Slide 1

Cartilage & muscles & jointsDr. Sabreen MahmoudLecturer of human anatomy

O B J E C T I V E SThis lecture introduces some of the basic structures that compose the body, such as cartilage, fascia, muscles, ligaments and joints.

Cartilagehard connective tissue. devoid of nerves & B.V & lymphatics. It consists of = chondrocytes + matrix.

resists pressure and friction. high capacity of growth. Hyaline cartilage is covered by perichondrium.

Nutrition of cartilage:cartilage is avascular gets its nutrients by diffusion from perichondrium.

Types of cartilage:

1) Hyaline cartilage: translucent & glossy. present in the articular cartilage, costal cartilages, trachea, bronchi. replaced by bone in old age, except the articular cartilage. It is incapable of repair when injured.

1) Hyaline cartilage:

2) White fibrocartilage:

rich in collagenous bundles tough. present in : 1 - Intervertebral discs . 2- Symphysis pubis. 3 - Articular discs in synovial Joints no ossification in old age.

3) Yellow elastic fibrocartilage:rich in elastic fibres yellow colour. never replaced by bone in old agepresent in the auricle of the ear, auditory tube.

JOINTSDEFINITION: the meeting place of 2 or more bones. The study of joints = arthrology

Fibrous jointsthe articulating bones are separated by fibrous tissue. no or very limited movement. Examples: 1) Sutures of the cap of the skull. 2) Inferior tibio-fibular joint 3) Gomphosis : it is a joint where a peg is fixed into a socket.

Cartilaginous jointsa disc of cartilage between the articulating bone. 2 types :1) Primary cartilaginous joint.2) Secondary cartilaginous joint.

1) Primary cartilaginous joint.

a temporary plate of hyaline cartilage which disappears in adulthood.represented by the epiphyslal plate of cartilage. called synchondrosls does not allow any movement

2) secondary cartilaginous joint:a disc of white fibrocartilage between the articulating bones. The opposed bony surfaces hyaline cartilage. lie in the median plane of the body. e.g. intervertebral discs & symphysis pubis.

characteristics:a - no fibrous capsule. b - ligaments. c - limited movement.

Synovial jointsa cavity synovial fluid. a fibrous capsule a synovial membrane does not cover the articular surfaces, discs or menisci. synovial fluid.

The synovial fluidpale yellow, viscous fluid resembles egg albumin. contains lymphocytes, macrophages and free synovial cells. for lubrication & nutrition of articular cartilage.

The articular surfaces hyaline cartilage.The articular cartilage is not visible in X-ray films.

Structures inside some joints:

1) Articular disc2) Menisci. 3) Tendons. 4) Ligaments.

N.B.: Any structure inside a joint cavity = intracapsular and extrasynovial.

TYPES OF SYNOVIAL JOINTS:

According to number of bones: 1) Simple joint: = 2 bones (shoulder joint). 2) Compound joint = more than 2 bones (elbow joint). 3) Complex joint: menisci (knee joint)

According to number of axes of movement:

Uni-axial joint: elbow joint. Bi-axial joint: the metacarpo-phalangeal joint MultI-axial joint: shoulder joint.

According to shape of articulating surfaces:

Plane joint: surfaces are flat, and the movements sliding, e.g. intercarpal and intertarsat joints.

2) Pivot joint:central bony pivot surrounded by a ring partly bony & partly ligamentous, e.g. superior radio-ulnar joint.

3) Bicondylar joint :2 convex condyles & 2 concave surfaces, e.g. knee joint.

4) Ellipsoid joint:a convex surface & concave surface, e g. radiocarpal (wrist).

5) Saddle joint:concavoconvex, i.e. the surface is concave in one direction and convex in a direction at right angle to the former direction; e.g. carpo-meacarpal joint of the thumb.

6) Hinge joint:As the hinge of the door, e.g. elbow joint.

7) BaIl-and-socket joint:a globular (rounded) head & a cup-shaped concave surface, e.g. shoulder and hip joints. movements in 3 axes (flexion-extension, adduction-abduction, circumduction and rotation).

Video

FACTORS AFFECTING STABILITY OF JOINTS:

1) Shape of bones. 2) Contraction of muscles. 3) ligaments.

Nerve supply of joints:

Hiltons law: joints are innervated by nerves which supply muscles acting on these joints. The nerves sensory = articular nerves. The synovial membrane is devoid of sensory nerves.

Blood supply of joints:by networks of arteries anastomoses.

MUSCLEMyology = the study of muscles. contractility = capacity of becoming short. 2 types of protein actin and myosin.

Muscle is classified into 3 types:

CARDIAC MUSCLEin myocardium of the heart. transverse striations,does not contract under voluntary control. Innervation : (autonomic) = sympathetic & parasympathetic fibers

Smooth (non-striated) musclein viscera & blood vessels. The muscle cells are not striated = smooth, plain or non-striated.Nerve supply : autonomic fibers = sympathetic & parasympathetic

Skeletal (striated) muscleattached to the skeleton. transverse (or cross) striations = striated. contracts under voluntary control.

Connective tissue sheaths muscle fibers are arranged in bundles.

These bundles have connective tissue sheaths as : 1) Endomysium: individual muscle fiber. 2) Perimysium: whole bundle. 3) Epimysium : whole muscle.

Innervation

I) Motor fibers 2) Sensory fibers to the muscle spindles. Cutting the nerve supply paralysis.

Attachments of skeletal muscles

1) Origin: fixed attachment. 2) Insertion: mobile attachment.

Form of muscles

The range of contraction of a muscle depends on the length of muscle fibersThe muscle fibers are arranged obliquely or parallel with the line of pull.

The line of pullextending between the origin and insertion. Muscles with fibers parallel with the line of pull better contraction.

1) Muscles with fibres arranged parallel with the line of pulla - Quadrilateral thyrohyoid muscle, b - Strap-like sartonus muscle. c - Fusiform lumbrical muscles.

2) Muscles with pennate fibres arranged obliquely to the line of pull

a - Unipennate: flexor pollicis longus. b - Bipennate: rectus femoris. c- Circumpennate: tibialis anteriord - Multipennate: deltoid muscle.

N. B:- Pennate = feather-like

3) Muscles with fibres arranged obllquely to the line of pull but are not pennate

a - triangular temporalis. b - Spiral supinator.c - Cruciate masseter.

4) A muscle with more than one fleshy belly

a - Biceps. b - Triceps. c - Quadriceps. d - digastric 2 bellies attached by an intermediate tendon.

Action of muscles

depends on the length of muscle fibers. 1) Prime movers: initiation of movement brachialis flexion of elbow. triceps extension of elbow.

2) Antagonist:

oppose the action of prime movers. triceps opposes the brachialis.

3) Synergist:eliminate the unwanted movement. Ex : flexion of the fingers by the flexor muscles is associated with flexion of the wrist. To eliminate the unwanted flexion at the wrist, the extensor muscles of the wrist contract = synergists.

4) Fixator (stabilizers):help the prime mover by stabilizing the joint. Ex: muscles around shoulder (muscle cuff) stabilizers.

Video

Tendons

parallel bundles of collagenous fibers. cord-like expanded sheet = apponurosis (muscles of the anterior abdominal wall).

Synovial sheath of tendons:in direct contact with bone. formed of 2 layers + cavity, : 1) Parietal layer = outer layer. 2) Visceral layer = inner layer. 3) Cavity: contains synovial fluid.

Synovial sheaths protect the tendons from injury to facilitate movement. Vincula = A synovial fold between the tendon and the bone blood vessels pass to tendons.

Blood and nerve supply of tendons:

1) supplied by few blood vessels. 2) sensory fibers only.

BURSAE a closed sac of synovial membrane filled with synovial fluid. where skin or tendons move over bony surfaces free movement.

types of bursae:

1) Subcutaneous. 2) Subtendinous. 3) Subfascial. 4) Interligamentous.