Lecture 11 - SQ Flashcards
- What are the functions and nerve supply of the gluteal muscles?
1) Superficial: gluteus maximus, a strong extensor of the thigh, is innervated by the inferior
gluteal nerve. Gluteus medius and gluteus minimus, strong abductors of the thigh, are
innervated by the superior gluteal nerve.
Deep: Lateral rotators of the thigh. Collectively these muscles are innervated by motor nerves
which arise from the sacral plexus.
- What is the role of gluteus medius and minimus muscles on the stance side when standing on
a single, weight-bearing lower limb, or during the stance phase of walking?
2) When standing on a single, weight-bearing lower limb, the gluteus medius and minimus
muscles, on the stance side, contract isometrically to prevent the unsupported side from
dropping. During walking, these muscles serve the same purpose
- What is the clinical importance of the arterial blood supply to the head and neck of the femur?
3) The head of the femur is live tissue which needs an adequate blood supply. A fractured femur
(commonly, but inaccurately, called a “broken hip”) can lead to aseptic necrosis of the
femoral head. This often leads to loss of mobility and wheelchair dependence in the
elderly.
- What are the relationships of the femoral, obturator and sciatic nerves in the pelvis? Where
do these nerves exit the pelvis?
4) The femoral, obturator and sciatic nerves all arise from the lumbosacral plexus. The femoral
nerve arises from the posterior divisions of the ventral rami of L2, 3, 4 and descends
along the iliac fossa and crosses the hip joint anteriorly. The obturator nerve arises from
the anterior divisions of the ventral rami of L2, 3, 4 and descends through the obturator
foramen. The sciatic nerve arises from the ventral rami of L4, 5, S1, 2, 3 and descends
through the greater sciatic foramen. It crosses the hip joint posteriorly.
- List the attachments, nerve supply and primary functions of the hamstring muscles.
5) The hamstring muscles are composed of the biceps femoris (long and short heads), the
semitendinosus and the semimembranosus. They take their attachments primarily from
the ischial tuberosity superiorly and the tibia or fibula distally. They receive their
innervation from the medial or tibial component of the sciatic nerve, except for the short
head of the biceps femoris, which receives its innervation from the lateral or common
peroneal component of the sciatic nerve. These muscles act across both the hip (except
the short head of the biceps femoris) and knee joints; they serve to flex the knee and
extend the hip. The most posterior portion of the adductor magnus also receives tibial
nerve innervation and assists in hip extension.
- What are the boundaries and contents of the popliteal fossa?
6) The popliteal fossa is a diamond-shaped area formed superiorly by the semimembranosus and
biceps femoris, and inferiorly by the medial and lateral heads of the gastrocnemius. The
major contents of the popliteal fossa are: tibial and common peroneal nerves, popliteal
vein, popliteal artery (the extension of the femoral artery), the small saphenous vein, the
sural nerve, fat, and lymph nodes
- What are the relationships of the tibial and common peroneal nerves within the popliteal
fossa?
7) The sciatic nerve normally splits into its tibial and common peroneal components above the
popliteal fossa. The tibial nerve descends through the centre of popliteal fossa while the
common peroneal nerve descends along the outer lateral side.
- What muscles abduct the thigh? What muscles extend the thigh? What muscles laterally
rotate the thigh?
8) ABDUCTION: gluteus medius, gluteus minimus and sartorius.
EXTENSION: gluteus maximus, biceps (long head), semitendinosus, semimembranosus and
adductor magnus.
LATERAL ROTATION: the short lateral rotators such as the piriformis and its companion
muscles, the gluteus maximus and sartorius can all assist in lateral rotation.
