Long thoracic nerve
15. The action of lumbricals is
A. flexion of the metacarpophalangeal joint and extension of the interphalangeal joint B. flexion of the metacarpophalangeal joint and flexion of the interphalangeal joint C. extension of the metacarpophalangeal joint and flexion of the interphalangeal joint D. extension of the metacarpophalangeal joint and extension of the interphalangeal joint Please go to the back of the book for the answers.
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PART 3
The lower limb
12. Introduction to the lower limb 157 13. The front and medial side of the thigh 159 14. The gluteal region 187
15. The popliteal fossa 199 16. The back of the thigh 207 17. The hip joint 211 18. The leg and foot 219
19. The joints of the lower limb 259 20. The nerves of the lower limb 283 21. MCQs for part 3: The lower limb 289
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CHAPTER 12
Introduction to the lower limb
sometimes called the pelvic girdle. Anteriorly, they articulate with each other at the pubic sym- physis. Posteriorly, they articulate with the sides of the sacrum at the two sacro-iliac joints.
The thigh (femur) extends from the hip to the knee. The thigh bone femur articulates at its up- per end with the hip bone to form the hip joint.
At the knee joint, the femur articulates with the tibia and with the patella (kneecap). The proxi- mal extent of the thigh is the gluteal fold posteri- orly, the groove of the groin (inguinal region) anteriorly, the perineum medially, and the surface depression on the side of the hip laterally. The greater trochanter of the femur can be felt through the skin, immediately anterior to the depression.
The ham (poples) is the lower part of the back of the thigh and the back of the knee. The depression on the back of the knee is the popliteal fossa.
The leg (crus) extends from the knee joint to the ankle joint. The term ‘leg’ is never used in anatomi- cal descriptions to refer to the entire lower limb, as it frequently is in colloquial speech. The soft, fleshy part of the back of the leg is the calf (sura).
The bones of the leg are the tibia, or shin bone, and the fibula. They lie side by side, with the slen- der fibula laterally. The tibia and fibula articulate with each other at their upper and lower ends—the superior and inferior tibiofibular joints. Along their length, they are united by the interosseous mem- brane. The lower ends of the tibia and fibula form prominences at the sides of the ankle—the medial and lateral malleoli which are readily felt. The medial and lateral malleoli hold the first bone of the foot (the talus) between them to form the an- kle joint. At the knee joint, the superior surface of the proximal end of the tibia is flattened to form
Introduction
The parts of the lower limb are the hip and but- tock, the thigh, the leg, and the foot.
The hip and buttock together make up what is called the gluteal region. This overlies the side and back of the pelvis, from the waist down to the groove (gluteal fold). It extends from the waist to the buttock inferiorly, and to the depression on the lateral side of the hip. The hip and buttock are not clearly distinguished from each other. The hip (coxa) is the upper part of the region in a lateral view; the buttock (natis) is the rounded bulge be- hind. The natal cleft is the groove between the buttocks. The lower part of the sacrum and coccyx (the end of the backbone) can be felt in the na- tal cleft. The perineum lies in front of the buttocks and continues forwards between the thighs.
The skeleton of the hip and buttock is the hip bone. It consists of three parts—the ilium, ischi- um, and pubis. These three bones fuse together at the acetabulum [Fig. 12.1] where the head of the femur articulates with the hip bone. The ilium is the large upper part. It has a crest at its superior margin which can be felt in the lower margin of the waist. The ischium is the posteroinferior part on which the body rests when sitting. The pubis is the anterior part. It can be felt in the lower part of the anterior abdominal wall. In the midline, it meets its fellow of the opposite side in the pubic symphysis (symphysis = union)—a joint between the right and left pubic bones.
The right and left hip bones, together with the sacrum and coccyx, make up the skeleton of the pelvis [Fig. 12.1]. The two hip bones together are
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Introduction to the lower limb
proximally with the calcaneus and distally with the lateral two metatarsals. The cuneiforms articulate with the navicular proximally and with the medial three metatarsals distally. Between the tarsal bones are the intertarsal joints.
The five metatarsal bones are set side by side.
They are numbered 1 to 5 from the medial side.
The proximal ends—the base of the metatar- sals—articulate with the tarsal bones at the tar- sometatarsal joints, and the base of the medial four metatarsals articulate with each other at the intermetatarsal joints. Each metatarsal has a head at the distal end which articulates with the base of the proximal phalanx of the corresponding toe at the metatarsophalangeal joint. The toes (digits) are numbered from the medial side. The first is the big toe, or hallux; the fifth is the little toe, or digitus minimus. The bones of the toes are the phalanges. The hallux has two phalanges; each of the other toes has three, though the middle and distal phalanges of the little toe may be fused to- gether. The proximal end of the phalanx is its base;
the distal end is its head. The phalanges articulate with each other at the interphalangeal joints.
There are several sesamoid bones in the low- er limb. The largest is the patella. The others are small and inconstant, except for two which are always present on the plantar surface of the meta- tarsophalangeal joint of the big toe.
the condyles which articulate with the femur. The proximal end of the fibula (head) does not take part in the knee joint. It reaches up to the inferolateral surface of the lateral tibial condyle. A large part of the tibia is subcutaneous and easily felt.
The fibula is mainly covered by muscles which are attached to it, so that only its head and distal quarter are easily felt.
The foot extends from the point of the heel to the tips of the toes. Its superior surface is the dorsum; its inferior surface is the sole (planta).
The bones of the foot, from proximal to distal, are the tarsal bones, the metatarsals, and the pha- langes. The tarsal bones are in two rows. The proximal row consists of two large bones—the talus and the calcaneus, with the talus resting on the calcaneus. The calcaneus is the largest bone of the tarsus and forms the skeleton of the heel.
The talus articulates with: (1) the superior surface of the calcaneus; (2) the tibia and fibula to form the ankle joint; and (3) the navicular distally.
The navicular lies between the proximal and distal row of the tarsal bones. The navicular articulates proximally with the talus and distally with the three cuneiforms. The distal row of tarsal bones consists of the cuboid bone laterally, and the three wedge-shaped cuneiform bones (cuneus = a wedge)—the medial, intermediate, and lateral cuneiforms—medially. The cuboid articulates
Sacro-iliac joint Lateral part
of sacrum
Iliac crest
Anterior superior iliac spine
Anterior inferior iliac spine Acetabulum
Ischial tuberosity Obturator foramen Pubic tubercle
Pubic crest Pecten pubis
For coccyx 3rd pelvic
sacral foramen
Superior articular process of sacrum
Body of 1st sacral vertebra
Fig. 12.1 The bony pelvis seen from the front (without the coccyx).
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The ilium is large, flat, slightly curved, and direct- ed upwards. The pubis and ischium lie inferiorly, the pubis more anteromedially, and the ischium more posterolaterally. The obturator foramen is a large aperture in the hip bone between the pubis and ischium. The ilium, ischium, and pubis meet at a narrow, thick central part which has the acetabular fossa for articulation with the head of the femur. The pubis and ischium are fused to- gether by a bar of bone, inferior to the obturator foramen. This is the ischiopubic ramus and
CHAPTER 13
The front and medial side of the thigh
Tubercle of iliac crest Anterior gluteal line
Posterior gluteal line
Posterior superior iliac spine
Posterior inferior iliac spine Greater sciatic notch
Ischial spine Lesser sciatic notch Groove for obturator externus
Ischial tuberosity
Ramus of ischium Acetabular notch
Obturator foramen Inferior pubic ramus
Body of pubis Pubic tubercle Superior pubic ramus Fossa
Lunate surface
Anterior inferior iliac spine Inferior gluteal line
Anterior superior iliac spine
of acetabulum
Fig. 13.1 Right hip bone seen from the lateral side.
Introduction
Before starting to dissect, study the surface anat- omy of the region on yourself or on another liv- ing subject, and relate this to the appropriate dried bones.