Midterm 1

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Questions and Answers

Which function is NOT attributed to skeletal muscle?

Cognitive processing (correct)

Stability

Physical movement

Heat production

Which property of muscle refers to its ability to respond to a stimulus?

Conductivity

Elasticity

Contractility

Excitability (correct)

How many types of muscle are identified in the skeletal muscle section?

3 (correct)

What does the term 'origin' refer to in muscle attachment?

The location on the stationary bone during contraction Signup and view all the answers

Which of the following best describes the role of fixators?

Muscles that stabilize a bone or muscle's origin Signup and view all the answers

Which criteria is NOT used in naming skeletal muscles?

Direction of nerve impulses Signup and view all the answers

What does adaptability in muscle properties refer to?

Ability to change characteristics in response to stimuli Signup and view all the answers

Which type of muscle is primarily involved in the involuntary movement of internal organs?

Smooth muscle Signup and view all the answers

Which muscle is primarily responsible for the elevation of the mandible?

Masseter Signup and view all the answers

What type of muscle shape is characterized by a feather-like arrangement of fibers?

Multipennate Signup and view all the answers

Which motion occurs in the transverse plane during trunk rotation?

Rotation Signup and view all the answers

In which plane does shoulder elevation and depression occur?

Frontal plane Signup and view all the answers

Which of the following describes the muscle action of abduction?

Moving a limb away from the midline Signup and view all the answers

Which muscle is involved in facial expressions and aids in closing the eyelids?

Orbicularis oculi Signup and view all the answers

Which term describes the movement of the foot turning inward?

Inversion Signup and view all the answers

Which of the following describes a circular muscle shape?

Sphincter Signup and view all the answers

Which muscle is primarily responsible for trunk flexion?

Rectus abdominis Signup and view all the answers

What function does the external abdominal oblique muscle serve?

Contralateral rotation of the waist Signup and view all the answers

Which of the following muscles is part of the intrinsic back muscle group?

Longissimus thoracis Signup and view all the answers

Which muscle is NOT involved in mastication?

Sternocleidomastoid Signup and view all the answers

Which muscle's contraction allows for rotation of the head?

Splenius cervicis Signup and view all the answers

What is the role of the internal abdominal oblique muscle?

Acts as an intermediate layer of abdominal muscles Signup and view all the answers

Which of these muscles is known to support the viscera?

External abdominal oblique Signup and view all the answers

Which muscle is the prime mover during spinal extension?

Spinalis thoracis Signup and view all the answers

Which muscle group is responsible for hip adduction?

Hip adductors Signup and view all the answers

What is the role of the transverse abdominal muscle?

Compresses the abdominal cavity Signup and view all the answers

Which muscle is NOT part of the rotator cuff group?

Trapezius Signup and view all the answers

What is the primary function of the iliopsoas muscle?

Hip flexion Signup and view all the answers

Which of the following muscles is primarily involved in elbow flexion?

Brachialis Signup and view all the answers

The deep muscles of the forearm primarily serve what function?

Finger flexion Signup and view all the answers

Which muscle is located lateral to the medial head of the triceps brachii?

Lateral head Signup and view all the answers

Which of the following muscles is involved in the movement of the shoulder girdle?

Pectoralis major Signup and view all the answers

Which muscles are primarily responsible for hip extension and knee flexion?

Hamstring group Signup and view all the answers

What is the insertion point for the adductor magnus muscle?

Gracilis Signup and view all the answers

Which muscle is part of the superficial layer of the posterior compartment of the lower leg?

Gastrocnemius Signup and view all the answers

Which muscle crosses both the hip and knee joints and is classified as bi-articulate?

Hamstring group Signup and view all the answers

What movement is primarily facilitated by the gastrocnemius muscle?

Plantar flexion Signup and view all the answers

Which structure is associatively linked to the inferior extensor retinacula?

Calcaneus Signup and view all the answers

The tendon of which muscle is located at the medial malleolus?

Flexor hallucis longus Signup and view all the answers

Which of the following muscles functions primarily in the lateral compartment of the lower leg?

Fibularis longus Signup and view all the answers

Study Notes

Muscle Structure and Function

Skeletal muscle accounts for approximately 50% of body weight.
Muscle function includes physical movement, stability, control of openings, heat production, and glycemic control.

Muscle Types

There are three types of muscle tissue: skeletal, smooth, and cardiac.
Skeletal muscle is responsible for voluntary movement.
Smooth muscle lines the walls of organs and blood vessels, responsible for involuntary movements.
Cardiac muscle is found only in the heart, responsible for involuntary heart contractions.

Muscle Properties

Muscles possess five key properties:
- Contractility: Ability to shorten and develop force, measured mechanically.
- Excitability: Ability to respond to a stimulus.
- Conductivity: Ability to transmit signals.
- Elasticity: Ability to elongate (stretch).
- Adaptability: Ability to change characteristics in response to stimuli like training, de-training, or immobilization.

Skeletal Muscle Attachment

Muscle attachment is the point where a muscle connects to bone, allowing for force transmission.
The origin is the fixed attachment point, typically closer to the body's midline.
The insertion is the moveable attachment point, typically further from the midline.
Muscle attachments connect to the fibrous periosteum of the bone, often at bony prominences like tubercles, trochanters, and crests.

Naming Skeletal Muscles

Muscles are named based on several criteria, including:
- Location: Refers to the muscle's body region.
- Shape: Describes the muscle's general form.
- Relative Size: Compares the size of the muscle to others in the region.
- Direction of Fascicles & Fibers: Indicates the muscle fiber orientation.
- Location of Attachments: Identifies the origin and insertion points.
- Number of Origins: Denotes the number of muscle heads.
- Actions: Describes the muscle's primary movement function.

Muscular System

Muscles work together to produce movement:
- Prime Movers (Agonists): Muscles primarily responsible for a specific action.
- Antagonists: Muscles opposing the prime mover's action.
- Synergists: Muscles assisting the prime mover, often stabilizing the joint.
- Fixators: Synergists that immobilize a bone or muscle's origin.

Muscle Mechanics (Shapes)

Muscles exhibit diverse shapes, influencing their power and range of motion:
- Circular: Arranged in a ring, closing openings (e.g., orbicularis oris).
- Convergent: Broad origin, converging towards a single tendon (e.g., pectoralis major).
- Parallel: Fibers run parallel to the long axis (e.g., sartorius).
- Unipennate: Fibers insert on one side of a tendon (e.g., extensor digitorum longus).
- Bipennate: Fibers insert on both sides of a tendon (e.g., rectus femoris).
- Multipennate: Several tendons with fibers inserting at an angle (e.g., deltoid).
- Fusiform: Thick in the middle and tapered at the ends (e.g., biceps brachii).

Muscles and Movement (Sagittal Plane)

Flexion: Decreases the angle between bones (e.g., bending the elbow).
Extension: Increases the angle between bones (e.g., straightening the elbow).
Dorsiflexion: Flexion at the ankle (lifting the toes).
Plantarflexion: Extension at the ankle (pointing the toes).

Muscles and Movement (Frontal Plane)

Abduction: Movement away from the midline.
Adduction: Movement towards the midline.
Elevation: Movement superiorly.
Depression: Movement inferiorly.
Inversion: Lifting the medial edge of the foot.
Eversion: Lifting the lateral edge of the foot.

Muscles and Movement (Transverse Plane)

Rotation: Turning a bone around its longitudinal axis:
- Medial (Internal) Rotation: Rotation towards the midline.
- Lateral (External) Rotation: Rotation away from the midline.

Muscles of the Head

Epicranius: Covers the skull, responsible for raising eyebrows and wrinkling forehead.
Orbicularis Oculi: Circular muscle surrounding the eye, closes the eye.
Orbicularis Oris: Circular muscle surrounding the mouth, closes the lips.
Temporalis: Located on the side of the head, elevates the mandible.
Masseter: Powerful muscle of mastication, elevates the mandible.
Buccinator: Muscle located in the cheek, compresses the cheeks during sucking and chewing.
Sternocleidomastoid: Large neck muscle, flexes the head and rotates the head to the opposite side.
Trapezius: Large muscle covering the upper back, elevates, depresses, and rotates the scapula.
Splenius Capitis: Muscle located in the posterior neck, extends and rotates the head.
Platysma: Superficial neck muscle, depresses the mandible and tenses the skin of the neck.

Muscles of Mastication

Masseter: Powerful muscle of mastication, elevates the mandible.
Temporalis: Elevates the mandible, assists with retraction.
Lateral Pterygoid: Depresses and protrudes the mandible.
Medial Pterygoid: Elevates and protrudes the mandible.

Neck and Vertebral Column

Sternocleidomastoid: Flexes the head, rotates the head to the opposite side, and laterally flexes the neck.
Scalenes: (Anterior, Middle, Posterior) Elevate the first and second ribs, flex the neck, and laterally flex the neck.
Splenius Capitis and Cervicis: Extend and rotate the head and neck.
Deep (Intrinsic) Back Muscles: Control posture, stabilize the vertebral column, and produce fine movements:
- Semispinalis: Extends, rotates, and laterally flexes the vertebral column.
- Longissimus: Extends the vertebral column and laterally flexes the spine.
- Iliocostalis: Extends the vertebral column and laterally flexes the spine.
- Spinalis: Extends the vertebral column.
- Multifidus: Extends and rotates the vertebral column, stabilizing vertebrae.
- Quadratus Lumborum: Extends and laterally flexes the lumbar spine.

Anterior Abdominal Wall Muscles

The anterior abdominal wall muscles support the viscera, aid in respiration, and contribute to trunk movement.
Rectus Abdominis: Flexes the trunk, enclosed within the rectus sheath.
External Abdominal Oblique: Laterally flexes the trunk, rotates the trunk to the opposite side.
Internal Abdominal Oblique: Laterally flexes the trunk, rotates the trunk to the same side.
Transverse Abdominis: Compresses the abdomen and supports the viscera.

Muscles of the Shoulder Girdle

Subscapularis: Medially rotates the arm, assists with adduction and extension.

Thorax/Shoulder Muscles

Trapezius: Elevates, depresses, retracts, and rotates the scapula.
Supraspinatus: Abducts the arm.
Infraspinatus: Laterally rotates the arm.
Teres Minor: Laterally rotates the arm.
Teres Major: Extends and medially rotates the arm.
Deltoid: Abducts the arm, assists with flexion and extension.
Pectoralis Major: Flexes, adducts, and medially rotates the arm.
Latissimus Dorsi: Extends, adducts, and medially rotates the arm.
Biceps Brachii: Flexes the elbow and supinates the forearm.
Brachialis: Flexes the elbow.
Triceps Brachii: Extends the elbow.
Brachioradialis: Flexes the elbow, assists with pronation and supination.
Anconeus: Extends the elbow.

Muscles of the Forearm (Anterior)

Flexor-Pronator Muscle Group: Flex the wrist and fingers, pronate the forearm:
- Flexor Carpi Radialis Longus: Flexes and abducts the wrist.
- Flexor Carpi Ulnaris: Flexes and adducts the wrist.
- Palmaris Longus: Flexes the wrist.
Deep Muscles: Flex the fingers, pronate the forearm:
- Flexor Digitorum Superficialis: Flexes the middle phalanges of fingers 2-5.
- Flexor Digitorum Profundus: Flexes the distal phalanges of fingers2-5.
- Flexor Pollicis Longus: Flexes the thumb.

Muscles Crossing Hip and Knee Joints

Iliopsoas: Flexes the hip.
Tensor Fasciae Latae (TFL): Abducts and medially rotates the hip.
Hip Adductors: Adduct the hip (e.g., adductor longus, adductor brevis, adductor magnus, gracilis, pectineus).
Quadriceps Femoris: Extends the knee:
- Rectus Femoris: Extends the knee and flexes the hip.
- Vastus Lateralis: Extends the knee.
- Vastus Medialis: Extends the knee.
- Vastus Intermedius: Extends the knee.
Hamstring Group: Extends the hip and flexes the knee:
- Biceps Femoris (Long and Short Heads): Extends the hip, flexes the knee, and laterally rotates the leg.
- Semitendinosus: Extends the hip, flexes the knee, and medially rotates the leg.
- Semimembranosus: Extends the hip, flexes the knee, and medially rotates the leg.
Gluteus Maximus: Extends and laterally rotates the hip, assists with abduction.
Gluteus Medius: Abducts and medially rotates the hip.

Lower Leg Muscles

Anterior Compartment: Dorsiflex the ankle and extend the toes:
- Tibialis Anterior: Dorsiflexes and inverts the foot.
- Extensor Digitorum Longus: Extends the toes.
- Extensor Hallucis Longus: Extends the big toe.
Lateral Compartment: Evert the foot:
- Fibularis Longus: Everts and plantarflexes the foot.
- Fibularis Brevis: Everts and plantarflexes the foot.
Posterior Compartment: Plantarflex the ankle, flex the toes:
- Superficial:
  - Gastrocnemius: Plantarflexes the ankle and flexes the knee.
  - Soleus: Plantarflexes the ankle.
  - Plantaris: Weak plantar flexor.
- Deep:
  - Popliteus: Flexes the knee, assists with medial rotation.
  - Tibialis Posterior: Plantarflexes and inverts the foot.
  - Flexor Digitorum Longus: Flexes the toes.
  - Flexor Hallucis Longus: Flexes the big toe.

Intrinsic Foot Muscles

Four layers of intrinsic foot muscles contribute to foot movements:
- Dorsal Interossei: Abduct toes 2-4 (spread toes).
- Plantar Interossei: Adduct toes 3-5 (bring toes together).
- Lumbricals: Flex the metatarsophalangeal joints and extend the interphalangeal joints.
- Other Intrinsic Muscles: Assist with complex movements of the foot and toes.

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