9-1

Selected Joints &Muscular System I:

Architecture

Lecture 9

9-2

Shoulder Joint

Ligaments of the Shoulder Joint• Glenohumeral (3)• Transverse humeral• Coracohumeral• Coracoacromial• Coracoclavicular

Fig. 9.15

Muscles of Shoulder Joint• Rotator cuff (4 muscles)

9-3

Knee Joint• Menisci: Fibrocartilage articular disks• Cruciate ligaments: Anterior cruciate ligament and

posterior cruciate ligament• Collateral ligaments: Fibular and tibial

Fig. 9.19

9-4

Knee Injuries and Disorders

• Football injuries– Damage to

collateral ligaments due to blow

– Torn menisci– Torn cruciate

ligaments

Figure from Clinical View on page 278

9-5

Properties of Muscle

• Contractility– Ability of a muscle to shorten with force

• Excitability– Capacity of muscle to respond to a stimulus

• Extensibility– Muscle can be stretched to its normal resting length and

beyond to a limited degree

• Elasticity– Ability of muscle to recoil to original resting length

after stretched

9-6

General Principles of Muscles• Tendons: Attach muscles to bones

– Aponeurosis: A very broad tendon

• Muscles– Origin or head: Muscle end attached to more stationary of two

bones– Insertion: Muscle end attached to bone with greatest

movement– Belly: Largest portion of the muscle between origin and

insertion– Synergists: Muscles that work together to cause a movement

• Prime mover: Plays major role in accomplishing movement

– Agonist: Muscle causing an action when contracts– Antagonist: A muscle working in opposition to agonist– Fixators: Stabilize joint/s crossed by the prime mover

9-7

Muscle Shapes

Table 10.5

9-8

Muscle Shapes

Table 10.5

9-9

Nomenclature

Fig. 10.14

9-10

Nomenclature

• Example - extensor carpi radialis longus

Fig. 10.14

9-11

Review Question

The muscle name transversus thoracis is derived from a combination of its

(a) Size and function

(b) Orientation and location

(c) Relative length and location

(d) Shape and orientation

(e) Function and shape

9-12

Points to Remember

• Skeletal muscles have many shapes and in each instance contraction of the muscle tissue causes body movements through their attachments to the skeleton or beneath the skin.

• Understanding the meaning of the parts of a muscle name helps one to learn the muscle.

9-13

Questions?