Download Biceps femoris

ANATOMY & PHYSIOLOGY
CHAPTER 10
THE MUSCULAR SYSTEM
1
Skeletal Muscles Work Together
• Since muscles can only contract and shorten, to produce
opposing motions it takes at least two different muscles.
• Muscle classifications:
• Agonist: muscle that causes an action
• Antagonist: a muscle working in opposition to agonist
• Example: the biceps brachii is the agonist when flexing
the elbow to lift weights, but is the antagonist when the
triceps brachii is extending the elbow to move a
bowling ball back to prepare to bowl
• Synergists: muscles that work together to cause a
movement
2
Information Revealed By the Names of
Skeletal Muscles
• The naming of muscles usually follows one of 7 criteria:
– Location of the muscle – frontalis, temporalis
– Relative size of the muscle – maximus, minimus
– Shape of the muscle – deltoid, trapezius, rhomboid
– Direction of muscle fibers – rectus, oblique, transversus
– Location of attachments – sternocleidomastoid
– Number of origins – biceps, triceps, quadriceps
– Action of the muscle – adductor, flexor
3
Connective Tissue Components
Muscle Fibers are covered by tissues
• Epimysium : Coarse sheath of CT
covering the whole muscle
• Perimysium : Middle layer covering
fascicles (groups of skeletal muscle fibers)
• Endomysium : individual muscle fibers
covered by this delicate CT
These are all continuous with the fibers that connect
muscle to bone
4
Arrangement of Fascicles
• The fascicles of muscles can be
arranged in a variety of ways – the
most common are:
1. Parallel - fascicles are parallel to the
long axis of the muscle.
– Some of these are also classified
as fusiform muscles.
2. Pennate - the fascicles are short and
attach to a central tendon
– Can be unipennate, bipennate or
multipennate
3. Convergent - muscle has a broad
origin but the fascicles converge to
one tendon.
– May be multipennate.
4. Circular - muscle has the fascicles
arranged in concentric circles.
5
Lever Systems
• Lever systems help move a load more
efficiently or with greater speed.
• Quickly show lever types next
6
Types of Lever Systems:
First Class
7
Types of Lever Systems:
Second Class
8
Types of Lever Systems:
Third Class
9
Origin and Insertion
• Origin is known as:
• Insertion is known as:
• Bring these two defined tomorrow to class.
10
Major Skeletal Muscles, Anterior View
Print on full page for use as reference
11
Major Skeletal Muscles, Posterior View
Print on full page for use as reference
12
For dissection labs
• Wear closed toed shoes
• Bring your own gloves
13
Muscles of the Scalp and Face
• Epicranius consists of:
– frontalis (or frontal belly of epicranius)
– occipitalis (or occipital belly of epicranius)
– These two muscles pull the scalp forward and backward
• Various muscles are involved in opening and closing the eyes
and mouth, and smiling
– Ex: orbicularis oculi, orbicularis oris, zygomaticus, etc.
• Usually insert in skin (rather than bone), and adjacent
muscles often fuse
• There are multiple muscles involved in mastication (chewing)
– Prime movers – temporalis and masseter
– Synergists – buccinator and orbicularis oris
14
Muscles of the Face
15
Muscles of Mastication
16
Muscles of the Neck: Head Movements
• Sternocleidomastoid muscles flex the head/neck if they are
both contracted or rotate the head if only one is contracted
• The trapezius muscle works with the deeper splenius
muscles to extend and hyperextend the head/neck
17
Muscles of the Deep Back:
Trunk Movements
Erector spinae is the prime
mover of back extension
Erector spinae muscles
consist of three columns
on each side of the
vertebrae
(iliocostalis, longissimus,
and spinalis)
Lateral bending of the back
is accomplished by
unilateral contraction of
these muscles
18
Muscles of Respiration: Inspiration
• Function of deep thoracic
muscles is to promote
movement for breathing
• External intercostals – more
superficial layer that lifts the rib
cage and increases thoracic
volume to allow inspiration
• Diaphragm – most important
muscle in inspiration
19
Muscles of Respiration: Expiration
• Internal intercostals – deeper layer
that aids in forced expiration
20
Muscles of the Abdominal Wall
•
•
•
•
The abdominal wall is composed of 4 paired muscles
1. external obliques
2. internal obliques
3. rectus abdominis
4. transversus abdominis
Their fascicles run at right and oblique angles to one
another, giving the abdominal wall added strength
They are involved with lateral flexion & rotation of the trunk
They help promote urination, defecation, childbirth,
vomiting, coughing, and screaming (and laughing)
21
Muscles of the Abdominal Wall
22
Muscles of the Abdominal Wall
23
Muscles of Pelvic Floor and Perineum
• Pelvic diaphragm: Funnel-shaped, supports the pelvic
viscera. Pierced by anal canal, urethra &, in female, vagina.
• Perineum: diamond-shaped area inferior to pelvic
diaphragm. Anterior half of diamond is urogenital triangle;
posterior half is anal triangle
24
Shoulder Muscles Found on Thorax
• Some of the muscles that control the shoulder (humerus
or scapula) are found on the thorax
– Anterior Thorax:
• pectoralis major,
• pectoralis minor, and
• serratus anterior
– Posterior Thorax:
• latissimus dorsi,
• trapezius,
• levator scapulae, and
• rhomboids
25
Shoulder Muscles on Thorax, Anterior View
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Shoulder Muscles on Thorax, Posterior View
27
Muscles Inserting On and
Moving the Humerus
– Flexion at shoulder (humerus moves anteriorly)
• Pectoralis major
• Anterior fibers of deltoid
– Abduction at shoulder (humerus moves laterally)
• Lateral fibers of deltoid
– Extention at shoulder (humerus moves posteriorly)
• Latissimus dorsi
• Posterior fibers of deltoid
– Stability and rotation at the shoulder (4 rotator cuff muscles)
• Supraspinatus
• Infraspinatus
• Teres minor
28
• Subscapularis
Muscles Inserting on Humerus, Ant. View
29
Muscles Inserting on Humerus, Posterior View
30
Rotator Cuff, Anterior View)
31
Muscles Moving the Antebrachium
• Elbow flexion
– Biceps brachii and
– Brachialis
• Elbow extension
– Triceps brachii
32
Muscles Moving the Antebrachium
33
Muscles Moving the Antebrachium:
Transverse Section
• This transverse section
shows the flexors in the
anterior compartment
and the extensors in the
posterior compartment
34
Movements at the Hip Joint
• Flexion of the Hip (femur moves anteriorly)
• Anterior compartment muscles
– Rectus femoris, tensor fascia latae and iliopsoas
• Extension of the hip (femur moves posteriorly)
• Posterior compartment muscles
– Gluteus maximus and
– 3 Hamstring muscles
» Biceps femoris, Semitendinosus, Semimebranosus
• Adduction of the hip (femur moves toward midline)
• Medial compartment muscles
– Adductors (5 of them)
• Abduction and Rotation of the Hip
– Gluteus medius, gluteus minimus, and sartorius
35
Movements at the Knee Joint:
Some of the Same Muscles (+hip)
• Extension of the knee (tibia and fibula move anteriorly)
– The Quadriceps:
•
•
•
•
Rectus femoris+hip
Vastus lateralis
Vastus medialis
Vastus intermedialis (deep to rectus femoris)
• Flexion of the knee (tibia and fibula move posteriorly):
– The Hamstrings:
• Biceps femoris+hip
• Semitendinosus+hip
• Semimembranosus+hip
• Because the knee is “backwards” compared to the hip and most
other joints, a muscle that flexes the hip would extend the knee.
• And a muscle that extends the hip, would flex the knee.
36
Movements at the Hip:
Flexors, Adductors and Rotators
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Movements at the Hip: Extensors
38
Movements at the Knee: Extensors
39
Movements at the Knee: Flexors
40
Muscles Moving the Hip and Knee:
Transverse Section
41
Movements at the Ankle
– Plantar Flexion (toes point downward)
• Posterior compartment muscles
– Gastocnemius
– Soleus
– Dorsiflexion (toes point upward)
• Anterior compartment muscles
– Tibialis anterior
42
Movement at the Ankle: Plantar Flexors
43
Movement at the Ankle: Dorsiflexors
• Muscles of the anterior
compartment are the
primary toe extensors
and ankle dorsiflexors
• They include the tibialis
anterior
44
Practice Questions
45
A muscle that assists the muscle primarily
responsible for a given action is a(n)
A. Antagonist
B. Synergist
C. Primary antagonist
D. Levator
E. Originator
46
A muscle that is inserted on the mandible is
probably involved in
A. Frowning
B. Kissing
C. Wrinkling the forehead
D. Chewing
E. Blowing
47
Muscles ending in the suffix "-costal" would
be associated with the
A. neck.
B. head.
C. groin.
D. abdomen.
E. ribs.
48
Muscles with fibers that run straight or
parallel to the long axis of the body are
called
A. Obliques
B. Rectus
C. Lateralis
D. Transversus
E. Medialis
49
The attachment site of the muscle tendon to
the more movable bone is called the
A. Proximal end
B. Insertion
C. Distal end
D. Origin
E. Belly
50
The names of the muscles can indicate all of
the following EXCEPT
A. The region of the body where the muscle
is located
B. Action of the muscle
C. Fat content of the muscle
D. The direction of the muscle relative to the
long axis of the body
E. Structural characteristics of the muscle
51
Muscles that act as sphincters to close
openings are circular muscles.
True
False
52
The deltoid muscle is named for its location.
True
False
53
Specific muscle questions
54
The muscle that extends the forearm while
doing push-ups is the
A. Biceps
B. Pectoralis
C. Deltoid
D. Brachialis
E. Triceps
55
The muscular wall of the abdomen is
composed of
A. glossal muscles.
B. oblique and rectus muscles.
C. spinal erector muscles.
D. pectoralis muscles.
E. muscles of mastication.
56
The major abductor muscle of the upper arm
is the
A. subscapularis.
B. deltoid.
C. coracobrachialis.
D. teres major.
E. supraspinatus.
57
Which of the following muscles is NOT a
muscle of the hamstring group?
A. Semimembranosus
B. Biceps femoris
C. Semitendinosus
D. Quadriceps femoris
58
The muscle that inserts on the acromion and
scapular spine is the trapezius.
True
False
59
The semimembranosus muscle belongs to
the group known as the "hamstrings."
True
False
60