Bio 502, Fall 2016: Hip & Gluteal Region Lecture #3
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Name the bones of the pelvis.
- 1) ischium
- 2) pubis
- 3) ilium
What are the functions of the pelvis?
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.
List five mechanisms that increase the efficiency of the human gait, the associated 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) Elongated stride: associated with transverse pelvic rotation and long femur, 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) Spine extension: 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 of the hip joint
- femor (proximal portion)
Describe the functions of the sacrotuberous and sacrospinous ligaments.
- 1) the convert the greater and lesser sciatic notches into the greater and lesser sciatic foramina, respectively.
- 2) they help prevent over anterior rotation of the ilium relative to the sacrum.
True or false: the fibrous joint capsule of the hip joint reflects back onto itself.
FALSE. The synovial membrane of the hip joint reflects back onto itself.
What structure(s) converts the inferior aspect of the acetabulum into a foramen?
The transverse acetabular ligament.
Where is the iliofemoral ligament found?
Superficial to the joint capsule of the hip, running from the ilium to the proximal femur.
True or false: both anterior and posterior rami contribute nerve fibers to the lumbosacral plexus.
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. Also provide the reason for your answer.
False: most of the anterior rami of L4 also contributes to the lumbar plexus and in 50% of people, T12 also contributes.
Trace the primary blood supply of the gluteus maximus muscle back to the abdominal aorta through the anterior trunk.
GMax/inferior gluteal artery/anterior trunk/internal iliac artery/common iliac artery/abdominal aorta
True or false: in general, the superior and inferior gluteal nerves enter the gluteal region inferior to piriformis.
FALSE: in general, piriformis divides the superior and inferior gluteal nerves.
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 innervation path of the obturator internus muscle back to its spinal levels and indicate the primary level(s)
obturator internus/nerve to obturator internus/L5, S1
S1 is primary
True or false: L4 contributes to the lumbar plexus, the lumbosacral trunk and the sacral plexus
At which spinal levels do sympathetic fibers leave the CNS?
True or false (if false, explain your answer): all symphyses are located a) in the postcrania and b) in the midline of the body.
FALSE. All are found in the midline of the body, but the mandibular symphysis is found in the cranium.
What contributes to the energetically efficient bipedal mode of locomotion practiced by humans?
- 1) lateral pelvic tilting action (AKA coronal pelvic tilt)
- 2) transverse pelvic tilt
- 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 two anterior rami and consequently no longer functioned, would lateral pelvic tilting action still take place? Explain your answer.
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 L4 and L5. So if it no longer functioned the three muscles responsible for lateral pelvic tilting action would lose contributions from their primary 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.
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 L5, S1, and S2 were entirely non-functional would muscles in the gluteal region still be able to laterally rotate the thigh at the hip? Explain your answer.
Yes, they would. Most of the muscles in the gluteal region that laterally rotate the thigh at the hip are innervated by fibers from spinal levels L4, L5, S1, and/or S2 (GMax, piriformis, gemellus inferior, gemellus superior, quadratus femoris and obturator internus). 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 was functional, lateral rotation will most likely still occur, though the overall contraction force will be significantly lower.
If the anterior trunk of the internal iliac artery were completely blocked, which gluteal muscles would lose their primary arterial supply?
Piriformis, gemellus superior, gemellus inferior, & quadratus femoris
True or false (if false, provide the correct answer): Elastic cartilage may act as a secondary shock absorber in primary weight bearing joints.
FALSE, elastic cartilage is found only in the head and neck in structures associated with vibration but it is not involved with joints.
True or false (if false, provide the correct information): Hyaline cartilage covers the entire interior surface 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) Synovial fluid is produced by the synovial membrane
B) The synovial membrane lines the articular surfaces
C) Hyaline cartilage is highly vascularized
D) A and B are true
E) A, B, and C are true
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
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 mediastinum cavities are covered in parietal pericardium
FASLE. The parietal layer of serous membranes clings to body walls. The visceral layer adheres to organs.
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
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
C) For each compromised muscle, state the associated function and name viable synergistic muscles for each compromised function, if present
- 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. The long hamstrings (semitendinosus, semimembranosus, LH of biceps femoris and HS portion of addctor magnus) are synergists. 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 compromised muscles
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