Lecture - General Plan of the Limbs

Question 1

Which body wall segments are in the upper limbs?

Answer 1

C5 to T1

Question 2

Which body wall segments are in the lower limbs?

Answer 2

L2 to S3

Question 3

Which rami control the limbs?

Answer 3

The ventral rami of the corresponding spinal nerves.

NOTE: all musculature is hypaxial

Question 4

For the hands and feet, name a preaxial structure and a postaxial structure.

Answer 4

Preaxial – thumb and big toe

Postaxial – little toe/finger

Question 5

For the upper limbs, what do flexion movements do?

Answer 5

Carry the distal part forwards.

NOTE: all anterior surfaces of the upper limbs are developmentally ventral (except the thumb).

Question 6

For the lower limbs, which surfaces are developmentally ventral and which are dorsal?

Answer 6

At hip: anterior surface is developmentally ventral
Thigh & leg: anterior surface is developmentally dorsal
Foot: Sole (planta) is ventral, and top (dorsum) is dorsal

Question 7

Describe the flexor/extensor muscles in the upper limbs.

Answer 7

• anterior = flexors

- posterior = extensors

Question 8

Describe the flexor/extensor muscles in the lower limbs.

Answer 8

• anterior compartment of THIGH has flexors of hip and extensors of knee
• posterior compartment of THIGH has extensors of hip and flexors of knee
• abductors of the HIP = gluteal region
• adductors of HIP = significant medial compartment along inner thigh
• anterior compartment of (lower) LEG has extensors
• posterior compartment of (lower) LEG has flexors

Question 9

What are the girdle bones?

Answer 9

Upper limbs = ‘pectoral girdle’
Scapula and Clavicle

Lower Limbs = ‘pelvic girdle’
Hip bone:
a)	Ilium
b)	Ischium
c)	Pubis

Question 10

What are the two divisions of the ventral ramus?

Answer 10

Dorsal division: extensors

Ventral division: flexors

Question 11

Describe the brachial plexus.

Answer 11

• 5 nerves, 4 from the neck
• 3 ‘trunks’
• each trunk has a posterior and an anterior division
• trunk divisions = ‘chords’. Anterior cord feeds flexor muscles, posterior cord feeds extensor muscles

Question 12

Describe the lumbar and sacral plexuses.

Answer 12

• simpler pattern (no trunks or chords)
• Part of L4 and all of L5 join sacral nerves
• L2,3, and part of 4 for one plexus
• The rest of L4, L5, S1, S2 and S3 form another plexus

Question 13

Where are epaxial muscles?

Answer 13

Muscles posterior to vertical column are epaxial. True ones are solely for functioning of vertebral column

Question 14

Where is the proximal segment of a limb?

Answer 14

The segment immediate to the girdle i.e. the upper arm/thigh Has a single bone

Question 15

Where is the distal segment of a limb?

Answer 15

Immediately attached to the proximal i.e. forearm or leg. Composed of two bones

Question 16

What are the distal segments of limbs attached to?

Answer 16

Proximal segments
AND
Carpus (wrist)/Tarsus(ankle). These are composed of 7-8 small, complicated bones

Question 17

What moves off the carpus/tarsus?

Answer 17

The metacarpals/tarsals - the five bones of the hand/foot.

Question 18

Where do you find phalanges?

Answer 18

These are the bones of the digits. The big toe and thumb have two, the rest of the digits have three

Question 19

What is a characteristic of developmentally ventral (at the front) surfaces?

Answer 19

They are softer, more pale and have much less hair than developmentally dorsal surfaces.
–Just look at inside of forearm/back of leg, compared to the front of the leg or the forearm