or FALSE (if false, provide the correct information): Organs in the mediastinal cavities are covered in parietal peritoneum.
FASLE for two reasons: The parietal layer of serous membranes clings to body walls, whereas the visceral layer adheres to organs. Second, organs in the mediastinum are covered in pericardium.
Describe the effects on the walking gait of the loss of motor impulses from L5, S1, and S2 of the inferior gluteal nerve by providing the following information:
A) The impacted muscles and whether they are rendered compromised or non-functional (compromised meaning that the nerve supply has been adversely impacted, but the muscle most likely still receives impulses from someplace)
B) For each muscle that is completely non-functional, state the associated function, the period during which it occurs, and name viable synergistic muscles for each lost function, if present. If none exist, state as much.
C) For each compromised muscle, state the associated function and name viable synergistic muscles for each compromised function, if present. If none exist, state as much.
A) Gluteus maximus and it is completely non-functional
B) function #1: pull back on pelvis to extend trunk, countering natural flexion moment that occurs during initial contact and loading response. Semitendinosus, semimembranosus, LH of biceps femoris and HS portion of addctor magnus are synergists (we will learn this in the thigh lecture). Function #2: restrain anterior movement of thigh (i.e., pull back on thigh) during terminal swing to prevent over flexion. There are no synergists.
C) There are no relevant compromised muscles
Trace the inferior blood supply of gluteus maximus back to the abdominal aorta, providing primary anatomical landmarks, and describe where the artery enters the muscle.
abdominal aorta (located anterior to the vertebral column, bifurcates at ~L4) / R&L common iliac artery (bifurcates at ~ SI joint) / Internal iliac artery (travels laterally & inferiorly, bifurcates at ~ superior margin of greater sciatic notch) / anterior trunk of internal iliac artery / inferior gluteal artery (passes through the inferior opening of the greater sciatic notch to enter the gluteal region). The artery enters G. max on the deep surface as a series of branches.